,

Why Are Photovoltaic Off-grid Systems Equipped with Energy Storage Lithium Iron Phosphate Batteries?

Solar-battery

Solar-battery

Lithium iron phosphate batteries (LiFePO4) used for energy storage account for a large proportion in photovoltaic off-grid systems. Compared to solar modules, they are similar in cost although LiFePO4 have shorter lives. Lithium iron phosphate batteries store energy to ensure stable system power at night. The load power is guaranteed on rainy days.

Generation and consumption time

The photovoltaic power generation time and the load power consumption time are not necessarily the same. In photovoltaic off-grid systems, the input is a component used for power generation and the output is connected to the battery. Photovoltaic power is generated during the daytime, and sunlight can generate electricity. The power generation is usually the highest at noon, but at noon, the electricity demand is not high.

For instance, many households use off-grid power stations to use electricity at night. These households should store the energy first and wait until peak electricity consumption (generally at seven or eight o’clock in the evening) to release the electricity.

Power generation and load power

The power of photovoltaic power generation and load power are also not necessarily the same. Photovoltaic power generation is not very stable due to the degree of radiation, and the load is not stable. Like air conditioners and refrigerators, the starting power is very large, and the operating power is usually small. The load will cause the system to become unstable, and the voltage will suddenly rise and fall.

The energy storage battery is a power balance device. When the photovoltaic power is greater than the load power, the controller sends the excess energy to the battery pack for storage. When the photovoltaic power cannot meet the load needs, the controller sends the battery power to the load.

Cost

The cost of off-grid systems is high. The off-grid system consists of a photovoltaic square array, solar controller, inverter, battery pack, load, and many other components. Compared with the grid-connected system, the extra battery accounts for 30-40% of the cost of the power generation system, which is almost the same as the component. The service life of the battery is not long either. Lead-acid batteries last generally 3-5 years while the lithium batteries generally last 8-10 years.

New energy-storage LiFePO4 batteries

The new energy-storage lithium iron phosphate battery can increase the energy storage efficiency to 95%, which can greatly reduce the cost of solar power generation. Lithium batteries have an energy efficiency of 95%, while the currently used lead-acid batteries are only about 80%. Lithium batteries are also lighter in weight and have a longer service life than lead-acid batteries. The number of charges and discharge cycles can reach 1600, which means that they do not need to be replaced frequently.

Right now, more and more photovoltaic energy storage have adopted lithium batteries, especially the LiFePO4 batteries,  with technological breakthroughs. The market share of ternary lithium (lithium nickel manganese cobalt oxide batteries, or NMC) or lithium iron phosphate batteries have also gradually increased in photovoltaic off-grid systems.

,

Can We Over-charge The LiFePO4 Battery?

LiFepo4-Battery-12V

LiFepo4-Battery-12V

Lithium iron phosphate battery is one of the safest batteries we using, and its durability and safety are definitely superior to other lithium ion batteries. So, can we overcharge lithium iron phosphate batteries? What range of voltage can be allowed it be overcharged? Under normal circumstances, the answer is NO!

What are lithium iron phosphate batteries?

The lithium iron phosphate battery is a lithium-ion battery that uses lithium iron phosphate as its positive electrode material. It is also called a LiFePO4 battery for short.

What is overcharging?

Overcharging a battery means that the battery charger is charging the battery too far past its fully-charged voltage. For example, the full-charge voltage of a monolithic lithium iron phosphate cell is 3.65V. When the charge exceeds 3.65V, it is overcharged.

What will happen when a lithium-ion polymer (LiPo)  battery is overcharged?

Overcharging a battery cell will cause permanent damage to the cell. In terms of testing for safety, we internally test the different overcharge levels of the battery cells. The following are our test standards:

LiPo battery cell: No fire when the charging voltage reaches 4.8V (one of the necessary conditions)

LiFePO4 battery cell: Charging voltage reaches 10V and does not catch fire (one of the necessary conditions)

Charging with a damaged or non-corresponding charger may also cause overcharging. When the voltage is too high, a large amount of lithium ions overflow from the positive electrode, and lithium ions that cannot be absorbed by the negative electrodes can form dendrites on the surface of the battery, which can cause a short circuit inside the battery. The short-circuit current will generate a lot of heat, and the rapid temperature increase may cause the electrolyte as an organic solvent to burn (organic solvents are extremely flammable). In severe cases, it will cause a decomposition reaction of the positive electrode or the reaction of the negative electrode and the electrolyte. This can generate a large amount of gas; this can result in an explosion especially since the cells are enclosed.

