Sunday, Oct 23, 2011 at 23:38
Hi Nick,
in a stock standard dual battery setup it doesn't make sense to have the solar panel wired to the battery (with or without regulator) during alternator charging.
That's because the battery voltage is limited by the alternator voltage setting.
Meaning that even though the solar regulator might want to push the battery voltage higher, it can't go higher because then the alternator would reduce its output current.
In order for the battery voltage to go higher in this scenario, the panel/regulator would have to be powerful enough to supply all running 12V loads of the vehicle.
Only an open ignition switch and/or isolation switch enables the battery voltage to go higher because then the solar current can only flow through the battery (and any loads connected to it directly/or through the solar controller).
But there's a technical solution which allows the battery voltage to increase beyond the alternator voltage during cruising, by means of solar charging current.
This involves wiring in series a special diode which allows bulk charging from the alternator, but prevents solar current from flowing through the vehicle's electrics, thus the battery voltage can rise to whatever level the solar regulator pushes it, while the alternator spins.
If you need details, just PM me.
cheers, Peter
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