I have seen this failure an a number of occasions.
Yes - It happens -NOW- in much less time than a human can respond.
Several conpanies (most notably F.W. Bell - also marketed by Fluke) sell
DC clamp on current probes. I have one just for this sort of thing, but
they are expensive and delicate.

A cheap and practical alternative is available at
J C Whitney http://www.jcwhitney.com
an inductive ammeter (they call it a current indicator)
Their SKU ZX179446X

It is just about a spring load compass that you hold near the wire, but
they do work and can get you headed in the right direction (no pun
intended). I used one for years diagnosing car electric problems.

Matt Colie


Wayne.B wrote:
On Thu, 29 Apr 2004 16:34:10 -0500, dazed and confuzed
wrote:

==========================================

This is an excellent way to burn out the diodes in your charging
system if you have any.

Not recommended in my book.


not saying you are wrong, but why do you say that?

==============================================

If you open up the circuit while it is under load the voltage can (and
frequently does) rise to the point where the Peak Inverse Voltage
rating of the diodes is exceeded, and the junction permantently fails.

Matt Colie wrote:
I have seen this failure an a number of occasions.
Yes - It happens -NOW- in much less time than a human can respond.
Several conpanies (most notably F.W. Bell - also marketed by Fluke) sell
DC clamp on current probes. I have one just for this sort of thing, but
they are expensive and delicate.

A cheap and practical alternative is available at
J C Whitney http://www.jcwhitney.com
an inductive ammeter (they call it a current indicator)
Their SKU ZX179446X

It is just about a spring load compass that you hold near the wire, but
they do work and can get you headed in the right direction (no pun
intended). I used one for years diagnosing car electric problems.

Matt Colie


Wayne.B wrote:

On Thu, 29 Apr 2004 16:34:10 -0500, dazed and confuzed
wrote:

==========================================

This is an excellent way to burn out the diodes in your charging
system if you have any.

Not recommended in my book.


not saying you are wrong, but why do you say that?


==============================================

If you open up the circuit while it is under load the voltage can (and
frequently does) rise to the point where the Peak Inverse Voltage
rating of the diodes is exceeded, and the junction permantently fails.


I was not doubting his statement. I have never tried it on a boat motor.
I have done it on other charging systems, but cannot argue with
experience.

--
the most committed always win