Date: Sun, 23 Sep 2012 13:31:28 -0400
Reply-To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject: Re: Alternator continuous-duty rating?
In-Reply-To: <505f3bf7.c8d5e00a.435e.ffffa8c7@mx.google.com>
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The Automotive/RV world is drastically different from the marine world for a
number of reasons. Some of the marine stuff just isn't needed and the
benefits are often limited once on land.
Marine batteries need to have charging closely monitors. In addition to the
fear of hydrogen accumulation in closed compartments off gassing can be a
real concern. Add some sulfuric acid to salt water and you get chlorine.
That is a huge driver for AGM or Gel batteries..
Larger boats will have the engines operating for hours on end, at speed with
alternators under load since most all accessories are always used. Our
radiator fans and even high beams, wipers, etc, are intermittent loads.
The Vanagon is one of a few vehicles where the engine runs at a high load,
speed for most of its travel time. But every time we stop or even slow down,
get fuel, whatever it gets to rest. In the electric motor world, a
continuous load is one that goes for three hours or more. How often do we
drive, full power, full electrical load for three hours? I can't go that far
in the Northeast without hitting a toll booth. Worse is needing a wee-wee
break.
My RV had one of those 160 Amp Leece-Neville Super-duper alternators from
the factory. Started failing last year. Luckily a standardized mounting was
used so I had choices to replace it. I went with the AC-Delco style due to
higher efficiency and greater output. (200 Amp). Makes a very noticeable
difference. Unfortunately after a few short successful trips I went from
home to Dover De. Last year and the regulator failed. So in less than 300
miles, a brand new, (not rebuilt) part caused me grief. You can boil some
batteries and take out a lot of light bulbs at 18 volts. Point is regardless
of what you spend stuff happens.
Dennis
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
David Beierl
Sent: Sunday, September 23, 2012 12:42 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Alternator continuous-duty rating?
At 09:56 AM 9/23/2012, Mike S wrote:
>"Electrical output must provide adequate current for all normal
>continuous loads. Twenty-five percent of intermittent loads such as
>brake lights, turn signals and radio transmitters should be added to
>continuous load; 50% for school buses, twenty percent...for battery
>charging...Generator output should be 50% more than vehicle load
>requirement."
Mike, that's great, thanks a lot.
Jack's looking at continuous output in terms of the alternator running flat
out for several hours at a time, charging deep-cycle batteries. That's the
(an) intended usage of those "light-duty" six- and seven- series Balmars.
He doesn't need the explosion-proofing (they call it ignition-protection
nowadays, clearer but boring), but it's more an industrial than automotive
application as such.
The history has gotten hazy in my mind, but I rather think that Balmar
(founded 1982) alternator production arose in response to demonstrated
failure of automotive alternators adapted for marine service
(recreational/cruising vessels) to survive deep-cycle battery charging
regimes, once properly designed multi-stage regulators were available.
The multistage regulator I got for Scamp ?15? years ago (Ample Power Next
Step, first series - cost $400 then; the second series is now under $300
with more capability, and I think the ones from Balmar now operate as well
and have similar prices) came with explicit warnings that a standard
alternator might not survive its attentions. I continued to use the
Motorola 35-amp alternator that came with the engine in '63, and with our
operating regime (cruising in Maine, engine box temps below 120F, duty cycle
~eight hours flat out every
4-5 days for ~three weeks a year) it held up fine.
Some multi-stage regulators have provision to throttle the alternator
output, but Jack's looking to stuff charge as fast as he can during limited
driving time between campsites where he'll operate dry for days at a time.
On Scamp we traveled with no engine for days at a time and then charged for
roughly eight hours. A bigger alternator would have been nice. My laptop
was the biggest overall drain (radar being next, followed by cabin lighting,
Loran plotter, running lights in that order). We used ice for
refrigeration. For Jack the fridge is the big item I imagine. He's looking
for longer time between charges with less battery capacity than we had (200
AH, cycled to 80% discharge for lower weight and initial cost), but he's
supplementing with solar.
Interesting document here:
http://www.prestolite.com/literature/alts/PACU_097.pdf . Great reading when
you can get past the fancy brochures to the people who have to actually make
it work.
Yours,
David