If a battery doesn’t have the Battery Management System (BMS), continuously charging the battery will raise the voltage. In this situation, the lithium ions remaining in the cathode are removed and more lithium ions are inserted into the anode than under standard charging conditions.

It has been observed through ARC studies that the thermal stability of a cell is highly dependent on its state of charge. An overcharged Li-ion cell was found to have much lower thermal stability with an onset runaway temperature as low as 40ºC

Source: Science Direct

Since LiFePo4 is safer, can we over-charge it?

Our suggestion is to never over-charge/discharge a cell!

The most common causes for premature failure of LiFePO4 cells are overcharging and over-discharging. Even a single occurrence can cause permanent damage to the cell, and such misuse voids warranties. A Battery Management System (BMS) is required to ensure it is not possible for any cell in your pack to go outside its nominal operating voltage range.

What is a BMS?

The Battery Management System is a piece of hardware with an electronic system on board that manages a rechargeable battery (cell or pack) and is the link between the battery and it’s user. It can more intelligently manage and maintain each cell, improve battery utilization, prevent battery overcharge and discharge, prolong battery life, and monitor battery status.

BMS

If you need a customizable BMS to prevent overcharging or other potential issues, please contact us to get more information.

,

What’s Deep Cycle LiFePO4 Battery

Deep-Cycle-LiFePO4-Battery

What is the deep cycle battery?

A deep-cycle battery is a battery that is designed to be able to store a large quantity of energy while having the ability to discharge from 100% down to 0% without hurting the battery. A deep-cycle battery also ensures that a steady amount of power is being delivered to applications over a long period of time without interruption or failure. It is constructed with thicker plates and a denser active material ratio. Due to these features, a deep-cycle battery achieves greater cycling capacities.

Deep-Cycle-LiFePO4-Battery

What is DOD (Depth of Discharge)?

The Depth of Discharge (DOD) of a battery represents the percentage of the battery that has been discharged relative to the overall capacity of the battery. For example, if a battery has a nominal capacity of 100kWh and discharges 30kW, the Depth of Discharge comes out to be 30%.

Its DOD is (30x 1) / 100 = 30%.

The more often a battery is charged and discharged, the shorter the battery life will become. It is generally not recommended to completely discharge a battery as it will greatly reduce the battery life. Many battery manufacturers specify the recommended maximum DOD in order to maximize the battery performance.

 

If a manufacturer of a 10 kWh battery recommends a maximum DOD of 80%, the battery should not use more than 8 kWh without charging. The DOD is an important factor to consider because a higher DOD means that more of the energy in a battery can be used. The DOD of many modern lithium-ion batteries is 100%.

 

A battery’s “cycle life,” the number of charge/discharge cycles in its life, depends on how much battery capacity is typically use. Rather than completely draining a battery to its maximum DOD, a user will be able to attain more cycles in their battery regularly discharging it with a lower percentage of charge.

 

For example, a battery may have 15,000 cycles at a DoD of 10%, but only have 3,000 cycles at a DoD of 80%.

What applications need deep-cycle batteries?

  • Floor Machines
  • Electric vehicles
  • Materials handling
  • Renewable energy
  • Aerial work platforms
  • Commercial transit
  • RV and Marine
  • HME Mobility Telecom UPS
  • Security Electronics

All of these applications require high energy retention, deep-cycle discharge, a large number of cycle lives, and a stable discharge performance.

Why choose LiFePO4 deep cycle batteries?

Another way to think of the DOD is the extent to which discharge begins to stop during use. 100% DOD refers to discharge at full capacity. The life of a lead-acid battery is greatly affected by the DOD. A lead-acid battery is likely to fail quickly on a user as it normally only allows 50 to 80% DOD.

In contrast, A LiFePO4 (Lithium Iron Phosphate) battery, which is newer technology, has a deep-cycle discharge, so it can reach 2000 cycles with 100% DOD. Lithium batteries can also be discharged at a specific C-rating. With a working temperature of 25° C and a discharge rate of 0.5C, a LiFePO4 battery can reach 4000 to 6000 cycles.

 

Compared to lead-acid batteries, the advantages of deep-cycle lifepo4 batteries are the following:

  • Eco-friendly
  • Good high-temperature resistance
  • Good safety characteristics
  • No memory effect
  • Higher-capacity compare with same size lead-acid battery
  • Longer cycle life than other lithium-ion batteries
  • Ideal drop-in replacement for lead-acid batteries
  • Lower total cost of average use

 

, ,

What Are the Dangers of Using the Wrong Wattage

Most smartphones on the market use LiPo (Lithium-ion Polymer) batteries. They are 3.8V per cell (4.35V when fully charged) and generally about 3 Ampere hour (Ah), or 3000 milliampere hour (mAh), in capacity. The charging voltage must be higher than the battery voltage. Because the battery is polarized when the battery is charged, the voltage must reach or exceed the sum of the battery voltage and the polarizing voltage in order to effectively inject current. Therefore, the standard output voltage of portable power banks on the market is 5V / 2.1A.

