What's wrong with just using a multimeter across the battery to measure the voltage?
Sam On Sun, Jun 26, 2011 at 3:40 PM, Ray Ayala <[email protected]> wrote: > Race cars don't have stereo systems that can easily be damaged by doing > that. > > > > ----- Original Message ----- From: "Eric Schieb" <[email protected]> > To: <[email protected]> > Sent: Sunday, June 26, 2011 12:32 PM > Subject: Re: Checking alternator? > > > > I agree that removing either of the battery leads would serve his intent. >> >> If I were going to do this, I would also turn on the high beams and any >> other large resistive loads I could. >> >> In my mind this would serve two goals: >> Make sure the that the alternator is doing more than putting out an amp or >> two, >> and provide a way to minimize the spike you could get. >> >> The spike would come from the alternator as it adapts from supplying a >> large current to charge the battery to the lower draw of an engine at idle. >> Without the battery in the circuit to absorb this, you can get a large >> voltage spike. >> >> Despite the alternator manufactures' warnings, what is being proposed is >> regularly done in race cars with cheap battery cut off switches. >> >> Eric Schieb >> >> On 6/26/2011 4:12 PM, Larry Alster wrote: >> >>> I think Lloyd means taking the negative off the battery so the car is >>> running on the alternator only and not drawing from the battery. >>> >>> >>> >>> >>> Larry Alster >>> >>> 91 Miata White Knight >>> 92 Miata Silver Bullet >>> 92 Miata Honey B >>> 04 MSM MX-5 Whooosh >>> 06 WRX STi Subie >>> >>> >>> -----Original Message----- >>> From: miatapower-bounces@miatapower.**net<[email protected]> >>> [mailto:miatapower-bounces@**miatapower.net<[email protected]>] >>> On Behalf Of Eric Schieb >>> Sent: Sunday, June 26, 2011 3:07 PM >>> To: [email protected] >>> Subject: Re: Checking alternator? >>> >>> Which cable is the "negative cable"? >>> >>> I suspect on a '91 that there is >>> a large positive output wire headed to the battery, >>> a small wire to energize the field in the alternator, >>> and a small wire to run the lamp on the dash. >>> The ground is handled through the frame of the alternator. >>> >>> Alternator manufacturers typically DO NOT recommend disconnecting the >>> large wire while the engine is running. They typically talk about >>> voltage spikes damaging things. >>> >>> Can you put a volt meter on the output wire? If you are getting voltage >>> levels above what the battery was at before starting the car, the >>> alternator is outputting something. >>> >>> However, this is based on experience with alternators of that period and >>> not specific Miata knowledge. >>> >>> Eric Schieb >>> >>> On 6/26/2011 3:52 PM, Lloyd Broussard wrote: >>> >>>> I think my alternator is going out. Will removing the negative cable >>>> while >>>> the engine running tell me if it's putting out juice. I know this is >>>> >>> really >>> >>>> old school, but it's a quick check. >>>> >>>> The car is a '91 with a Link computer. >>>> >>>> >>>> ______________________________**_________________ >>>> Miatapower mailing list >>>> [email protected] >>>> http://list.miatapower.net/**cgi-bin/mailman/listinfo/**miatapower<http://list.miatapower.net/cgi-bin/mailman/listinfo/miatapower> >>>> >>> ______________________________**_________________ >>> Miatapower mailing list >>> [email protected] >>> http://list.miatapower.net/**cgi-bin/mailman/listinfo/**miatapower<http://list.miatapower.net/cgi-bin/mailman/listinfo/miatapower> >>> >>> >> ______________________________**_________________ >> Miatapower mailing list >> [email protected] >> http://list.miatapower.net/**cgi-bin/mailman/listinfo/**miatapower<http://list.miatapower.net/cgi-bin/mailman/listinfo/miatapower> >> > > ______________________________**_________________ > Miatapower mailing list > [email protected] > http://list.miatapower.net/**cgi-bin/mailman/listinfo/**miatapower<http://list.miatapower.net/cgi-bin/mailman/listinfo/miatapower> >
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