[RE-wrenches] unique battery bank design question

[Hugh]

At 19:39 -0400 1/9/11, Jason Szumlanski wrote:
>Sorry - I missed the 4 days part of your post. I'm not sure where you
>came up with 4 days - sounds kind of arbitrary.

Any chosen time is arbitrary.  Maybe I should have chosen a month. 
700 amphours.  Dead flat 12 volt battery.  I often use 4 days in the 
design of stand alone battery systems.

>
>I'd be interested to know if it makes any difference at all if you tap a
>12V load only when there is a 48V charging source present (assuming the
>charging source current is significantly greater than the load).

Not really because the other batteries get 1 amp more charge, and 
will reach the point where the current is limited by the 48 volt 
controller, whereas the one that is on load will not get properly 
charged up.

>  Assume you want to run a small 12V fan only when batteries are charging.

Then it's maybe only on for 25% of the time and it takes 4 times 
longer for everything to go pear shaped.
>
>Another option I've been reading up on is a Battery Equalizer/Battery
>Balancer.

This seems like a valid solution, yes.

best wishes,
-- 
Hugh Piggott

Scoraig
http://www.scoraigwind.co.uk