Battery isolator question... With solar

Hi,


I have a van conversion I am putting together. I put a topper on it and also put 240W of solar on the back. The backup battery is also in the back, the battery that will run the lights, inverter, but not start the van. I also have a hitch winch that uses that battery for winching backwards (So the battery has to remain in the back.)

I have a SurePower 3202 battery isolator. It has input from alternator one, and two, and output to battery one, and two.

I have run a heavy gauge wire from the starting battery to the isolator. The issue here is that I want the solar to charge both batteries. It's almost a ten foot run from the front to the back and calculated that's .7 voltage drop. The solar electrics come together in the back, that is where the panels are.

I originally though maybe I could run the solar output to the alternator 2 input, but have them connected together. But, then the isolator would think there's voltage going to the alternator 2 and possibly connect it to the starting battery, which is not isolating it from inverter drain.

If I run the solar to the isolator as alternator 2, then I do lose some voltage in that run, which I really don't want to do.

the instructions do not say if the isolator has a signal from alternator 1, if it goes to both batteries. Or if it has a signal from alternator 2, if it goes to battery one, and battery two.

Bottom line, I would like to have both batteries charged by the alternator, and both batteries charged by solar... But if the back battery dies, I do not want the front starting battery to die, too. I am not sure if it is worth the voltage drop to run the solar output voltage all the way to the front where the isolator is located. Any help is appreciated!

OK, I sort of follow that.

Can you give us an idea of why you want the solar to charge the vehicle starting battery as well? if I understand correctly, you are not expecting the vehicle starting battery to provide power for the coach. Are you planning to leave the vehicle for months at a time without starting the engine? Is that the only reason for having the solar charge the vehicle starting battery?

The answer is yes... I would like the starting battery to be trickle charged as well when the van sits. Also in an emergency situation I *may* end up using the starting battery to power the inverter as well, but that is not likely- however it is possible. Then I would have to wait until the sun recharged both in that situation before I could start the van again.

Would something like this work for you?

https://www.amazon.com/Sunway-Solar-Maintainer-Motorcycle-Snowmobile/dp/B06WP95W51

Frank B said:

Would something like this work for you?

https://www.amazon.com/Sunway-Solar-Maintainer-Motorcycle-Snowmobile/dp/B06WP95W51

Click to expand...

It might yes!

I was wondering about possibly running a line to the starting battery with a diode so the current only goes one way...

Are you concerned that the solar panel may discharge the vehicle battery after the sun goes down? It won't. A solar panel is itself a sort of diode.

Use the solar to charge the house battry.
Then you have two options
ONe (suggested) using the current isolator add a Trick-L-Start
Two. Switch to an Intellitec Battery control system with BIDIRECTIONAL isolator (BIRD) this system lets either or in your case ANY charging system to charge all batteries.

Thanks, John. I think that is what OP was looking for to begin with. Do you have a link or recommendation on a brand?

I too think that a trick-l-start is the best way to go

I have never heard of the trick-l-start, it doesn't need ac power? How does it work, a dc-dc converter to ramp up the voltage? Witht he solar power it should work well indefinitely, that sounds awesome, and it's not too expensive either, wow thanks for the recommendation!

I think what I will do is run the one wire from the front underhood compartment to the auxiliary battery output and to the coach battery, that way the alternator will charge it and the starting battery, but the coach battery won't draw down the starting battery. Or maybe just a high current disconnect so I can use the starting battery in an emergency... I just don't want to run 2 heavy gauge wires to the back. Have a "Camping" setting on the disconnect that disconnects the starting battery, and a "Storage/emergency" setting that connects both batteries... That's all I can come up with right now... Would the trick-l-charge still work in that situation?