2p charging
 

I plan on running 2 zippy 5000 mah packs in parallel in my maxx, and also want to charge them in parallel. Can I just wire them in parallel and only balance one pack, and switch which pack I balance every other time? Is there any way to balance both packs when charging 2p? Since I will run them 2p I want to keep the two packs at the same voltage at all times.

I do it with 2500mAh Zippy-R 4s packs, I made custom parallel balancer wire and charge it as 5000mah unit. Just sometimes split them and check voltage, and balance them sepparatly to get same voltages in cell safety reasons

You will have to have a custom harness made to balance the packs in parallel with one balance. Check out briang's sig, he has some diagrams there that you can play with. Oh, forgot to say "BALLS"

man, everyone's bustin my..... Ooooh! something shiny........

so if I just hardwire the pack leads and balancer leads from each pack together in parallel they'll always be balanced to each other, just like a purchased 2p pack, correct?

Yes, but I would make harnesses. Mainly cause I like to. Will you stack the packs and tape/shrink them together?

nope, riding on either side of the center diff on my e-maxx, motor mounted above diff for perfect balance, due to the placement harnesses would work better and look cleaner while the batteries are on the truck, I haven't done any wiring in some time, good excuse to buy a stripper. Oh, something to take the insulation off the wire might be a good purchase too..............

Hmm, I just pay the stripper per dance...

Wire strippers are great, I have dozens. I like to buy stuff...

you're right, renting sounds like a much better option, then I don't have to feed it.

i'm unclear how to wire the balance wires in parallel. i built 2 5s packs that are wired in parallel by connecting to 1 plug. looking at brian g's diagrams it looks as though I would have to have a 10 cell balance plug to make the balance wires in parallel. is this the case or am i missing something?

You need to do Y-balancer harness and Y-main wire

I just bought 2 these wires on 4s setup http://www.hobbycity.com/hobbycity/s...idProduct=5099
cut it in middle took every wire from two female and one male connector and soldered to Y. Made that with every wire, be sure that you paralleling exactly same wire do not twist them.
Same with main leads with Deans connectors.

Before charge be sure that every pack is discharged (i mean discharged to safe LiPo voltage which is close to 3V per cell but not less) and every cell on same voltage, balanced. If difference 0,01V its ok not terrible. Ideally every cell must be same voltage. Connect to your harness and charde as One big unit. Thas all.
Sometimes check voltage difference in every pack and balance (not charge) it sometimes separate.

I just spent about 10mins thinking about this (trying to determine what could go wrong with it, but it should work). You would make a harness for the two 5s packs such that all of the corresponding wires are in parallel, and are outputted to a single 5s balance connector. I drew up a quick thing to help demonstrate this:

If one pack is a weaker pack, won't this be dangerous ? I would charge the two packs together through the main charge leads to 90%, and then finish them individually on the balancer.

Actually, with the cells in parallel, each set (1 cell from each pack) of paralleled cells will try and stabilize at a voltage that equalizes them. Essentially, the balancer then will balance each set of paralleled cells as a single cell since the voltage will be equal in the cells.

However, while it should work fine, it would really be easier to just use 2 balancers and parallel the charging input into the balancers instead.

I cant confirm that actualy. Usualy after couple cycles I balance cells on every pack separately becouse notices that cells no not stabilize each other. If one cell is 3,5V and second paralel cell is 3,7V on avaraege shows 3,6V if both batteries connected parallel. Whats why i do it.
And if packs are same type and brand etc parallel using should do OK.
If they are not equal I am not recommend to doi it because difference in cells will rise and avarage can be OK but for example one weak cell will be over discharged.