Auxiliary Battery


When I first got my van I knew that I was going to be taking it camping as often as possible. Even though I like the great outdoors, sometimes mother nature may intervene and I might have to wait out inclement weather with a movie or something, I decided that a second battery was in order. The second battery also helps when I'm at VW shows, so I can play the radio and Playstation as well as watch movies.

I did quite a bit of looking around and found the the Optima "yellow top" deep cycle battery fit my needs just about the best. One of my big reasons for purchasing this battery is the fact that, because it can be mounted in ANY orientation, it fit easily within the compartment under the driver's seat, with no modification to the compartment or the hinged cover. NOTE: If the factory swivel seats are installed, the base plates for the seats might have to be modified to allow the battery to get into the compartment.



The first thing I did during install was to line both battery compartments with sound deadening material. I used Dynamat, but there are quite a few brands out there (many of which cost less than Dynamat). There were two main reasons I did this. The first was the obvious sound damping. The second was that it added a layer of insulation to the compartments that would protect them and the batteries from shorting to ground. One Note: The stock battery is NOT a sealed battery! There is a vent hole in the bottom of the main battery compartment. If you decide to go this route with your van, make sure to put a hole in the sound damping material so this vent hole is still functional! Not doing so increases the risk of Bad Things happening exponentially.


I initially had installed the Hella Auxiliary Battery Relay kit from Bus Depot with its included 10 gauge wire to handle the charging of the aux. battery. In my application, however, I kept blowing the fuse that was connected to the relay, and therefore wasn't getting any charging.  Fellow list member Mark Drillock pointed me toward Newark Electronics and the Stancor Model 120-901 relay which has since solved those charging issues.


To install the new relay I drilled a 5/8" hole in each battery compartment, installed rubber grommets in the holes, then routed 4 gauge wire (more like 1/2" diameter cable) down through the grommet in the main battery box, under the floorboards, then up into the aux. battery box to the relay. If I remember correctly, I used about 4' of wire going between the two battery boxes. Because I had the Hella relay set up previously, I already had a wire run from the steering column to the aux battery box to switch the relay when the ignition is turned on. Once the cable was run between the boxes, and the wire was run from the ignition, it was a simple matter to get the battery to charge.


Once I got a charge to the battery, the next order of business was to get power from the new battery to my accessories. To do this, I got an auxiliary fuse block from J.C. Whitney. They have an assortment of fuse blocks depending on the number of accessories you plan on adding. Not knowing how many things I was eventually going to add, I decided to get the biggest one they had. It holds 18 blade style fuses. Currently, I have my air horn (finally I've got a horn that can be heard by other drivers at freeway speeds!), cigarette lighter, radio, and subwoofer connected to it.


On the occasions that I want to watch movies or play video games in the van, I have this little inverter installed in the same compartment as the aux battery. It's only a 350w RMS (continuous) power inverter, but it's enough to run the things that I need it to.



Here is the nearly final product. The only thing that I don't have pictured yet is the small box mounted under the jumpseat support tube in the rear passenger compartment that houses an external switch for the inverter and a pair of external 110v sockets. That way, I don't have to mess with the seat in order to plug things in or fire up the inverter.