Vanagon Sunset

Vanagon Sunset

Tuesday, May 2, 2017

Auxiliary Battery Install

Ferdinand is running good and ready for some excursions, yet I still have many small projects to attend to (and always will).  One of the most recent upgrades stemmed from my wife buying me an Engel MT-45 portable fridge for my birthday.  Awesome gift, especially since we were getting ready to do a 9-day road trip in the van.  However, I knew that our standard car battery setup was not going to suffice and that I needed to make some upgrades. My Westy is an '82 and did not already have an Aux battery installed, so he was a blank slate for the most part.

I had been researching this for the past few months, and had settled on a setup that I ran across online from Ken Wilford (you can find a video he made on Youtube).  He utilized a few smaller 12v, 22Ah wheelchair batteries that fit perfect in the box beneath the drivers seat, in fact, you can fit 4 of them in there.  These are a sealed, lead acid battery and you can find them on Amazon for about $35-40 each and free shipping.  I chose to start with 3 because that affords you a little extra space under the seat to mount your relay and run wires a bit easier.  I figured that I could always add one more later if my energy demands are too high for this setup (see next paragraph).  I also have an empty spot under the passenger's seat for yet more batteries in the future because my engine battery is now located under the rear seat.
UB 12220, 12v 22Ah.
I bought mine on Amazon
Next, figure out your energy demands and battery needs.  You begin by figuring out what you plan to run off of your Aux battery setup.  Lights? Stereo? Fridge? Sink Pump? Inverter? Other?  Then make a list and try to calculate/log what each of those devices will draw per hour.  This will give you a number to start with.  The calculations from this point on get a little more complex, and I'm no expert, so I would recommend referring to various websites to help explain it.  I will however post below the quick calculations that my friend drew up for me and my application so you can see what I did.  The particular setup was done somewhat temporarily for our 9-day trip, knowing that we were not going to be sitting in any one spot for more than 3 days, and it worked perfectly.  I also didn't want to spend the extra money on a solar panel that I may or may not need.  I already had a smaller one in my possession, so decided to start with that.

The smaller batteries are wired in parallel, which keeps the same voltage and adds the amperage, so 3 of these 12v, 22Ah batteries wired in parallel, will equal 66Ah, but remain at 12volts.
 Here's a quick reference to how they "should" be wired to help equalize the load and charging on the batteries.
The pic of mine below is not wired for best longevity/performance, but has since been remedied, see if you can find the problem. Disregard the red wires on the negative side.  I had lots of red wire, so decided to use it up.
Located under the driver's seat
So, once you've got the batteries, you'll need to think about how you're going to charge them.  I purchased the Aux Battery charging kit from GoWesty, which is essentially a large solenoid/relay, a fuse and some wires.  What this does, is it isolates your aux battery when the key is off and separates them from your car battery so that you don't drain your main battery when camping.  When the ignition is turned on. the relay connects both batteries so that the alternator is charging everything.

I also chose to install a small solar panel up in the cargo tray to help extend the life of the aux system when we're camping.  It's a small panel for now, but I plan to add a larger one later for extended life.  My small panel is approx 16"x16" and acts like more of trickle charger.  On our last trip, I was able to run my fridge (and sink pump occasionally) for at least 3 days.  I still have my radio wired to the car battery, but we use a bluetooth speaker connected to our phones for music anyhow.
If you're using a solar panel, you'll need a controller.  The one in the picture below, runs about $25 online and offers 2 USB ports for charging your devices. Works great, but is slightly hard to read the screen in the location that I chose.  Just something to think about if you buy this one.

I also put in a fuse block so that I can add on more things as time goes on.  I've since wired in a cigarette lighter port for my fridge to plug into.

This setup was done pretty inexpensively and cost me about $180 total all said and done (batteries, controller, aux wiring kit and solar panel).  You can spend more and probably less, but that's what I paid and am happy with the results.

There are many different ways to go about this and you'll read about folks who run utilize huge solar panels and enormous battery banks.  It's really up to you and your needs.  For what we do, this works great.


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  2. Thanks for this, this is my plan before the end of the summer.
    Can you tell me what type of wire you used and what type of connector you used to connect in parallel? Thanks

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  4. I installed my aux with the same battery. I can fit two, but can't figure out to put in the third battery. Do you have a video or instructions how to add the third 22ah battery? Thanks!

  5. Are you having problems with figuring out the wirring?