Date: Thu, 22 May 2008 18:59:33 -0800
Reply-To: Troy <colorworks@GCI.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Troy <colorworks@GCI.NET>
Subject: Re: Battery Woes/Choice
Content-Type: text/plain; charset=UTF-8
#2 gauge--wow! I assume that you set things up so that you could use your auxiliary battery for starting in the event the main one dies?. I believe the sure power has a model that allows for that if I remember correctly. #2 gauge seems way overkill otherwise. Did you end up drilling through the battery box wall behind the driver seat to route the wires? Number two gauge is heavy stuff and probably pretty stiff as well. Right now, I just have a #8 gauge running from the main starter battery to the auxiliary via a path over the gas tank, but I don't use it as a starting battery. It's still protected by a 50amp fuse nevertheless. Technically, eight gauge wire can handle 40 amps I believe, but would not melt down before the fuse blew. I found that by a flipping a switch I installed that connects the batteries together, a certain amount of juice will flow from one battery to the other. If the main battery were low, I could flip the switch and get some juice from the auxiliary battery to start the vehicle, turning the switch off first. It's all theory, I have never depleted my main battery yet, although I have borrowed power from the main battery with the same switch, which works well.
What do you think about running some eight gauge wire or perhaps number six wire directly from the alternator or starter to the sure power mounted under the rear seat, and then to the auxiliary battery? I can then run a #8 or even 10 gauge to the connections behind the driver seat? Easiler to route the smaller gauge wire for sure. I would still need to route the blue trigger wire for the relay, which I assume originates somewhere around the alternator, although I don't know for sure--do you? The ground I would think you could just attach to one of the bolts on the floor after removing the paint.
There's no question that your setup will work (is working). I just question whether or not you need such heavy gauge wire if you're not going to use the aux. battery as a starting battery were it would carry huge amounts of current.
By the way, which 100 AH battery did you choose? So for the interstate, group 29 was mentioned and one other person mentioned several golf cart batteries, although they are extremely heavy and hard to get service were I'm at.
Have you had any problems charging the 100AH battery fully with the stock alternator? If the auxiliary battery is undercharged routinely, that could certainly lead to stratification (I think that's what they call it) which make your 100AH battery act like a 10AH battery overtime. I installed a separate voltage gauge on my current setup, so I know what's going on. I'm amazed how many people have no clue about this, they just say that "it works fine". Guess I'm a little more technical than that;)
Troy
----- Original Message -----
From: Loren Busch
To: Troy
Sent: Thursday, May 22, 2008 5:57 PM
Subject: Re: [VANAGON] Battery Woes/Choice
RE: Since all my wiring is now behind the rear driver's seat, I'd like to do this as painless as possible.
When I added a second 100AH AGM battery (to handle the Norcold) under the rear seat I had the same thought and it worked out well. I ran two #2 cables through and behind the cabinets up to the battery compartment under the driver seat and initially hooked the positive to the actual cable that had been hooked to the original Group 41 aux battery, the ground to the ground point that that battery had used. This eliminated the need to re route the existing accessory wiring that I had already installed. Since then I've added the Surepower separator and an additional breakers and a single terminal point where all aux devices get their power. So what you propose will work just fine.
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