Battery capacity (how many amp-hours it can hold) is reduced as temperature goes down, and increased as temperature goes up. This is why your car battery dies on a cold winter morning, even though it worked fine the previous afternoon. If your batteries spend part of the year shivering in the cold, the reduced capacity has to be taken into account when sizing the system batteries. The standard rating for batteries is at room temperature 25 degrees C (about 77 F). At approximately -22 degrees F (-30 C), battery Ah capacity drops to 50%. At freezing, capacity is reduced by 20%. Capacity is increased at higher temperatures – at 122 degrees F, battery capacity would be about 12% higher.
Wide temperature variations
Battery charging voltage also changes with temperature. It will vary from about 2.74 volts per cell (16.4 volts) at -40 C to 2.3 volts per cell (13.8 volts) at 50 C. This is why you should have temperature compensation on your lead-acid battery charger or charge control if your batteries are outside and/or subject to wide temperature variations.
Internal temperature of a battery
Thermal mass means that because they have so much mass, they will change internal temperature much slower than the surrounding air temperature. A large insulated battery bank may vary as little as 10 degrees over 24 hours internally, even though the air temperature varies from 20 to 70 degrees. For this reason, external (add-on) temperature sensors should be attached to one of the POSITIVE plate terminals, and bundled up a little with some type of insulation on the terminal. The sensor will then read very close to the actual internal battery temperature.
Battery life reduces at higher temperatures
Even though battery capacity at high temperatures is higher, battery life is shortened. Battery capacity is reduced by 50% at -22 degrees F – but battery LIFE increases by about 60%. Battery life is reduced at higher temperatures – for every 15 degrees F over 77, battery life is cut in half. This holds true for ANY type of lead-acid battery, whether sealed, Gel, AGM, industrial or whatever. This is actually not as bad as it seems, as the battery will tend to average out the good and bad times.
One last note on temperatures – in some places that have extremely cold or hot conditions, batteries may be sold locally that are NOT standard electrolyte (acid) strengths. The electrolyte may be stronger (for cold) or weaker (for very hot) climates. In such cases, the specific gravity and the voltages may vary from what we show.
Now we have launched a low temperature battery, HiMASSi Smart & Temp battery, which supports charging at -31 ℉.
Welcome to consult! (sales6@himaxelectronics.com).
/wp-content/uploads/2019/05/Himax-home-page-design-logo-z.png00administrator/wp-content/uploads/2019/05/Himax-home-page-design-logo-z.pngadministrator2021-11-24 02:29:532024-04-28 15:29:49Temperature effects on batteries
By now, the winter has been successful in many areas. Climate experts predict that the cold air may hit us frequently this winter, and we have ourselves prepared to prevent the cold. Will the batteries, the essential energy supply, and the energy storage device that we live in, also be prepared for the cold days?
For example, in terms of the necessary phone, a fully charged cell phone flies from a warm place to the cold north, when off the plane its power drops sharply or immediately shows “low power for low temperature, automatic shut”. Not only unpaid but also the temperature defeats it. when the phone battery encounters a low temperature beyond its acceptable range, it stops running (also phone freezing phenomenon) so that the mobile phone powers down or automatically off. Knowing the temperature accepted by our batteries is necessary.
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Definition of Series and Parallel Connection of Lithium Batteries
Due to the limited voltage and capacity of the single battery cell, the series and parallel connection is needed in the actual use to obtain higher voltage and capacity, so as to meet the actual power demand of the equipment.
Lithium batteries connected in series
Add the voltage of batteries, capacity remains the same, and internal resistance increases.
Lithium batteries connected in paralle
Constant voltage, added capacity, reduced internal resistance, and extended power supply time.
Lithium batteries connected in series and parallel
3.7V single battery can be assembled into battery pack with a voltage of 3.7*(N)V as required (N: number of single batteries)
For example, 7.4V, 12V, 24V, 36V, 48V, 60V, 72V, etc.
Capacity of Parallel Connection
2000mAh single battery can be assembled into a battery pack with capacity of 2*(N)Ah as required (N: number of single batteries)
For example, 4000mAh, 6000mAh, 8000mAh,5Ah, 10Ah, 20Ah, 30Ah, 50Ah, 100Ah, etc.
Lithium Battery Pack
Lithium battery pack technique refers to the processing, assembly and packaging of lithium battery pack. The process of assembling lithium cells together is called PACK, which can be a single battery or a lithium battery pack connected in series or parallel. The lithium battery pack usually consists of a plastic case, PCM, cell, output electrode, bonding sheet, and other insulating tape, double-coating tape, etc.
Lithium cell: The core of a finished battery
PCM: Protection functions of over charge, over discharge, over current, short circuit, NTC intelligent temperature control.
Plastic case: the supporting skeleton of the entire battery; Position and fix the PCM; Carry all other non-case parts and limit.
Terminal lead: It can provide a variety of terminal wire charging and discharging interface for a variety of electronic products, energy storage products and backup power.
Nickel sheet/bracket: Connection and fixing component of the cell
Lithium Battery Series and Parallel Connection
Due to security reasons, lithium ion batteries need an external PCM used for battery monitoring for each battery. It is not recommended to use batteries in parallel. If connect in parallel, make sure the consistency of the battery parameters (capacity, internal resistance, etc.), the other batteries in series need to have consistent parameters, otherwise, the performance of the battery pack can be much worse than the performance of a single cell.
