Your phone is about to go dead—again—and you can’t find a place to plug it in. Your laptop is getting hot…is the battery about to catch on fire? How far from home should you drive your electric vehicle? As scenarios like these become increasingly common, it’s clear that we need batteries that store more, last longer, and are safer to use. Fortunately, new battery technologies are coming our way.

Let’s take a look at a few:


1.     NanoBolt lithium tungsten batteries


Working on battery anode materials, researchers at N1 Technologies, Inc. added tungsten and carbon multi-layered nanotubes that bond to the copper anode substrate and build up a web-like nano structure. That forms a huge surface for more ions to attach to during recharge and discharge cycles. That makes recharging the NanoBolt lithium tungsten battery faster, and it also stores more energy.


Nanotubes are ready to be cut to size for use in any Lithium Battery design.



2.      Zinc-manganese oxide batteries


How does a battery actually work? Investigating conventional assumptions, a team-based at DOE’s Pacific Northwest National Laboratory found an unexpected chemical conversion reaction in a zinc-manganese oxide battery. If that process can be controlled, it can increase energy density in conventional batteries without increasing cost. That makes the zinc-manganese oxide battery a possible alternative to lithium-ion and lead-acid batteries, especially for large-scale energy storage to support the nation’s electricity grid.

Source: www.pnnl.govSource:

3.     Organosilicon electrolyte batteries


A problem with lithium batteries is the danger of the electrolyte catching fire or exploding. Searching for something safer than the carbonate-based solvent system in Li-ion batteries, University of Wisconson-Madison chemistry professors Robert Hamers and Robert West developed organosilicon (OS) based liquid solvents. The resulting electrolytes can be engineered at the molecular level for industrial, military, and consumer Li-ion battery markets.





4.     Gold nanowire gel electrolyte batteries


Also seeking a better electrolyte for lithium-ion batteries, researchers at the University of California, Irvine experimented with gels, which are not as combustible as liquids. They tried coating gold nanowires with manganese dioxide, then covering them with electrolyte gel. While nanowires are usually too delicate to use in batteries, these had become resilient. When the researchers charged the resulting electrode, they discovered that it went through 200,000 cycles without losing its ability to hold a charge. That compares to 6,000 cycles in a conventional battery.




5.     TankTwo String Cell™ batteries


A barrier to the use of electric vehicles (EVs) is the slow recharging process. Seeking a way to turn hours into minutes, TankTwo looked at modularizing a battery. Their String Cell™ battery contains a collection of small independent self-organizing cells. Each string cell consists of plastic enclosure, covered with a conductive material that allows it to quickly and easily form contacts with others. An internal processing unit controls the connections in the electrochemical cell. To facilitate quick charging of an EV, the little balls contained in the battery are sucked out and swapped for recharged cells at the service station. At the station, the cells can be recharged at off-peak hours.




For now, we may have to put up with phones going cold, laptops getting hot, and EVs not ranging far from home. Solutions seem to be on the horizon, however, so a better battery-powered future is within sight.



When I started this hobby the thing that shocked me the most was how short flight times were.

5 minutes??? Sometimes more. Sometimes less.

To make matters worse, most people drive to a park or a field where they don’t have access to electricity to recharge their batteries.

Yes, you can buy a couple dozen batteries so you can get a couple hours of flying in. But what many people do is they make portable charging stations so they can stay out in the field.

Car Batteries

A lot of DC input lipo chargers will work at 12 V. For example, the SKYRC iMAX B6AC V2 has an input voltage range of 11 V to 18 V.

This means you can use a lead acid car battery to power you lipo charger.

And because a lot of us drive our cars to get to where we want to fly, this has become a popular solution for charging in the field.

There are a couple options here.

  • You can literally use your car battery.
  • You can buy a separate car battery that you only use for charging lipos.

Option 1 is cheap. The only thing you have to worry about is killing your battery. By charging your lipos with your car battery you are, of course, discharging your car battery. Discharge it too much and your car might not start.

Option 2 involves buying another car battery, which can cost a lot. They are also heavy to move around. And if you are going to be regularly discharging it you are going to need a battery charger to charge it back up.

There’s one more problem with using a car battery for this.

Car batteries were meant to start your car’s engine. This means it needs a whole lot of current for a short period of time. Starting your car only discharges about 3% of your battery. This is the opposite of what you need when charging lipos … a little bit of current for a long time.

More on this in the next section.

Deep Cycle / Marine Batteries

As I mentioned above, car batteries aren’t designed to be discharged all the way and then charged back up.

Because of this a better solution would be to use a deep cycle batteries. Deep cycle batteries are designed with thicker lead plates that allow it to be fully discharged and fully charged for many cycles. This is ideal for field charging lipo batteries.

These are sometimes called marine batteries because they are used for things like trolling motors.

High Capacity Lipo Batteries

Deep-cycle lead acid batteries aren’t the only type of batteries that are made to repeatedly go through a charge-discharge cycle. Lipo batteries like we use on quadcopters are designed to do that, too.

This means they would be perfect for charging in the field.

The 2 things you need to keep in mind if you go this route would be 1) input voltage and 2) capacity. If you need a refresher on what those terms mean, check out my lipo battery guide here.

