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AGM or GEL? Choosing best solar battery for solar power system. Solar battery over discharge

AGM or GEL? Choosing best solar battery for solar power system. Solar battery over discharge

    Solar Charge Controllers Battery Charging

    Hey, do you know what solar charge controllers are? They’re devices that regulate the voltage and current coming from your solar panels to your batteries. They prevent overcharging, over-discharging, and reverse current flow. They’re pretty important if you want to keep your solar system running smoothly and efficiently. There are different types of solar charge controllers, such as PWM (pulse width modulation) and MPPT (maximum power point tracking). PWM controllers are cheaper and simpler, but they waste some of the solar power by reducing the voltage. MPPT controllers are more expensive and complex, but they can adjust the voltage and current to match the optimal power point of the solar panel. So, depending on your budget and needs, you might want to choose one or the other. Or maybe you want to have both, just in case. You never know when you might need some extra juice from the sun, right?

    Charge Controllers

    Midnite Classic 150

    Midnite Classic 200

    Midnite Classis 250

    Midnite Hawkes Bay

    Why a charge controller?

    Proper Battery Charging prevent excessive overcharge of the batteries within a battery based power system. Unlike other types of generators, solar panels can be short circuited or open circuited without causing damage to them. Controllers contain a relay that opens the charging circuit, terminating the charge at a pre-set high voltage and, once a pre-set low voltage is reached, closes the circuit, allowing charging to continue. Manage your battery life, Get the amp needed using mppt

    Charge controllers are the gizmo that goes between the solar array and the batteries and are sized to the systems they protect by the short circuit array current and watts matched to the battery voltage. Most common are 12, 24 and 48 volts. Because of cold temperatures and the “edge of Cloud effect”, sporadically increased current levels are not uncommon. For these and other reasons, the size of a controller’s amperage should be increased by a minimum of twenty five percent of the peak solar array current rounded up. You can also use the manufactures string calculator to correctly size the right charge controller for your battery based system for your zip code.

    What Size do I Need?

    Take the number of panels x watts to get the total watts of the solar array. You then divide it by the voltage of your battery bank to get amps, add 25% to allow for cold temperatures and as always, round up. Example: 2. 140 watt solar panels in series = 280 watts / 12 VDC battery bank 25% = 29.18 amps. You would choose a 30 amp, 12 VDC charger in this example. Another example would be 4. 250 watt solar panels = 1,000 watts / 24V battery bank = 41.7 amps 25% = 52.09 rounded up = 60 amp controller. Note; Solar charge controllers are rated and sized by the solar panel array current and system voltage. These examples are simple calculations for small systems. If you have a larger system with muliple strings you are considering, you should look at our Off-Grid Living page for some preconfigured systems that include the right sized charge controller or consult the charge controllers manufactures string calculator.

    MidNite Solar

    Midnite Solar is an American manufacture that produces a wide range of alternative energy products primarily used in off-grid battery applications. MidNite’s Classic series of Maximum Power Point Tracking (MPPT) charge controllers are the most powerful, full featured controllers on the market as well as being the only ETL listed controllers designed to work with Solar, Wind, and Micro Hydro Electric systems.

    The typical solar string for battery based systems is three common 60 cell solar panels in series. Throughout North America, 3 in series is a safe string for MPPT most controllers. The higher voltage Midnite Classic controllers may accept strings of 4 or even 5, depending on the solar panels and the local climate.

    On a cold clear morning if your solar panel or string of panels Voc exceeds the controller’s limit, the charge controller will protect itself by refusing to turn on. If you grossly exceed the Voc for example by wiring a large string of panels in series or miss-match your single panel to the controller for instance, you’ll get smoke. Smoke coming our of your charge controller is a bad thing.

    Most MPPT charge controllers work with higher array voltages, which can greatly reduce the required wire size between the array and the charge controller. While more expensive than PWM controllers, MPPT charge controllers can boost system performance by up to 30% making them very cost effective.