The purpose of lithium battery matching is to ensure that every cell in the battery has consistent capacity, voltage and internal impedance, because inconsistent performances will make lithium battery have various parameters during using. Voltage imbalance will happen. After a long run, the battery will overcharge, over discharge, capacity lost, or even fire to explode.
1.Series and Parallel Connection Mode of Lithium Battery
The length of the plug and lead of the lithium battery pack can be customized according to the customer’s electrical equipment.
3.Calculation Lithium Battery Connected in Series and Parallel
We all know that lithium battery voltage increases after series connection, capacity increases after parallel connection, then how to calculate a lithium battery quantity of series or parallel connection, and how many cells?
Before the calculation, we need to know which cell specification of the battery pack is adopted for the assembly, because different cells have different voltage and capacity. The cell quantity of series and parallel connection required to assemble a specific lithium battery pack varies. The common lithium cell types on the market are: 3.7V LiCoO2, 3.6V ternary, 3.2V LFePO4, 2.4V lithium titanate. The capacity is different because of the cell size, material and manufacturers.
Take 48V 20Ah Lithium Battery Pack for Example
Suppose the size of the single cell used is 18650 3.7V 2000mAh
Cell quantity of series connection: 48V/3.7V=12.97. That is 13 cells in series.
Cell quantity of parallel connection: 20Ah/2Ah=10. That is 10 cells in parallel.
18650-3S6P/11.1V/15600mAh Lithium Battery Assembly Process
Cell Capacity Grading
Capacity Difference≤30mAh
After capacity grading, stay still for 48-72h and then distribute.
Voltage Internal Impedance Sorting and Matching
Voltage Difference≤5mV
Internal Impedance Difference≤5mΩ 8 cells with similar voltage internal impedance are distributed together.
Cell Spot Welding
The use of formed nickel strip eliminates the problems of spurious joint, short circuit, low efficiency and uneven current distribution
Welded PCM
Make sure that the circuit board has no leakage components, and the components have no defective welding.
Battery Insulation
Paste the fibre, silicone polyester tape for insulation.
Battery Pack Aging
For the quality of the battery, improve the stability, safety and service life of the lithium battery.
PVC Shrink Film
Position the two ends after heat shrinking,
then heat shrink the middle part.
Put PVC film in the middle. No whiten after stretching. No hole.
Finished Product Performance Test
Voltage:10.8~11.7V
Internal Impedance:≤150mΩ
Charge-discharge and overcurrent performance test.
Battery Code-spurting
Code-spurting cannot be skewed, and it needs legible handwriting
Precautions for Lithium Batteries in Series and Parallel
Don’t use batteries with different brands together.
Do not use batteries with different voltages together.
Do not use different capacities or old and new lithium batteries together.
Batteries with different chemical materials cannot be used together, such as nickel metal hydride and lithium batteries.
Replace all batteries when electricity is scarce.
Use the lithium battery PCM with corresponding parameters.
Choose batteries with consistent performance. Generally, distributing of lithium battery cells is required for series and parallel connection. Matching standards: voltage difference≤10mV, impedance difference ≤5mΩ, capacity difference ≤20mA
1.Lithium Battery With Different Voltage Connected in Series
Due to the consistency issue of lithium batteries, when the same system (such as ternary or lithium iron) is used for series or parallel connection, it is also necessary to select the batteries with the same voltage, internal impedance and capacity for matching. Batteries with different voltage platforms and different internal impedance used in series will cause a certain battery to be fully charged and discharged first in each cycle. If there is a PCM and no fault occurs, the capacity of the whole battery will be reduced. If there is no PCM, the battery will be overcharged or over discharged, which will damage the battery.
2.Lithium Batteries With Different Capacities Connected in Parallel
If different capacities or old and new lithium batteries are used together, there may be leakage, zero voltage and other issues, because during the charging process, capacity differences make some batteries overcharge, some batteries not, while during discharge process, high capacity batteries do not run out of power, but low capacity batteries over discharge. In such a vicious cycle, the batteries will be damaged by leakage or low (zero) voltage.
To assemble lithium batteries, connect them in parallel or in series first?
Topological Structure of Lithium Battery Connected in Series and Parallel
The typical connection modes of a lithium battery pack are connecting first in parallel and then in series, first in series and then in parallel, and finally, mixing together.
Lithium battery pack for pure electric buses is usually connected first in parallel and then in series.
Lithium battery pack for power grid energy storage is tend to be connected first in series and then in parallel.
First Parallel and Then Series of Power Battery Module Topological Structure
First Series and Then Parallel of Power Battery Module Topological Structure
First Parallel, Then Series and Parallel Again of Power Battery Module Topological Structure
Advantages of Lithium Batteries First Connected in Parallel and Then in Series
If a lithium battery cell automatically exits, except the capacity reduction, it does not affect parallel connection;
In parallel connection, a short circuit of a lithium battery cell may cause short circuit due to large current, which is usually avoided by using fuse protection technology.
Disadvantages of Lithium Batteries First Connected in Parallel and Then in Series
If a lithium battery cell automatically exits, except the capacity reduction, it does not affect parallel connection;
In parallel connection, a short circuit of a lithium battery cell may cause short circuit due to large current, which is usually avoided by using fuse protection technology.
