-Havoc-

I have a Maxamps 8000HV 11.1v battery. While my Hyperion 720i charger was charging it, the voltage got to 12.6. Is this dangerous or normal? Because afterwards, the cells were between 4.10 and 4.20 and the charger had to balance the pack when charging was finished.

Is it necessary to let it balance down to 11.1v after charging or can I just run it?

Trips

iTrader: (16)

Sounds completely normal. A single cell "3.7" LiPO will come off the charger at 4.2 when fully charged,. a 2 cell "7.4" comes off at 8.4 when fully charged.

A three cell 11/1 coming off at 12.6 is what you should expect to see when everything is working.

Duster_360

iTrader: (21)

To get all your 3S can deliver, you want it as close to 12.6v as possible. Max charge for lipo cells is 4.2v/cell. If your 0720i works like my 0610i does, it'll do most of the balancing while its charging. When charger beeps, its finished - I don't let it sit there and let balancer continue. If you just balance, it will just lower the cells to the lowest voltage on any cell.

-Havoc-

Great, thanks guys, was getting scared when I saw it go over 11.1v and into the 12v range.

Duster_360

iTrader: (21)

Lipo is confusing cause there are 3 voltages tossed around. The 3.7v is called the "nominal" cell voltage - this is supposed to be cell voltage under load or during discharge. Then as you now know there is a max cell voltage - 4.2v/cell. Cell can be damaged if charged above this max value. This is why there is a special charging protocol for lipo - CC/CV, the CV part of the lipo charge routine protects against overcharging.

Last there is a minimum cell voltage to not go below when the cell is discharged, lipo manuafacturers actually list this as 2.7v/cell. RC useage generally considers this to be 3v/c. There is some diff here based on the quality of the cell - the better ones will go to 2.7v and not swell or puff. A cheap lipo cell will puff like crazy and is finished.