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post #74 of Old 01-08-2019
texlan
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Re: Electric Conversion log for Kahleesea

Quote:
Originally Posted by mbianka View Post
Of course that's the way it is wired. My issue was with battery that was connected to the positive lead I'm able to monitor the voltage of each individual battery in the string at the helm. The one most positive in the string which is connected to the positive lead to the controller. It started dropping fast as I drew more current while the other three batteries showed pretty much the same voltage. The most positive battery quickly dropped to 12+ down to 11.8 and beyond. I had to start the generator and electro sail because of it instead of operating on battery alone. I think it might have some internal damage that shows up when higher amps are drawn from the battery bank.
I'm traveling on business so not a lot of time to post, but a quick note Mike -- The reason why parallel wired batteries can suffer charge/draw asymmetries is because each battery is connected to the loads by a different length of wire. Due to that, the voltage drop/resistance of the lengths of wire connecting them are different. The shortest-wired-battery is effectively on the least-resistance-path and gets the most charge (and discharge) current.

When wired in series, current through each battery is identical and has no other path, right up to and including when a weak/damaged battery becomes completely discharged and the other batteries in the string drive it into negative voltage (this is one way to set Lithium Ion chemestry batteries on fire (does not apply to LiFePO4, but you still perm damage LiFePO4 cells in this situation))

I think your particular circumstance was due to manufacturing defect or shipping damage to the bad battery.

Sean

Last edited by texlan; 01-09-2019 at 12:44 AM.
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