Advantages of Lithium Batteries First Connected in Series and Then in Parallel
First connecting the batteries in series according to the capacity, for example, 1/3 of the whole battery capacity are connected in series, and then connecting the rest in parallel, will reduce the failure probability of high-capacity lithium battery modules. First series and then parallel connection help the consistency of the lithium battery pack.
From the perspective of the reliability of the lithium battery connection, the development trend of voltage inconsistency and the influence of performance, the connection mode of first parallel and then series is better than that of first series and then parallel, and the topology structure of first series and then parallel lithium battery is conducive to the detection and management of each lithium battery cell in the system.
Lithium Batteries Charging in Series and Parallel
1.Charging Lithium Batteries In Series
At present, lithium battery tends to be charged in series, which is mainly due to its simple structure, low cost and easy realization. But as a result of different capacity, internal impedance, aging characteristics and self-discharge performance, when charge lithium battery in series, battery cell with the smallest capacity will be fully charged first, and at this point, the other battery cell is not full of electricity. If continue to charge in series, the fully charged battery cell may be overcharge.
Lithium Battery overcharge will damage the battery performance, and even lead to explosion and injuries, therefore, to prevent battery cell overcharging, lithium battery has equipped with Battery Management System (BMS). The Battery Management System has overcharge protection for every single lithium battery cell, etc. When charging in series, if the voltage of a single lithium battery cell reaches the overcharge protection voltage, the battery management system will cut off the whole series charging circuit and stop charging to prevent the single lithium battery cell from being overcharged, which will cause other lithium batteries unable to be fully charged.
2.Charging Lithium Batteries In Parallel
In parallel charging of lithium batteries, each lithium ion battery needs equalizing charge, otherwise, the performance and life of the whole lithium ion battery pack will be affected. Common charging equalization technologies include: constant shunt resistance equalizing charge, on-off shunt resistance equalizing charge, average battery voltage equalizing charge, switch capacitor equalizing charge, step-down converter equalizing charge, inductance equalizing charge, etc.
Several problems need to be paid attention to in parallel charging of lithium batteries:
Lithium batteries with and without PCM cannot be charged in parallel. Batteries without PCM can easily be damaged by overcharging.
Batteries charged in parallel usually need to remove the built-in PCM of the battery and use a unified battery PCM.
If there is no PCM in parallel charging battery, the charging voltage must be limited to 4.2V and 5V charger cannot be used.
After lithium ion batteries connecting in parallel, there will be a charging protection chip for lithium battery charging protection. Lithium battery manufacturers have fully considered the change characteristics of lithium battery in parallel before battery production. The above requirement of current design and choice of batteries are very important, so that users need to follow the instructions of parallel lithium batteries charging step by step, so as to avoid the possible damage for incorrect charge.
3.Notes for Lithium Battery Charging
Special charger must be used for lithium battery, or battery may not reach saturation state, affecting its performance.
Before charging the lithium battery, it does not need to discharge completely.
Do not keep the charger on the socket for a long time. Remove the charger as soon as the battery fully charged.
Batteries shall be taken out of electric appliances that have not been used for a long time and stored after they are fully discharged.
Do not plug the anode and cathode of the battery into the opposite direction, otherwise, the battery will swell or burst.
Nickel charger and lithium charger cannot be used together.
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When it comes to the words’ lithium battery’ it’s safe to say that lately, these two words have generated a lot of confusion, fear, and speculation. So, it’s no wonder you might ask yourself, “why on Earth would anyone use Lithium batteries?” But rest assured, we’ve done our homework. At Himax, we’ve dedicated over a decade of our time on, research & development, learning, design, and optimization of our products, to ensure that we always provide customers with safe technology and innovative solutions. Before we can get into what makes our Lithium batteries safe, let’s cover the basics.
Lithium 101
Lithium was discovered in 1817 by Swedish Chemist, Johan August Arfwedson. You might remember seeing “Li,” on the periodic table on your school teacher’s wall, but Arfwedson first called it ‘lithos’, which means stone in Greek. Li is a soft, silvery-white alkali metal and its high-energy density makes it a great choice to give batteries an extra boost.
1. Safety:
LiFePO4 is more chemically stable, and it is incombustible, which means that it is not prone to thermal runaway (and remains cool at room temperature). It can also withstand high temperatures without decomposing, and it is not flammable. The bottom line is, you don’t have to worry about it exploding or catching alight on the job.
2. Sustainable:
LiFePO4 batteries have a longer cycle life, and the fact that they are rechargeable makes them sustainable. In essence, you can keep using a LiFePO4 batter over and over again. LiFePO4 is a nontoxic material and doesn’t give off dangerous or hazardous fumes, which makes it safe for you and the environment too.
3. Long lasting:
A Lithium LiFePO4 battery does not need to be fully charged to use. This means that you can connect several batteries in parallel, without damaging the batteries which are less charged than others. It can also be discharged quickly without damaging the cells either. LiFePO4 batteries have a shallow rate of self-discharge, which means they can be left standing for months and not run out of juice or cause permanent damage. They also have a longer and better life cycle, ranging in the thousands. (2000 cycles).
4. Efficiency:
A Lithium LiFePO4 battery has a much higher charging rate, it charges quicker than other batteries, and charging it is effortless. It also requires zero maintenance, which means you’ll experience minimal downtime and maximum productivity when you use Lithium LiFePO4 battery tug. Lithium LiFePO4 batteries are lighter and occupy less space, which makes pushing and pulling a compact tug with a Lithium LiFePO4 battery, ergonomic. Our Lithium LiFePO4 battery is versatile and easily intergrade with many of our tugs. Since the battery is rechargeable and simple to charge, which means they are ready to move when you are.