Here to mention, the fast charging technology we see is the next level of 3 Amps charging technology.

In this situation, the watts of phone batteries needed is around 18.5W (3.7 Volts times 5 Amps Hour capacity), and the portable power bank is around 37W, the battery has higher wattage than the device and it is sufficient to power the phone. What if it is lower than the device needed?

Battery (Watts) < Device (Watts)

Light bulbs are marked as 10W, 20W, 30W, etc. Suppose we use a 10W battery to power a 40W bulb, the result would be a lightbulb that is less bright and feels dim. If the power differs too much, the bulb may not even light up.

 

The secondary issue with this is that, the battery now needs to displace more power to meet the demand of the bulb, thus lowering overall battery capacity.

Battery (Watts) > Device (Watts)

A lightbulb has a sticker that clearly specifies the maximum wattage acceptable, if the power of battery is higher, it could cause a hazardous situation. There are two watts on a light bulb, equivalent watts and actual watts. For example, an LED light bulb may produce 95W equivalent lighting, but only requires 25W to power.

You must not exceed the required watt.

 

If you exceed actual watts, e.g. an incandescent 75W bulb that uses a real 75W in a socket that says max 60W then you may risk overheating and fire, and may have the following consequences:

  • The fixture might overheat
  • The fixture could be discolored and/or destroyed
  • The lamp could burn-out prematurely
  • The house could be burnt down
  • The wiring could be damaged
  • If there were enough of them in a circuit, it could overload the circuit
  • Other bad consequences

Why not overload when using high power batteries/wall socket?

The input voltage and power of our home appliances are different, but whether it is converting 110V civil AC (220V in China) to about 5V DC to mobile phone batteries, or 370V DC to Electric vehicles, only require two steps: “rectification” and “voltage transformation”.

 

In order to supply power to our different household appliances, the electrical plug is used to transform the voltage, and its power is adjusted to deliver electricity to the device.

Imagine that our electricity is like water, which is transmitted to all the devices in your home through pipes (grid network). The wall socket is the gate, and the plug is the water pipe connected to this gate. The water pressure is adjusted to prevent too much water pressure to damage the devices.

The AC voltage in different countries and regions is also different, so there are various plugs for us. If you want to use Chinese appliances in the United States, you need to buy a conversion plug.

Related information:

Complete list: Plug, socket & voltage by country

Plug, socket & voltage by country

Plug & socket types

Plug & socket types

That mobile power is the same reason, the voltage is transformed through the plug. However, the battery like the portable power station does not have the high voltage and power of the wall socket.

 

At present, the maximum power of most portable power solutions only offer about 150W ~ 200W. So utilizing a standard portable power solution to power a 1200W kettle is pretty unrealistic. Therefore, before purchasing equipment and batteries, pay attention to the power requirements of the device and if the battery is able to support it.

, ,

What is The Best Battery For Kayaking?

Kayaking-Battery

According to Yakgear, kayak fishing has advantages over the traditional method by boat.  Just to name a couple, anglers can fish more economically and in smaller bodies of water.

What the general public might not know is that batteries are needed for motorized kayaks.

Kayaking-Battery

What do I need to know before choosing a battery?

Users should be aware of the basic terms outlined below:

  • Voltage (V):Like water pressure, it is the pressure from an electrical circuit’s power source that pushes charged electrons (current) through a conducting loop.
  • Ampere hours (Amps, A): This is the measurement of the current of electricity. It is also used to represent the battery capacity (Ah).
  • Life cycles: This is the measurement of battery life or the number of complete charge/discharge cycles that the battery is able to support before its capacity falls below 80% its original.
  • Depth of discharge (DOD): The DOD is often paired with life cycles, representing the percentage of the battery that has been discharged relative to the overall capacity of the battery.
  • Operation temperature (℃):This is the battery’s operating range of temperature. The battery should not be used outside this temperature rang as it will be damaged and become a safety hazard.
  • Watts:Watts represent how much energy is stored in the battery. If you want your electronics to work properly, you must confirm that the watts of the battery are sufficient (higher than the devices you used).

 

Where is the battery used on a kayak?

