Parallel charing of lipos

[miniGranis]

Now that I have a more powerfull charger on its way, what do you experts say about charging lipos in parallel ?
http://www.rcgroups.com/forums/showthread.php?t=932319

I have used serial charging when running 2x 2S packs as 4S in my Revo but I am abit scared of parallel connecting lipos with different voltage to each other. A part of the idea seems to let the packs level out each other.

Any thoughts from you experts ?

[_paralyzed_]

good write up in rcgroups, everything he wrote is %100 correct.

no problems with parallel charging whatsoever

[MetalMan]

The only problem I have really encountered with connecting any batteries in parallel is voltage differences between the packs. In the thread he mentions parallel charging of packs with <30% charge left in them. So if Pack A has 5% charge and B has 30% charge and they are connected in parallel, there will be a current flowing from B to A. The current level will be determined by the IR of the batteries and the resistance of the wiring/connectors. IMO it's not a good idea to connect packs of such charge discrepancy together in parallel due to rapid charging of Pack A (unless you have one of the newer 5C+ charge capable batteries...).

[lincpimp]

Always seemed to me like parallel wiring of cells caused issues, but this was with MA packs, and during discharge. Not 100% sure if I would parallel different capacity packs together and charge them all at once, but the principle seems sound. Given the dangers of overcharging lipo (see Gee's thread!) I generally stick to charging individual cells in series, either wired as packs or multiples of packs. The current crop in internal balancer equipped chargers monitor each cell, and will stop the charge if there is an issue. So if you have multiple cells in parallel, a cell that will just not accept a full charge could place other cells in an overcharged state, not good. Yes this is unlikely, but I usually charge my packs unattended, so I like to remove as many variables as possible.

Seeing that HC has a 4 position charger that can handle 4 different battery types at the same time with 50watt output per for 100 bucks... Well if I had to charge alot of packs at the same time (especially packs that can only handle 50watts or less max charge rate) that would be what I would buy as it is more versatile. Just my 2 cents.

Imagine a 4s setup in an emaxx running a pair of 2s 5000mah packs. You could have 4 sets of packs, and 1 of those 4 position chargers and almost run continiously. You should get about 20mins out of a pair, and have 1 charged pair ready and 2 others on the charger at the same time. After you run the 1st pair let them cool, and run the second. Put the 1st back on the charger as you run the 3rd pair and you can run the 3rd and 4th while the 1st charges again. Even better if you ran a lower discharge load setup, of maybe a 2s vehicle.

[suicideneil]

I believe that the OPs charger has a suitable balancer board for dual lipos, upto 2x 4s lipos iirc. With that in mind, and assuming the charger is designed suitably, he should be able to wire the packs up either in series or parallel and then plug in the balance plugs and ht the charge button- depends how the balance board is wired up really- to see a pair of 4s lipos, or one 8s pack?

For the record though, if the charger and powersupply are powerful enough, and you have a suitable balancer, then charging in series & parallel will take the same length if time, so no real advantage either way from what I can see...

[miniGranis]

Thanks for the insights, I guess Lipos and shortcuts doesnt mix well.

As I dont want to move to the US (not even sure that the linc would want me in his basement) I will stick to one pack charging :-)