[Boatanchors] off-topic: Batteries for a UPS

[Mike McCarthy, W1NR]

Ron Hunsicker wrote:
> Hi all:
>
> Since some of you likely run remote locations with batteries, I 
> thought that you might have a ready answer for this (off-topic) question:
>
> The batteries in my UPS have died.
>
> Rather than replace the pair of internal batteries, is it possible to 
> use a rather larger battery that I install behind the UPS?
>
> Hopefully, I will have much more run time for my computer if the 
> utility power is interrupted for a many fewer $$ than a dedicated UPS 
> with a larger capacity.
>
> Surely, if the UPS is called upon, recharging will take rather longer.
>
> Are there any other concerns?
>
>
> Thanks,
>
> Ron
>
It depends a lot on the UPS.  In the 2006 ARRL Handbook, there is an 
article about converting one to a backup/portable power source.  The UPS 
should be able to charge larger batteries.  Just get the same voltage 
and number of cells, but larger amp hour rating and make extensions for 
the connections.  The only concern I would have is going too large on 
the batteries might crowbar the charging circuit from too much current 
draw when the batteries are drained.

Mike, W1NR