Trojan Boat Forum

Posted: **Thu Jan 20, 2011 9:33 pm**

I disconnected the + wire on my Alt and it is pumping out 1.2 to 1.5 volts at around 1,200 RPMs.................. bad alt, right?

Posted: **Thu Jan 20, 2011 9:42 pm**

Never run with the power wire off the alt. hook it back up and you should have 13.5 - 14.5 if you have just battery voltage then most likely its bad .

Posted: **Thu Jan 20, 2011 9:46 pm**

Ops, well before I disconnected it I couldn't get more than 12.4 volts, same as the battery (engine off) so I guess it's bad.

Thanks Paul

Posted: **Thu Jan 20, 2011 9:48 pm**

Time tobuy a new one , or have that one fixed

Posted: **Thu Jan 20, 2011 11:14 pm**

The way I check my alternator voltage is to start the engine then disconnect the positive battery terminal from the battery and test voltage between the positive battery cable and the negative terminal, that way the battery is not in line. If you do this, make sure you run the bilge blower for several minutes before disconnect.

Posted: **Fri Jan 21, 2011 6:28 am**

wowzer , that can cause the alt to go in to a over charge state and can burn up the alt. and maybe other electrical systems . I have seen a 12 volt alt go over 20 volts with no load.

The battery must be connected to test the alt . And yes some times a bad battery will cause a lower reading on a charging test but thats rare .

Posted: **Fri Jan 21, 2011 11:10 pm**

OH. I've been testing like that for years and countless times and have never had an issue but I'm glad you told me because there is always a first time. Thanks for the info.

Posted: **Fri Jan 21, 2011 11:25 pm**

wowzer52
your not he first one to do that and won't be the last I am sure.

Posted: **Fri Jan 21, 2011 11:29 pm**

Get a cheap battery load tester; start with the battery sitting idol with the engine off and measure voltage; then using your load tester put a load on the battery to make certain it handles the load (needle on load tester stays in the green area). This will rule out your battery if it's still good. Next fire the engine and measure the voltage at the battery with engine running which will tell you if your alternator is working properly.

If you always test in that sequence you will get it right every time.

Prowlerfish is right; any equipment that is powered on when you run the engine with the positive cable off is at risk.

Good luck.

Posted: **Sat Jan 22, 2011 12:41 am**

Replaced the alt today, 13.8 on the volt gauge at 1,100 RPM. thanks Guys.

BTW, why is it any time you say Chrysler at the parts counter the guy has to give you a strange look? I know that they are old but come on.

Posted: **Sat Jan 22, 2011 12:53 am**

Try saying 63 Interceptor...

Posted: **Sat Jan 22, 2011 5:12 am**

I hope you got a marine rated one

Posted: **Sat Jan 22, 2011 1:15 pm**

Captain Blast Off wrote:Try saying 63 Interceptor...

Did you get those Interceptor Marine manuals I sent you?

Posted: **Sat Jan 22, 2011 9:53 pm**

alexander38 wrote:I hope you got a marine rated one

Sure did

Posted: **Sat Jan 22, 2011 10:24 pm**

Yes sir I did get the manuals. I had a crappy copy in the boat; it was nice to print a fresh set

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