To be fair, none of these bucket analogies are very good. But if you connected 2 identical buckets with different amounts to a single pump, and they were sitting on the same surface, I wager they would balance out. Connected to 2 separate but identical pumps perhaps not.

by the way: i don't know anything really about this electric stuff. i am just trying to look at it from a somewhat logical point of view, so it makes somewhat sense to me!:sweat:

from my understanding than, an unbalanced pack is not really a problem by itself. it only becomes a problem if the imbalance makes one cell go lower than the recommended voltage?! is that correct?

G

It's a bigger problem, at least in my opinion, if one cell goes over voltage, then the cell will burst into flames. With virtual certainty. That's the reason for balance charging.

Under voltage it may puff up, may not charge, if charged may then burst into fire, but not always.

i get it now...the charger measures the total voltage of the pack when charging...since one cell is super low, it will cause another one to get over full?! is that it?

thanks,
G

p.s. do i have to put taps on the a123 cells when i want to charge them with another charger, other than the one i am using now?

I built 5S and 6S pacs from a123s taken from Dewalt 36v power pacs. I would advise wiring them for balancing. Its pretty easy and the harness/tap I used was $2.25. It took me all of 30min to build a 5S pack including the balance wiring. These are supposed to last 1000+ or so cycles and in the interest of that longevity, I wanted to balance them.

I use a Hyperion 0610i balancing charger and there is always balancing activity when I charge my a123 pacs. I run a pr of 5S pacs in parallel so it is effectively a 5S2P pack - need that for run time, 2300mach is not a lot of capacity. These cells are indutrial in nature and were adapted to rc when plane guys figured out they were 30C capable, so I don't think they are as carefully produced as a rc intended lipo batt. There is prob more variation in manufacturing these than with something like a lipo cell at the Kokam plant.

You can charge a123s without balancing - you can prob get a few dozen charges before there will be enough imbalance to cause probs - but depends on how you're using them too - if you're pulling them hard, will see more imbalance versus easy duty. These cells can vent when they have major probs - have seen the pics and some just go bad - they quit holding voltage.

With my 0610i charger, its just too easy not to balance everytime. You can charge these at low rate and they'll stay closer to balanced. Guess a low charge rate gives cells enough time to lessen the impact of cell to cell differences.

Correct.

I should point out that this started with A123 cells, then went to lipos along the way. I’m not sure about the discharge thing with A123, my comments regarding over discharge were for lipos. Sorry for any confusion caused.

once again, thanks for the info...i am actually thinking about getting the Hyperion II 0610i duo...i like it a lot...

G

no confusion at all...thanks though for the concern...

the lipo info is as important to me as the a123 info...

G

i just picked up the pack i bought of ebay. its the same as the ones you see on the picture...i measured the voltage...3.76V...isn't that too low?!

thanks,
G

p.s. its a 2s2p pack

a123s right? Not prob - there's not really a min voltage issue with a123s like there is for lipo. Ask your seller for his advice on the low voltage, see what he says. Should charge and work fine, just been sitting for a while.

If thats a lipo @ 3.76v - yes, you've got a prob and it needs to be returned.

thanks Duster! i mailed the seller and told him i can try to charge it or i can send it back...he told me to charge it and if i doesn't work, to send it back...i charged it and it held 7.11V...i guess that is good enough?!:sweat:

thanks,
G

p.s. i need advice on a charger! hyperion duo or something else? what do you think?

Yep, you're good, 3.6v/cell is max for a123s and from there it depends on how accurate your charger is and how it does terminating the charge. Use it a few times and if it holds up, its fine.

If you're going to need to do 2 batts at once routinely - DUO II would be hard to beat. If you don't need the 2 at once capability, look at the Hyperion0610iNet or 0720iNet chargers. They're basically one half of a DUO with a little more output power. I charge my a123s at 10amps and even the 6S pacs are no probs. The 0610i does not have a real discharge capability - the 0720i does, thge 0720 can charge at 20amps (same output power limit though, 250watts), which may be handy if lipos start going 2C and up for charge rates - 0610i is limited to 10amps.

Charger selection depends on what you need/want to do and if you have plans that would require a new charger at some later point.

thanks for the advice, i will take a closer look at those chargers!

it always depends on what you are planning on doing AND on the mood you are in, ha ha. i have an e-maxx and a brushless 8T mmm combo 2200kv. i only have one 6s 5000mah and four a123 2s2p packs as of right now. i can run the 6s fine but if i want to run the a123's, i run 2 packs in series, as you know. same with the e-maxx. so right now, i would be charging 2 packs at the same time...until i get one or more lipos from china for 80 bucks/4s 5000mah pack. once i get one or more lipos, i am gonna have enough run time to satisfy my needs and wont need to charge at the track!
you know how it is, i can flip flop back and forth...

G

p.s. what about charging two a123's in series on a normal charger? is that an option?

have to get ready...heading to the track. i don't even know how much run time i am getting of these a123 packs, ha ha...

thanks again for all the help duster and everyone else!!!

G