LiPo storage Voltage
02-09-2010, 12:00 PM
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LiPo storage Voltage
Im a noob on what voltage you should have in the LiPo batt for storing long times between use.
I have read that they shouldn't be @ full 12.6 v. What is best? And how long can you safely have a full charge in them ?
Thanks , RM
I have read that they shouldn't be @ full 12.6 v. What is best? And how long can you safely have a full charge in them ?
Thanks , RM
02-09-2010, 12:16 PM
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RE: LiPo storage Voltage
Because of the way LiPo's work, you really cannot go by the voltage levels.
In effect LiPo voltage decreases initially under load, then levels out for quite a long time, before the voltage curve drops off abruptly as they approach lower capacity.
Instead of using voltage, charge the pack up to full capacity, then discharge the LiPo pack by about 60% of full capacity.
So if you have a 2200mAh LiPo pack, charge it up FULLY, so you see 2200mAh or so being put back in, then discharge the pack removing about 900mAh of current.
LiPo's have a fairly slow self discharge rate, typically LESS than 5-8% per MONTH(!), so doing this gives you about 7 months of storage. You'll need to recharge the packs after 7 months or so.
You never want to let the LiPo capacity drop under 10% which is indicated by a corresponding and abrupt voltage drop under load.
Drop the voltage and capacity too much and you've ruined the LiPo packs.
In effect LiPo voltage decreases initially under load, then levels out for quite a long time, before the voltage curve drops off abruptly as they approach lower capacity.
Instead of using voltage, charge the pack up to full capacity, then discharge the LiPo pack by about 60% of full capacity.
So if you have a 2200mAh LiPo pack, charge it up FULLY, so you see 2200mAh or so being put back in, then discharge the pack removing about 900mAh of current.
LiPo's have a fairly slow self discharge rate, typically LESS than 5-8% per MONTH(!), so doing this gives you about 7 months of storage. You'll need to recharge the packs after 7 months or so.
You never want to let the LiPo capacity drop under 10% which is indicated by a corresponding and abrupt voltage drop under load.
Drop the voltage and capacity too much and you've ruined the LiPo packs.
02-09-2010, 04:22 PM
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RE: LiPo storage Voltage
thanks , but I don't understand clearly. I have a volt meter only. I can't tell if 900 mah has been taken out of a 2200 mah battery. Do you mean that the Lipos should be stored with 60%
charge and you can't tell by volts?
charge and you can't tell by volts?
02-10-2010, 12:47 AM
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RE: LiPo storage Voltage
ORIGINAL: obsbob
thanks , but I don't understand clearly. I have a volt meter only. I can't tell if 900 mah has been taken out of a 2200 mah battery.
thanks , but I don't understand clearly. I have a volt meter only. I can't tell if 900 mah has been taken out of a 2200 mah battery.
RC Voltmeters for NiCD, NiMH use feature a load resistor circuit, so you can test the packs under load.
For LiPo's a typical load means nothing, as the voltage curve is VERY flat, unlike NiCD's and NiMH packs.
ORIGINAL: obsbob
Do you mean that the Lipos should be stored with 60%
charge and you can't tell by volts?
Do you mean that the Lipos should be stored with 60%
charge and you can't tell by volts?
You store them with 50-60% of their rated capacity, and the best way to do so is to watch what you are drawing from the pack or what you are putting into it.
Computer controlled chargers permit you to monitor this.
OK, I got it. Thankyou very much.
Sorry for bugging you if I did. You really seem to know your stuff.