[s-cars] Alternator Musings

[Brian Powell]

Dave,

I went out, removed the battery cleaned the contacts and ground strap
on both ends (everything was spotless already).

I then hooked my voltmeter between the engine and the battery ground
and had a voltage drop of 67 mV when everything was running. It should
be less than 50 mV. So, I removed the engine ground wire, cleaned the
contacts and wire thoroughly and reconnected. Now, from where the
engine ground wire connects to the body to the battery, there is about
3 mV drop; however, from points around the engine (such as where the
coils are grounded to the head), there is still a 60mV voltage drop.

It seems like the engine itself isn't grounded very well; however, the
ground line for the engine is operating well and its ground point is
perfect.

I'm not sure what else to do other than add another ground wire to the
engine somewhere.

On 7/13/05, Djdawson2 at aol.com <Djdawson2 at aol.com> wrote:
>  
>  
> In a message dated 7/13/2005 8:51:25 PM Mountain Standard Time,
> powellb at gmail.com writes: 
> Thanks for the info. I just did a test. I fired it up, turned on all 4
> seat heaters, rear defrost, AC, high beams, and radio. I tested the
> alternator and it was at 13.44V with the car idling and everything on.
> I tested at the battery and it was 13.1V during the same period. I let
> things go, turned things on and off, and retested. The largest
> difference I got was the battery being 0.45V below the alternator. Is
> this enough of a drop to cause it? It seems like less than 0.5V would
> be in the "acceptable" range, but I really don't know.
>  
>  
>   
> Yeah... you've got resistance in there that will cause you problems.  You
> can verify this by measuring the resistance (ohm meter... you prolly know),
> but the easiest thing to do is just clean things up and measure voltage
> again.  I think you'll find that this will solve your problems. 
> Good luck! 
> Dave 


-- 
Cheers,
Brian