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Battery Charger Reading Low Voltage

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Battery Charger Reading Low Voltage

Old 06-22-2020, 02:06 PM
  #1  
lbolsen
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Default Battery Charger Reading Low Voltage

Good afternoon everyone,

I am getting back into my RC Truck after 3+ years. I have used them maybe 4-5 times. My questions are:

- Are the batteries still good after sitting for so long? I do not think i discharged them the last time they were used .
- I am using a Venom Pro3 Charger and I am getting a low Voltage read on the charger. Do I just need to get them to a certain Voltage?
- I am using 2x 3s 5000 50C Venom batteries 11.1v.
- Will the charger automatically turn off when at full charge or how much time should they charge for?

Thanks in advance for the help!!
Old 06-23-2020, 12:47 PM
  #2  
ticedoff8
 
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- Are the batteries still good after sitting for so long? I do not think i discharged them the last time they were used .
LiPo batteries that sit for 3 years may still be ok - but it will depend.
If they were fully discharged or fully charged when you put them away 3 years ago, they are probably bad.
You can try to charge them and see. But, only charge at 1C (1C for a 5000mAh pack is 5A (or 5000mA)) for the first few cycles and then don't over-discharge them when you run them in the truck.
If you have been using the Low Voltage Cutoff (LVC) setting in the ESC as the gauge for run time, then I expect they are long gone, wore out and bad anyway.
The best way to tell if you are over-discharging them is to make a note on how much you recharge back into them.
If they are 5000mA batteries, then a full recharge back to 4.2v per cell should take no more than 4000mA (80% of 5000 = 4000).
If a full recharge takes more than 4000mA, then you have to run the truck for less time or less load.
The LVC is the ESC "last resort" to prevent damage to the packs. If you hit that point regularly, the pack's are are getting more damaged every time you do that.
- I am using a Venom Pro3 Charger and I am getting a low Voltage read on the charger. Do I just need to get them to a certain Voltage?
That may mean the voltage on the pack is too low for the charger to safely begin to try and recharge it.
Checking them with a volt meter on the main discharge lead is not good enough. While a 3S LiPo should be in the 11v to 12.6v range on the main discharge lead, the charger checks the pack's individual cell's voltage through the balancer lead and compares that to the voltage on the main discharge lead.
A pack may read 11.1v on the main discharge lead, but one cell could be much lower while the other 2 are closer to "normal" (eg: C1=4.0v, C2=4.1, C3=3.0). That would be a bad pack because Cell #3 is way below its lowest safe voltage. And, there is no way to resurrect that 1 "bad" cell.
And, if you did not hook up the balancer lead when you tried to charge them, 11.1v is pretty low anyway.
- Will the charger automatically turn off when at full charge or how much time should they charge for?
Never charge a Lithium battery pack based on time!

Always charge a multi-cell Lithium battery pack with the balance lead connected to the charger. Use the charger's "automatic cell count detection" and only use the charger's balance charge option.
If you do it this way, the charger should turn off automatically
This will let all the cells in the pack reach full charge (4.2v) without over-charging the ones that reach their peak sooner.

If you charge based on time, there is a real good change that 1 or 2 cells will reach peak sooner and start to heat up. And, at a certain point, those cells will catch fire.

Last edited by ticedoff8; 06-23-2020 at 01:15 PM.

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