For input voltage, I would recommend using a 4s lipo for most DC chargers. The nominal voltage of a 4s battery is 14.8 V and this puts you right in the middle of the voltage input range for most chargers.

For lipo capacity, I would recommend the biggest you can afford. The higher the capacity, the more times you are going to be able to use it to charge in the field. This battery is 16,000 mAh.

The great thing about this solution is that you don’t have to buy an extra charger like you do with a lead acid battery. You can use the same charger that you would use for your quad batteries.

(One caveat with this … Some of these bigger batteries use XT90 connectors while smaller capacity batteries usually use a smaller connector, like an XT60. Again.)

Portable Generator

portable generator for lipos
Why use a battery when you can make the electricity yourself?

There are a number of advantages to using a generator.

  • You don’t need to worry about capacity. Most generators will be able to provide more than enough energy to parallel charge multiple lipos.
  • Most generators have both an standard AC output and a 12 V DC output.  This means you have more options for what charger you can use.
  • You don’t have to worry about charging up yet another battery.  All you have to do is fill it up with gas.
  • Generators can be used for all sorts of other things: in emergencies if your electricity goes out, if you go camping and want to be able to do things like make coffee in the morning, etc.

There are some disadvantages, of course. They will be noisier than the other options (although not as noisy as you would expect) and they will be more costly. But other than that, they are a good option.

Find a field with electricity

The last option is maybe the best option if it is available. Find a place to fly that has electricity available. Some RC clubs may have fields that have electricity available.  Or try to find a park that has publicly available outlets.


I’m sure there are other options that people have come up with for charging your lipos in the field.  It’s a pretty common problem.  Let me know in the comments if you’ve tried anything else.

puffed lipo

Anybody who uses lipos will eventually encounter a puffy or swollen battery.

And the first question that inevitably comes up is “What should I do?”

This post is all about what causes that swelling and what to do when it happens to one of your lipos.

Are Swollen Lipo Batteries Dangerous?

Yes. Next question.

Seriously, there are so many examples of puffed batteries that start on fire that this shouldn’t even be a question.

That doesn’t mean that every battery that is puffed is going to explode as soon as you use it but it does mean that a high enough percentage of them are going to be dangerous that it isn’t worth the risk.

What Causes Lipo Batteries to Puff Up?

puffed lipo batteryGas generation in lithium ion batteries is a normal thing. Even if you don’t abuse your battery, the normal everyday use of your battery will generate gas through a process called electrolyte decomposition.

The electrolyte decomposition occurs even faster if you overdischarge a battery or overheat a battery.

What is electrolyte decompostion?

Simply put, a battery is made of three things: the anode, the cathode and the electrolyte. The cathode and the anode are the positive and negative terminals on your battery.

The electrolyte is a chemical inside the battery that allows charged ions to flow from the anode to the cathode during discharge (and the other way during charging).

Electrolyte decomposition is what happens when that electrolyte chemically breaks down. So in a lipo battery, as the electrolyte breaks down you end up with lithium and oxygen. This forms lithium oxide on the anode and cathode (depending whether you are charging or discharging).

But what you also end up with is excess oxygen that doesn’t adhere to the anode or cathode. This excess oxygen is part of what causes a battery swell. And oxygen likes to burn. See here for more details. He also goes over some other reasons a battery might swell.

Other gases that can be found in the battery during the normal chemical reactions of a battery are carbon dioxide (CO2) and carbon monoxide (CO). For a technical overview of this, see this paper.

How to Fix a Swollen Battery


Just Don’t.

Dispose of it properly (see below) and buy a new one.

It’s not worth injuring yourself or burning your house down to save a few bucks.

How to Dispose of Puffed Lipo Batteries

The proper way to dispose of a swollen lipo battery is the same as what you would do when you throw out any old battery. You need to discharge it completely first.

The two main methods that people use to discharge a battery completely is to hook it up to a light bulb or to put it in a bucket of saltwater.  There are debates about which method is better but I will avoid that debate here for now.

If you decide to hook it up to a light bulb, I would recommend these 12 V, 20 Watt halogen bulbs. They are easy to solder to so you attach lead wires and connector pretty easily. This makes it easy to just plug in your battery to let it discharge. You can hook multiple in parallel to get the discharge rate you want. If you have any questions about this, let me know in the comments.

After you’ve completely discharged the battery, I recommend finding your nearest battery recycling drop-off point and bringing it there. Make sure you call ahead and ask if they accept damaged batteries.

Tips to Avoid a Swollen Battery

  • Proper charging – Make sure you charge your battery properly using a quality battery charger.  For safety, make sure you put your batteries in a lipo bag while charging.  If you don’t have a lipo bag, I highly recommend you buy one.  For around $10, you can insure that if something does go wrong at will at least be contained.
  • Don’t over-discharge – Make sure you stop using your battery before the voltage gets to the minimum cut-off voltage.
  • Heat kills batteries – Don’t use batteries or charge batteries when they are warm. After you’re done using them, give them a little time to cool off before you charge them. And after you are done charging them, give them a little time before you use them.
  • Proper storage – Do not store your batteries in a hot location. (For example, don’t keep them in the trunk of your car during in the summer.) Store lipo’s at the proper storage voltage. The article I linked to above showed that swelling increased significantly after only 4 hours of storage when batteries were at a state of charge above 80%.


