RC Battery questions.

[vrooom]

if i use 7x 1.2v AA 1600mah batteries, and join them up 7 of said batteries, that would make 11,200mah batteries running 8.4v
Would it work? and is it simple like that?

[Le TVR]

Not quite.

7 1600maH nicads in series gives 8,2v @ 1600maH

If it was possible to wire the nicads in parallel (dont do it!) that would give 1,2v @ 11,200maH.

Parallel connecting is only really possible with LiPo batteries.

[Philbes]

Should that 8.2V be 8.4V? Or is a 'bit' of volts lost when connecting batteries in series?

[Davi]

Le TVR said:

If it was possible to wire the nicads in parallel (dont do it!) that would give 1,2v @ 11,200maH.

Parallel connecting is only really possible with LiPo batteries.

this one always me

the only issue with Nicads is the low internal resistance can result in very rapid charge / discharge from one battery to another - as long as you have batteries of the same age and condition then I don't understand why you can't connect them up in parallel - in fact I have several packs that are exactly that, and have never had a problem with them. About the only precaution I use is a cell balancer.

[Le TVR]

Ah yes, should have written 8,4 v

I dont have a problem with running parallel Rx packs (NiMH) and they are charged separately. Wouldnt be happy with doing the same with flight packs though - although virtually everything I use now is LiPo.

NiCads (and NiMH) use a charge technique that looks for a voltage dip to know when they are fully charged. Whereas LiPo uses an absolute voltage value. Therefore with LiPos you know that the charged packs will have the same voltage. With NiCads this voltage is 'unknown' and could result in significant current flow when you parallel the cells.
For example your NiCads have a difference of 0,040 v
Internal resistance is 4mohm.
That gives a current of 10A when you parallel them