The Dodge Challenger Message Board

Hello,

Battery, when cold is only showing about 12.2 V (should be about 12.5 or 12.6, right?). Started it up today, cranked a little slow. Drove some serious highway miles, man is that fun (First time I've had it over 50 ). Came home, shut it down, tried to start it hot, as it feels a little sluggish at times when starting, and nothing. Just a click. Battery was down to 12.01. Slightly above idle, it should be at 13.2, right?

Alternator is new, but only 50 amps (tried to save a few dollars). I am running nothing but the coil (i.e. - no fan, radio, nothing). Turn signals go real slow, lights are dim, etc. Have a black box external regulator, new as well. Battery is new too. With the key in the run mode, one side of the ballast resister shows 11 V, and the other is 5. It think the voltage should be about ½ from side to side, but should that read 12 on the high side?

I have heard that bypassing the bulkhead and running a heavier gauge wire directly from the altnernator to the relay may help. Any other thoughts on this? Thanks,

What is the voltage on the battery with the engine running at idle?

If it is less than 14 volts at idle it is not charging the battery.

See what the voltage goes up to as you increase rpm. Should go no higher than 14.6v.

I will give it a jump, and then post what I find. thanks,

This may help.

Yep. That is a good article. If the voltage over the battery at idle was too low i was going to suggest putting full battery voltage on the field to see if it is the alternator at fault or the voltage regulator.

I would disagree about the voltages stated though. A voltage below 14 volts will maintain the battery but not charge it. Below 12 will drain it.

A voltage 15 volts and over can boil the battery. Unless it is maintenance free.

Maintenance free batteries take a bigger voltage to charge them. Which means if the voltage is on the low side they slowly discharge.

Bad ground(s) are my official guess. I think +12 volts will turn and start a motor if all is correct.

Thanks to you both. Eddie, I had just received my MA mag, but my wife had conveniently misplaced it. We had dinner plans last night, and I end up reading it cover to cover when it arrives

I am going to jump start it and check voltage, my guess is that it will be below 14, so I think that testing the alternator will be next. Any other components to check on this (i.e. - relay, ballast resister, etc.).

Thanks again for all the help.

Thanks Jon. Checked the body and engine ground, what else to look for? Starter is just clicking.

No expert here but this would be my plan.

Set a high idle and check the voltage at the alternator. Then trace the heavy black wire to the bulkhead and check . While there check the return heavy gauge red wire .This is where the charging circuit has contacted the rest of the cars electrical system. A large drop in voltage here without any major accessories in play means a short.

Next check the relay main lug. (there should be a fusible link in between the two points).

Last and worst of all, down on the solenoid. If all are around 13-14 volts then the charging system should be reaching the battery.

MLMFLCN wrote:Battery is new too.

Just some thoughts.

There is no guarantee that a new battery is OK. It might be damaged from the factory. It is probably very unusual, but you never know.

Is the battery new but has been stored for some time? I do not know if this is the case, but to store a battery on a concrete floor is a bad idea and might damage the battery (I think). If it has been stored for a couple of months then I suggest that you use a battery charger to get it back to normal.

I suggest that you try to switch batteries if you have another working battery.

Okay. Started the car. Only getting 12.5 volts at the alternator output stud, same at the battery at about 2,000 rpm. Did a full field on the alternator, and it passed, got up to over 15.5 volts at the alternator output stud.

Does this mean the regulator is bad? Checked wiring, with key in on position, both wires going into the regulator have 12 volts per the prick tester. Seems to me the regulator is keeping the alternator from developing more than 12.5 volts (which is basically what the battery has to begin with) and effectively charging the battery. Regulator is a MOPAR unit, black one P/N 3438150. Is there a way to test the regulator?

Thoughts on this one? Hate to go randomly buy parts, especially when they are all new.

Did two more tests. Each wire going into the voltage reg. is showing 11.9 V. Should this be slightly higher, or is this not that critical?

Also, with the full field on the alternator, the volatage test on the battery hit almost 16 V before shutting off. The ammeter in the car also pegged. Does this eliminate the wiring as a potential problem?

Still seems like a regulator to me. Is the chrome box unit a better regulator?

Thanks again.

- rich

I think you have narrowed it to either the battery or the regulator. You can test the regulator by using a DVOM or analog voltmeter by placing the Positive lead to the #1 terminal lead on the ballast,( on the one or two blue wires), the other end has a brown or blue and brown wire. The ground lead from the tester goes to a good ground, the battery or stud will do. Turn the engine on with all accesories off. The voltage should be a minimum of 13.8@80 degrees F.

Thanks Eddie. That was the ticket. Dug out my 36 year old regulator, and by God it worked. Now I am getting between 13.5 and 14.5 at the battery, depending on rpm.

Don't want to buy another black one, anyone have better luck with the chrome OEM replacement? Maybe I will buy two

Thanks again, this website is awesome.

- rich

MLMFLCN wrote:Thanks Eddie. That was the ticket. Dug out my 36 year old regulator, and by God it worked. Now I am getting between 13.5 and 14.5 at the battery, depending on rpm.

Don't want to buy another black one, anyone have better luck with the chrome OEM replacement? Maybe I will buy two

Thanks again, this website is awesome.

- rich

Glad to hear it Rich. I use the Orange box but keep an extra as a spare in the glovebox. Some guys use the NAPA/Echlin or Borg&Warner replacement and have had good results that way.

Ammeter gauge was going nuts with the old 36 year old regulator, car was starting to backfire, etc. Put in the "new" regulator, and checked for ground...nothing. Scraped some paint off the new black regulator, and got a solid ground. Ammeter calmed down and the charging system seems to be working great. Timing seemed to be fine once again, and the car ran great.

Thanks again for the tips everyone.

Those grounds are something else eh Rich! Glad to hear it!

How right you are