Date:         Wed, 17 Feb 1999 19:07:17 -0600
Reply-To:     Joshua Van Tol <jjvantol@USWEST.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Joshua Van Tol <jjvantol@USWEST.NET>
Subject:      Re: Battery Circuit Breaker
Comments: To: kenneth d lewis <kdlewis@JUNO.COM>
In-Reply-To:  <19990217.122703.7375.0.kdlewis@juno.com>
Content-Type: text/plain; charset="us-ascii" ; format="flowed"

>
>         I agree with you that electrical protection is a good thing. I am
> planning to add a separate feed and relays  to the headlights. I will
> branch off the positive terminal with a fuse rated at about 25% more than
> all four lamps draw. Then I will fuse each light 10% over.
> Drive Safely & Good Luck
> Ken Lewis<Kernersville,NC>86 VW crewcab;60 T-5 Coupe


You'll have problems with nuisance blowing if you only go 25% over
capacity. Typical sizing is 1.5 to 2.0 times the rated current. Some
loads, such as motors, have fuses that are sized to take the turn on
current, which could be several times higher than the running current.

As an example of what I'm talking about, your headlights are probably
45 W low beams. They have a 10A fuse, which translates to a load of
10 * 14 = 140 W at 14 volts.

As you say, there's really no good way to fuse the battery lead.
You'd need a 400 A fuse or so, and that really wouldn't do any good
unless the power lead fell off and touched the frame.

Joshua Van Tol -- jjvantol@uswest.net