    Pulse Width Modulation (PWM) is an effective means to achieve constant voltage battery charging by switching (or pulse) the charge controller’s power devices. When in PWM regulation, the current from the solar array tapers according to the battery’s condition and recharging needs. The PWM charge controller constantly checks the state of the battery to determine how fast to send the electrical pulses, and how long the pulses will be. In a fully charged battery with no load, it may just tick every few seconds and send a short pulse to the battery. In a discharged battery, the pulses would be very long and almost continuous. The charge controller checks the state of charge on the battery between pulses and adjusts itself each time.

    Maximum Power Point Tracking (MPPT). A solar panels ideal voltage is that at which it can put out maximum power. Maximum power point, also called peak power voltage abbreviated Vpp is the maximum energy produced. Maximum power point tracking (MPPT) is a electronic design that charge controller manufactures use to get the maximum possible power from a solar panel. The cells that make up a solar panel have a complex relationship between solar irradiation, temperature and resistance that produces a non-linear output efficiency known as the I-V curve. It is the purpose of the MPPT controller to sample the output of the cells and apply the proper load to obtain maximum power for any given environmental conditions. Essentially, this defines the current that the inverter should draw from the solar panel in order to get the maximum possible power, as power equals voltage times current. MPPT controllers are more effective that PWM controllers and save considerable money on larger systems since they provide 16% to 30% more power to the battery.

    Charge Controllers, Off-Grid, Deep Cycle Battery Chargers.

    Charge controllers are solid-state electronic devices used in nearly every solar and wind energy system that uses batteries. A charge controller is often times used in off-grid solar systems with 12 volt to 48 volt battery banks to keep the voltage to the batteries within acceptable limits. A charge controller automatically tapers, stops, or diverts electrical power when systems batteries become fully charged. Charge controller capacities range from 4 to 80 A and multiple charge controllers can be used in parallel for larger solar battery systems. Some charge controllers offer additional features, like charge status display, data logging, automatic battery equalization charging and generator starting.

    The simplest charge controllers cut the power when the battery reaches a set voltage, and turn it on when a low voltage set point is reached. Pulse width modulated (PWM) charge controllers turn on and off very rapidly, maintaining the batteries at full charge with whatever power is available. Maximum power point tracking (MPPT) charge controllers optimize the voltage of the PV array to maximize total power output then convert that to the correct voltage to charge the battery. This process significantly increases the power from a solar array, particularly in low temperatures when battery voltage is significantly below the PV array voltage. Most MPPT charge controllers work with higher array voltages, enabling the use of larger solar modules, which can be more economical on a cost per watt basis. A higher voltage solar array also minimizes the required AWG wire size between the solar panels and the charge controller. While more expensive than PWM controllers The Charge controllers Blue Pacific Solar sells employ the latest in power electronics to regulate the battery charge by controlling the charging voltage and current from a solar panel array. Charge controllers regulate the charge of the battery, but also prevent the battery from being over discharged which can damage the battery bank.

    Charge controllers have multiple stages of control it uses to regulate different voltage and current levels. The voltage and current of a battery varies over the different stages of battery charge. Though the amount can vary, the bulk charge usually is approximately 80%, the absorption charge is 10% with the float charge representing the balance of the battery charging process. The bulk charging stage of the charge controllers process is the first stage to used to bring the battery depth of discharge (DOD) back to 100%. The bulk charge stage happens first in in the morning after the batteries DOD has drained down since sunset the previous day. The bulk charging stage pushes as many amps into the battery bank as possible from the solar panels and gets the voltage up in the process. The effect of a charge controller is not unlike trying to fill a glass of water from a faucet. You first turn the faucet on full while the glass if filling, then slowly taper off the pressure until the glass is full. When the battery bank reaches a predetermined level known as the bulk voltage set-point, the charge is then substantially slowed. Because the bulk voltage set point is determined by the type of battery you are using, many charge controllers have to be pre-set to the type of battery which will dictate the rate of charge.

    The second state of charge a charge controller employs is the absorption stage. After a battery system has been brought up to the bulk voltage set point, the charge controller slows down the charge rate because the battery bank cannot accept the same Rapid charging pace without overheating and damaging the battery bank. At the absorption stage a battery bank is only about 80% full. The absorption charge is the function level in the process that tops off the battery bank. During the absorption stage, the charge controller holds the battery volts constant and reduces the amount of current sent into the battery. When the absorption stage is complete, the battery bank is fully charges.