To sum up: As lipo’s age and if they are misused, gases start to form in the battery and cause it to swell. Once you have a puffy lipo, the safe thing to do is to discharge it completely and then recycle it.

If you want to learn more about lipo’s, check out my in-depth lipo battery guide. There I go into a lot of detail about all aspects of lipo’s.

Bluetooth Headsets Battery

Compared with ordinary earphones, the battery life and battery life of Bluetooth headsets are relatively short when you keeping connect with Bluetooth. In addition, the Bluetooth headsets currently on the market have made the size smaller and handy to adapt the needs of market users for portability and appearance. Therefore, we have to extend the battery life, and its the most significant part for Bluetooth headsets.

Excluding the impact of battery quality and environmental factors, in order to extend the battery life of our Bluetooth headsets, I think there are only three things we can do:

  1. Reduce the power consumption of the headset;
  2. Make a bigger battery (bigger size);
  3. Break through the energy density of the lithium battery.

Reducing the power consumption of the headset

Devices connected with Bluetooth capabilities will generally consume extra power. Even when the device is not in use, power will still be drained to a certain degree.

In 2020, SIG (Bluetooth Special Interest Group) attempted to increase the potential for lowered power consumption when it officially released its Bluetooth 5.2 of the audio technology standard, LE Audio (LE Power Consumption).

LE Audio not only improved the audio quality of headsets but also added low-power consumption features. It optimized the power consumption of Bluetooth devices and maximized the battery life and lifespan of lithium batteries in Bluetooth devices.

Those interested in this technology can find more here. This video introduces the basics of power consumption in Bluetooth and LE battery life.

Making a bigger battery

Longer battery life is always ideal, and the logical next step would be to make a bigger battery to do so. However, Bluetooth headsets are already designed to be as portable and small in size as possible, and they are generally made with rectangular batteries. There really isn’t the space to produce a bigger battery without sacrificing size for the overall product itself.

What if we change to a Round battery?

So then, what other options can we consider?  We can consider changing the shape of the battery first.

Combined with a PCB, a rectangular battery doesn’t occupy the full space of Bluetooth headsets.  In the below images, you can see how only about ⅔ of the device is inhabited, which wastes potential space.

 JBL T450BT Bluetooth Headsets (Disassembly)
JBL T450BT Bluetooth Headsets (Disassembly) – from YouTube
 JBL e55bt Bluetooth Headsets (Disassembly)
JBL e55bt Bluetooth Headsets (Disassembly) – from YouTube

If we leave the confines of a standard rectangular battery, we move onto considering special-shaped batteries.  These batteries can be customized into a plethora of different shapes according to the needs of a product.

Of shaped batteries, the round battery is the most frequently requested shape, and this shape in particular can maximize the use of the battery while filling up the internal space of Bluetooth headsets.

To customize round batteries, the radios (R), height (H), and thickness (T) of the battery must be provided.

Line drawing of the Round Shaped battery
Line drawing of the Round Shaped battery

Let us “pretending” to replace its original battery with a Round battery. Is this a perfect match?

Lithium Round battery replace JBL e55bt rectangle battery

Energy density of lithium batteries

Lithium batteries have one of the highest energy densities of any battery technology today (100-265 Wh/kg or 250-670 Wh/L). In addition, Li-ion cells can deliver up to 3.6V, which is 3 times more than that of technologies like Ni-Cd or Ni-MH.

So what does this mean?  Energy density represents how much energy can be released by different batteries under the same weight or volume.  If we want to achieve longer battery life, we need to break through the energy density threshold of lithium batteries.

Increase the upper limit of battery voltage

Generally, the nominal voltage of a lithium-ion battery is 3.7V (and 3.2V for lithium iron phosphate batteries), and the fully-charged voltage is 4.2V (and 3.65V for lithium iron phosphate battery).

The discharge cut-off voltage of a lithium-ion battery is 2.75V to 3.0V. Therefore, the higher the upper voltage limit, the higher the capacity and energy.  This creates a high-voltage lithium-ion battery (read more here).

High-voltage batteries have high energy density and high discharge platforms. They can also deliver more capacity under the same conditions of use, so their battery life is longer while delivering more power. Under normal circumstances, the lifetime of Grepow’s high-voltage batteries will increase by 15-25%.

Comparison of 4.2V and LiHv 4.35V, 4.4V, 4.45V Grepow lithium battery
Comparison of 4.2V and LiHv 4.35V, 4.4V, 4.45V lithium battery


The power output depends on the battery, and the battery management system (BMS) is the core of it. It is a system for monitoring and managing the battery. It controls the charge and discharge of the battery by collecting and calculating parameters such as voltage, current, temperature, and SOC. The process, the management system that realizes the protection of the battery and improves the overall performance of the battery is an important link between the battery and the battery application equipment.

BMS mainly includes three parts: hardware, bottom layer software, and application layer software.

