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LiPo battery packs in parallel

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Ron:
Thanks Dave,

Yes, I've been in electronics all my life so no bother with the buckets of water  :lol:  :lol:
But don't know much about the chemistry of LiPos, and knowing their potential for dishing out the current I was worried about huge currents out of one and into the other, before they balanced out.

Not sure, overall, if it's a good idea.
Maybe we need an electronic switch that can detect the falling voltage level of one and switch to the other.
(Thinks.. :?:  :?:  - marketing idea  8) )

A six pack?
Would that make it 6P ?
Or does that come later :lol:

DaveMc:
Ron,

Yes I had a 6S 1P evening last night. :)

I think so long as you make sure both packs are individually charging and discharging equally, and that your paralell harness is rated to handle the potential amps involved all should be safe.

What we need is an ESC with a Dual input and breed that with Balance charger. :)

I might hook up a couple of packs in paralell myself. My 50" Edge used Lipo's and I am getting pretty tired of landing after 5min... So I am trying to avoid buying more Lipo's and just use the ones I have.
Lipo's are a bit of a pain in the arse to store and manage and I can't see myself trying to maintain any more than the 6 packs i have now.

Go for it Ron, it will be fine.

D.

Happy Days:
Dave,

The harness won’t be handling any more current than it would with a single pack. Just that each battery pack is giving up half as much as it would, so it'll run twice as long. Think about it………The motor isn’t pulling any more current, it’s just running for a longer period.
So the same cables that are used for a single pack would be fine.

K.

Aidan:
Yep, What Dave said.

You can connect packs of the same series cell count in parallel but they should be close to the same charge state when you connect them as they will equalise and you don't want any high currents while that happens.

I've been charging my indoor lipo packs in parallel for a while now (Up to 20 at a time!) which works in the same way, just reversed. I make sure all packs are within about 0.2V before connecting them to the harness and leave the packs to equalise for a while before starting the charge. While checking the advisability of this method I did come across some figures for the sort of currents likely to occur when you connect packs of dissimilar voltage but I can't remember the figures and never measured it myself. I decided 0.2V was safe and went from there.

So, I'd suggest you check your packs are at similar voltage before connecting them to the harness and let them equalise for a short while after hook-up before use. Other than that you should have no problems. There's no reason you couldn't charge them in parallel too but you wouldn't be able to use the balancing function on your charger (if it has one) as it's the overall pack voltage and not the individual cells that will equalise voltage. If in doubt, charge separately.

Aidan

Ron:
Thanks guys.  :clap:
Yes I guess it's a matter of keeping an eye on fully charged voltage per pack.

Was thinking I might try a Schottky Diode to separate the packs, like this one.

http://www.westfloridacomponents.com/mm5/graphics/ds2/40CPQ060.pdf

And it will handle both packs.
But even so, you're still talking 0.5v drop at 20 amps.

Ron

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