What is resistance when balance charging?

[heli227]

I am using http://www.ebay.com/itm/Blade-nano-c...-/400832321412 to balance charge 6 1s 150mAh batteries.

It seems to be balancing and charging. But the charger shows a resistance of 640 m ohm. Is this a safe value? Does it indicate a problem?

FWIW, the charger (HiTec X1 touch) manual has a picture of a 6s pack being charged with a resistance of 85 m ohm.

[LubeMan1]

Your Batts are probably getting tired and the ir is really going up. Which is close to end of life.

[RedOctobyr]

Don't read too much into it.

Smaller-capacity cells have higher IR. 150mAh cells are very small. The 6S pack for the picture is probably quite a bit larger.

Remember that you are series-charging with that cable. When charging cells in series, their IRs add.

When charging cells in parallel, however, their effective IR is reduced (if charging 6 cells in parallel, the measured IR would be 1/6 that of a single cell).

Also, measuring the IR of batteries that don't have separate main & balance leads is difficult to do accurately. The current flow involved in the measurement also causes a voltage drop through the wires, which is included in the IR measurement. Batteries with separate main and balance leads allow the charger to more effectively ignore this voltage drop in the wires.

[heli227]

Originally Posted by RedOctobyr

Don't read too much into it.

Smaller-capacity cells have higher IR. 150mAh cells are very small. The 6S pack for the picture is probably quite a bit larger.

Remember that you are series-charging with that cable. When charging cells in series, their IRs add.

When charging cells in parallel, however, their effective IR is reduced (if charging 6 cells in parallel, the measured IR would be 1/6 that of a single cell).

Also, measuring the IR of batteries that don't have separate main & balance leads is difficult to do accurately. The current flow involved in the measurement also causes a voltage drop through the wires, which is included in the IR measurement. Batteries with separate main and balance leads allow the charger to more effectively ignore this voltage drop in the wires.

OK, thanks for the info!