5. Performance:
Lithium LiFePO4 batteries have an optimal energy density in both volume and weight and have good specific energy, which means the battery can give the necessary power when needed. It’s also worth mentioning that Lithium LiFePO4 batteries have excellent cycling performance too.
Bonus: Battery management system
Our Lithium battery comes standard with a battery management system (BMS) to manage the rechargeable Lithium LiFePO4 battery. How it does this is by monitoring the battery’s state and the cells. It also collects various sets of data to calculate and control the battery’s environment. One of the critical functions of the BMS is to balance the cells to ensure that the battery can perform at its best while protecting it by observing its voltage and temperature to avoid cell failure.
Wondering how to charge a deep cycle battery the right way? You’ve come to the right place!
So you took the plunge and invested in a deep cycle battery. You’re excited about spending endless hours on the water and powering your trusted trolling motor and favorite fishing gadgets. But in order for your battery to continue working for years to come, you’ve got to put in a smidge of work to keep things running smoothly.
Now of course, if you have a lithiumdeep cycle battery, your maintenance “to do” list is pretty short. Nearly as short as Santa’s naughty kids gift list. That’s because lithium batteries don’t need electrolyte “topping-up”, cleaning, or any of that nonsense that lead-acid batteries require.
However, there is one thing you must do for any battery–even lithium. You must charge it the right way!
Why Do You Need To Charge Your Battery Correctly?
Why does it matter how you charge your deep cycle battery? Well, charging the right way can actually affect your battery’s performance and lifespan. For lead acid batteries, overcharging can ruin them. Leaving them at a partial state of charge can do a real number on them too.
Luckily, those no-nos don’t exist for lithium marine batteries. You can use them past 50% battery capacity without damaging them. And you don’t have to charge them right away after using up your charge. This is super convenient when coming home from a fun but exhausting day out on the lake.
But there are a few things you’ll want to keep in mind when charging a deep cycle battery, even if it’s ionic lithium. Read on to find out how to charge a deep cycle battery the right way!
Cycles of Battery Charging
A deep cycle battery is designed to attain a considerable depth of discharge, and then be recharged to full capacity for many cycles during its lifespan. A typical deep cycle battery cycle would begin with the battery at 100 percent capacity, then drain the battery to between 20 and 50 percent of its original capacity, then recharge to 100 percent.
The normal depth of discharge of your batteries will also affect their lifespan. A battery that is often pushed to 50% depth of discharge will live longer than one that is frequently pushed to a higher depth of discharge. Repeated shallow discharge (5-10%) of a deep cycle battery, on the other hand, correlates to reduced lifespans.
Again, quality deep cycle batteries are designed to be drained and then recharged to full capacity from a practical viewpoint. On the water, you really don’t need to be conservative with your batteries. Drain them, and when you get back to dry ground, recharge them with a charger to automatically restore their full capacity.
How to Charge a Deep Cycle Battery Correctly
Ready to juice up your battery? Here’s how to charge a deep cycle safely and efficiently:
Choose the correct charger type.
It’s a no-brainer that the BEST charger for a deep cycle battery is the one that’s built specifically for its type. That means an ionic lithium battery will charge better with a lithium battery charger.
Sure, it’s possible to “mix-and-match” battery types and chargers. But you run the risk of your charger reaching different voltage limits than your battery can handle. It’s possible to damage your battery, or at the very least, you’ll see an error code and your battery won’t charge.
Also, consider the fact that a correctly-matched charger will help your battery charge faster. For example, ionic lithium batteries can take a higher current. They charge much faster than other types, but only when paired with the correct charger.
So how do you choose the right charger? Simply put, read the charger’s description. It will specify what type(s) of batteries you can use it to charge. For lithium deep cycle batteries, we suggest Ionic single chargers and Ionic bank chargers. Built for lithium LiFePO4 marine batteries, they are smart chargers that supply constant voltage and stop charging once they reach max voltage. Some models may also be used to charge lead acid and AGM batteries.
Onboard chargers for batteries – the options.
Both offer the same set of key advantages:
Charges your batteries more quickly and conveniently.
Up to four 12V lithium batteries can be charged at the same time.
Can be used to charge both lead-acid and AGM batteries.
The cable is five feet long.
Charge status is shown via colored LEDs.
When utilizing Ionic Lithium Batteries, the Ionic Lithium app displays the charge level.
Lightweight
Affordable
These onboard chargers are perfect for competitive fishermen and boaters. They’re also ideal for anyone looking for the most advanced onboard battery chargers available on the market, and people who hate to wait long for their battteries to charge.
Portable chargers for batteries – the options.
Sometimes, installing an onboard charger is impossible or impracticable. Take for example, a tiny boat with limited storage, or a trolling motor-powered kayak or canoe — in these cases, you’ll probably need a portable battery charger. It’s probably impractical otherwise, and that’s okay — you’ve got options.
12v Portable Chargers
24v Portable Chargers
Both of these chargers are single bank, and offer the same basic functions. These “Smart” chargers for 12V LiFePO or lead-acid batteries are constant current, constant voltage (CCCV). When 14.6V is achieved, these smart chargers cease charging.
Both are great options for fishermen and boaters who need portable battery charging for their trips.
Choose the right charger voltage/amps.
