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?
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"