There are only three instances where we will need batteries on a kayak: When you need to charge your phone and power your light source and fish finder. The batteries must provide sufficient voltage and capacity to these devices while you are fishing so that you have enough power.

 

What is the best battery for kayaking?

A 12V and 10Ah battery is sufficient for most fish finders while providing extra power for other devices.  Most people choose between either Lithium-ion Polymer or Lead-Acid batteries.

 

Lead-Acid batteries

Lead Acid batteries have the advantage of lower cost and little to no maintenance fee, but they can be heavyweight.

For safety reasons, users should choose a brand new Lead-Acid battery and ensure it is made of strong materials that prevent leakage of hazardous chemicals.

 

Lithium-ion Polymer (LiPo) batteries

Users have also used LiPo batteries by connecting them in series or parallel.  They have they advantage of weighing less than other traditional power sources although they range from having 200 to 500 cycles.

 

Lithium Iron Phosphate (LiFePO4) batteries

LiFePO4 batteries have a cycle life of more than 2,000, and they do not require frequent as much maintenance and replacements as compared to their Lead-Acid counterparts.  These batteries are also more environmentally friendly.

Why Himax?

Himax is a cell and battery pack manufacturer that specializes in Lithium batteries.  As we have various designs for numerous applications, we can custom-make Lithium batteries for your marine uses.

,

What is The Industrial Battery System?

Industrial-Battery

What is an industrial battery?

Batteries for industrial applications have certain characteristics, such as high discharge and large capacity.  These batteries consist of three parts: Customized battery + BMS + Charging system

Industrial applications

Let’s look at where industrial batteries are used. Industrial applications cover a wide area, but we can separate them into 3 larger categories:

– Measuring, Mapping and Surveying equipment

– Detection and Inspection equipment

– Filming and Production equipment

In these three industrial areas, the batteries must be adjusted according to their different use.

For example, in areas with extremely cold temperatures, the batteries should have the ability to withstand low temperatures and continue to discharge at low temperatures all while fulfilling the charging capabilities. If a device can be charged in these extreme environments, users can save time and the cost that it takes to remove and replace a battery or device in these settings.  This can increase the overall efficiency.

 

Why are industrial batteries needed?

Technically, not all industrial applications require industrial batteries. However, they are the preferred norm as a complete power system will ensure that a customer’s equipment maintains sufficient power without causing any delays or decreasing inefficiency due to power problems.

 

The BMS

A BMS (Battery Management System) is the intelligent component of a battery pack that is responsible for advanced monitoring and management. It plays a critical role in safety, performance, charge rates, and longevity. By monitoring the SOC (State of Charge) of the battery and managing the charge and discharge, the BMS can overall increase the efficiency and life of the battery.

Major functions of the BMS:

  • Overcharge protection
  • Over-discharge protection
  • Overcurrent protection
  • Overheat protection
  • Short-circuit protection
  • Cell monitoring & balancing
  • Communication interface
  • Self-diagnosis
  • Power gauge

 

Customized batteries

It is impossible for one battery to fit all the different industrial applications. Its voltage, capacity, and discharge current may easily meet the requirements of one device, but its size, internal resistance, temperature range, charging rate, and may not meet the requirements of another device.  It is for this reason that industrial batteries must be customized. Take a forklift that must operate a cold storage warehouse or facility.  Let’s say that the ambient temperature at which the forklift works in such an environment is -10℃ to -40℃.

At this point, one must ask: Can the battery powering the forklift discharge at -40℃? Can the discharge current start the forklift? How long can the battery keep supplying power? Mor importantly, how long does the forklift work?

Forklifts working in cold storage facilities generally need to be driven to a separate room with normal temperatures for charging.  This is because a Lithium battery’s charging performance below 0 degrees is extremely poor, and the battery may pose a safety hazard.  When the battery returns to normal temperatures, moisture can generate on the surface.  If the battery is also used or stored in an environment with high humidity for a long time, the battery cells will corrode and affect the battery life.

Himax LiFePO4 Battery

Himax low-temperature LiPo battery charge curved

On the other hand, if the battery has been customized to work in low-temperature environments, then the battery will be able to be charged in the cold storage facility without having to go through the hassle of moving the forklift to another space.  This will overall increase efficiency and save on costs, which is why a customized battery is important for industrial applications.

 

The charging system

In general, the power of industrial battery chargers is relatively large; after all, the voltage and capacity of industrial batteries are relatively large, but the essentials of industrial battery chargers are to create synergistic effects with industrial batteries.