    The final step a charge controller performs is the float charge. Typically a charge controller enters into a float charge state when the other charge levels of the battery bank has been achieved. When the number of peak sun hours is limited, a solar charge controller may not be able to get the battery bank back to the float stage before the next cycle begins.

    MorningStar, Outback and Xantrex are adding new and updated charge controllers technology everyday. Various new charge controller models are released every year making what seems like a dilemma at first, but is actually a better solution. There is in fact a right charge controller for every off-grid solar application. Blue Pacific Solars’ consultants can help you sort through the different challenges of matching the right charge controllers to your battery bank.

    AGM or GEL? Choosing best solar battery for solar power system

    In this article, We will introduce the battery characteristics, let us tell you a few basic advantages and disadvantages of parallel and series circuits; We will talk about what is AGM battery ? what is GEL battery ? How to choose solar battery for solar power system ? What is the battery over-discharge ? What is the battery series connection ? What is the battery parallel connection ? AGM or GEL ? How to choose solar battery for solar power system ?

    What is AGM battery ?

    VRLA AGM battery is valve-regulated lead-acid battery (VRLA ) Absorbent Glass Mat (AGM) technology battery. This is one kind of lead-acid battery for energy storage.

    The technical features of AGM battery technology :

    • Sealed with special compound epoxy and using pressure controlled vent valves.
    • Electrolyte acid is absorbed in special glass mat separators to prevent electrolyte acid leaking or evaporating.
    • No spilling. can be operated in any position. However, upside-down installation is not recommended.
    • Using a recombination reaction to prevent hydrogen and oxygen gases escaping and make this two gases into water, which can keep acid water in same level.
    • Maintenance free. No need to add water like flooded battery.

    VRLA AGM battery uses recombinant technology. The oxygen produced from the positive plates of the battery is absorbed by the negative plates. This suppresses the generation of hydrogen at the negative plates. The recombination of oxygen and hydrogen leads to Water, retaining the electrolyte amount within the battery. Water re-filling is never required.

    Compared to flooded battery, the advantages of AGM battery are :

    • Vibration resistance due to sandwich construction
    • Performance well in cold temperature
    • Spill-proof through acid liquid encapsulation in glass mat technology
    • High specific power, low internal resistance
    • Up to 5 times faster charge than flooded technology
    • Better cycle life than flooded systems
    • Water retention (oxygen and hydrogen combine to produce water)
    • Less sulfation because no need to open and add water

    The advantage of AGM battery in application :

    Maintenance free When battery is charging, hydrogen would be absorbed and reversed to electrolyte by plates. It doesn’t need to refill water and balanced charge, which makes maintenance free.

    Flexible installation AGM separator keep electrolyte absorbed in glass mat and still. Battery can be used or positioned in any orientation.

    Extremely safe When excessive gas production by inappropriate charging occurs, safety valves will automatically emit the gas to prevent battery cracked.

    Long standby life, Better cycle performance Anti-corrosion lead-calcium alloy plate provides longer float charging life. AGM separator can trap electrolyte and prevent active materials on positive plate dropping at the same time. over, it gives better deep discharge cycle performance.

    Longer shelf life Special lead-calcium alloy plates make lower self-discharge for longer shelf life.

    High rate performance Low inner resistance allows higher discharging and charging current for better performance in high rate application

    What is GEL battery ?

    VRLA GEL battery is valve-regulated lead-acid battery (VRLA ) Gel electrolyte cell technology battery. This is one kind of lead-acid battery for energy storage.

    Gel battery is using gel as electrolyte instead of liquid acid. Gel is usually produced by homogeneous dispersion of pyrogenic silica in diluted sulfuric acid. Pyrogenic silica is a kind of powder of very well dispersed SiO, which absorb more than 10 times of its weight acid liquid to produce gel. Because of the thixotropic property of gel, the agglomerates are connecting themselves together as a network which keeps the liquid inside and become gel structure after a certain gelling time. The Gel battery has no liquid inside, the electrolytes is in gel form and stand solid between positive and negative plate inside battery.

