A LiPo battery can last for years, but that is not how its life expectancy is measured. A battery life is determined by the number of cycles and how it is used. A higher quality, well treated battery will give you between 300-500 cycles if you follow the manufacturers recommendations .
You can get up io 1000 cycles from a LiPo if you use a balancing charger, and follow the 80% rule. If you have a 2000mah 7.4 lipo pack, you should never draw more than 1600 mAh out of the pack (80% x 2000). Over-discharging a battery is the most common problem that shortens their life and causes them to puff. The manufacturers recommend a 3.1v per cell minimum voltage rating. If you follow the 80% rule, the number is much higher then that; it’s about 3.7v per cell. Close to the end of your flight, fly up-wind. That way, if you feel the power start to drop, cut the power and glide land your plane. Never use a low battery and you will see a lot less puffs.
You can continue to use a battery after it has puffed a little. I have used puffed batteries for over a year after they started puffing, most continued to work almost like a new battery. The puffiness isn’t gas, do not puncture the covering. The puffiness is the materials the battery is made of are beginning to swale (expand). A battery will only puff if you misuse it by overheat it, this shortens the batteries life and decreases its capacity. The best you can do, is make sure you set up the charger correctly, use a balancing charger, and use the battery without overheat it. Always charge on something fire proof and babysit your charging batteries.
You CAN continue to use a battery after it has puffed
PUFF RULES, How to take care of your battery:
- A battery will puff up because of the speed or amount it was charged or discharged, or the way it’s stored. This will result in overheating and the laminates will begin to separate. Overheating usually occurs because;
- It was over-discharged
- It was used near or below its 3.1v per cell minimum voltage restriction. When you feel the battery getting low, cut the power, glide and land.
- It was over-charged
- A LiPo should never be charged to more than 4.2 volts per cell. For a 3 cell lLiPo, that’s 12.6 volts.
- Often, when charging with two wires (a non balancing change), the cell with the least resistance will charge faster than the rest. On a non balancing change, all the charger knows is to stop at 12.6 volts. That’s cell number 1 at 4.1 volts, cell number 2 at 4.0 volts, and cell number 3 at 4.5 volts. Cell number 3 is dangerously over charged, yet the charger did its job correctly. A balancing change always stops right at 4.2 volts per cell. It is for this reason I always do a balancing change; not only is it safer, but the batteries perform better and last longer.
- It was charged too quickly
- It was charge at too high of a rate. A 1800mAh is the same as 1.8Ah, a 1.8 amp rate is the maximum recommended rate (max) and will take 1 hour. I have seen many a fiends battery destroyed like this, I would never charge at this rate. I would use half this (.9 amps). It will take 2 hours but it is always safe, your battery will have a longer life, and the charge will always be problem free. “.2 amps” below max (1.6 amps) to half max (.9 amps) is safest; the closer to half, the longer the battery will last. Charging at less than half max has no advantages.
- It was discharged too quickly
- It is used in an application that called for a higher C (current) rating than the battery could handle. The 20c, 25c, 30c rating needs to be used with the “mah” rating to calculate the allowable amp draw. The number of cells does not matter. For a 5000mah 3s lipo is the maximum safe current a motor can draw from this battery. I like to have 5 to 10 amps above the motor’s max amp draw. You left it in the sun or a hot car A LIPO will puff setting in the sun or a hot tool box. Also, If you start a flight with a 120°F battery, you have very little head room before it puffs. Keep Lipos away from excessive heat.
The weather you fly in A LiPo will run a lot hotter on a hot summer day than it will in the winter. On a hot day, have at least 10 amps of headroom in the C rating. The internal resistance is at its lowest when they are ran with a starting temperature between 90°F (32°C) and 100°F (38°C), so this is where you will get the best performance. Do not start with a battery that is too hot or too cold.
You stored the battery empty Store a battery with at least half a charge. This way, when they self discharge over time, they will never fall below the 3.1v per cell minimum voltage restriction.
If you connect two batteries, they must both be fully charged to the same voltage. If you use two batteries on a Y-connector (a parallel connection), if they are at different voltages when you connect them, they will quickly equalize. This will cause them to both exceed their C rating and puff.