Date:         Wed, 25 Jun 2003 19:08:54 -0400
Reply-To:     Julian Burden <julian.burden@VIDEOTRON.CA>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Julian Burden <julian.burden@VIDEOTRON.CA>
Subject:      Alternator & dual battery question
Content-Type: text/plain; charset=iso-8859-1

OK, two days before a two week trip around Eastern Canada, my Westie's charge light comes on.

Not a problem, mechanic is fitting a changeover alternator tomorrow and all will be well.

Now, the core charge for the alternator is C$50 (about US$35).

I'm kinda thinking of keeping the old alternator - purely for the diode pack.

My theory is that I could wire the diode pack in parallel with the new alternator's diode pack and end up with a dual-output alternator - one for the engine battery, one for the house battery.

The two batteries would be isolated (current would have to flow the wrong way through a diode to get from one battery to the other), and current from the alternator to the batteries would not be crossing multiple diodes (as is the case with a battery isolator - current goes through the alternator's diode pack, and then through the diode in the isolator).

No problems with battery isolator voltage drop (I know about the "remote sensing" terminals on some battery isolators - in my mind the best solution available "off the shelf"), full alternator output available to which ever battery is lowest (unlike the bus depot relay system which only charges the house battery at a slow rate - nice and simple, but not suitable for my requirements).

Now, two questions:

1. Has anyone done anything like this (unlikely, I'd think)?

2. How easy is it to disassemble an alternator? Are there any tricks?

Thanks.

PS I was looking at installing a battery isolator (Harald and Nancy's site is a great resource) and had a thought about the best location for it. Most people seem to install the isolator near the right taillight (lots of space, near the alternator - a logical choice).

But my thought is that a better place would be near the junction box at the front left of the engine bay. Why? Because all of the necessary wires go through there.

I was thinking that I could undo the bolt in that box that connects the alternator, the starter, and the power for engine bay electrics - re-route the starter and alternator leads to the other side of that wall, where the isolator would be placed.

I would then connect the alternator's blue wire (which also goes through the terminal box) as the remote sensing wire for the alternator (it gets disconnected at the alternator anyway - why not connect it to the regulator prong that needs to be bent up?).

So far pretty minor work - the only modification to existing wiring being the alternator end of the blue wire.

All that then remains is to run a big cable to the second battery (which is closer to this location than the right taillight is), and smaller wire into the terminal box to reconnect the engine electrics.

I really should draw a diagram to assist this explanation - let me know if I haven't made it clear enough and I'll put something together.

Your thoughts?