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Ford 9N, 2N & 8N Discussion Forum

High ammeter reading? Delco 12SI

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Ken S.

02-16-2006 16:22:22

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My 12V conversion worked perfect for two months till today while I was grading, I noticed the ammeter was reading almost 30! The battery is new and charged so something ain"t right. Doe"s that sound like alternator problem? I"m not familiar with an ammeter. Any thoughts?

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Ken S.

02-17-2006 11:28:18

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 Re: High ammeter reading? Delco 12SI in reply to Ken S., 02-16-2006 16:22:22  
Thanks guys, I took the alt. to get it tested. It tripped the breaker on the test machine. LOL

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02-16-2006 22:48:56

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 Re: High ammeter reading? Delco 12SI in reply to Ken S., 02-16-2006 16:22:22  
You need to check the charging voltage at the battery.

Obviously, a defective regulator in the alternator can make it overcharge.

Also, a battery with a shorted cell will not come up to proper voltage, and the alternator will appear to be overcharging, if you look at the ammeter.

Check the voltage at the battery, if it's much over 14.5 Volts, the regulator is not doing it's job. As the others have said, be sure there is a good connection to the regulators voltage sense (#2) terminal.

If the voltage at the battery is not excessive, but the high charging rate continues, it would point to a bad battery.

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02-16-2006 16:41:58

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 Re: High ammeter reading? Delco 12SI in reply to Ken S., 02-16-2006 16:22:22  
I would look for a problem with the reference (I think P2) line.. In most simple conversions this will be connected directly to the BAT terminal (connected to the battery) but can go to any number of reference locations. If it is loose or shorted, it will affect the output of the alternator..J2

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02-16-2006 16:36:54

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 Re: High ammeter reading? Delco 12SI in reply to Ken S., 02-16-2006 16:22:22  
Ken -

Doesn't sound like the alternator is self regulating.

1st, check P2 on the alternator to make sure it's connected to the BAT post on the alternator. That is where it gets its voltage for the internal regulator circuit.

2nd, check the voltage at the battery posts and report back the value back here.

3rd, after running a while does the BAT wire coming off the alternator feel warm or hot?

4th, do you have an ampmeter with two posts or one with a coil of wire on the back?

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