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Re: Battery flight packs, parallel charging?

| Here is the situation. I have 4 battery power packs, 10 - 3000 MAh sub | C cells at 12 volts. I normally charge them one at a time at about 4.5 | Amps for about one hour. Then when one is peaked, I have to replace it | with another pack and wait for an hour for it to peak. | | Repeating this 4 times and I have put in about 4 hours to get them all | fully charged. This is kind of labor intensive, disconnecting and | reconnecting. | | I wonder if I could wire a harness to accept all 4 packs in parallel. | Then would it take about 4 hours to fully charge them without | deleterious effects on each pack?

It won't work properly. The problem is that each pack will have slightly different internal resistances and voltages, so when put in parallel, one pack will get charged more than the others, and it may not even peak properly, grossly overcharging one of the packs.

If your charger can handle over 20 cells, what you can do is set it up a harness to charge two packs in parallel. Your charger will then shut off when the first pack peaks, so if both packs are approximately equally discharged, both packs will then be approximately charged.

You can then peak each pack at a lower rate if you need to make sure that they're completely charged.

It's not perfect, but it'll get your packs mostly charged in half the time.

Or you could just buy another peak charger. It'll probably cost a good deal less then all those packs :)

Reply to
Doug McLaren
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| "what you can do is set it up | a harness to charge two packs in parallel." | | Don't you mean charge the two packs in SERIES?.

Yes, of course. Thanks.

Reply to
Doug McLaren

You would probably get better results if you could wire multiple packs in Series for charging. That is if your charger can handle 20 cells or more.

Your last statement sounds like your wanting to cycle each pack 4 times, and finish in 4 hours.

If a Ni-cad pack is good for say 1,000 charge cycles and you cycle them 4 times after each use. Then you will only get 250 uses from each pack before all the charge cycles have been depleted.

Unless you meant you would like to be about to charge all 4 packs >Here is the situation. I have 4 battery power packs, 10 - 3000 MAh sub

Reply to
emcook

I realized my statements above do sound confusing, especially the second paragraph. By "Repeating this 4 times", it was meant to say if I charged each pack about an hour apiece. Since I have 4 packs, I'd need about 4 hours altogether. I hope I have it right.

I also forgot to mention the packs are composed of 10 cells of NiMH

3000 mAH cells and my charger can charge 1 - 14 cells. I've been charging each pack at about 4.5 amps.

I am wondering if the packs were to be hooked in series, wouldn't that make four 12 volts packs into 48 volts? And if four 12 volt packs are in parallel wouldn't it still be 12 volts?

Thanks for helping, Wan

Reply to
Wan

| I am wondering if the packs were to be hooked in series, wouldn't that | make four 12 volts packs into 48 volts? And if four 12 volt packs are | in parallel wouldn't it still be 12 volts?

Yes.

But as I mentioned before, in parallel you can't be sure that each pack will get an equal amount of charge. In series, you can -- each pack will have exactly the same number of amps go through it as all the others.

If you had a charger that could put out 60+ volts you certainly could put all four of them into series, but I'm not aware of any standard peak chargers that can do it. My Triton charger goes up to to 24 cells, and my Astroflight 110D can do 18 cells.

So, if you've got a Triton, you could charge two packs in series. An Astroflight 110D, only one.

Also note that putting all four packs in series will give you up to 56 or so volts. The OSHA starts getting worried at 50 volts. It's extremely unlikely that a mere 50 volts could kill you, but it is possible under the right (er, wrong) conditions.

(On the other hand, if you short out 60 volts worth of packs, it'll melt down fast and can very easily burn you or start a fire. But that's true with just one pack as well.)

Reply to
Doug McLaren

The GP Triton will handle 24 cells, so you could charge 2 of your packs in series. Cannot think of one that will handle 40 cells.

David

Reply to
David AMA40795 / KC5UH

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