T&T: Adding batteries

[Peter Bennett]

Friday, January 19, 2007, 5:30:57 AM, Randy wrote:

RP> Last spring, before leaving Fla for the Chesapeake, I replaced my house bank
RP> of  four 6V gel cells.  Since we have a propane refer, the bank is adequate.
RP> Lately I've been suffering from amp-hour envy and am thinking about adding two
RP> more 6V gel's.  I know that in a perfect world, all the batteries would be the
RP> same age but that ain't gonna happen now and since my old house bank was 9
RP> years old when they were replaced, I'm thinking that its gonna be a long wait.
RP> If I add two more batteries now am I going to mess things up. Remember, my
RP> current system is adequate.  What say the group?

RP> Regards,
RP> Randy Pickelmann

Certainly, having all batteries of the same vintage and usage history
is idea, but I don't think you will cause any problems paralleling new
batteries with your old one.  I will, however, suggest that the
batteries should be wired so that you can turn each 12 volt pair on or
off individually.  Then you should test all the batteries periodically
by running on a single 12 volt set for a few hours - this should
quickly tell you if a set has failed - otherwise the failed set(s) may
be "hidden" until the last one fails....

I have twice (on different boats) mixed old and new batteries - I
didn't notice any problems in either case until I tried using the
older battery by itself, when I discovered that it wouldn't run
anything, so normally I was really only running on the newer battery.

-- 
Peter Bennett, VE7CEI    Vancouver, B.C., Canada
Lien Hwa 28 (AKA Polaris 30) "Sea Spray"
GPS and NMEA info: http://vancouver-webpages.com/peter 
Vancouver Power Squadron: http://vancouver.powersquadron.ca