Industrial batteries are biased towards customized energy solutions, so chargers need to be able to detect the state of the battery to provide the highest quality charging solution, such as determining its own charging cycle rate to adjust the charging current based on the battery’s discharge state. Through the BMS, the charger can detect whether the battery has an abnormal voltage gap and remind the user that the battery needs to be replaced. Fail-safe designs also protect the battery and device when the state of charge is abnormal.

 

Advantages of an industrial battery system

The profitability of the manufacturing industry is constantly in a state of flux. Therefore, capacity and cost control are particularly important, and cost reduction will help factories have a greater advantage in profitability and bargaining power. Being able to achieve this goal allows these companies to maintain their profitability despite the rise and fall of commodity prices. If you want to learn more about industrial batteries, please contact us.

, ,

A LiFePO4 Battery Vs Lithium Ion Polymer Battery

LiFePO4-vs-li-ion-polymer-battery

LiFePO4-vs-li-ion-polymer-battery

The cycle life of a Lithium iron phosphate (LiFePO4) battery is more than 4 to 5 times that of other lithium ion polymer batteries. The operating temperature range is wider and safer; however, the discharge platform is lower, the nominal voltage is only 3.2V, and the fully-charged voltage is 3.65V.

 

Lithium iron phosphate is mostly used to replace traditional lead-acid batteries. We also often find that lithium iron phosphate batteries are used in household solar energy systems, fishing, golf carts, outdoor portable energy storages, and electric motorcycles.

 

What is a Lithium iron phosphate battery?

Lithium-ion polymer (LIPO) battery

 

A lithium ion polymer battery is a kind of rechargeable battery that mainly relies on the movement of lithium ions between positive electrode and negative electrode to work. Lithium ion batteries use an intercalated lithium compound as an electrode material. At present, the commonly used cathode materials for lithium ion batteries are: lithium cobalt oxide (LCO battery), lithium manganate (LMO battery), lithium-ion ternary (NCA, NMC battery), and lithium iron phosphate (LiFePO4 battery).

 

Lithium iron phosphate (LiFePO4, LFP) battery

A lithium iron phosphate battery is a type of lithium ion polymer battery that uses LiFePO4 as the cathode material and a graphitic carbon electrode with a metallic backing as the anode.

 

The LiFePO4 battery, also called the LFP battery, is a type of rechargeable battery. It is the safest Lithium battery type currently available on the market today. It is made to be small in size and light in weight, and the cycle life can reach thousands of cycles.

 

The difference between LiFePO4 batteries and other li-ion batteries

Inherited some advantages from Lithium-ion batteries

Large current charging and discharging are one of the advantages of LiPo batteries, which allows a device to release more energy in a short period of time.  These batteries are used more in racing and power tools: almost all drones and RC model batteries use lithium ion batteries.

 

Batteries for RC models normally reach 15C, 30C, 50C discharge. Lithium-ion polymer batteries with high discharge rate can reach a maximum of 50C (continuous) and 150C (pulse). They are light in weight, have a long life, and can be manufactured into various shapes. These are just some of the advantages of lithium ion batteries, and lithium iron phosphate batteries have these advantages.

 

Long cycle life

Because a LFP battery’s cycle life is 4 to 5 times that of other lithium ion batteries, it can reach 2000 to 3000 cycles or more. The LiFePO4 battery can also reach 100% depth of discharge (DOD). This means that, for energy storage products, there is no need to worry about over discharging a LFP battery, and it can even be used for a longer period of time. A good LiFePO4 battery can be used for 3 to 7 years, so the average cost is very affordable.

 

For more content on depth of discharge (DOD), you can read this article: What is DOD for LiFePO4 batteries?

 

However, a LiFePO4 battery is not suitable for wearable devices as its energy density is lower than that of other lithium-ion batteries.  Furthermore, the battery compartment has limited space, so the capacity is relatively lower.

 

Thus, compared to another LiPo battery, a LFP battery does not have quite as good endurance and compatibility with the conditions and internal space of wearable devices.

 

Why are most lithium iron phosphate batteries 12V?

It is said that the lithium iron phosphate battery can perfectly replace the lead-acid battery. The nominal voltage of a lead-acid battery is 2V, and the six lead-acid batteries connected in series are 12V.

 

However, the 12V LiFePO4 battery pack is generally composed of 4 battery cells connected in series. The nominal voltage of a single lithium iron phosphate pouch cell is 3.2V.  When adding the voltage of the series, we get 12.8V (3.2V * 4 = 12.8V). There are also the 24V (25.6V) and 48V (51.2V), which are commonly used.

