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Date:         Wed, 2 Jul 2003 22:10:54 -0400
Reply-To:     vw_traveler <vw_traveler@HOTMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         vw_traveler <vw_traveler@HOTMAIL.COM>
Subject:      Auxiliary Battery Installation I: Hawker Odyssey battery,
              Hella relay, Chargetek AC charger (v. long)
Content-Type: text/plain; charset="iso-8859-1"

This email is the first installment - this report is too long to fit in a single email and be accepted by listserv.

Introduction:

I recently decided to add an auxiliary battery system to my '87 Westfalia. I thought I would convey what I learned in the process. Because auxiliary batteries have evoked some rather impassioned debate over the years, and because there are few detailed reports on installation, I have explained both my rationale and the implementation at some length.

Disclaimer:

This discussion is meant solely as a report of my experience, and no assurances or warranties, express or implied, are intended. I am entirely self-taught in messing with automotive electrical systems. This installation hasn't been vetted by an automotive electrical expert. A lot of what I've learned has come from other amateurs and their reports. This installation should be viewed as an experiment, not a definitive statement. It hasn't been in use long enough to reveal bugs, gremlins or errors. Any comments, suggestions, corrections or improvements are welcome.

The Goal:

1. Add high quality auxiliary battery capable of being "deep cycled" to provide "coach power" when camping.

2. Transfer Fuse 3 loads (cabin lights, lighter socket, radio memory, clock) from starter battery to aux batt to avoid discharging starter batt when van isn't being driven

3. Add AC charger for both batteries to maintain charge when van is in the garage, but with enough amp output to recharge a discharged battery.

Approach:

1. Keep it simple to avoid mistakes

2. Minimize modifications to stock configuration

3. Avoid temptation to overbuild

4. Keep cost under control

References:

The authoritative background on automotive electrical systems:

Harold Barre, Managing 12 Volts: How to Upgrade, Operate, and Troubleshoot 12 Volt Electrical Systems, Summer Breeze Pub, 2nd edition (September 2002)

ISBN: 0964738627, $14 at Amazon, $20 at West Marine

Bentley, of course. Most useful here were the refrigerator and water pump circuits and the auxiliary battery wiring diagram found on 97.225. It was important to identify all the wires are that come into the aux batt compartment - refrigerator power, water pump power, and controls for the fridge relay. The aux batt diagrams on p. 97.9a I found highly misleading.

The Sittsers' installation, with impressive use of the "hidden compartment" next to the water tank:

http://www.sittser.com/ElecReport.htm

http://www.sittser.com/ElecPictures.htm

I didn't do my installation this way (they put the battery in the hidden compartment) but I drew a great deal from their detailed report

Another fairly classy installation, but one that I imagine will only work in some Westies with different seat platforms:

http://www.vgonman.com/auxbat.htm

Harald Rust's excellent comparison of relay vs. isolator circuits: http://www.geocities.com/harald_nancy/dualbattery.htm

Harald is a firm believer in isolators, and his case is good, but as you will see below I opted for the relay setup.

Some clever installs and gadgets:

http://www.semyan.com/OurVan/Elect.htm

Some circuit diagrams and a discussion of why a 15 amp relay with thinner wires should comprise a workable charging circuit:

http://www.globalserve.net/~jrivers/aux-batt.htm

General Vanagon Inspiration:

http://www.haywood-sullivan.com/vanagon/

http://members.shaw.ca/albell/vanagon.html

Discussion in the Vanagon archives. (Many of the passionately held views look electrically incorrect but debunking them was instructive.)

Principal Decisions:

1. I wanted the battery to fit in the aux batt compartment under the driver's seat, WITHOUT modifying the compartment. Like many owners, I was attracted to the Optima yellow top, but its dimensions require modifying either the battery or the compartment.

Fortunately, I found the Hawker Odyssey PC 925 MJT battery.

Its advantages:

-- with dimensions of 7" x 6-3/8" x 5-3/4"h it fits the compartment in any orientation

-- it is a sealed AGM battery that does not require venting.

-- its charging voltages are similar to the standard starting battery, so it can share the same AC charger

-- it can be deep-cycled

-- it should generate enough cranking amps to start the vehicle if the starter battery fails

2. Keep the fridge on the starter battery. The fridge draws so much current it would run down the auxbatt quickly with the engine off. I always need a lot more cooler space so the fridge is backup to a cooler with ice anyhow (The Igloo Ice Cube from West Marine doubles as a table or seat, and fits snugly against the rear seat and the cabinets.)

3. Use the 30A Hella relay system sold by Bus Depot instead of the solenoid or isolator systems often advocated. My rationale:

-- There aren't a lot of heavy loads on the aux batt so I'm unlikely to profoundly discharge the aux batt often.

-- A quick calculation suggests the 15A system with 12 ga wire should charge the battery fairly readily.

-- I didn't buy the argument that the relays are less reliable than isolators. The relays in my vehicle are 16 years old and not one has failed.

-- A relay-based system is consistent with the rest of the antiquated wiring design; I was able to resist my customary urge to overbuild with a modern isolator system, elegant and robust though it might have been.

