Are Zippy Lipos safe with a Castle MMM Speedy?

[pasan]

I use only Zippys in both my E-Maxx and E-Revo. I've bumped up the gearing quite a bit on the E-Revo sometimes to 22/58 and do a one or two speed runs a week, perhaps for about 5 minutes each session. The batteries have held up fine. I agree Zippys aren't the greatest by any stretch, but at the price they are an extremely viable alternative and perfect for bashing with proper gearing. The only issue I've been having with them is one of my 4S packs has a cell which holds about 0.01v less than the rest. I'm pretty anal when it comes to balancing, and need the tolerance to be +-0.005V

[BrianG]

Originally Posted by pasan

...The only issue I've been having with them is one of my 4S packs has a cell which holds about 0.01v less than the rest. I'm pretty anal when it comes to balancing, and need the tolerance to be +-0.005V

Are you sure that is a real issue? Balancers are not 100% accurate either. Even components with 1% value tolerance can easily introduce enough variance to account for 0.01v. Heck, even dirty balance connectors can cause an erroneous reading. I would measure each cell with a multimeter to be sure.

And even if the cells are 0.01v off, that's nothing to worry about at all. Believe me, I'm pretty anal about having things properly matched. If you are worried that a cell could get above 4.2v because of this, just set your charger CC/CV threshold to 4.15v/cell, if it supports this feature. You lose VERY little runtime. Actually, I have my Xtrema set to this value for this very reason.