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[DPRG] connecting two batteries

Subject: [DPRG] connecting two batteries
From: Sluggy slugmusk at linuxlegend.com
Date: Mon Jul 23 09:06:37 CDT 2001

"montgomery f. tidwell" wrote:

> if i take two 9V batteries and connect them like:
>      +9V-|+9V-
> IIRC, i end up with 18V. what benefit do i get if i
> connected them like:
>      |+9V-|
>      |+9V-|

9V, but at the sum of their AH ratings. Actually, the state of charge of
both batteries and other factors affect the actual AH rating, but for
identical batteries, you get essentially twice the AH rating.

With no load, if one is lower charge or say one is alkaline and one is
zinc-carbon, the slightly higher voltage of the zinc-carbon will try to
charge the slightly lower alkaline. In the end, they will both die off
sooner that either alone, but under a load, you can draw their combined
current. Its much simpler to just parallel identical batteries and
disconnect each when not in use. :)


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