Aux battery draining starter battery?

[vanagonforever]

I would love to understand why I am seeing this:

I bought the GoWesty aux battery kit for my Westy. I installed the kit using the instructions however I skipped the additional wiring at the fuse panel for now. I hooked up a type 41 battery under the driver's seat and tested it using a multimeter - it is receiving charge (goes to over 13 volts while the engine is on) and all looks well.

Everything looks good so far but then I remembered that I had a second deep cycle battery that wouldn't fit under the driver's seat. I hooked the positive of that battery to the positive of the aux battery as well as the ground thinking it would now get a lot of extra capacity. I then fired up the van and noticed that neither aux battery was getting charge (the deep cycle I hooked up read 11.1 volts before I hooked it up) but the starter battery was showing that it was getting charge. I figured the load was just too much for the alternator and I just couldn't have both batteries hooked up and get a charge. I ran the engine for a while so I could bleed the coolant system from work I did earlier in the day and then called it a day.

I go out this morning and the van won't start. My starter battery had 10.2 volts and my aux battery/deep cycle battery showed 11.3. So did I somehow overload the isolator by having multiple batteries on the circuit and then zap the starter battery? That doesn't make sense to me. Could I have just misread the multimeter when I had things hooked up previously and mistakenly thought my starter battery was getting charge with the engine on when in reality it was getting sucked dry by the load placed on the alternator?

I jumped the van off, unhooked the deep cycle battery, and drove to work. When I reached the office and shut off the engine both the aux battery and the starter battery showed over 12 volts. I'm taking away from this that you just can't have more than one battery hooked up to the alternator on the aux circuit. I'd love any additional insight though.

Thanks!
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1986 2WD 2.1L WBX Vanagon Weekender
1983.5 1.9L WBX Vanagon Westfalia

[MarkWard]

Is the deep cycle battery bad? If it is, it could be causing all your problems. I'd disconnect the deep cycle battery and recheck everything.
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[Bruce Wayne]

I have the GW kit installed on mine with these as my two aux. batteries:http://www.gotbatteries.com/items.asp?params=batteries/SLA/1/Hawker/Enersys/SBS40/SL203/36L203S1
maybe the isolator is bad. it shouldn't matter if you have 1 or 10 batteries hooked up once the engine is off the isolator should "isolate" those batteries from the starting battery. maybe someone with more knowledge can confirm this.

[MarkWard]

[vanagonforever]

Good advice. I'll use an external charger and go from there.
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1986 2WD 2.1L WBX Vanagon Weekender
1983.5 1.9L WBX Vanagon Westfalia

[greg334]

I am thinking that the solenoid is fine, I am thinking it is not wired up right.

I have installed a lot of these, and fixed even more in my life.

Random thoughts;

If the batteries are tied together (electrically) but is still tied to the rest of the van, this is one problem and bypasses the isolator. You have to isolate the batteries completely and the rest of the camper stuff should be too.

So check the solenoid first to see if there is power going to it when the ignition key is turned to the on position. If it does not click, then there is a wiring problem.

1 - If it clicks, then leave the key off and disconnect the wire on the solenoid to see if it clicks. If it clicks, it is wired up wrong. You can test it with a meter but I like to physically remove the wire.

2 - If it does not click, check to see if the solenoid is grounded, a meter works good for this. If it is grounded, then the wire for the power is not hooked up right.

As suggested, charge the batteries up. Don't worry about the alternator because if you are, than don't use an Aux battery at all because when you drain it, you have to charge it up with that alternator.

Also check to make sure that you didn't leave a light on or something that will drain the battery. I have and I bet a lot of people have done that thinking it was another problem.

[vanagonforever]

I do remember it making a loud click when I hook up the ground to the starter battery.

I started from a non-stock setup so I may just need to pull out the Bentely, put it back stock, and then reinstall the kit. Its quite possible I just screwed up the install. It was not my most dilligent work.
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1986 2WD 2.1L WBX Vanagon Weekender
1983.5 1.9L WBX Vanagon Westfalia