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# Inter-Battery Discharge

## Inter-Battery Discharge

(OP)
Assume that we have two automotive starting type batteries, one discharged to 10.5V and the other fully charged at 12.5V. 2/0 type SGX cable is used to connect them to a three-way battery selector switch, 10-ft for each battery. If these two batteries are connected in parallel by the battery selector switch, how can the discharge rate between the two batteries be estimated? It seems to me that this current could be quite high, but I haven't been able to locate an accurate method to determine just what this current might be.

Dave

### RE: Inter-Battery Discharge

While these are probably not quite the same as your batteries, the page does list the internal resistance which is the ultimate current limiting of the battery.

Using that value for each battery plus a comparable amount for the wiring and switch resistance would imply a current dump of around 200 A.

TTFN

### RE: Inter-Battery Discharge

(OP)
This is along the same lines as I was thinking, so I feel a little more comfortable with my data now. Now I just need to develope a method to test it. Thank you for your help.

-Dave

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