    The technical features of Gel battery technology :

    • Using gel as electrolyte
    • Plate thickness tolerance is not critical since the high compression of plates group assembly is not necessary
    • electrolytes for better contact with plates and active materials and container walls, it is good for releasing internal heat and cooling battery temperature.
    • Using the extra microporous separator which can: a/ reduce the depolarization of the negative electrode and avoid negative plate sulphation b/ without any liquid, significantly decreases thermal runaway c/ Help to prevent short circuits by dendrite growth between the positive and negative plates during deep discharge
    • Better vent valve design to lower gas leaking rate to extend battery lifetime.

    Compared to flooded battery, the advantages of Gel battery are :

    • Maintenance free, no need to add water
    • Safe operation since no liquid inside
    • Can be installed sideways ( upside-down is not recommended )
    • Long cycle life
    • Low self-discharge makes shelf life longer.
    • Long standby life due to its ability to keep electrolyte inside and steady
    • Performance stays high and stable until the end of life
    • Tolerance to abuse and heat during operation, good for extreme weather

    The advantage of Gel battery in application :

    Maintenance free When battery is charging, hydrogen would be absorbed and reversed to electrolyte by plates. It doesn’t need to refill water and balanced charge, which makes maintenance free.

    Flexible installation AGM separator keep electrolyte absorbed in glass mat and still. Battery can be used or positioned in any orientation.

    choosing, best, solar, battery, power, system

    Longer lifespan in extreme weather Gel cell electrolyte prevent electrolyte being evaporated in high temperature or being frozen in low temperature, which keep battery in high performance in extreme weather. Extremely safe When excessive gas production by inappropriate charging occurs, safety valves will automatically emit the gas to prevent battery cracked.

    Long standby life, Better cycle performance Anti-corrosion lead-calcium alloy plate provides longer float charging life. AGM separator can trap electrolyte and prevent active materials on positive plate dropping at the same time. over, it gives better deep discharge cycle performance.

    Longer shelf life Special lead-calcium alloy plates make lower self-discharge for longer shelf life.

    High rate performance Low inner resistance allows higher discharging and charging current for better performance in high rate application

    What is the battery over-discharge ?

    Over discharge may cause difficulties in recharging the cell by increasing the battery’s internal resistance. Also, over discharging may cause lead to be precipitated in the separator and cause a short in the cell or between cells.

    See the photo, this battery already dead and there is no way to discharge, so we open it, and We can find that the battery terminals have been oxidized, white crystals adhere to the terminals of the battery, It can be judged that after a long period of use, the battery does not have maintenance and supplemental power, and causes the battery to have a low battery voltage for a long time

    We do not recommend using battery voltage lower than 10.5V, it will make battery over-discharge. For a low voltage battery, the battery should be stopped immediately, and the battery should be supplemented by electricity immediately. Proper maintenance can extend battery life.

    What is the battery series connection ?

    a “series circuit” will share the voltage given from the supply evenly … however the current will remain the same across the entire circuit. When the battery is connected in series, the battery voltage increases, battery current does not change.

    For example: 12V 100AH x4pcs in series connection:

    The total capacity is 48V 100AH (12Volts 12Volts 12Volts 12Volts = 48Volts) When you connect the batteries in series, you are keeping the total capacity the same.

    What is the battery parallel connection ?

    a parallel circuit in the same scenario will split the current evenly across all paths … however the voltage across the entire circuit and all paths will be same as supply.

    When the battery is connected in parallel, the battery voltage does not change but battery capacity increases.

    For example: 12V 100AH x4pcs in parallel connection: The total capacity is 12V 400AH (100AH 100AH 100AH 100AH = 400AH) When you connect the batteries in parallel, you are keeping the total voltage the same.

    AGM or GEL ? How to choose solar battery for solar power system ?

    We can easily understand the difference of AGM and GEL by the following chart : AGM and GEL’s deep cycle are suitable for solar However, if it is a more extreme climate or outdoor, Gel’s deep cycle will have a longer life span.