Once you know what type of charger you need, you need to pick one with the right amount of voltage and amps. For example, a 12V charger is compatible with a 12V battery. Within the 12V battery category, you can choose from different charge currents (i.e. 4A, 10A, 20A).
To choose the right amount of amps, check the amp hour (Ah) rating of your battery. Make sure the amp rating isn’t higher than the amp hour rating of your battery. Using a charger with an amp rating that is too high can damage your battery.
You can also use a bank charger to charge multiple batteries at once.
Charge in the right conditions.
Did you know that high and low temperatures can affect your marine battery? Lithium batteries are the most resilient of the bunch. You can charge them at temperatures between -4°F – 131°F (0°C – 55°C) with no risk of damage. But the optimum charging temperature for Ionic Lithium Batteries is above freezing. If you need to charge your battery below freezing temps, no need to fret. Our 12V 300Ah battery is a beast of a battery and comes equipped with a heater, so no more worries about freezing temperatures!
How to Charge a Deep Cycle Battery Correctly (& Safely): Step by Step
Once you have the right charger, charging your battery is a cinch. Here’s what to do, step by step:
Make sure the battery terminals are clean.
First, connect the red (positive) cable to the red terminal. Then connect the black (negative) cable to the black terminal.
Plug in the charger. Turn it on.
If using a smart charger, you can “set it and forget it”. It will stop charging on its own. Ionic lithium chargers feature Bluetooth capabilities that let you check charge status on your phone. Other chargers, like those used for lead acid batteries, may require you to set a timer and disconnect it once it’s charged.
To disconnect, unplug the charger. Remove the black cable, then the red one.
Now you know how to charge a deep cycle battery safely and correctly. Here’s to many more adventure out on the water!
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Are you wanting to use solar power off grid? If so, you’re going to need off grid solar batteries–and they’d better be reliable.
If you use a grid-tied or hybrid system, it’s possible to run your solar without batteries. But as soon as you go off the grid, batteries become an essential part of your setup. Without them, you can’t store solar energy for use at a later time. You know, times when the sun’s not shining.
And what if you invest in solar batteries, only for them to malfunction, or run out of energy earlier than expected? Well, if the skies are dark, unfortunately your house or RV will be too.
So save yourself the trouble. Keep reading to discover the pros and cons of each battery type so you can choose the best one!
Off Grid Solar Batteries Aren’t Just for Camping
Years ago, solar batteries had their habitat in remote campsites and mountaintop cabins. Today, they’re still essential for boondocking and dry camping but with “grid defection” on trend, solar setups are making their way towards many towns and cities.
People are going off grid in places where grid power is available. They’re building eco-friendly tiny houses that completely rely on solar power. Others are installing solar panels on rooftops as backup power in places where the grid’s frequently unreliable. Some are saving big money by using solar only, and relying on the grid as a backup.
So now, more than ever, off grid solar batteries need to be reliable, long-lasting, and efficient. But not all batteries are created equal. Below, we’ll discuss the different types of off grid solar batteries so you can decide which is best for you.
What Are the Best Solar Batteries?
There’s no denying that lead acid batteries have been used in off grid solar setups for a long time. They’re the “OG” (original) batteries, and in the early days of solar energy, you wouldn’t see a setup without them.
But technology has evolved since then. So while lead acid batteries still get the job done, we wouldn’t say they’re the best off grid solar batteries on the market. They may be the most affordable up–front, but their benefits don’t go far beyond that.
Now each battery type has its pros and cons. Let’s compare the top contenders for off grid solar batteries, specifically lead acid, AGM, sealed gel, and lithium. These are the four most popular solar batteries available today and that’s why each is worth discussing. So let’s get to it!
Lead Acid Batteries
Lead acid batteries have been around for over 150 years. Most folks who use them as off grid solar batteries do so because of their low up-front cost.
Pros
Low cost
Good for short-term backup solar power
Cons
Short lifespan (3-5 years). Can be shorter if overcharged or not maintained correctly.
Require maintenance (watering, cleaning).
Contain toxins that may harm the environment.
Aren’t leak-proof and must be stored in a ventilated area.
Not ideal for remote off-grid sites that aren’t visited frequently, because of maintenance needs.
Usable capacity is 50%.
Sealed Gel Cell Batteries
Sealed gel cell batteries have electrolytes stored in gel form. This prevents them from spilling. They are similar to AGM batteries.
Pros
Can tolerate long periods without being charged.
Low self-discharge rate.
Longer cycle life than AGM batteries.
Maintenance free.
Cons
Medium-high cost.
Not suitable for constant use in remote places (where replacement is difficult).
Charges slowly.
Short lifespan (2-5 years).
Limited ability to deliver peak power.
50% usable capacity.
AGM Off Grid Solar Batteries
AGM stands for absorbed glass mat. These are similar to gel cell batteries and are sealed.
Pros
Low maintenance
Good for intermittent use, such as in a vacation cabin
Performs better than gel batteries when delivering peak power
Spill-proof, will not leak
Low self-discharge rate
Cons
Medium to high cost
Not suitable for constant use in remote places (where replacement is difficult).
Susceptible to overcharging.
Short lifespan( 4-6 years). May be shorter if overcharged.
50% usable capacity.
Lithium Off Grid Solar Batteries
LiFePO4 lithium batteries are the newest off grid solar battery type. They’re currently the most reliable battery on the market for solar setups. Here’s why:
Pros
Longest lifetime of any battery type.
