"CS" wrote in message
oups.com...

The last 250A continuous DC contactor I bought last year was around
£20. Vetus and Sidepower do this all the time.

But, successful operation depends on equal charging and discharging of the
batteries. In fixed installations, this is achived by making the lengths of
the connecting cables in the parallel sections equal, to make the resistance
in each branch equal. If you do this with relays, there can always be a
slight variation in contact resistance (we're talking milliohms here). This
will eventually shorten the life cycle of the batteries.

Meindert