 

In addition, the voltage requirement of most industrial applications is 12V or above, which is also the minimum standard of the nominal voltage of general industrial batteries. There are also many applications that need to reach 220V, even 380V or above, such as an industrial forklift, winch, electric drill, etc.

 

The sales of 24V and 48V electric forklifts are on the rise especially recently, so a primary concern is over how safe a battery is. Compared to the lithium cobalt oxide and lithium manganese oxide batteries, lithium iron phosphate batteries are a lot more safe. The advantage of high life can reduce the whole costs of maintaining and replacing the battery as well.

 

The shortcomings of cold temperature

Compared to other LiPo and lead-acid batteries, lithium iron phosphate batteries have poor resistance in low-temperature environments; generally, they can only discharge at -10℃ to -20℃.

 

However, clients think positively of LFP batteries and their high safety functions.  They sacrifice some battery performance and specify that they discharge at -30℃ to -40℃.  These batteries are mostly used in the military or deep sea and space equipment.

 

Learn more about batteries

Keep an eye out on Himax’s official blog, where we regularly update industry-related articles to keep you up-to-date.

, ,

Why High Voltage Batteries?

High-Voltage-LiPo-Batteries

High-Voltage-LiPo-Batteries

Drones are being used more and more widely in all our lives, so the batteries that power these devices are increasingly advancing and being pushed to their limits. One of the biggest challenges to these batteries is endurance; more and more users need the power to last longer.

One such example is with an agricultural drone. Let’s say that the drone carries 10kg of pesticide with two ordinary Lithium Polymer (LiPo) batteries that have a capacity of 16000mAh in 6S (22.2V). This drone will only be able to last about ten minutes with these batteries, which farmers generally find to be too short. However, the use of high-voltage batteries with the same capacity and C rating can increase this flight time by 15-25%, which will increase the efficiency and operations.

We will explore why high-voltage batteries can improve flight duration and also look at the advantages of such batteries.

1. Weight

Without an increase in weight, high-voltage batteries provide better performance.  This is key for UAVs since each drone has a specific payload that it cannot go over.

2. Higher Voltage

If we compare ordinary LiPo batteries to that of those with high voltage, we see a subtle change in voltage. Through this little voltage increase, users are able to get increased performance in their products.

Ordinary LiPo Batteries

The nominal voltage for a single LiPo cell is 3.7V. A 6S battery pack has a nominal voltage of 22.2V, and a 12S has 44.4V.

A single LiPo cell that is fully charged has 4.2V while a 6S has 25.2V and a 12S 50.4V.

High-Voltage LiPo Batteries

The nominal voltage of a single high-voltage LiPo cell is 3.8V, a 6S pack has 22.8V, and a 12S has 45.6V.

A single LiPo cell that is fully charged has 4.35V while a 6S has 26.1V and a 12S 52.2V.

3. Better Cycle Life

Battery-cycle-life

In the chart above, we can follow the discharge rate of several batteries. The high-voltage 4.4V batteries (shown in green) demonstrate a higher discharge rate and discharge capacity.

Battery-cycle-life-1

The above chart shows that, under the same discharge currents and cycles, the 4.4V (in blue) has a longer cycle life than the other batteries at 4.35V or 4.2V.

4. Increased Efficiency

Similar to the example offered at the beginning, we put two drones together for a simple test.  Both drones carried 15kg of water with two batteries of 25C and 22000mAh in 6S.

The drone with the non-high-voltage batteries (22.2V) lasted 17 minutes and 50 seconds.

The drone with the high-voltage batteries (22.8V) lasted longer for 22 minutes and 10 seconds, lasting 4 minutes longer than the ordinary batteries.

Conclusion

According to the above data, the advantages of high-voltage UAV batteries are obvious.

We are able to custom, high-voltage cells and offer a one-stop service for your battery designs and solutions.

, ,

How To Store 18650 Batteries Safely

warehouse

warehouse

What is the best way to store an 18650 battery?

In this blog post, rather than do my own testing – I will rely on the specification sheets provided by Panasonic, Samsung, and LG. We’ll look at the storing section of these spec sheets, and break down the important factors and what they mean. Scroll to the end, the overview, to get to the conclusions of the post quickly.

Panasonic-18650-B

18650B

 

What does it mean?

There are three rows, each with different storage conditions. Note the second and third column are locked in place by the fourth. Each row represents recovering 80% of the battery’s usable capacity. Since the rated capacity of the NCR18650B is 3200 mAh, this 80% represents 2560 mAh after storage.