The hardware of the battery management system (BMS)

1. Architecture

The topology of Battery Management System(BMS) hardware is divided into two types: centralized and distributed.

(1) The centralized type

The centralized type is to concentrate all the electrical components into a large board, the sampling chip channel utilization is the highest and the daisy chain communication can be adopted between the sampling chip and the main chip, the circuit design is relatively simple, the product cost is greatly reduced, but All the collection wiring harnesses will be connected to the mainboard, which poses a greater challenge to the security of the BMS, and there may also be problems in the stability of the daisy chain communication. It is more suitable for occasions where the battery pack capacity is relatively small and the module and battery pack types are relatively fixed.

(2) The Distributed type

Distributed includes a mainboard and a slave board. It is possible that a battery module is equipped with a slave board. The disadvantage of this design is that if the number of battery modules is less than 12, the sampling channel will be wasted (generally there are 12 sampling chips. Channel), or 2-3 slave boards to collect all battery modules. This structure has multiple sampling chips in one slave board. The advantages are high channel utilization, cost-saving, flexibility in system configuration, and adaptation to different capacities. Modules and battery packs of different specifications and types.

2. Function

The hardware design and specific selection should be combined with the functional requirements of the vehicle and battery system. The general functions mainly include collection functions (such as voltage, current, and temperature collection), charging port detection (CC and CC2), and charging wake-up (CP and A+) ), relay control and status diagnosis, insulation detection, high voltage interlock, collision detection, CAN communication and data storage requirements.

(1) Main controller

Process the information reported from the controller and the high-voltage controller, and at the same time judge and control the battery operating status according to the reported information, realize the BMS-related control strategy, and make the corresponding fault diagnosis and processing.

(2) High voltage controller

Collect and report the total voltage and current information of the battery in real-time, and realize timely integration through its hardware circuit, and provide accurate data for the calculation of the state of charge (SOC) and the state of health (SOH) for the motherboard. Charge detection and insulation detection function.

(3) Slave controller

Real-time collection and reporting of battery cell voltage and temperature information, feedback of the SOH and SOC of each string of cells, and a passive equalization function, effectively ensuring the consistency of cells during power use.

(4) Sampling control harness

Provide hardware support for battery information collection and information interaction between controllers, and at the same time add redundant insurance function to each voltage sampling line, effectively avoid battery short circuit caused by wiring harness or management system.

3. Communication method

There are two ways to transfer information between the sampling chip and the main chip: CAN communication and daisy chain communication. CAN communication is the most stable. However, due to the high cost of power chips and isolation circuits, daisy chain communication is actually SPI communication. The cost is very low, and the stability is relatively poor. However, as the pressure on cost control is increasing, many manufacturers are shifting to the daisy chain mode. Generally, two or more daisy chains are used to enhance communication stability.

4. Structure

BMS(Battery Management System) hardware includes power supply IC, CPU, sampling IC, high-drive IC, other IC components, isolation transformer, RTC, EEPROM, CAN module, etc. The CPU is the core component, and the functions of different models are different, and the configuration of the AUTOSAR architecture is also different. Sampling IC manufacturers mainly include Linear Technology, Maxim, Texas Instruments, etc., including collecting cell voltage, module temperature, and peripheral configuration equalization circuits.

Bottom layer software

According to the AUTOSAR architecture, it is divided into many general functional modules, which reduces the dependence on hardware, and can realize the configuration of different hardware, while the application layer software changes little. The application layer and the bottom layer need to determine the RTE interface, and consider the flexibility of DEM (fault diagnosis event management), DCM (fault diagnosis communication management), FIM (function information management), and CAN communication reserved interfaces, which are configured by the application layer.

Application layer software of the BMS

The software architecture mainly includes high and low voltage management, charging management, state estimation, balance control, and fault management, etc.

1. High and low voltage management

Generally, when the power is on normally, the VCU will wake up the BMS through the hardwire or 12V of the CAN signal. After the BMS completes the self-check and enters the standby mode, the VCU sends the high-voltage command, and the BMS controls the closed relay to complete the high-voltage. When the power is off, the VCU sends a high-voltage command and then disconnects and wakes up 12V. It can be awakened by CP or A+ signal when the gun is plugged in in the power-off state.

2. Charging management

(1) Slow charge

Slow charging uses an AC charging station (or 220V power supply) to convert AC to DC to charge the battery through an on-board charger. The charging station specifications are generally 16A, 32A, and 64A, and it can also be charged through a household power supply. The BMS can be awakened by CC or CP signal, but it should be ensured that it can sleep normally after charging. The AC charging process is relatively simple, and it can be developed in accordance with the detailed regulations of the national standard.

(2) Fast charge

Fast charging is to charge the battery with DC output from the DC charging pile, which can achieve 1C or even higher rate charging. Generally, 80% of the power can be charged in 45 minutes. Wake up by the auxiliary power A+ signal of the charging pile, the fast charging process in the national standard is more complicated, and there are two versions of 2011 and 2015 at the same time, and the different understanding of the technical details of the charging pile manufacturer’s unclear technical details of the national standard process also causes the vehicle charging adaptability A great challenge, so fast charging adaptability is a key indicator to measure the performance of BMS products.