    Electrical performance The pores of the gel structure are narrow, so the ions are more clogged, and the internal group of colloidal sealed lead acid batteries is larger than AGM. Therefore AGM’s high-power discharge performance is better. AGM is better
    Size GEL electrolyte is 20% more than AGM, and it adopts flooded process, so AGM energy density is high AGM is better
    Ventilation requirements GEL is flooded battery, The cracks generated by the gel provide oxygen circulation. GEL must be well ventilated. AGM has 8% of the gap in the separator, and no electrolyte is filled. AGM is better
    Thermal runaway The AGM sealed lead-acid battery adopts a liquid-lean design. In the separator plate, 8% of the porosity must be maintained and the electrolyte is not allowed to enter. Therefore, the internal heat of the battery is poor, and the oxygen generated during charging reaches the negative electrode, which generates heat.If you can’t dissipate heat immediately, the battery temperature will increase. GEL is better
    Operating temperature GEL working temperature adaptability is better than AGM GEL is better
    Cycle Life AGM battery cycle life is about 400 times; GEL battery cycle life is about 600.800 times GEL is better
    Standby Life Both AGM and GEL can have a long life design. Both are good

    What does the depth of discharge of a battery represent?

    A battery’s depth of discharge (DoD) indicates the percentage of the battery that has been discharged relative to the overall capacity of the battery. For example, if you have a LG Chem RESU that holds 9.3 kilowatt-hours (kWh) of electricity, and you discharge 8.8 kWh, the DoD is approximately 95 percent.

    The more frequently a battery is charged and discharged, the shorter its lifespan will be. It’s generally not recommend to discharge a battery entirely, as that dramatically shortens the useful life of the battery. Many battery manufacturers specify a maximum recommended DoD for optimal performance of the battery.

    For example, if the manufacturer of a 10 kWh battery recommends a maximum DoD of 80 percent, you shouldn’t use more than 8 kWh from the battery without recharging. You can see why DoD is an important factor to consider: a higher DoD means you can use more of the energy being stored in your battery. Many modern lithium ion batteries these days advertise a DoD of 100 percent.

    What is a battery’s cyclic life?

    Your battery’s “cyclic life,” or the number of charge/discharge cycles in its useful life, depends on how much of the battery’s capacity you normally use. If you regularly discharge the batteries at a lower percentage amount, it will have more useful cycles than if you frequently drain the battery to its maximum DoD. For example, a battery may have 15,000 cycles at a DoD of 10 percent, but only 3,000 cycles at 80 percent DoD.

    Below is a table of some of the more popular battery options, as well as the suggested maximum DoD as given on the product’s detailed specification sheets :

    DoD of popular home battery options

    BatterySize (total energy, kWh)Depth of Discharge (DoD)Maximum discharge before recharging (kWh)
    Tesla Powerwall 13.5 100% 13.5
    sonnen eco 10 100% 10
    Enphase Encharge 10.08 100% 10.08
    LG Chem RESU 9.3 95% 8.8
    Generac PWRcell 12 84% 10.08

    These manufacturers produce batteries of different sizing/capacity, only one of which is listed in this chart.

    Battery temperature: why does it matter?

    Most solar batteries these days are guaranteed to last somewhere between five to 15 years. This partially depends on how often the battery is discharged and the number of cycles it’s gone through, but there are other things that have a big impact.

    Another factor affecting the lifetime of your battery is how well you maintain it, and more particularly the temperature it’s kept in. Batteries in a hot atmosphere (over 90 degrees F) may overheat, which shortens the lifetime of the battery. Very cold temperatures also have a negative impact on the battery, because it has to work harder and at a higher voltage to charge. To maximize your battery’s useful life, try to keep it in a relatively mild environment – not too hot and not too cold.

    Why is storage becoming more popular?

