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lipo's in series and why one would be different in voltage? |
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(#1)
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RC-Monster Carbon Fiber
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lipo's in series and why one would be different in voltage? -
12.03.2007, 05:38 PM
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 |
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(#2)
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RC-Monster Admin
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12.03.2007, 05:42 PM
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? |
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(#3)
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RC-Monster Carbon Fiber
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12.03.2007, 05:45 PM
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 |
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(#4)
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RC-Monster Admin
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12.03.2007, 06:10 PM
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.  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? |
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(#5)
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RC-Monster Mod
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12.03.2007, 07:07 PM
Do each of them have different numbers of cycles on them? If so, that could be your problem.
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(#6)
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RC-Monster Mod
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12.03.2007, 07:14 PM
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) |
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(#7)
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RC-Monster Aluminum
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12.03.2007, 09:34 PM
This post never happened
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(#8)
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RC-Monster Mod
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12.03.2007, 09:55 PM
Should be able to check the volatge across the balancing taps without breaking them open...
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(#9)
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RC-Monster Aluminum
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12.03.2007, 10:09 PM
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.
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(#10)
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RC-Monster Carbon Fiber
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12.03.2007, 11:30 PM
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. |
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