3. Estimation function

(1) the State Of Power

SOP (State Of Power) mainly obtains the available charge and discharge power of the current battery through the temperature and SOC lookup table. The VCU determines how the current vehicle is used according to the transmitted power value. It is necessary to consider both the ability to release the battery and the protection of the battery performance, such as a partial power limit before reaching the cut-off voltage. Of course, this will have a certain impact on the driving experience of the whole vehicle.

(2) state of health

SOH (state of health) mainly characterizes the current state of health of the battery, which is a value between 0-100%. It is generally believed that the battery can no longer be used after it is lower than 80%. It can be expressed by the change of battery capacity or internal resistance. When using the capacity, the actual capacity of the current battery is estimated through the battery operating process data, and the ratio of the rated capacity to the rated capacity is the SOH. Accurate SOH will improve the estimation accuracy of other modules when the battery decays.

(3) the State Of Charge

SOC (State Of Charge) belongs to the BMS core control algorithm, which characterizes the current remaining capacity state, mainly through the ampere-hour integration method and EKF (Extended Kalman Filter) algorithm, combined with correction strategies (such as open-circuit voltage correction, full charge correction, charging End correction, capacity correction under different temperatures and SOH, etc.). The ampere-hour integration method is relatively reliable under the condition of ensuring the accuracy of current acquisition, but the robustness is not strong. Because of the error accumulation, it must be combined with a correction strategy. The EKF has strong robustness, but the algorithm is more complex and difficult to implement. Domestic mainstream manufacturers generally can achieve accuracy within 6% at room temperature, and it is difficult to estimate high and low temperatures and battery attenuation.

(4) the State Of Energy

SOE (State Of Energy) algorithm manufacturers do not develop much now or use a simpler algorithm, look up the table to get the ratio of the remaining energy to the maximum available energy in the current state. This function is mainly used to estimate the remaining cruising range.

4. Fault diagnosis

According to the different performance of the battery, it is divided into different fault levels, and in the case of different fault levels, the BMS and VCU will take different treatment measures, warning, limiting power, or directly cutting off the high voltage. Failures include data collection and rationality failures, electrical failures (sensors and actuators), communication failures, and battery status failures.

5. Balance control

The equalization function is to eliminate the inconsistency of the battery cells generated during battery use. According to the shortboard effect of the barrel, the cells with the worst performance during charging and discharging first reach the cut-off condition, and the other cells have some capabilities. It is not released, causing battery waste.

Equalization includes active equalization and passive equalization. Active equalization is the transfer of energy from more monomers to fewer monomers, which will not cause energy loss, but the structure is complex, the cost is high, and the requirements for electrical components are relatively high. Relatively passive The balance structure is simple and the cost is much lower, but the energy will be dissipated and wasted in the form of heat. Generally, the maximum balance current is about 100mA. Now many manufacturers can achieve better balance effects using passive balance.

The BMS(Battery Management System) control method, as the central control idea of ​​the battery, directly affects the service life of the battery, the safe operation of the electric vehicle, and the performance of the entire vehicle. It has a significant impact on battery life and determines the future of new energy vehicles. A good battery management system will greatly promote the development of new energy vehicles.


We have introduced voltage difference in battery packs and used it as an important criterion for measuring the quality of batteries.  At this time, we’ll review how to prevent voltage difference.

Match the cells

The best method in preventing cell voltage difference is to match the cells before the battery pack is assembled and to select the cells with the closest consistency for assembly. To put it simply, you match the batteries with the most similar specifications according to the configuration of the battery pack. There are many ways you can match the cells, but the most important elements to consider are the capacityinternal resistance, and voltage difference.

Ensure the quality

In Grepow, in addition to the conventional matching standards, we match the content of the battery cell’s production batchesmaterial batches and other standards to ensure that the quality of the battery packs we produce is the best. If the matching standard is stricter, then the probability of the battery cell voltage difference will be smaller. On the contrary, if the battery cell matching standard is less strict or if there is no matching at all, the probability of the cell voltage difference will be greater, and this will result in premature battery failure.

Use the BMS

In addition to the matching of cells before assembly, the use of a BMS balancing circuit is another great way to prevent voltage differences. At present, most BMSs on the market have charging balancing circuits.  The function of the balancing circuit is to equalize the voltage of each cell during the battery charging process and to keep the voltage of the cell as consistent as possible. If you are using a BMS to prevent voltage difference, ensure that the one you are using or selecting has the balancing feature.


There are other possibilities that may also cause a voltage difference, such as cell damages and high-temperature storage.

Li-Polymer Battery



One of the differences between pouch cell batteries and other batteries is the material of the casing. Cylindrical batteries have a hard casing, which are made of nickel and steel or aluminum alloy.

pouch cell on the other hand consists of many types of layers to form a multilayer film consisting of an outer layer, middle layer, and an inner layer.

Outer layer consists of nylon, middle layer contains an aluminum foil, and in the inner layer – a heat sealing layer, which allows for better heat dissipation.


There are four distinct advantages for a pouch cell compared to cylindrical batteries.

