Parallel Charging

[Peter Marsh]

Hi all,

Just got hold of this parallel charger that will cope with 6 batteries, so there are 6 battery connectors and 6 sets of balance ports.

Now, how can you tell which ports go with which pair of connectors? or can

you simply plug balance leads into any port?

[PatMc]

If they are parallel, the ports will also be parallel so it should be any with any. The batteries being charged must each have the same cell count in series.

Personaly I'd keep a sharp eye on this during charging. I may be over-cautious but I'd prefer to charge on an individual battery basis.

Edited By PatMc on 09/07/2013 17:31:56

[Peter Marsh]

Thanks for that,PatMc,makes sense, I guess.

My idea is to save some time at the field, but I don't envisage charging more than 2-3 batts at a time. I presume I'm limited in any case to the 6A output from the charger.

[John Olsen 1]

The problem is not so much the charging, it is the moment when you plug two batteries in parallel. If they have widely different states of charge, a large current will flow until they are equalised. So ideally you would ensure that all the batteries to be paralleled were at the same state of charge before connecting them. There are ways to do this by first paralleling them with some resistance but so far it has all seemed like too much trouble to me, and it will take time too. This would especially be so with the charger being limited to 6 A, unless your batteries are pretty small capacity. With 6A you can do one 3000mAh at 2 C or two in parallel at 1 C, which would take the same time anyway.

I think the best way to hurry things up is with a more powerful charger, I am using one that can do 40A if the source battery is 24 Volts, and twenty Amps if the source is 12Volts. I have only used the latter, and I can charge my 4200MAh packs in about twenty minutes by doing them at 2.5 C. (eg putting 10 Amps in) They are rated at 5C, so this gives a bit of a margin. That means that with two packs I can have a flight, chat with the guys for a bit, and then be ready to fly with the other battery. (With the timer set to eight minutes I am typically using 75% of the capacity of a pack.)

The other approach I quite like is to have more than one charger. Some of them have two built into one box, so you can independently charge and balance two packs at the same time.

John