Charging at 15.1 volts. Anybody?

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MoparMuscleGuy

MoparMuscleGuy

Still plays with cars.
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Hello, Ever since I bought this dart it has charged at 15.1 volts. It's a 74 Dart Swinger 318. I've given it a full tune-up Plugs, wires, Cap, rotor, new distributor, Coil, voltage Regulator, Alternator, all filters, fuel pump, new carburetor, etc. I haven't changed the battery, it seems fine. Checking the battery with the engine off it reeds 12.88 volts. With the engine running at about 750 rpm it reads 15.1 volts. Could it be a bad battery? Any suggestions? Thanks, Christopher
 
Being that new it should have the electronic voltage regulator. The alternator should have three wires going to it. The big battery wire then two field wires. You should check voltage right at the output of the alternator if you haven't already. Also check voltage at both the field wires @ the alternator. It should be regulated between 13.8 to 14.2 volts. The new regulator or alternator could be bad. Wouldn't be the first time
 
I had it one time that the alternator just kept charging no matter what. The car started and ran good. Just that the battery kept calling for more charge. I changed the regulator and it still charged all the time. It ended up being the battery was bad. Don't know what was wrong with the battery, but it kept wanting a charge. Replaced the battery and all was ok.
 
nothingbutdarts said:
Being that new it should have the electronic voltage regulator. The alternator should have three wires going to it. The big battery wire then two field wires. You should check voltage right at the output of the alternator if you haven't already. Also check voltage at both the field wires @ the alternator. It should be regulated between 13.8 to 14.2 volts. The new regulator or alternator could be bad. Wouldn't be the first time
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I haven't checked the output right at the alternator. I will do this tomorrow. Your right about new things not working as they should.:-D
 
I had a 70-GTX, wiring wasn't that great from the factory.. I was racing a guy one night and my battery blew up, sounded like a grenada went off, only thing I could figure was it overcharged... I'd figure out the problem asap before I'd drive it much...
 
green1 said:
Gauge wrong? What does multimeter show?
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Multimeter shows 15.1 at 750 rpm and 12.88 with engine off.

68 Rat Rod said:
I had it one time that the alternator just kept charging no matter what. The car started and ran good. Just that the battery kept calling for more charge. I changed the regulator and it still charged all the time. It ended up being the battery was bad. Don't know what was wrong with the battery, but it kept wanting a charge. Replaced the battery and all was ok.
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I have suspected this and you may be right. This is the only thing that I haven't changed. This is one of those things that will drive you crazy.
 
You need to load test the battery for sure. As stated earlier a bad battery will cause the alternator to work overtime. Sounds like a dead cell to me.
 
........Could b at the bulk head connector..........plug that goes on the regulator.......or the gauge in the dash.........kim..........
 
Just checked the voltage at the alternator output and it measures 15.35 volts. Checked at the battery again and it read 14.9 to 15.0 volts this time. I just wonder if it could be a bad cell in the battery as previously stated? Could a bad cell be raising havoc with the electrical system?
 
I'm going to change the battery tomorrow. This is the last thing to replace. I'll let everyone know what the outcome is. Any other suggestions welcome. Thanks, Christopher
 
The regulator should catch the high voltage and shut off the alternator. Did you check voltage at the two field wires in the back of the alternator? Also as mentioned, make sure the regulator has a very good chassis ground! You might try running a good jumper wire from the negative battery post to the regulator and then checking output voltage to see if it will change. Do you have the old regulator?
 
nothingbutdarts said:
The regulator should catch the high voltage and shut off the alternator. Did you check voltage at the two field wires in the back of the alternator? Also as mentioned, make sure the regulator has a very good chassis ground! You might try running a good jumper wire from the negative battery post to the regulator and then checking output voltage to see if it will change. Do you have the old regulator?
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You should do this before buying a new battery. It could be as simple as an improperly grounded VR.
 
nothingbutdarts said:
The regulator should catch the high voltage and shut off the alternator. Did you check voltage at the two field wires in the back of the alternator? Also as mentioned, make sure the regulator has a very good chassis ground! You might try running a good jumper wire from the negative battery post to the regulator and then checking output voltage to see if it will change. Do you have the old regulator?
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Hello, I will check everything you mentioned tomorrow. I don't have the old voltage regulator, I pitched it. I'm still replacing the old battery tomorrow, it can't hurt. Thanks for your input brother.
 
I took the old battery in today to get tested and it was bad. I replaced it with a excellent battery. Before sticking in the new battery, I cleaned and tightened all ground straps to block and battery. Stuck in the new battery and started the car. Car runs great. Checked the voltage and it read 15.0 volts at idle. Without a load on the battery such as lights or accessories it will run a little higher, I forgot this little fact. An exceptable limit on the alternator is 13.8 to 15.3 depending on the load. I did verify this in a few areas on the net. This is one of them, http://www.aa1car.com/library/charging_checks.htm

Well, I just thought I would do a follow-up to this thread. Thanks for everyones input. Christopher
 
MoparMuscleGuy said:
I took the old battery in today to get tested and it was bad. I replaced it with a excellent battery. Before sticking in the new battery, I cleaned and tightened all ground straps to block and battery. Stuck in the new battery and started the car. Car runs great. Checked the voltage and it read 15.0 volts at idle. Without a load on the battery such as lights or accessories it will run a little higher, I forgot this little fact. An exceptable limit on the alternator is 13.8 to 15.3 depending on the load. I did verify this in a few areas on the net. This is one of them, http://www.aa1car.com/library/charging_checks.htm

With a load on such as ac and radio it dropped to 14.1 volts. Well, I just thought I would do a follow-up to this thread. Thanks for everyones input. Christopher
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Digital voltmeter? Where are you taking this reading of 15.0 volts. I've been a mechanic for 25 years and 15.0 volts is to high! It could lead to boiling your battery, burnt out bulbs and so on.
 
nothingbutdarts said:
Digital voltmeter? Where are you taking this reading of 15.0 volts. I've been a mechanic for 25 years and 15.0 volts is to high! It could lead to boiling your battery, burnt out bulbs and so on.
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Hello, I'm taking the reading at the battery and the alternator. both read the same, about 15 to 15.1 volts. Do you think I could have got a bad Voltage Reg. Maybe I'll change that out again. Your thoughts?
 
MoparLvr said:
You should do this before buying a new battery. It could be as simple as an improperly grounded VR.
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Exactly. The battery has nothing to do with the problem except that it will be ruined by the high voltage. There is no regulation which does not mean the regulator is pooched necessarily. It could be connections, wiring, grounding too. I found that the electronic regulators regulated to 13.5 volts.
 
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