Battery problems
03-23-2016 | 05:53 PM
#1
Thread Starter
Tech Rookie
Joined: Feb 2016
Posts: 10
Battery problems
I've been having problems with my lipos or so I believe. Correct me if I'm wrong but shouldn't the voltage drop evenly down to my esc cut off voltage of 3.2v? Because my packs that is not the case. My venom 3s only a single cell drops way down around 2.8 while the other two are still around 3.5 I figured it was just a bad cell but the same thing happened to my Reedy 2s. Is this normal or is it bad for the lipos since they aren't supposed to be discharged below 3.0v?
03-24-2016 | 04:28 AM
#3
Thread Starter
Tech Rookie
Joined: Feb 2016
Posts: 10
Yes they were balanced, however they were both only at storage voltage when I ran them down if that makes a difference? This Is somewhat disappointing as both packs are basically brand new
03-24-2016 | 05:48 AM
#4
I can't imagine the start voltage being a factor. Balance charge them (I would watch them during the charge since there's such a big gap in voltages, use a lipo sack if you have one), then run them again for maybe 5-7 minutes or so. Then check cell voltages. If they still have this variance, I'd contact your place of purchase or the manufacturer.
03-24-2016 | 06:20 AM
#5
You didn't mention if you're in the habit of running these packs until the LVC kicks in.
If so, I suspect the low voltage cutoff is too low for those packs. You probably have one lipo cell that's weaker than the others. As you approach the battery being empty that one cell has already crossed the line. The ESC only measures total battery pack voltage, so the stronger cell(s) mask the low voltage of the weaker cell.
Klaymon's advice for testing is spot on. It's possible this cell has already become damaged. A test run that's half as long as you normally get out of a pack should leave the cells in a somewhat even charge state. If not, it's time for a new battery.
To prevent this, you can try raising your LVC to something like 3.4v. Also when the LVC kicks in you should stop driving. The bigger/heavier the vehicle and bigger the motor, the more potential for damage running after LVC.
If so, I suspect the low voltage cutoff is too low for those packs. You probably have one lipo cell that's weaker than the others. As you approach the battery being empty that one cell has already crossed the line. The ESC only measures total battery pack voltage, so the stronger cell(s) mask the low voltage of the weaker cell.
Klaymon's advice for testing is spot on. It's possible this cell has already become damaged. A test run that's half as long as you normally get out of a pack should leave the cells in a somewhat even charge state. If not, it's time for a new battery.
To prevent this, you can try raising your LVC to something like 3.4v. Also when the LVC kicks in you should stop driving. The bigger/heavier the vehicle and bigger the motor, the more potential for damage running after LVC.
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