Advantage 1: They’re Safer

Firstly, it has a very high barrier property; secondly, it has a good heat sealing property; thirdly, the material is resistant to electrolyte and strong acid corrosion; it also has good ductility, flexibility and mechanical strength, and this advantage makes the pouch cell battery safer.

When a safety hazard occurs, the pouch cell battery will only swell and crack at most. Unlike the steel shell battery where a sudden explosion phenomenon might occur.

 Advantage 2: Better space utilization

The pouch cell’s exterior is flexible thus making the most efficient use of space and can reach a packaging efficiency of 90-95%, which is unreachable by other types of casing. The flexibility will allow the external case to form to the battery, rather than the other way around.

Advantage 3: Higher energy density

Eliminating the metal case can reduce weight. In terms of weight, a pouch cell battery of equivalent capacity is 40% lighter than a nickel-steel cased lithium battery and 20% lighter than an aluminum-cased battery. In terms of energy density, pouch cell batteries of the same size are usually 10-15% higher than steel-cased batteries and 5-10% higher than aluminum-cased batteries.

Advantage 4: Customizable 

Pouch cell batteries can be custom designed according to the specific requests of the customer. With their soft exterior and ability to be reshaped and sized, custom designed packs can be formed to meet all challenges.

How to Keep Solar Batteries Warm in Winter

Note: Most of the information in this article comes from the Solar Living Sourcebook.

Sunlight doesn’t just power your solar panels – it heats your batteries. With fewer hours of sunlight per day, winter is the time of year when it’s most important to make sure the energy storage component of an off-grid solar system or grid-tie solar system with battery backup is working efficiently. Unfortunately for those of us in the northern U.S. and Canada, winter can bring extreme cold, creating the worst environmental conditions for those deep-cycle batteries.

But just because deep cycle solar batteries have a harder time in cold temperatures doesn’t mean you need to suffer through the winter with them. Learning a few simple tricks to keep solar batteries warm in winter will substantially improve their performance during the part of the year in which you rely on them most.

Note: Lithium-ion and sealed lead acid batteries (AGM and gel cell) fare much better in cold weather than traditional flooded lead acid batteries do, and are now so safe that they can – and should – be installed indoors. If you’ve got these batteries and they’re installed indoors, you should have nothing to worry about when it comes to cold weather!

Why Are Cold Temperatures Bad for Solar Batteries?

First let’s clarify that cold temperatures are actually good for batteries when it comes to holding a charge; a battery placed in a refrigerator will self-discharge more slowly than the same battery in a warmer setting (and in fact, some people keep their household AA and 9V batteries in the fridge). Where cold becomes a detriment to batteries is in situations where charging and discharging is frequent and the cycles are deep – like in a renewable energy system. This is because cold slows down the chemical reactions that take place inside a battery as it supplies electrical current. Colder temperatures reduce current, which in turn lowers energy storage capacity.

The cold weather problem is compounded with deep cycle batteries used for solar storage because cold weather usually coincides with storms or the shorter days of winter. In both cases, PV production is lower due to the reduced number of sun hours, and the loads in the house are often higher due to active heating.

How Cold is “Cold” When it Comes to Solar Batteries?

Most batteries are rated at 77°F (25°C), meaning their technical specs are based on how the battery’s cells perform at 77 degrees. As a rule of thumb, batteries lose about 10% of their rated capacity for every 15-20 degrees below 80°F as measured in the cells.

How Can You Keep Your Solar Batteries Warm?

The best way to keep deep cycle solar batteries warm is simply to give them shelter and insulation. Let’s look at how to best do this, depending on what kind of deep cycle batteries you have.

How to Keep Lithium-Ion Solar Batteries Warm in Winter

Lithium-ion solar batteries can be safely installed inside your house, meaning the “shelter” and “insulation” boxes are already checked and no additional action needs to be taken. However, if they are installed someplace where there’s a risk of freezing, special care must be taken because – while they can safely discharge in temperatures as low 0°F (-18°C) – lithium-ion batteries should never be charged in sub-freezing temperatures (below 32°F or 0°C).

Nearly all lithium-ion solar batteries on the market today include at least a basic built-in battery management system (BMS) that can activate an external heating source when ambient temperatures approach freezing, ensuring the battery’s environment stays warm enough for safe charging. A few more advanced lithium batteries even have internal heaters that are managed by their BMS.

How to Keep Flooded Lead Acid Solar Batteries Warm in Winter

Even though flooded – or “wet cell” – lead acid batteries can charge at lower temperatures than lithium-ion batteries (as low as -4°F or -20°C), they typically require the most attention in winter because they cannot be installed inside your house where temperatures are nicely regulated. (When in use these batteries release hydrogen gas – which is explosive at even a modest 4% concentration.)

Instead, flooded lead acid batteries should be kept inside a battery box or enclosure with 2″ holes near the top and bottom for ventilation. If the enclosure is inside an insulated garage or shed, they most likely won’t need any extra help staying warm. But if the enclosure itself is not in an insulated area, it should be “reinforced” with insulation and thermal mass to stabilize temperature swings. Because the batteries generate a bit of heat when they are charging, the insulation will keep that heat inside the enclosure, keeping the batteries warmer.