Protected from overcharging or undercharging.
Eco-friendly, toxin-free, and will not leak.
Maintenance-free.
Lowest lifetime cost of any battery type.
Fastest charging battery type.
Great for both long-term, short-term, and intermittent use
Does not need to be replaced often; good for remote locations.
Most energy-efficient of all battery types.
Usable capacity is 80-100%, the most of any battery type.
Best battery for hot and cold climates.
Cons
Higher up-front cost
Which Solar Batteries Should You Choose?
Everyone’s energy needs are different. Lead acid or gel type batteries may work if you’re looking to test a solar setup short-term to see if it’s a right fit for you.
But when you consider efficiency, reliability and lifetime cost, it’s clear that lithium comes out on top as the best contender among all off grid solar batteries. So don’t let the slightly steeper up-front cost rain on your parade! Keep things sunny (and your electricity running smoothly) by powering your setup with lithium.
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Know how to apply an equalize charge and not damage the battery.
Stationary batteries are almost exclusively lead acid and some maintenance is required, one of which is equalizing charge. Applying a periodic equalizing charge brings all cells to similar levels by increasing the voltage to 2.50V/cell, or 10 percent higher than the recommended charge voltage.
An equalizing charge is nothing more than a deliberate overcharge to remove sulfate crystals that build up on the plates over time. Left unchecked, sulfation can reduce the overall capacity of the battery and render the battery unserviceable in extreme cases. An equalizing charge also reverses acid stratification, a condition where acid concentration is greater at the bottom of the battery than at the top.
Experts recommend equalizing services once a month to once or twice a year. A better method is to apply a fully saturated charge and then compare the specific gravity readings (SG) on the individual cells of a flooded lead acid battery with a hydrometer. Only apply equalization if the SG difference between the cells is 0.030.
During equalizing charge, check the changes in the SG reading every hour and disconnect the charge when the gravity no longer rises. This is the time when no further improvement is possible and a continued charge would have a negative effect on the battery.
The battery must be kept cool and under close observation for unusual heat rise and excessive venting. Some venting is normal and the hydrogen emitted is highly flammable. The battery room must have good ventilation as the hydrogen gas becomes explosive at a concentration of 4 percent.
Equalizing VRLA and other sealed batteries involves guesswork. Observing the differences in cell voltage does not give a conclusive solution and good judgment plays a pivotal role when estimating the frequency and duration of the service. Some manufacturers recommend monthly equalizations for 2–16 hours. Most VRLAs vent at 34kPa (5psi), and repeated venting leads to the depletion of the electrolyte, which can lead to a dry-out condition.
Not all chargers feature equalizing charge. If not available, the service should be performed with a dedicated device.
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Learn what you can do to prevent a Li-ion battery to fall asleep.
Li-ion batteries contain a protection circuit that shields the battery against abuse. This important safeguard also turns the battery off and makes it unusable if over-discharged. Slipping into sleep mode can happen when storing a Li-ion pack in a discharged state for any length of time as self-discharge would gradually deplete the remaining charge. Depending on the manufacturer, the protection circuit of a Li-ion cuts off between 2.2 and 2.9V/cell.
Some battery chargers and analyzers (including Cadex), feature a wake-up feature or “boost” to reactivate and recharge batteries that have fallen asleep. Without this provision, a charger renders these batteries unserviceable and the packs would be discarded. Boost applies a small charge current to activate the protection circuit and if a correct cell voltage can be reached, the charger starts a normal charge. Figure 1 illustrates the “boost” function graphically.
Figure 1: Sleep mode of a lithium-ion battery.
Some over-discharged batteries can be “boosted” to life again. Discard the pack if the voltage does not rise to a normal level within a minute while on boost.
Do not boost lithium-based batteries back to life that have dwelled below 1.5V/cell for a week or longer. Copper shunts may have formed inside the cells that can lead to a partial or total electrical short. When recharging, such a cell might become unstable, causing excessive heat or show other anomalies. The Cadex “boost” function halts the charge if the voltage does not rise normally.
When boosting a battery, assure correct polarity. Advanced chargers and battery analyzers will not service a battery if placed in reverse polarity. A sleeping Li-ion does not reveal the voltage, and boosting must be done with awareness. Li-ion is more delicate than other systems and a voltage applied in reverse can cause permanent damage.
Storing lithium-ion batteries presents some uncertainty. On one end, manufacturers recommend keeping them at a state-of-charge of 40–50 percent, and on the other end there is the worry of losing them due to over-discharge. There is ample bandwidth between these criteria and if in doubt, keep the battery at a higher charge in a cool place.
Cadex examined 294 mobile phones batteries that were returned under warranty. The Cadex analyzer restored 91 percent to a capacity of 80 percent and higher; 30 percent were inactive and needed a boost, and 9 percent were non-serviceable. All restored packs were returned to service and performed flawlessly. This study shows the large number of mobile phone batteries that fail due to over-discharging and can be salvaged.
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Compare battery energy with fossil fuel and other resources
Lifting off in a large airplane is exhilarating. At a full weight of almost 400 tons, the Boeing 747 requires 90 megawatts of power to get airborne. Take-off is the most demanding part of a flight and when reaching cruising altitude the power consumption decreases to roughly half.