  1. If you are storing an 18650 battery for less than a month, you may store it in an environment as hot as 50°Cand be able to recover 2560 mAh.
  2. If you are storing an 18650 battery for less than 3 months, you may store it in an environment as hot as 40°Cand be able to recover 2560 mAh.
  3. If you are storing an 18650 battery for less than 1 year, you may store it in an environment as hot as 20°Cand be able to recover 2560 mAh.

In the last case, storing for one year with a 20% drop in capacity translates to 1.6% loss of capacity per month, or 53 mAh.

In the first case (storing at high temperatures for less than one month) translates to a loss of 21 mAh per day.

Storage temperature and conditions

We can see from the above 3 items, it is temperature as the main factor determining the resulting capacity after storage, and ultimately how long you can store your battery for.

18650 batteries can be stored at very low temperatures, but high temperatures degrade them quickly. Rule of thumb: They must always be stored at less than 60°C.

Lithium-ion batteries, in most cases must maintain a voltage above 2.5V before they start to break down and decompose. Therefore, for long-term storage it is best to “top-up” your batteries when their voltage drops too low.

  • Note 1:When receiving new cells, the manufacture will ship them at a 40% charge. However, it is very likely this will soon be set at 30% as airline safety regulations demand safer transport, and less charge is safer.
  • Note 2:In these tests, Panasonic fully charged the batteries at 25°C, up to 4.2V. However, for long-term storage it is recommended not to store at a full charge, but to seek a lower voltage (more on that ahead).

Finally, the environment should be dry, or low humidity – without dust, or a corrosive gas atmosphere. Optimizing your cell’s environment becomes more important the longer they are kept stored. Anything above 3 months may start to be considered long-term.

Samsung-25R

Samsung 25R

 

Differences between the Samsung 25R and Panasonic 18650B

The Samsung 25R performs better during storage on all fronts. Across the board, the 25R can store at ten degrees lower than the 18650B. As well, the difference in higher temperatures, in favor of the 25R from 1 month, 3 months, to 1.5 years, is +10°C, +5°C, +5°C.

Most importantly, this 18650 battery can be stored a full six months longer and retain 90% capacity (10% more than the NCR18650B).

The optimal storing voltage

The 25R spec sheet notes that for long-term storage, the voltage should, rather than be fully charged, set at a lower, more optimal voltage. This is to prevent the degrading of performance characteristics. In the case of the 25R, the recommended voltage is 50 ± 5% of its standard (4.2V) charged state.

  • This works out to be a range between 3.64V and 3.71V

Other batteries have different ranges, but most are close to ~50% voltage which is usually around ~3.7V.

Storing 18650 batteries

Overview

It is good to reference at least three batteries, and off the blog I have checked more. All 18650 batteries researched need a storage range of between -20 ~ +50°C (-4°F ~ + 122°F) or they will degrade, so this is a good rule of thumb to use.

Also keep in mind the maximum temperature for storage should never exceed +60°C (140°F). It is better to store in a cold environment, than a hot one.

Optimally, a good storage temperature should be closer to 25°C (77°F) or a somewhat lower. The closer you are to an optimal temperature, the longer you will be able to store your batteries without “topping up” and recharging them.

For the most part, the maximum time for 18650 storage before recharge is about one year.

If you are intending long term 18650 storage, a storage charge closer to 50% of usable capacity (~3.7V) rather than 100% (4.2V) will prevent faster battery degradation.

Frequently asked questions and notes

What happens if I don’t store my 18650 batteries correctly?

It will cause a loss of performance and your cells may leak and/or rust, and ultimately become unusable. Cells becoming unstable enough and exploding in storage is a possibility. In the worst case – explosion – it is not clear why this sometimes happens but it could be due to static, pressure, temperature, or packing incorrectly (allowing metal objects or batteries to touch).

Notes
  • For very short-term storage, don’t store the battery in a pocket or a bag together with metallic objects such as keys, necklaces, hairpins, coins, or screws when you are travelling.
  • Remove the battery from its application before storing it. For example, from your e-cigarette, flashlight, or electric bike. You should optimally store the batteries in a fire-proof container, with optimal environmental conditions.
  • Do not store 18650 batteries in or near objects that will produce a static electric charge.
  • Quick pressure changes can also cause 18650 batteries to malfunction

 

,

The difference between UPS and EPS

Emergency-Power-Supply

What is a UPS?

A UPS (Uninterruptible Power Supply) ensures that users can save data in emergency situations to avoid unnecessary losses due to power outages. This is a technology developed for power grids, network and medical systems, and other systems that rely on a centralized power supply of a network of computer systems.