    There are a number of reasons why storage is becoming a popular addition to solar, but one key factor is state incentives: a growing number of states and utilities are offering incentives for installing battery storage. (Some examples of this include the Self-Generation Incentive Program (SGIP) in California, Maryland’s Home Energy Storage Tax Credit, and the Massachusetts Smart program that offers a tariff adder for batteries.) If you live in one of these states, you might be looking at some of the popular battery options for residential applications like the Tesla Powerwall, the Generac PWRcell, or the LG Chem RESU.

    Which battery is the right option for you?

    Depth of discharge is important when comparing battery options, but it isn’t the only factor to evaluate.

    Outside of DoD and costs, one of the most important things to consider is whether the battery will fit your particular situation. A small battery will be less expensive, but works best if you are just trying to reduce demand charges or avoid costly time of use rates. If you’re looking to go off the grid, you’ll need batteries that can store as much energy as possible (or, multiple smaller batteries stacked on top of one another). Homeowners who experience frequent (and long) power outages may also consider getting a large battery for peace of mind.

    Compare storage options on EnergySage

    With any large purchase like solar and batteries (paired or separately), you want to consider your options. You can sign up on the EnergySage Marketplace to receive turnkey quotes for solar installation from pre-screened local solar installers. If battery storage is something you’re interested in pairing with your system, we recommend adding a note in your account preferences specifying you’re interested in pricing and information about batteries. Even if a solar installer doesn’t install batteries themselves, they can design a solar panel system so that you can add a battery later down the line.

    reading on EnergySage

    Looking to go solar? Here’s everything you need to know in… Are solar panels worth it in 2023? Best solar panels in 2023: Top products compared How to install solar panels Solar shingles: what you need to know in 2023

    Introduction: Restoring/Recharging Over-discharged LiPo (Lithium Polymer) Batteries!

    About: I’m an aerospace research engineer with a B.S. in Aeronautical Engineering and an M.S. in Mechanical Engineering. I have a tremendous interest in Radio Control (RC) aircraft and have developed many skills i… About ElectricRCAircraftGuy »

    choosing, best, solar, battery, power, system

    LiPo batteries should never be discharged below 3.0V/cell, or it may permanently damage them. Many chargers don’t even allow you to charge a LiPo battery below 2.5V/cell. So, if you accidentally run your plane/car too long, you don’t have your low voltage cutoff set properly in the ESC (Electronic Speed Controller), or you leave the power switch on, forget to unplug the LiPo, get your plane stuck overnight in a tree (the same tree, three separate times, for foolishly flying in areas too small because you are too excited to fly and it’s almost dark), etc. etc., you may find yourself in a situation where you’ve discharged your LiPo down well below 3.0V/cell. What do you do?

    Many people toss the LiPos in the trash. I don’t. I restore them. Here’s how.

    -So, if you want to read the latest version, click the link just above.

    If this article interests you, you will probably enjoy this one too, so be sure to check it out!

    -Also, please subscribe to my site via the icons at the top-right when you click the link aboveMany additional articles can be found via the tabs at the top of the page that opens when you click the above link, and via the many links on the right-hand sideLinks to additional articles you may like are at the very end of this instructable. =

    Step 1: Background, Cautions Warnings

    Before you begin this, you need to know that LiPos are traditionally considered to be somewhat volatile and dangerous. This is because abused LiPo batteries are known to sometimes catch fire, and some have burned down houses or cars, and a fair number of Radio Controlled airplanes have caught on fire during crashes, due to damaged LiPos.

    During a reasonable or slow discharge, however, LiPos will not catch on fire, even if discharged all the way down to 0V/cell. It is the recharge phase that would cause a fully discharged LiPo to catch on fire, not the discharge phase. The reason is that when a LiPo is brought below ~3.7V/cell, its internal resistance to taking on a charge begins to increase, some of which is permanent. Below ~3.0V/cell the damage becomes significant enough to care about. Below ~2.5V/cell, most manufacturers of LiPo chargers have said that the battery is too dangerous to be recharged. This is because the battery’s internal resistance to charging has increased enough at this point that a standard recharge rate would be much too great for a LiPo at this low of a voltage level, since a standard 1C (1 x the battery’s capacity) charge current could cause potentially unsafe heat build-up within the battery. Below ~2.0V/cell the LiPo’s rate of permanent internal damage has accelerated, below ~1.5V/cell the rate of damage (again, permanent increase in internal resistance) has increased more still, and it only gets worse and worse. The rate at which this damage increases is not linear. It is perhaps a power function of, or exponentially related to the battery’s voltage. In either event, it’s bad, and special care must be taken.