Simply get a sheet or two of rigid foam insulation from your local hardware store:

  • Do a quick internet search for the proper R-value of insulation you should buy based on where you’ll be using it
  • Insulation rated for use below grade use is best because it is moisture resistant

Diagram of an insulated outdoor enclosure for flooded lead acid batteries

Wires and cables pass through wall at bottom of battery box to prevent hydrogen from entering the house (hydrogen rises).

When installing insulation in your battery enclosure:

  • Cut the sheet to size with a circular saw, or score it with a utility knife and snap it over an edge for a clean cut
  • Leave an inch or two between the batteries and the insulation (and a little space between the batteries themselves) to allow air to circulate and keep temperatures as uniform as possible across all the batteries
  • Don’t cover your ventilation holes
  • Don’t permanently adhere the insulation to the enclosure – you’ll want to remove it when the weather warms up so the batteries don’t overheat in the summer

How to Keep AGM/Sealed Lead Acid Solar Batteries Warm in Winter

Like lithium-ion batteries, sealed lead acid batteries (AGM and gel cell) are safe enough to be installed indoors, giving you a huge leg up on temperature regulation. Also working in your favor is the fact that sealed battery cells freeze at lower temperatures than flooded/wet cells do. It’s best to check the manufacturer’s specs for your specific batteries regarding minimum charging and discharging temperatures. If your batteries are going to be exposed to temperatures lower than the minimums listed by the manufacturers, the same techniques suggested for lithium-ion and flooded lead acid batteries can be used to keep your sealed-cell batteries warm enough for safe use (insulated enclosure and a BMS/heater).

Tools and Tech to Help Keep Solar Batteries Healthy in Winter

MPPT Charge Control Technology

A charge controller with maximum power point tracking (MPPT) technology is probably already part of your battery-based solar system, but those short winter days are when you’ll be happiest to have it. MPPT solar charge controllers squeeze 15-30% more power out of a PV array on average than non-MPPT controllers by converting excess PV voltage into amperage. MPPT controllers perform best with cold PV modules and hungry batteries (sounds like winter conditions!), and can adjust the battery voltage based on battery temperature to help the cells reach 100% state of charge.

Battery Temperature Sensor

A battery temperature sensor can provide an early warning if battery temperatures drop below recommended levels. Some charge controllers will stop charging at certain low temperatures.

Battery Management Systems (BMS)

A battery management system includes functions beyond just temperature sensing, typically including features like voltage and depth of discharge at both the cell and battery bank level. This level of insight can help you identify problem areas in your battery bank, some of which may be cold-related.

A BMS is an absolute necessity for lithium-ion solar batteries (to prevent overcharging and thermal runaway), but most Li-ion batteries on the market today already have a BMS built in.

Battery Desulphators

These deep cycle battery maintenance tools simply connect to the battery terminals and then work automatically to remove lead sulphate buildup on the plates. Lead sulphate will otherwise build up on the plates over time, reducing a lead acid battery’s capacity and ultimately shortening its life. When you’re already contending with cold weather reducing battery capacity during the winter, you don’t need sulphate buildup compounding the problem.

Battery desulphator

Keep the Water Topped Off

It is important year-round to not let your flooded lead acid batteries go dry. In winter it’s especially critical to make sure there is plenty of water in them. A battery with low water levels is more likely to freeze.

Likewise, keep them charged up. The acid in the water prevents freezing, so a battery with a low charge is more likely to freeze than a charged one.

Adding More Battery Storage

Sometimes all the tricks in the book just aren’t enough to keep an older lead acid battery bank powerful enough to get you through the winter comfortably. Over time, batteries age and their capacity falls, and we add more electric loads to our homes. Sometimes the best way to combat the problem of cold weather limiting your batteries’ performance is to simply add capacity with a couple of new deep cycle lead acid batteries.

Winter or Not, Don’t Forget to Perform Regular Maintenance on Your Lead Acid Deep Cycle Batteries

For lithium-ion and sealed cell lead acid batteries (AGM and gel cell), a simple annual maintenance routine of cleaning the tops of the batteries with baking soda and water (then rinsing with water), and then cleaning/tightening the terminals is sufficient.




The 2020 coronavirus (COVID-19) outbreak has – to put it mildly – created a lot of uncertainty for people all around the world.

By now, hopefully you are doing your part to practice the self-quarantining or “social distancing” behaviors recommended by the World Health Organization to help slow the spread of this new and particularly hardy coronavirus and give the world’s various healthcare systems time and bandwidth to deal with the outbreak.

If so, you may be experiencing a new (or renewed) appreciation for the relative fragility of the production and delivery networks for food, water, energy, and information that aggregate to create the standard of living we’re used to here in the U.S. You may be considering the benefits of being self-sufficient in one or more of these areas, and wondering how realistic that would be. And you may be weighing whether the peace of mind that comes with self-reliance in times of social unrest is worth the effort and expense of actually becoming self-reliant.

Setting aside the healthcare system, which is facing real challenges in the coming weeks, we can say that, fortunately, American infrastructure has been largely able to cope with the changes in shopping behavior, remote working habits, and resource usage the new coronavirus has forced us to make. But if you have found yourself interested in moving toward self-sufficiency lately, know that you are not alone and you are not without trusted professionals to advise you about your options.

