Using an isolator and solar sources

[meyermobile]

I know there is a lot of information about having an isolator unit alongside a solar charger and how they don't charge as efficiently and over charging...

Here's my idea: when the bus is running the isolator runs current to the battery. Could this same current power a relay that would turn off the solar charging? Then when the vehicle is turned off the solar will resume charging?
By the way, I'll be running that wire from the isolator about 15 feet. Recommended gauge to the battery?

Setup is 4x 6v 220Ah, = final output 12v @ 440 Ah

Final arrangement is different than the picture (and different location for that matter), I'll be venting the box through the floor with a continuous low draw (.06 Amp 12v fan) since they are a acid batteries. Ignore my silly colors, was trying to explain something to a friend.

[Defjr333]

Unless you drive ALOT you will get minimal benefit from the alternator. In my setup of 1.2k watt of panels i would likely get more from it than the alternator even when driving. BUT I will be installing a charge loop from alternator to coach bank for EMERGENCIES only, on a keyed relay(charge if all other options gone/ and, or if start battery dead, can start from coach).If you do still decide to use charge from alternator, I recommend a DC to DC multistage charger to maximize its benefit and extend your battery life. Alternators dont tend to like deep cycle batteries as they have slightly diff voltages.
Doug

[meyermobile]

Originally Posted by Defjr333

Unless you drive ALOT you will get minimal benefit from the alternator. In my setup of 1.2k watt of panels i would likely get more from it than the alternator even when driving. BUT I will be installing a charge loop from alternator to coach bank for EMERGENCIES only, on a keyed relay(charge if all other options gone/ and, or if start battery dead, can start from coach).If you do still decide to use charge from alternator, I recommend a DC to DC multistage charger to maximize its benefit and extend your battery life. Alternators dont tend to like deep cycle batteries as they have slightly diff voltages.
Doug

That's a lot of sun power! I've only got a 100w charger, and a 10 amp 120v charger, when I'm plugged in.

I guess this could lead to another question. Could the charger be set up to turn off solar automatically through a relay when plugged in? Again, so I'm not getting voltage from two places.

[Iceni John]

Originally Posted by meyermobile

That's a lot of sun power! I've only got a 100w charger, and a 10 amp 120v charger, when I'm plugged in.

I guess this could lead to another question. Could the charger be set up to turn off solar automatically through a relay when plugged in? Again, so I'm not getting voltage from two places.

I have just over 2kW of PV panels - I see no reason to charge the house batteries from the alternator while driving because the panels are still generating useful power whether stationary or at 60 MPH. They actually may be more efficient while driving because they are cooled better! Use the alternator only for the start batteries: that's what it's designed to do.

I do have a pair of Blue Sea switches to connect the house battery banks to the starter, but that is just to boost the start batteries in cold weather, not to charge the house batteries while driving. I would be worried about overloading the alternator if I wanted it to charge 900aH of house batteries: my solar charge controllers can push up to 120A into the house batteries, but the 160A alternator shouldn't be used continuously at more than half its rated capacity to prevent it overheating.

John