    I will now say that I have successfully restored dozens of batteries. Some of the worst ones which I have continued to use were as low as ~1.0V/cell. I have successfully recharged, however, batteries as low as a few mV/cellperhaps 10mV/cell, or 0.010V/cell. These batteries were useless, however, and rapidly self-discharged back to ~0V/cell after removing them from the charger.

    Define restore: Before I go on, let me define what I mean when I say that I have restored these LiPos. I do NOT mean I have fixed them, or reversed their damage. I do NOT mean I have brought them back to good-as-new. Rather, I mean I have simply recharged them to a safe, usable level where they can continue to be used. That is all.

    A word of caution: What I describe below is how I’ve restored the batteries. Use caution. If your battery is at 0.5V/cell, its internal resistance is far higher than if it has only fallen to 1.0V/cell, and both of these cases have internal resistances far higher still than a LiPo at 1.5V/cell. Again, it seems to me that the relationship is not linear. And remember: high internal resistance is what causes heat buildup (and potentially fires if you are not careful), during recharge. So, if you attempt to restore your over-discharged LiPos, YOU take full responsibility of what happens next.

    Having said that, I’ve never had a problem. The only battery that really concerned me was the one at ~0V/cell, so I really watched it carefully, and I charged it especially slowly.

    Step 2: You’ll Need a Smart Charger

    I’m not going to go into the details of LiPo balancing chargers, but you’ll definitely need a nice charger that can balance multi-cell packs and which has the ability to control the charge current.

    Here are some links to get your started:

    Note: if shipping speed and customer service are a high priority, just jump straight down to #4 in the list below to look at the Amazon prime LiPo charger options in the search results. 1) I highly recommend this charger; it works great and has an outstanding value. Comparable chargers to this at many other retailers cost at least 2x more. 2) Turnigy Accucel-6 50W 6A Balancer/Charger w/ accessories. also an outstanding, and dirt-cheap, yet highly functional Smart charger. Excellent value; however, it requires an external power supply, such as this: Hobbyking 105W 15V/7A Switching DC Power Supply. 3) general list of chargers; be sure to READ THE REVIEWS!

    4) And last but not least, don’t forget Amazon! Here’s the results for an Amazon search for LiPo Charger. Check this list out for sure, as you get Amazon’s excellent shipping speed and customer service too!

    Step 3: Important Instructions Just Before You Begin Charging the Over-discharged LiPo

    LiPo-safe charging bags can be purchased in many places, but Amazon always has a good selection and super fast shipping, so take a look at Amazon’s search results for LiPo charge bag here.

    Step 4: Begin the Charge (LiPo Is

    Example: for the LiPo battery shown at the top of this instructable, a 1/20 C charge rate would be 1/20 x 1.3Ah = 0.065A. This is because the battery’s capacity, as stated on the label, is 1300mAh (read as mili-amp-hours), or 1.3Ah (read as amp-hours). So, a 1/20 C charge rate is 1/20 of 1.3, or 0.065A. A 1/10 C charge rate is 1/10 x 1.3 = 0.13A. Note that although some Smart chargers can charge at currents as low as 0.05A, many cannot charge at a rate lower than 0.1A. If you cannot set your charger to charge at a current as low as you’d like, simply choose its lowest setting possible, and carefully monitor the battery during the charge.

    Additional Charge Setting Notes: recharging a LiPo below 3.0V/cell may require using a NiMh or NiCad charger setting on the LiPo batteries, as most Smart chargers have safety features which prevent a user from attempting to charge a LiPo which is below 2.5V/cell, as this can be dangerous if a standard charge rate is used. Since all we are after is setting a low (and safe) constant charge current to get the LiPo back up to a safe charge level, using a NiMH/NiCad setting is fine until we get the battery 3.0V/cell. WHEN USING AN NIMH or NiCad SETTING TO GET THE LIPOS ABOVE 3.0V/CELL, NEVER LEAVE THEM UNATTENDED. You should not leave them unattended because the NiMh/NiCad end-of-charge detection method is not compatible with Lithium based batteries, and if left on the charger until full, the end-of-charge state will never be detected and the LiPo battery will be overcharged until it (likely) catches fire and destroys itself.

