Battery Overcharging

dodgeaspenrookie · 05-08-2008, 06:41 PM

I have a 79 dodge aspen with a 318 it has a new alternator (correct one) and a new voltage reg. but is getting about 16V at idle. Whats wrong?

440roadrunner · 05-12-2008, 09:01 AM

It could be the regulator itself, but it ALSO could be a number of things. Do you have a wiring diagram? Do you have a good voltmeter?

The regulator gets it's operating voltage from a long sordid path, which includes The battery--cable--connections--firewall connector--ignition switch--connector--back through the firewall--etc

The ground connection is equally rambling. The battery should normally be grounded directly to the block, and of course if you have a trunk-mount-battery, the block needs a great big jumper from the block to the frame/ body.

The regulator is grounded to the body, but NEEDS a solid ground to the battery, so there should be a jumper of at least no.10 from the regulator ground/ mounting bolt to the block, if that's where the battery cable is grounded.

One quick check you can make is to take an accurate voltmeter and stab one probe DIRECTLY on the negative battery post, and the other DIRECTLY on the regulator case. Do this with the car on fast idle. There should be VERY little reading, perhaps less than 2 tenths of a volt, and in NO case more than 1/2 a volt at the very, very most. If there is much more, you have a ground problem as mentioned above.

This much overvoltage will cook your battery, and boil out electrolyte, causing corrosion problems on your car. If you can't fix it yourself, find a good auto electric shop. Any good mechanic should be able to find this.

05-08-2008, 06:41 PM	#1 (permalink)
dodgeaspenrookie Junior Member Join Date: Jan 2008 Posts: 14	Battery Overcharging I have a 79 dodge aspen with a 318 it has a new alternator (correct one) and a new voltage reg. but is getting about 16V at idle. Whats wrong?

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05-12-2008, 09:01 AM	#2 (permalink)
440roadrunner Senior Member Join Date: Nov 2007 Posts: 272	It could be the regulator itself, but it ALSO could be a number of things. Do you have a wiring diagram? Do you have a good voltmeter? The regulator gets it's operating voltage from a long sordid path, which includes The battery--cable--connections--firewall connector--ignition switch--connector--back through the firewall--etc The ground connection is equally rambling. The battery should normally be grounded directly to the block, and of course if you have a trunk-mount-battery, the block needs a great big jumper from the block to the frame/ body. The regulator is grounded to the body, but NEEDS a solid ground to the battery, so there should be a jumper of at least no.10 from the regulator ground/ mounting bolt to the block, if that's where the battery cable is grounded. One quick check you can make is to take an accurate voltmeter and stab one probe DIRECTLY on the negative battery post, and the other DIRECTLY on the regulator case. Do this with the car on fast idle. There should be VERY little reading, perhaps less than 2 tenths of a volt, and in NO case more than 1/2 a volt at the very, very most. If there is much more, you have a ground problem as mentioned above. This much overvoltage will cook your battery, and boil out electrolyte, causing corrosion problems on your car. If you can't fix it yourself, find a good auto electric shop. Any good mechanic should be able to find this.