Figuring LiPo charge percentage

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tired bob - 11 Apr 2009 16:48 GMT

So far I know that a LiPo cell is 100% charged at 4.2 volts. I don't,
however, know what the danger reading is when discharging a cell. I
also don't know how to figure a 50% charge voltage for storage. I'd
appreciate an explanation of this basic stuff. Thanks kindly.
rr
Incidentally, I got several responses recently about a 3-cell battery
that had a sharp voltage drop. Mfgr agreed that the cell was bad and
is replacing the battery. Thanks to responders on that one.

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Chuck - 13 Apr 2009 02:59 GMT

Numbers from E-Station BC6 manual
LiPo (per cell)
3.7v Nominal
3.85v Storage
4.2v Max charge voltage
Minimum discharge cut off 3.0v (or higher)
Allowable charge rate 1C or less, unless battery spec allows for a faster
rate.
IC should also be used for discharge charge cycling

Charge time limit example
2000mah battery
1C=2A or 2000ma
2000/2.0=1000, 1000/11.9=84 minutes (This would result in the input of
~140% of capacity if the time was the charge limit.)

> So far I know that a LiPo cell is 100% charged at 4.2 volts. I don't,
> however, know what the danger reading is when discharging a cell. I
[quoted text clipped - 4 lines]
> that had a sharp voltage drop. Mfgr agreed that the cell was bad and
> is replacing the battery. Thanks to responders on that one.

Reply to this Message

tired bob - 13 Apr 2009 16:14 GMT

Thanks much -- that's what I needed.
rr

>Numbers from E-Station BC6 manual
>LiPo (per cell)
[quoted text clipped - 20 lines]
>> that had a sharp voltage drop. Mfgr agreed that the cell was bad and
>> is replacing the battery. Thanks to responders on that one.

Reply to this Message

Chuck - 16 Apr 2009 10:04 GMT

Not from the manual--
IF time permits, 1/10 C is a safe charge rate for most rechargable
batteries, LiPo included.
When you go to 1C or greater rates, it's really a good idea to monitor
battery temp.
Make sure you do NOT exceed the Battery Mfrs recommended charge rate,
whatever that might be.

> Thanks much -- that's what I needed.
> rr
[quoted text clipped - 23 lines]
>>> that had a sharp voltage drop. Mfgr agreed that the cell was bad and
>>> is replacing the battery. Thanks to responders on that one.

Reply to this Message

Model Forum / Radio Controlled / Air Models / April 2009

Figuring LiPo charge percentage