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Electric Stunt => Gettin all AMP'ed up! => Topic started by: Perry Rose on April 12, 2023, 06:23:00 AM
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What would make a battery lose a cell? I have more than one battery brand, 4and 5 cells, three brands of chargers and, again today, one battery, a Turnigy, has a very weak cell. They are all charged in balance mode, no special charger programming.
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I cannot speak to the technical but I have a similar problem with mine. I have a 4 battery TP set that is about 3 years old and I am starting to get weak cells. What I have noticed is the balancing leads are developing breaks from the constant bending. I don't know if battery life is measured by time or cycles. I think mine are just getting old.
Ken
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What would make a battery lose a cell? I have more than one battery brand, 4and 5 cells, three brands of chargers and, again today, one battery, a Turnigy, has a very weak cell. They are all charged in balance mode, no special charger programming.
How many cycles?
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30 to 50 cycles on average.
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30 - 5 cycles is not alot. What will hurt them is running them down too low. You don't want to use more than 80% of the total mah capacity, 75% is a better place to be. For example, if you use a 2800 mah battery pay attention to what you put back in it. 2240 mah replaced on a charge would mean you used 80%. If you've been flying electric for a while you've probably tried flying on the same battery unintentionally. I'm guilty, that battery is usually toast...
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I divided the end voltage by the start voltage and got 90%. That's 19V divided by 21V. I'm not Reddy Kilowatt.
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Perry, There are lipo battery testers available than tell how much battery % is left. The battery checker will also tell if one cell is weaker that the others. I don't remember what brand mine is, I can check when I get home from work but I'll bet someone else will chime in with a good lipo tester sooner.
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Some general information on battery life and why capacity slowly gets less.
https://3dinsider.com/lipo-lifespan/
If you start with a new 2800 ma battery and use it for many cycles, the actual capacity may only be about 2500 mah. You then can only use 80% of 2500 instead of 80% of 2800 ma. As nosted, storing or keeping at near full charge and over discharging may rapidly decrease the capacity or may directly damage the cells.
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I divided the end voltage by the start voltage and got 90%. That's 19V divided by 21V. I'm not Reddy Kilowatt.
Voltage and percent charge are not linear. Voltage will not estimate % charge without a reference table and they don't always agree.
Some info here
https://www.helifreak.com/showthread.php?t=333661
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Some rules to live by:
No battery is going to last forever. They all have a limited number of charge/discharge cycles.
Cheap batteries, just like cheap engines, aren't going to last as well as good quality ones.
Cheap batteries also tend to suffer from spec inflation -- basically they'll claim a higher capacity just by moving the goal posts as far as what's altogether charged or altogether discharged.
LiPo cells, specifically, don't like to be over charged, or discharged too deep, and they don't like to spend too much time at either end of the charge curve. Which is why folks tend to obsess over the whole "storage charge" thing.
So, whatever you get, the more you pamper it the longer it'll last, and you may want to pamper the cheap cells a bit more. The closer you get to the ThunderPower end of the spectrum, the longer it will last.
50 cycles for Turnigy cells is kind of on the low side for battery life, but it's not absolutely horrible.