Monday, October 15, 2012

The VW Camper gets an Upgrade

Mrs Elliott and I do a lot of "dry" camping, that is, we camp for days at a time in remote locations far from electricity, water, and people. Along rivers and lakes, atop a butte, or out in the desert. To provide power for the VW Vanagon camper van's refrigerator and LED lighting the van used to have a large 130 amp-hour battery, but I killed that battery last winter by letting it discharge in the van while it was hibernating.

So I needed to replace it, and I wanted to replace it with more capacity and a better charging method. Several people (notably David Beierl and Dennis Haynes) on a mailing list devoted to Vanagons provided some great ideas and insight into the limitations of the Vanagon's stock battery-charging wiring and ideas on how to properly charge bigger batteries.

I worked up a wiring diagram and ordered parts when I could not find them locally. Specialty Auto Electric here in Bend had the needed wire and terminals. Here's what I I did:

A hefty dedicated 1/0 gauge wire (red) from the alternator to the charging circuit. 

Main charging circuit bits under the rear bench seat. The big wire from the alternator comes in at the lower left and connects to a Stancor contactor (relay). The relay connects the battery to the alternator for charging when the engine has started. The brass thingy above the contactor is a current shunt used a the battery monitor gauge. Over on the right is a new panel with control switches on it. 

The new control panel has a switch at the top to select between two different charging methods: direct from alternator for "bulk" (fast) charging, and lower-current but higher voltage "absorption" and "float" charging from an onboard smart charger (below). The lower knob is a battery cutoff switch. Not disconnecting the battery while the van was in storage was the reason why I killed the other battery -- the battery monitor draws 0.2A 24/7 and there are a couple other light loads, so this switch will entirely disconnect everything.

This smart charger (Powerstream PST-BC1212-15) takes the voltage from the alternator and increases it for the lower-current but higher voltage "absorption" and "float" charging stages. I'll switch over to this charger once the alternator has put all the amps into the batteries it can. I reckon I can pick up an additional 10 to 20 amp-hours using this as a "finishing" charger.

The new battery bank inside a new battery box.  I'm using a pair of 6-volt GC2 golf cart batteries from Costco. The two of these cost less than the single battery I killed last winter, and have greater capacity. I measured 175 amp-hours off them (at a 5-amp load) when I got them, and I'm told they will get better. I never measured the old battery with this test so I can't comment on how it compared. The yellow caps are "Water Miser" vent caps intended to reduce and ease maintenance (it says here). When the lid goes on the box, two strong nylon straps help hold the box in place. The closed box is nearly too tall to let the bench seat close, but it does. 
I'm not accustomed to working with such fat cables and burly terminal, so I had to develop some techniques. It was a lot of work and it all had to go in this weekend because I'm taking the van out for a four-night camping trip on BLM land near Pine Mountain starting on Wednesday morning. One or both of our sons will be joining me for the weekend.

If anyone wants a scan of the hand-drawn wiring diagram, please send your email address in a comment (below). Your comment won't be published unless you request. 


8 comments:

  1. Nice setup Jack. I'm sure you did your research, but is 1/0 really necessary for the primary feed? That's a lot of wire! How many amps is the alternator putting out? Just asking because I need to do something similar to replace my semi-permanent jumper battery. Jonathan

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  2. Hey Blue Highway -- yeah, 1/0 is probably silly bit. 2 meters of the stuff has about .0006 ohms, and assuming that the battery can accept, say, 50 amperes from the 90-amp stock alternator, that's a voltage drop of 0.03 volts. But I have been dealing with a lot of wire resistance losses in the old setup so I thought I'd just nail this one flat.

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  3. Replies
    1. Nice job - that should be a huge increase in electrical capacity! Question for you - is your battery box sealed to the inside of the van and vented to the outside? Was your previous battery sealed (AGM type or similar)?

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    2. Jack - is your battery monitor working correctly? It looks like you only have one side of your ground cable hooked up to it? It should be in-line between your battery's negative terminal and the actual vehicle chassis ground. Perhaps you've changed it since the photo? A decent battery monitor is so nice to have - good call!
      cheers,
      Josh

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    3. whoops... I just realized that you took the photo of the shunt before the battery box and batteries were in, thus why there is nothing to connected to the other end of your shunt. Ignore the last comment, move on...
      josh

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  4. Hi Josh, thanks for the comments.

    The van ain't a submarine or boat with a sealed compartment. Hydrogen gas won't build up inside, it floats up to the top of the van and goes through the canvas top like water through chicken wire. The system works -- the photo of the wiring was taken before the final battery wiring was installed. The negative terminal first goes to the current shunt, then the cutoff switch, then a big ol' bolt to the chassis.

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  5. This is good information. I would like to see your wiring diagram please. I installed a house battery under the drivers seat using plans I got from Samba using a Yandina combiner switch. I need more battery power and was thinking of going under the bench seat. Your method does not try to combine at all does it? You left the original alternator charging circuit to the vehicle battery as it is and added an additional charging wire from the alternator to house battery?
    Thanks so much
    Dean

    deanzimmer@shaw.ca

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