how much imbalance is too much

[th3tick]

Charging a 6S 5000mAh pack today, it started off with an imbalance of .060, so I let it set on the TP-210V for an hour or so until it was .029 - below .030 as it says in the manual. I then started a 5A charge on my TP-1010C.

After a half-hour or so, I checked the imbalance, and found it at .088. I stopped the charge, and let the balancer do it's thing some more.

Two questions come to mind:

1) If the TP-210V balancer detects an excessive imbalance, can it tell the TP-1010C to stop the charge?

2) How much imbalance between cells is "too much", and I should be stopping it myself?

John

[Brent@paradise]

I don't have a TP-210V so can't help with question 1
But i am happy with 0.1V of inbalance.

Some Brand new batteries i have had have a bigger inbalance untill after a few flights.

[Pinecone]

From 210V instructions:

A: Imbalance under 0.03V: Yellow status LED “on” steady and red LED’s “on” for 5 seconds.
Normal charging, proceed as usual.

B: Imbalance 0.03 to 0.2V: Yellow status LED “off” and red LED’s flash for 5 seconds.
Charge at 0.3A to balance the pack or proceed carefully with up to 1A maximum charge rate.

C: Imbalance over 0.2V: Yellow status LED “off”and red LED’s flash for 60 seconds.
Battery may require repair. Keep battery plugged into the balancer until balancing stops.
DO NOT charge the battery until balancing stops.


So 0.088 volts is condition B, which says continue to charge at a reduced rate. But if this keeps happening, is sounds like a cell is going in that pack.

[th3tick]

From 210V instructions:
...

I did read that but assumed that was for when you first plug it in. I can't imagine having to manually monitor the charge, and if the imbalance goes to .030 or above, stopping the charge, drop it to 1A, and continue.

In fact, when I first plug in the whole thing, it drops the imbalance to .029, and doesn't do any more balancing at that point. Once the charger run, the imbalance almost always jumps above .030, and the balancer will then attempt to get the imbalance below .010, but not until I've started a charge.

This is the first time I've ever seen the imbalance go that high, but I've seen .06 before. Any other time, I've let it go, and had no issues. In fact, it would greatly concern me if I'm supposed to manually monitor the imbalance and stop it if it goes over a certain point. Heck, the charger itself won't even stay on the screen showing the imbalance but for about 5 or 6 seconds, so I'd be there poking the button over and over again for an hour.

[Pinecone]

If the balance gets that much worse while charging, then I would suspect a bad cell.