AnswerID: 464165 Submitted: Sunday, Sep 04, 2011 at 09:25
Battery Value Pty Ltd
in a typical dual battery setup (with isolation switch/solenoid), solar energy can't be absorbed by the aux battery while it's being charged by the alternator (the solar current would just reduce the alternator current proportionally, but the sum of the two will stay the same).
So there's nothing to be gained during cruising, in terms of higher charging amps.
Different story of course when stationary.
Now the starter battery/alternator is electrically isolated from the aux, no need to put in an additional switch to prevent solar current from entering the starter battery.
And no, you can't do any damage to any components if you permanently wire the solar regulator to the aux battery.
In fact, this is what we recommend to our battery/solar customers.
But be aware that the solar regulator draws a small current, so if the system is left sitting around for months with no solar input, the aux gets drained slowly - so in this case you might want to pull the fuse in the positive leg to the aux battery.
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