Emergency-Power-Supply 

Advantages of EPS (Emergency Power Supply)

An EPS (Emergency Power Supply) has a conversion time that is generally in the millisecond level (2ms-250ms), which fluctuates according to different load characteristics to ensure the timeliness of power supply;

It has strong load adaptability, including capacitive, inductive, and hybrid loads, and strong overload and shock resistance;

There are multiple outputs to prevent failure caused by a single output;

There are fire linkage and remote control signals, which can be switched between manual and automatic;

It can adapt to its environment.  It is suitable for a variety of harsh environments with measures to prevent failure in high and low temperatures and hot and humid environments.  It can work against, salt spray, dust, vibrations, and rat bites;

An EPS has a long service life, fast battery charge, and management capabilities.

 

Differences between an EPS’s backup power and UPS’s power

Applications

An EPS is mainly used in electrical equipment for the fire protection industry.  It is used for those who look for a continuous power supply that can be used in an emergency in case of sudden power grid failure.

A UPS is generally used for precision instrument loads (such as computers, servers and other IT industry equipment), which require a high power supply quality.  It is used for those who look for certain requirements, such as a quick switch-over time to an inverter, output voltage, frequency stability, and purity of output waveforms.

 

Functions

An EPS generally does not have high requirements for a switch-over time to an inverter. Special applications have certain requirements. There are multiple outputs and monitoring and detection functions for each output and a single battery. The daily focus is on bypassing a power supply and switching to an inverter only when the main power fails, and the power utilization rate is high.

The On-Line UPS has only one total output and generally emphasizes its three major functions:

Voltage and frequency stabilization

A quick switch-over time

The rectifier / inverter double-conversion circuit: The inverter is switched to bypass the power supply only when the inverter fails or is overloaded.

The power utilization rate is not high (generally 80-90%). However, some places in European and American countries, where power grids and complete power supplies are used, have switched over to a UPS with a short switch-over time to an inverter (less than 10ms) to save energy.

 

Structure

An EPS mainly provides power for power protection and fire safety. The load has both inductive, capacitive, and rectified non-linear loads, and some loads are only put into operation after the power supply is cut off. Therefore, EPS is required to provide a large inrush current, good output dynamic characteristics, and a stronger anti-overload. A UPS, on the other hand, mainly supplies power to computers and network equipment, and the nature of the load (input power factor) is not much different.

The main purpose of a UPS is to maintain the transferage of information, and the main purpose of an EPS is to prevent major disasters. In other words, a UPS focuses on saving data while an EPS mainly focuses on saving people. Generally, EPS power is large, and the inverter in the machine is in a standby state.

EPS power inverters have a larger redundancy: both the incoming and outgoing cabinets are inside the EPS, and the motor loads are started with variable frequency. The casing and wires are flame retardant, and there are multiple ways to input power, which can be linked with fire protection. An EPS power load is also generally inductive and resistive. It can come with motors, lighting, fans, pumps, and other equipment.

UPS power inverters, on the other hand, have a relatively small redundancy, do not need to be flame retardant, and have no mutual investment function. A UPS power load is also a capacitive load. The main belt device is usually a computer, which is mainly used in computer rooms to ensure uninterrupted power supply and voltage stabilization.

 

Different power supplies

A UPS prioritizes an inverter to ensure its power supply while an EPS prioritizes city power to ensure saving energy. There are differences in the design specifications of the rectifier / charger and the inverter.

An EPS uses an offline power supply; unfortunately, when the utility power fails and an EPS cannot be powered by the emergency battery, it cannot do anything, and consequences are dire.

A UPS is on-line. Even if there is a power failure, it can be alarmed in time. With the backup power in city power supply, the user can grasp the power failure in time and eliminate it without causing greater losses.

 

Precautions against using a UPS

A UPS should be used in a well-ventilated and clean environment to facilitate heat dissipation.

Do not carry inductive loads, such as money counters, fluorescent lamps, air conditioners, etc., to avoid damage.

The output load control of a UPS is best at around 60%, and the reliability is the highest.

A UPS with a light load (such as a 1000VA UPS with a 100VA load) may cause deep discharge of the battery, which will reduce the battery life and should be avoided as much as possible.

Appropriate discharge can help the activation of the battery. For example, if the main power is not interrupted for a long period of time, the main UPS should be manually disconnected and discharged once every three months.

A small-sized UPS can generally be on and off when the employees are at and off work respectively. A UPS in a network room must run around the clock, however, since most networks work 24 hours.

A UPS should be charged after discharging to prevent the battery from being damaged due to excessive self-discharge.