As a company born out of the “back-to-the-land” movement that spawned in part from the uncertainty and social anxiety of the 1960s and 1970s, Real Goods has always championed the merits of self-sufficiency and facilitated making it available to anyone who wants to achieve it. From this position, we think it’s worth noting a few things:

We should be grateful that most of our resource infrastructure – power, water, food production, Internet – has been able to handle the shifting demands the COVID-19 pandemic has placed on it.
Ideas like self-isolation, social distancing, and disaster preparedness are not new. For plenty of folks, these are – and have been for decades – lifestyle choices. They are things that come, to varying degrees, with the decision to live “off the grid”.
Moving toward self-sufficiency does not have to be an all-or-nothing endeavor. In fact, we don’t recommend you try to make it one (not many of us could do what Richard Proenneke did). A simple step toward partial self-sufficiency, like setting up a small emergency backup power supply, is enough to make a lot of families feel much better about their overall preparedness when the unexpected strikes.
Self-sufficiency can (and absolutely should) be researched before being attempted. Our own Solar Living Sourcebook is a truly excellent primer on the considerations and basics of off-grid living.
Out of crisis can come opportunity. Think back a few months…Did you catch yourself saying “I’m so busy! If only there were more hours in the day!” a month ago, and then “I’m so bored! How long am I going to be stuck in my house?” a week ago? There may be no time like the present to learn a new skill, catch up on reading, call some long-lost friends or relatives, or deep clean the house.
We are in this together and it’s not going away soon. The spring of 2020 – and likely the summer too – is going to be different from any we’ve lived through before. We are going to need to be patient, get by with less shopping and fewer luxuries, and be helpful to others while respecting their boundaries with social distancing.
We are not attempting to stoke fear, to say “I told you so”, or to leverage this global pandemic for financial gain. We are simply trying to make people aware that if self-sufficiency is a new, enticing, and/or daunting proposition that you’ve recently been forced to confront, there are professionals out there like us and others who specialize in building systems to deliver power and water to people who either need or want to be self-reliant in attaining these essentials.

We’re all in this together, and we here at Real Goods have been helping people secure their own power and water supplies for 41 years now. Give us a call at 800-919-2400 or check out these resources and products if you want to explore your self-sufficiency options.

Self-Sufficiency Resources
The Solar Living Sourcebook
“Solar Power for Beginners” video series with Solar Queen Amy Beaudet
Get a free quote for a battery backup system
Get a free quote for an off-grid solar power system
Get a free quote for a solar water pumping system
Self-Sufficiency Equipment
The Solar Living Sourcebook
Portable emergency backup power sources
Medium (7.5 kWh) integrated backup power supply
Large (over 10 kWh) integrated backup power supplies

Why Do Car Batteries Die in Winter

Car batteries are one of the most important components of any vehicle, yet for some reason, they are often overlooked. Your car needs the electrical charge it gets from the battery to start the engine, which is why you should always be aware of the age and status of the battery in your vehicle. It can be a major inconvenience if you go to start your car one day only to find that the old battery has lost its charge. To help you avoid this issue, and to get the most out of your battery during its natural lifespan, take a look at some of the guidelines below that will help you determine when it is time to change your old car battery.

Average Battery Lifespan

To get started, let’s think about how long a brand new car battery will last under typical driving conditions in a city like Vancouver. There are many factors that affect the amount of time your automobile battery will function efficiently. Weather can have a big impact, especially cold temperatures. The power demands you place on a battery will also have an impact on how long the unit will last. In ideal conditions, a battery can last more than five years. Unfortunately, ideal conditions for a battery are not exactly common in a place like Vancouver, which sees a significant amount of precipitation, as well as hot and somewhat cold weather each year. Also, with the increasing number of electronics owned by a typical person, and the corresponding chargers, cables and devices that connect to a car’s electrical system, the average driver asks more of their car battery than ever before. With these factors in mind, you shouldn’t be surprised if your battery doesn’t last longer than three years. There really is no exact amount of years that a car battery is guaranteed to last, so let’s say the average lifespan in a city like Vancouver could be between three and five years.

When to Change?

There are a few telltale signs that indicate your battery is nearing the end of its lifespan. For the most part, if you check your car battery every six months or so, you should avoid any unwanted surprises or startup issues. If during your check you notice a bad smell coming from the battery that reminds you of rotten eggs, you should start looking for a replacement right away. You should also keep an eye on the regular electrical components of your vehicle such as interior lighting and headlights. If these lights flicker for any reason while you’re driving, idling or starting your car, that is also a good sign your car battery is near the end of its lifespan. You should also make more frequent checks if your car battery is more than three years old, especially if, as discussed above, you live in an area that sees high temperatures in the summer and significantly low temperatures in the winter. One final indicator that your battery needs to be changed is the battery light on your vehicle’s dashboard. When this light starts to appear on a regular basis, regardless of how old your battery happens to be, you should take a look and consider a replacement as soon as possible.

For more helpful tips about car batteries, or if you have any inquiries about other battery Himax, be sure to visit the experts at Polar Battery today!



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