Li-Po charging ?

Being new to Li-Po's I need to get things right ! Can anyone explain the following ..... I have a battery pack , I think it is 4 cell pack as it says 14.8v 4S rated at 2200mAh , but I have read that a cell is 4.2v which does not seem to add up ? 4 cells at 4.2v = 16.8v; or 3 cells at 4.2v = 12.6v . If anyone can point me in the right direction it would be appreciated as I do not want to charge incorrectly !!!

Hi Gary.

Lipo pack voltages are normally designated by taking the average cell voltage, typically 3.7v per cell. So 4 times 3.7 is 14.8v.

4.2v is the normal maximum cell voltage for lips. 3.0v is the normal minimum cell voltage under load.

Hope that helps. If you need anything else explaining, give me a shout on Sunday. I'll bring my blackboard and some coloured chalks

you've been waiting for that opportunity

Gary,

The average isn't the average of the four cells added together and divided by four.

Its the nominal 'halfway' voltage between fully charged and fully discharged. As Andy states fully charged each cell = 4.2 volts and fully discharged = 3.0 volts

Each cell in a pack should have the same voltage give or take a little bit. This is the purpose of the balancing lead. It is important the cells are 'balanced' so the lead should always be used when charging

Thanks for the info. chaps, I have some extra wires with a connector on the pack (+,-, & 3 white) so I take it they are the balancing lead ? If that is correct I take it that I will need a new charger, even though mine is ok for Lipo it does not have a balancing lead connection .

Yup

Thanks for the very concise reply Tim! I will try & get a new charger tomorrow ! See you Sunday

Sorry I did not make St Asaph on Sunday , hope it went well. I have got a new Lipo charger with balance & it worked well until.... when connected to the speed controller there was a bang & something in the controller went up in smoke ! ( think it was a capacitor) I have now got the speed controller replaced & am now waiting to get the jet in the air !

Hi Gary for the money these are hard to beat but not many left in the uk HKing

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=57969