Questions about using inverter in van

nopeda

Newly Enlightened
Joined
Aug 26, 2013
Messages
10
Hi,


I had a little cabin boat with two trolling motor batteries that powered some LED lights and a small inverter that powered a portable DVD player. The batteries were in parallel, and I could stay out for three nights at least and had plenty of power, then charged them up when the boat came back to the dock.


Now I want to do something similar with a pair of gel type batteries in a van with a Whistler 1600 watt inverter and want to connect the batteries through a switch to the alternator so they can be connected to the alternator when I want to charge them and want to use more power to run a microwave, but then the switch can also disconnect and isolate them mainly from the starting battery when they're only using very little power to run the LEDs and portable DVD player.


A friend who does car audio competitions showed me his setup. He ran an additional heavy cable from the alternator to the positive on the starting battery up front, and the negative on that battery has a good heavy additional ground to the frame. From the positive on that battery he has a heavy cable running back to the positive on one of his two gel batteries which are in parallel. From that terminal he has a cable to the positive on his amp, which would be the positive on my inverter. From the negative on that battery he has a cable to the negative on his amp, which would be the negative on my inverter. He also has a cable from that battery's negative grounded to the frame.


With the little boat setup it was pretty easy. Two batteries in their own world with no frame grounding and a little inverter drawing little power. But with the new attempt it's more complicated. In the diagram here:


http://www.qualitypowerauto.com/images/AuxBatteryWiring.png


the inverter batteries are powered directly from the alternator but don't go through the starting battery like his do, and it looks like it allows for a switch to disonnect them from the alternator which I do want to have. Is that wiring a better way for what I'm trying to do? The friend says it's better to connect all batteries together and they will even the voltage out between themselves, though the starting battery is not a gel type and is not similar to the other two.


Also I'm not clear about the grounding. Would the inverter batteries only need to be grounded when they're connected to the alternator, or should they stay grounded all the time even when they're isolated from it? From my ignorant position it seems that if they were grounded when not being charged by the alternator they could lose electrons into the frame and drain themselves down through the ground wire. Or is that not possible? I don't understand that part.


Thank you for any advice or explanations about this!
David
 
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