    Step 5: Next Charging Steps

    Once above 3.0V/cell, you may optionally increase the charge rate to 1/10~1/5 C rate until the LiPos are ~3.7V/cell or higher.

    You may stop holding the battery/constantly feeling it at this time, and place the LiPo in a fireproof container or LiPo-safe charge bag at this point, if desired.

    Once above approximately 3.7V/cell, you may optionally increase the charge rate again to 1/2 C rate until they are full (4.20V/cell).

    Step 6: Back to Regular Use

    Now, use the batteries as normal. The lower the battery was discharged, the more permanent damage it will have. If you use the battery (ex: to fly an RC airplane), and it works ok, then you can safely assume that subsequent charges at 1C are again acceptable. Watch it over the next few cycles, however, and ensure the battery does not puff during discharging or charging. This would be an indication that the internal resistance of the battery is still too high for normal use and standard 1C charge rates.

    In any event, due to having over-discharged the LiPos, you may notice a permanent decrease in their capacity (mAh) or maximum discharge rate (ie: they will likely have a reduced discharge C-rating, as noted by lower power output reduced performance), as the battery’s internal resistance will have been increased, and some permanent damage will exist. Additionally, the longevity of the over-discharged LiPo (ie: how many cycles you can get out of it) will have been reduced.

    Let me know how this works out for you! Be safe!

    Be sure to read my other articles here, especially this one:Parallel Charging Your LiPo Batteries

    I also highly recommend this one, called The Power of Arduino.

    =Other Articles I’ve Written That You May Be Interested in Reading:

    What are the Solar Battery Charging Stages?

    Home » FAQ » What are the Solar Battery Charging Stages?

    Solar charge controllers put batteries through 4 charging stages:

    What are the 4 Solar Battery Charging Stages?

    Bulk Charging Voltage

    For lead-acid batteries, the initial bulk charging stage delivers the maximum allowable current into the solar battery to bring it up to a state of charge of approximately 80 to 90%. During bulk charging for solar, the battery’s voltage increases to about 14.5 volts for a nominal 12-volt battery.

    Absorption Charging

    When Bulk Charging is complete and the battery is about 80% to 90% charged, absorption charging is applied. During Absorption Charging, constant-voltage regulation is applied but the current is reduced as the solar batteries approach a full state of charge. This prevents heating and excessive battery gassing. At the end of Absorption Charging, the battery is typically at a 98% state of charge or greater.

    Float Charging

    Float charging, sometimes referred to as “trickle” charging occurs after Absorption Charging when the battery has about 98% state of charge. Then, the charging current is reduced further so the battery voltage drops down to the Float voltage.

    The Float charge of a battery keeps the battery at maximum capacity throughout the day.

    Equalization Charging

    For flooded open vent batteries, an Equalization charge is applied once every 2 to 4 weeks to maintain consistent specific gravities among individual battery cells. The more deeply a battery is discharged on a daily basis, the more often equalization charging is required. Solar Charge Controller Equalization is for flooded, not for sealed, GEL, or valve-regulated batteries which can be damaged by equalization.

    Figure 3: Multi-Stage Battery Charging Diagram

    Although lead-acid batteries are the most common type of battery regulated by solar charge controllers, lithium batteries are starting to gain traction. Morningstar launched an Energy Storage Partner program that involves working with many lithium iron phosphate battery manufacturers to maintain the highest state of charge for their batteries and to help maximize battery life.

    The integration guides you can download provide custom solar charge controller voltage and time settings for absorption and float charging, and other information that you will need to charge your batteries safely and to increase their longevity. In addition to lead-acid and lithium, Morningstar solar charge controllers can also charge nickel, aqueous hybrid ion, and flow or redox flow batteries.

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