lipo's in series and why one would be different in voltage?
 

I have an Emaxx with 2- 7.4v 8000mah in series. Why is it when I do a full run on the batteries and check the voltage with my charger it is different between the 2 batts? one battery is lower than the other? usually by one volt.. Why?

MM ESC with built in cuttoff

I can think of 3 reasons:

1) One of the batteries/cells are on the way out.

2) The UBEC (if you have one) is only hooked to one pack (instead of across both of them).

EDIT: One more reason I thought of...

3) What do you have your cutoff set for? If it's 3v/cell, then try raising it to 3.1 or 3.2v/cell. Maybe that one pack is just not quite as strong so it dump a bit faster?

I have the Ubec hooked up like the Brian G chart, positive and negative to the mm esc on my deans

I posted this in the wrong forum I wanted to post this in the brushless forum, some someone move it?

Thanks

Actually, it probably should go into the General Electric section given the topic.

I wouldn't go by any of BrianG's charts since he doesn't know what he is talking about. :smile: j/k.

Anyway, then I would say that either one of the cells is a bit weaker and/or the cutoff is a bit too low. Try increasing the cutoff to 3.2v/cell. I assume you balance the packs when you charge them?

Do each of them have different numbers of cycles on them? If so, that could be your problem.

Can I just check you mean a whole volt or .1 of a volt....

Do you charge them individually? How many MAH does each battery take? Do they start at the same voltage?

Are they balanced to?

Lots of questions...

PS I can't believe i piped in after the above two... They know the meaning of everything (at least related to RC)

This post never happened :whistle:

Should be able to check the volatge across the balancing taps without breaking them open...

Yeah, try and check the voltage with a multi meter at the balancing plug to see if there's one cells that lower than the others. Don't touch the multi meter probes together. 1 full volt is a big difference for lipo.

Have 2 sets of the same lipo's. It happens in any combination with the batts.

I will try and raise the cuttoff. They are brand new batts, and Yes it is one volt and not one tenth of a volt.