Powerful engines were also used to propel the mighty Queen Mary that was launched in 1934. The 81,000-ton ocean liner measuring 300 meters (1,000ft) in length was powered by four steam turbines producing a total power of 160,000hp (120 megawatts). The ship carried 3,000 people and traveled at a speed of 28.5 knots (52km/h). Queen Mary is now a museum in Long Beach, California.
Table 1 illustrates man’s inventiveness in the quest for power by comparing an ox of prehistoric times with newer energy sources made available during the Industrial Revolution to today’s super engines, with seemingly unlimited power.
SINCE
TYPE OF POWER SOURCE
GENERATED POWER
3000 BC
Ox pulling a load
0.5hp
370W
350 BC
Vertical waterwheel
3hp
2,230W
1800
Watt’s steam engine
40hp
30kW
1837
Marine steam engine
750hp
560kW
1900
Rail steam engine
12,000hp
8,950kW
1936
Queen Mary ocean liner
160,000hp
120,000kW
1949
Cadillac car
160hp
120kW
1969
Boeing 747 jet airplane
100,000hp
74,600kW
1974
Nuclear power plant
1,520,000hp
1,133,000kW
Table 1: Ancient and modern power sources
Large propulsion systems are only feasible with the internal combustion engines (ICE), and fossil fuel serves as a cheap and plentiful energy resource. Low energy-to-weight ratio in terms of net calorific value (NCV) puts the battery against the mighty ICE like David and Goliath. The battery is the weaker vessel and is sensitive to extreme heat and cold; it also has a relatively short life span.
While fossil fuel delivers an NCV of 12,000Wh/kg, Li-ion provides only between 70Wh/kg and 260Wh/kg depending on chemistry; less with most other systems. Even at a low efficiency of about 30 percent, the ICE outperforms the best battery in terms of energy-to-weight ratio. The battery capacity would need to increase 20-fold before it could compete head-to-head with fossil fuel.
Another limitation of battery propulsion over fossil fuel is fuel by weight. While the weight diminishes when being consumed, the battery carries the same deadweight whether fully charged or empty. This puts limitations on EV driving distance and would make the electric airplane impractical. Furthermore, the ICE delivers full power at freezing temperatures, runs in hot climates, and continues to perform well with advancing age. This is not the case with a battery as each subsequent discharge delivers slightly less energy than the previous cycle.
Power from Primary Batteries
Energy from a non-rechargeable battery is one of the most expensive forms of electrical supply in terms of cost per kilowatt-hours (kWh). Primary batteries are used for low-power applications such as wristwatches, remote controls, electric keys and children’s toys. Military in combat, light beacons and remote repeater stations also use primaries because charging is not practical. Table 2 estimates the capability and cost per kWh of primary batteries.
AAA CELL
AA CELL
C CELL
D CELL
9 VOLT
Capacity (alkaline)
1,150mAh
2,850mAh
7,800mAh
17,000mAh
570mAh
Energy (single cell)
1.725Wh
4.275Wh
11.7Wh
25.5Wh
5.13Wh
Cost per cell (US$)
$1.00
$0.75
$2.00
$2.00
$3.00
Cost per kWh (US$)
$580
$175
$170
$78
$585
Table 2: Capacity and cost comparison of primary alkaline cells. One-time use makes energy stored in primary batteries expensive; cost decreases with larger battery size.
Power from Secondary Batteries
Electric energy from rechargeable batteries is more economical than with primaries, however, the cost per kWh is not complete without examining the total cost of ownership. This includes cost per cycle, longevity, eventual replacement and disposal. Table 3 compares Lead acid, NiCd, NiMH and Li-ion.
LEAD ACID
NICD
NIMH
LI ION
Specific energy (Wh/kg)
30–50
45–80
60–120
100–250
Cycle life
Moderate
High
High
High
Temperature performance
Low when cold
-50°C to 70°C
Reduced when cold
Low when cold
Applications
UPS with infrequent discharges
Rugged, high/low temperature
HEV, UPS with frequent discharges
EV, UPS with frequent discharges
Cost per kWh ($US)
Load leveling, powertrain
$100-200
$300-600
$300-600
$300–1,000
Table 3: Energy and cost comparison of rechargeable batteries. Although Li-ion is more expensive than Lead acid, the cycle cost may be less. NiCd operates at extreme temperatures, has the best cycle life and accepts ultra-fast charge with little stress.
Power from Other Sources
To reduce the fossil fuel consumption and to lower emissions, governments and the private sector are studying alternate energy sources. Table 4 compares the cost to generate 1kW of power that includes initial investment, fuel consumption, maintenance and eventual replacement.
Fuel type
Equipment
to generate 1kW
Life span
Cost of fuel
per kWh
Total cost
per kWh
Li-ion
Powertrain
$500/kW (20kW battery
costing $10,000)
2,500h (repl. cost $0.40/kW)
$0.20
$0.60
($0.40 + $0.20)
ICE in vehicle
$30/kW
($3,000/100kW)
4,000h (repl. cost $0.01/kW)
$0.33
$0.34
($0.33 + $0.01)
Fuel cell
– portable
– mobile
– stationary
$3,000–7,500
2,000h
4,000h
40,000h
$0.35
->
->
->
$1.85 – 4.10
$1.10 – 2.25
$0.45 – 0.55
Solar cell
$12,000, 5kW system
25 years
$0
~$0.10*
Electricity
electric grid
All inclusive
All inclusive
$0.20
(average)
$0.20
Table 4: Cost of generating 1kW of energy. Estimations include the initial investment, fuel consumption, maintenance and replacement of the equipment. Grid electricity is lowest.
