Date:         Sun, 23 Sep 2012 09:56:52 -0400
Reply-To:     Mike S <mikes@FLATSURFACE.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Mike S <mikes@FLATSURFACE.COM>
Subject:      Re: Alternator continuous-duty rating?
Comments: To: David Beierl <dbeierl@ATTGLOBAL.NET>
In-Reply-To:  <505e8f08.c8d5e00a.435e.5b44@mx.google.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

On 9/23/2012 12:24 AM, David Beierl wrote:
> At 11:49 PM 9/22/2012, Stuart MacMillan wrote:
>> That is the continuous duty rating.  All alternators are rated for
>> continuous duty. 90 amps x 14 volts equals 1.26 kw, which is what it's
>
> Stuart, there's a reason that a Balmar [alternators are expensive]...

Sure. They're made for marine use, which means having to handle a
corrosive environment, a hot, enclosed location, and expectations of
reliability bordering on "life critical."

Below is how Delco-Remy uses the term "continuous," its focus is on
determining the average amount of current drawn for more than brief
intervals, and they then add 50% to alternator size. It's making sure
you have enough capacity to not drain the battery during normal
operation. Balmar would probably say "continuous" means 7x24 operation -
something quite different.

"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."