-- There are plenty of happy Westfalia owners who have never had a problem with the relay system

-- I REALLY didn't want to drill holes in the metal or string wires between the front of the van and the engine compartment. Doing this could have exceeded my abilities and tool collection.

Key concept:

The relay (or isolator in the alternative installation) acts to isolate the starter battery from the auxiliary battery at all times EXCEPT when the engine is running and the alternator is providing charging amps. By disconnecting the auxiliary battery it can be drained by lights, electronic devices, etc. when the van is at rest, without affecting the starter battery.

The good news is that in Westfalias the refrigerator is controlled in _exactly_ the same way. Moreover, the relay that controls the 12V power supplied to the fridge is _exactly_ where one would want it - in the auxiliary battery compartment. The control wires keep the relay open not just until the key is turned, but until the alternator is generating electricity. This installation taps into those control wires to control the aux batt charging relay.

What about using the auxiliary battery to backup the starting battery if it dies? There appear to be some sophisticated isolator systems that can detect a discharged starter battery and automatically bring the aux batt on line to help start the engine. But I considered how often that's likely to happen - rarely. I've been carrying jumper cables in the van all along; even with this setup I would continue to carry them, so if the starter battery ever dies I can easily jump it from the neighboring compartment.

Materials:

Hawker Odyssey PC925MJT battery

http://odysseyfactory.com

East coast source: http://www.batterymart.com/battery.mv?c=odyssey

West coast source: http://odysseybatteries.com/auto.htm

Batteries Plus stores are spread around the U.S. and my local store said they could order it:

http://batteriesplus.com/Product/slacidrechg.html

Location of the vendor is important: the batteries are heavy and shipping over distance can get expensive. Batterymart got it to me in two days for a nominal charge.

Hella aux batt relay kit from Bus Depot (I suppose I could have found the Hella #87105 15A fused relay somewhere and used my own wires but this was easy and I like doing business with Bus Depot.) www.busdepot.com

Chargetek CT500 5A two-battery charger

http://www.chargetek.com/products.html

purchased from BatteryStuff.com: http://www.4unique.com/battery/chargetek/chargetek_500.htm

I decided to take a chance on a small company and relatively unknown product. The more established, highly regarded alternative is the Xantrex Truecharge10A charger available from West Marine. The advantage of the Xantrex is that it puts out twice the amps. I chose the Chargetek because it's smaller, comes fully wired, doesn't need ventilation, and is a bit cheaper. Specified output voltages of both the Xantrex and Chargetek appear to be within the ranges required by both the starter battery and the Odyssey. Both are chip-controlled to avoid over-charging when used to maintain the batteries. I looked at Deltran and Guest chargers, which have gotten good reviews, but they didn't seem suited to this application. If the Chargetek doesn't work out I'll replace it with the Xantrex.

Electrical Supplies from FLAPS

- 4 ga, 12" battery ground wire with battery post terminal at one end and flat ring lug at the other

Electrical Supplies from West Marine (www.westmarine.com)

Many of these parts are available from Radio Shack, but I favor West Marine parts because they are generally more rugged and higher quality.

- 6-circuit ATC fuse block, #487801

- 8 ft, 12 ga duplex safety wire, #297426

- 2) 30A in-line fuseholders, #191637

- 2) 5/16", 12 ga ring terminal connectors for attaching wires to battery

- miscellaneous ring terminal connectors, #10 and 1/4"

- insulated quick disconnects: female 16 ga

- insulated quick disconnects: male and female in 12 ga

- 12 ga spade lug

- interlock ("vampire") connectors #385864

- 12 ga crimp connectors

- 10A and 15A and 30A ATC fuses

- a few feet of 12ga red wire

- misc 16 ga wire, various colors

- 10 ft. "split loom" wire wrap #1919968

- Additional 14 ga wire for attaching accessories such as extra lighter sockets

Misc Hardware

- 8mm bolt, ~1" long, with flat washer and lock washer (ground bolt)

- piece of 1/2" MDF or plywood, about 7-1/4 x 9" (base for fuseblock and relay, and brace for battery)

- contact cement

- short length of 3/16" cord

- machine screws, 1/2" and 1-1/8"

- 12 x 14" piece of 1/4" minicell foam to serve as battery mat and shim

- 13 x 6" piece of 1" minicell foam to insulate battery compartment lid. Available from Nantahala Outdoor Center: http://www.noc.com/ss/wkrepair.htm.

(I always get more than I think I need. Once you have it there are a zillion uses for minicell foam)

Approximate Cost:

$105 for the battery

$100 for the charger

~$100 for the electrical parts and wire

Tools:

Drill and bits

Sabre saw or coping saw

Screwdrivers

Wire cutter

Wire stripper

Crimping tool

Needlenose Pliers

Socket wrenches

Allen wrenches

Assembly:

For the time being I have posted photos on my Yahoo account. Not sure this link works:

http://photos.yahoo.com/bc/chartres456/lst2?.tok=bcLVsyRB1fEA_k3W&.dir=/Vanagon+Battery&.src=ph

This URL needs to be on one line, of course.

Intstallation follows....


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