Date: Sat, 5 Sep 2009 14:43:28 -0700
Reply-To: mark drillock <mdrillock@COX.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: mark drillock <mdrillock@COX.NET>
Subject: Re: Run time to charge Aux battery
In-Reply-To: <BAY132-DS110266CA6080175E9B290A0ED0@phx.gbl>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Agreed, extended idling is not an ideal solution to a low battery
situation but it is at times the only solution at hand. The point is
that alternators can and do put out significant current at idle speeds,
as evidenced by their getting hot. The alternator has a fan inside
and/or outside the case that cools it so of course the faster the
alternator spins for a given current output the faster the fan spins too
and the more cooling available. When I need to charge at idle for
extended periods I use my steering wheel Club wedged between the front
seat and the gas pedal to get the rpms up some and help out the
alternator cooling. I'm sure I have done this 50 times or more, camped
on a beach far from electricity. In my 20 years of multiple Vanagon
ownership I have never had one of my Bosch alternators fail, other than
from bad bearings and worn brushes, normal wear items. I would expect
severe heat induced failures to involve the diodes or windings in a
distinct fashion. What kind of heat failures have you seen?
Mark
Dennis Haynes wrote:
> I've worked on a number of dual battery systems with both the Bosch and
> Subaru alternators. From a cold start they both work the same. The Subbie
> alternators tens to heat up when delivering a lot of current at low speed
> and will start reducing output to protect themselves. The Bosch do what they
> can until they fail.
>
> Personally, engine idling for battery charging is a bad plan. Engines do not
> like it. The tranny input bearings do not like it and it is just a real
> inefficient way to get power. You will use about 1 gallon/hour of fuel to
> gain a few amp hours. That is why the westy had the propane fridge to begin
> with. While it is an OK approach short term you really need another plan if
> long term camping is the goal.
>
> Dennis
>
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
> mark drillock
> Sent: Saturday, September 05, 2009 1:29 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: Run time to charge Aux battery
>
> Agreed, generalizing about the idle charging capabilities based on the
> failure of a single charging system to work right is not valid. I have
> charged my batteries at idle many times in various Vanagons. Maybe the
> Bosch alternators are better at this than the Subaru ones but I doubt
> it. I think the key is healthy wiring of a proper size.
>
> If you measure the voltage at the alternator while idling and then turn
> on the headlights, dash fan, etc you can judge easily enough how able
> the alternator itself is of keeping up with the load. The voltage will
> not drop much if it is keeping up. If you also measure at the battery
> and see a much bigger drop, it is the wiring that is not keeping up.
>
> Mark
> with 2 electric only fridge Camper Vanagons only on alternator charging
>
>
|