I have two 250 Mah Li-Po in parallel. Do I charge them at on the one cell setting, for the 4 v limit and 500 Mil for the curent ?
bobbdd

You need to charge each cell individually or connect the cells in series then charge the pack

I have wondered about this myself, as some of the commercially available Lithium Poly packs appear to have paralleled cells internal to the pack for higher capacities. We have always been told that charging NiCD and NiMH in parallel was a NO-NO. I suppose that the Lithium cells are more like a lead acid battery in this matter and charging them in parallel is OK. But I would sure like some assurance about this........... RJ

When you buy a 2p or 3p pack you have to charge them in parallel. Thats the way the pack is made. Does anybody know if there is circuitry inside the pack for charging? That the only thing I can think of that might make a difference.

I would think that the difference in a pre-made parallel pack is the fact that all of the cells are more or less identical and were initially subjected to the same charging and discharging conditions. Parallel charging should not be any problem unless there was an extreme imbalance between cells. Lithium cells do not show the same sort of voltage rollover upon completion of charge so a cell that is discharged less would draw less current than a fully discharged one. More of a problem with unbalanced nicads- when a cell reaches full charge, the charging voltage actually drops and the cell will start taking more current which could effectively cook it while a partly charged cell would draw less current.

Ross

You can't PEAK charge cells in parallel. That's why you don't normally see NiCd or NiMH cells used in parallel.

The constant current, constant voltage used on Lithiums works fine on cells in parallel. In fact you are much better off to charge two cells in parallel than series.

You have to charge LiPo cells to 4.2V each. If they are in parallel and the charger goes to 4.2V, then both cells must be at 4.2V. If the cells are in series then the charger will need to go to 8.4V. One cell could be 4.1V and the other 4.3V.

If Li-po batteries(or any other type) are hooked in parallel, provided there are no faulty cells, then each cell will be at the same voltage. Batteries will equalize when hooked in parallel. So, when you charge them each cell will draw current proportional to is charge state until all cells reach their full charge state.
Batteries in series can each be at a different voltage but the current through the string will be constant. They too will increase in voltage until full charge but there is a possibility of overcharging individual cells in the string. It is better to know what you have before you start charging. The best way is to follow the manufacturers instructions as they know what their batteries like to be fed for long life.