2-Battery Electrical System
 with Charger

Can't get no satisfaction

For a little more than a year, I'd been using a wheelchair battery as the second battery for my Vanagon Westfalia camper. This is a fairly good solution... it fits under the driver's seat, it's sealed, and it's a gel cell, so there is no leakage. At 30 amp/hours, it's a fairly good backup power supply. I had a inverter hooked into the battery, which allowed me to run (and charge) a laptop computer.

In early 1997 I added a Propex propane heater to the van. The Propex has a stingy 1 amp draw, but nevertheless I was worried about the small wheelchair battery's staying power. I've been looking for a second battery for some time that would hold more power but still fit under the driver's seat. (With the Propex heater taking up a substantial amount of my under-bench space, taking advantage of the under-driver space is fairly critical.)

I looked at every battery catalog that I could find and searched the web, but found nothing. Apparently, the battery compartments in the Vanagon are designed for European-spec battery sizes, and no one makes deep-cycle batteries in that size.

The battery of my dreams

The Optima battery company recently answered my prayers when they came out with a deep-cycle version of their battery. The Optima is already popular with car stereo afficianados. It features a spiral-wrapped dual-plate design, which fits more lead surface (and therefore power storage) into a smaller space.

The Optima is also nearly leakproof, since the acid is held in a glass fiber mat. The company has a demonstration where they fire a bullet into an Optima leaving a huge hole in the center. Even with the battery's interior exposed, there was no leakage and when placed into a vehicle, it performs perfectly. (This may be useful on the Tierra del Fuego trip!)

The new "Yellow Top" deep-cycle version of the Optima battery comes in two 12 volt configurations. One has top posts, while the other has both top and side posts. To install the battery into a Vanagon, I used the side posts. This model is the Optima 750U, and it has the following specifications:

Terminal type: Top & side posts
BCI group size: 34
Volts: 12v
Amp / hours: 52
Cold cranking amps:    800 Amps
Cranking amps: 1,100 Amps
Reserve capacity: 124 minutes
Length: 9.94 inches
Width: 6.88 inches
Height: 7.81 inches
Weight: 46.1 pounds

Unfortunately, it's very expensive. I bought it for $180, though I expect you may be able to find it for less on the Internet.

This battery will fit into the space under the driver's seat, though it's not easy. First, the battery is too tall, so you need to remove the top posts so that they are level with the top of the battery. Unfortunately, this is not a simple procedure. I had it done by the folks who sold me the battery, Performance Sound & Security (408.369.9597). After removing the posts, they tell me they needed to reconstruct (with solder) the connection to the side terminals.

A simpler solution was proposed by James Matthisen. He writes:

I am going to use the side terminals and drill holes in the black access cover (and carpet) for the top terminals -- the access cover then closes. Top terminals come with plastic caps and will stick up through the carpet (but not so high that the driver's seat won't swivel). They will be out of harms way when driving, and if I need to jump-start someone I can just slide the seat forward a bit and take off the plastic caps.

An even simpler solution was proposed by Jim Davis. He writes:

There's no cutting or grinding required for the Optima. Just mount it on it's side so that the 'top' posts face forward. It fits fine this way.

Lastly, Bill writes:

My Optima rests nicely under the driver's seat of my 90 Westy and the lid is still on its hinges. Put the Optima on its side with top posts pointing forward (left plastic caps on) and side posts up. Right above the side posts cut notches in the lid and then taped across the notches with black fabric tape so there can be no contact of the posts to metal. In order to get the Optima in the hole had to cut two notches... one for each of the top posts... in the metal lip at the forward part of the battery box so the top posts would pass by the lip... not a big deal.

(This works because the Optima can be mounted in any position... even upside-down! If you do this, you can use the Optima 750, which doesn't have the side connectors.)

In order to get the battery into the battery compartment you need to remove the driver's seat entirely. When the driver's seat is removed, there may be a metal bracket towards the front of the under-seat compartment that interferes with installing the battery. Knock or cut this off, as it serves no purpose other than to get into your way. Once this bracket is removed, the battery will easily slide down into the compartment.

The battery can be connected as described in the electrical section of the FAQ. Use the side terminals, which must be positioned so that they face forward. The battery will be flush against the back of the battery compartment. Use a block of wood to keep the battery from sliding side to side in the compartment.

Getting a charge

Another thing I wanted was to be able to plug my van into the power grid and have my heater run right off the grid. Transformers are available that will do this, but they're way expensive (about $500.) They're also bulky.

There is a 'secret socket' in the cabinet under the sink. This socket is a standard electrical socket pair. One socket in the pair is used for running the Westie fridge off of 120v power. The other is unused. I decided to use this socket for a trickle-charging system.

I purchased an Exide 1.5amp Onboard Battery Charger (model # 7001204). It's about 1.5 inches by 4 inches by 6 inches, and comes complete with two screw mounting holes. It knows to shut down whenever the battery is charged, and to power up when needed. It has an LED charging light. I bought it at Kragen for $25. It's perfect.

I mounted the charger just below the shelf in the cabinet under the sink. If you look into the cabinet, and peek under the shelf, the charger sits just below the shelf on the left wall. (This is the wall near the fridge.) It's mounted horizontally, and the plug sneaks up along with the propane pipes to plug into the socket. Since it's mounted just under the shelf, it doesn't take any significant cabinet space.

The charger comes with its own cable and aligator clips. I removed the clips and wired the charger directly into the battery. The wire runs behind the thin wood partition behind the cabinet (through a hole) and across to the battery compartment.

Getting totally wired

I've run wires to this second battery to run the Propex heater, my stereo amplifier, and the inverter. At some point, I'd also like to hook in the rear cabin lights, but I haven't gotten around to doing this yet. When running line, run the thickest line possible. (8 or 10-gauge is good.) I ran 8 gauge to the amplifier. For the Propex, I used the line which came with the heater, which looked to be about 10-gauge.


Desert Ratthis link leaves vanagon.com sells the Optima 750U for $168, including delivery to California.

I got the Exide trickle charger at Kragen Auto Partsthis link leaves vanagon.com in Campbell, California (408.374.7650) for $25.99.

Copyright © 1997–2017 Ron Lussier. All Rights Reserved.

vanagon.com is not affiliated with Volkswagen of America, Volkswagen AG, or Westfalia AG. 'Vanagon' and the VW logo are trademarks of Volkswagen.