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Date:         Thu, 28 Jun 2001 12:15:45 -0400
Reply-To:     David Beierl <dbeierl@ATTGLOBAL.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@ATTGLOBAL.NET>
Subject:      Re: 130Amp alternator upgrade?
Comments: To: Alistair Bell <albell@UVIC.CA>
In-Reply-To:  <B760202A.6522%albell@uvic.ca>
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 02:47 AM 6/28/2001, Alistair Bell wrote: >Westies often become sailboats when on camping trips, ie. often have >subtantial current draw on battery when parked and infrequent use of engine >for recharging. What you want is for the alternator to recharge the battery >more quickly when the engine is on, fiddling with an adjustable voltage >regulator is one way of doing that, and is done on sailboats... > >ahoy David B.!

<hobbyhorse>

Aye. Nobody wants to hear this because it's expensive. But sometimes expensive is what you gotta do. Automotive regulators are *utterly unsuitable* for charging deep cycle batteries; they are built on the assumption (correct for starting batteries) that the battery *is already charged* and that *losing battery capacity by improper charging is an acceptable cost.*

Rheostats to manually control alternator field are fairly cheap in money but expensive in time, attention, and consequences to the batteries if you forget to turn them down at the right moment. Also, the numbers change with battery temperature, and battery temp changes with charging -- the possibility exists for a thermal runaway culminating in battery explosion.

Automatic regulators cost let's say $300 (Ample Power entry-level model, called Next Step) and work beautifully. Models that do not actively measure battery temp are not worthy of consideration IMO.

Both these solutions will cause the alternator to deliver full output for extended periods, which may not have been in the plans of the people who made the alternator. The magic smoke will tell you...in which case a "hot-rated" alternator intended for this sort of use will be a few hundred more.

http://www.amplepower.com/ will give you several evenings of light reading.

Note: Our camping habits in the Vanagon are such that we get by with the starting battery -- we draw 1.5 amps for a few hours in the evening, and we don't camp for long periods. We have to replace the battery more often than ideal, but on balance it works for us. On the boat however I've struggled with batteries for 30 years -- lengthy charge times at low amps and batteries never giving anything like claimed capacity, and losing that much too soon. I recently bit the bullet, paid the big bucks for the regulator (and am holding my breath on the alternator) -- and the results are marvellous. Charging actually works the way it's supposed to. I'm charging about 400 amp-hours of capacity, and the alternator goes up to 30 amps (max hot output) and stays there for a few hours, then tapers off. These days with radar and such I use 60-100 amp-hours a day so we can go 2-3 days without running the motor. Before it would be down to ten amps or less within half an hour, and just dribble charge indefinitely until we couldn't stand the racket any more -- and the batteries never were fully charged.

</hobbyhorse>

david

David Beierl - Providence, RI http://pws.prserv.net/synergy/Vanagon/ '84 Westy "Dutiful Passage" '85 GL "Poor Relation"


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