* Amortization of investment yielding 200 days of 5h/day sun; declining output with age not included.
Power from the electrical utility grid is most cost-effective. Consumers pay between $0.06 and $0.40US per kWh, delivered with no added maintenance cost or the need to replace aging power-generating machinery; the supply is continuous. (The typical daily energy consumption per household in the West is 25kW.)
The supply of cheap electricity changes when energy must be stored in a battery, as is the case with a solar system that is backed up by a battery and in the electric powertrain. High battery cost and a relatively short life can double the electrical cost if supplied by a battery. Gasoline (and equivalent) is the most economical solution for mobility.
The fuel cell is most effective in converting fuel to electricity, but high equipment costs make this power source expensive in terms of cost per kWh. In virtually all applications, power from the fuel cell is considerably more expensive than from conventional methods.
Our bodies also consume energy, and an active man requires 3,500 calories per day to stay fit. This relates to roughly 4,000 watts in a 24-hour day (1 food Calorie* = 1.16 watt-hour). Walking propels a person about 40km (25 miles) per day, and a bicycle increases the distance by a factor of four to 160km (100 miles). Eating two potatoes and a sausage for lunch propels a bicyclist for the afternoon, covering 60km (37 miles, a past-time activity I often do. Not all energy goes to the muscles alone; the brain consumes about 20 percent of our intake. The human body is amazingly efficient in converting food to energy; one would think that the potato and sausage lunch could hardly keep a laptop going for that long. Table 5 provides the stored energies of calories, proteins and fat in watt-hours and joules.
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Learn about the revival of the fuel cell for transportation
The fuel cell as a propulsion system is in many ways superior to a battery because it needs to carry less energy storage by weight and volume compared to a vehicle propelled by batteries only. Figure 1 illustrates the practical driving range of a vehicle powered by a fuel cell (FC) compared to lead acid, NiMH and Li-ion batteries.
Figure 1: Driving range as a function of energy storage.
The logarithmical curves of battery power place limitations in size and weight. The FC has a linear progression and is similar to the ICE vehicle.
Note: 35MPa hydrogen tank refers to 5,000psi pressure; 70MPa is 10,000psi. Source: International Journal of Hydrogen Energy, 34, 6005-6020 (2009)+
One can clearly see that batteries simply get too heavy when increasing the size to enable greater distances. In this respect, the fuel cell enjoys similar qualities to the internal combustion engine (ICE) in that it can conquer great distances with only the addition of extra fuel.
The weight of fuel is most critical in air transport. Airlines only carry sufficient fuel to safely reach their designation, knowing that the airplane becomes more fuel efficient towards the end of the journey as the weight eases. A study group calculated that if the kerosene in an aircraft were replaced with batteries, the flight would last less than 10 minutes.
Although the fuel cell assumes the duty of the ICE in a vehicle, poor response time and a weak power band make on-board batteries necessary. In this respect, the FC car resembles an electric vehicle with an on-board charger that keeps the batteries charged. This results in short cycles that reduces battery stress over the EV; a propulsion system that bears a resemblance to the HEV.
The FC of a mid-sized car generates around 85kW (114hp) to charge the 18kWh on-board battery and drive the electric motor. On start-up, the vehicle relies fully on the battery; the fuel cell only contributes after reaching a steady state in 5–30 seconds. During the warm-up period, the battery must also deliver power to activate the air compressor and pumps. Once warm, the FC provides enough power for cruising; however, during acceleration, passing and hill-climbing both the FC and battery provide throttle power. Braking delivers kinetic energy to the battery.
Hydrogen costs about twice as much as gasoline, but the higher efficiency of the FC compared to the ICE in converting fuel to energy bring both systems on par. The FC has the added benefit of producing less greenhouse gas than the ICE.
Hydrogen is commonly derived from natural gas. Folks might ask, “Why not burn natural gas directly in the ICE instead of converting it to hydrogen through a reformer and then transforming it to electricity in a fuel cell to feed the electric motors?” The answer is efficiency. Burning natural gas in a combustion turbine to produce electricity has an efficiency factor of only 26–32 percent while a fuel cell is 35–50 percent efficient. That said, the machinery required to support the FC is costlier and requires more maintenance than a simple burning process.
To complicate matters further, building a hydrogen infrastructure is expensive. A refueling station capable of reforming natural gas to hydrogen to support 2,300 vehicles costs over $2 million, or $870 per vehicle. In comparison, a Level 2 charging outlet to charge EVs can easily be installed by connecting to the existing electric grid. The benefit with FC is a quick refill similar to filling a tank with liquid fuel.
Durability and cost are further deterrents for the FC, but improvements are made. The service life of an FC-powered car has doubled from 1,000 hours to 2,000 hours. The target for 2015 is 5,000 hours, or a vehicle life of 240,000km (150,000 miles).
A further challenge is vehicle cost as the fuel cell is more expensive to build than an ICE. As a guideline, an FC vehicle is more expensive than a plug-in hybrid, and the plug-in hybrid is dearer than a gasoline-powered car. With low fuel prices, alternative propulsion systems are difficult to justify on cost alone and the environmental benefits must be considered. Japan is making renewed efforts with FC propulsion to offer an alternative to the ICE and the EV. Toyota plans to phase out the ICE by 2050 and other vehicle makers are observing the trend.
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