Voltage Issue

[Stealth78]

About two weeks ago I had my voltage alarm (beep) go off while sitting in traffic at idle, I look down and my red voltage light was on and my voltage was at 10. About 5-10 seconds after I pulled out of the stop light the voltage jumped right back up to 14 and all seemed fine. It was 90* out and I did have my AC on so my first thought was the comments I have heard others mention about UD pulleys, AC on and possible voltage issues.

I took the car out last night for the first time since that last episode, drove about 20-30 miles with no issue. Got into heavy traffic while crossing through the city and at the third intersection I was stopped at "BEEP".... the damn alarm goes off again and the voltage is at 10, AC is NOT on this time. Same as last time as soon as I drove for 5-10 seconds the light goes off and voltage jumps right back to 14, all was perfectly fine for the rest of my drive home. Any ideas???

I will add that I have had UD pulleys on both of my SRT-10 Rams and never had an issue. I'm not saying this is the issue but wanted to point that out.

[City]

How old is your battery?

[Stealth78]

How old is your battery?

You know..... I was wondering the same thing as I am sitting here in my office. I'll have to check when I get home. Car starts very strong so I wouldn't think it's the battery but as I said I was wondering that today too. Figured I'd start out simple with that as well but wanted to pick peoples brain as well. Battery was in the car when I bought it about a year ago. I'll pull the cover and check it out.

[Steve M]

So you have an underdrive pulley, correct?

I did some calculations a while back, and I'm pretty sure I came to the conclusion that you'd need an idle speed of around 925-950 RPMs in order to maintain a full charge, based on the stock idle speed of 700 RPMs and the percentage difference between the diameter of the stock vs. UD pulley. This issue isn't always going to be present, but will potentially rear its ugly head with warmer temps and more load on the alternator, especially in heavy traffic when you are idling a lot. The in-cabin voltage meter has a pretty slow response time, so I'm not sure you'd even notice a voltage drop just by watching it, and it's not exactly something you'd want to watch while maneuvering through traffic.

The first thing to check is going to be your battery...if your alternator isn't charging, the vehicle has to rely on the battery to provide the extra juice it requires. An old battery is going to have a hard time coping with this, so it could be part of your problem. These cars also have a large key-off battery draw, so if you don't keep the car on a tender of some sort, that will also contribute to a weak battery.

If you really wanted to test the issue, you'd probably have to put the stock pulley on and see if the problem persists, but that takes time and effort, and doesn't sound like a lot of fun. Check the battery first, and if that checks out, then you can start looking at the other contributors. If you end up going with a custom tune at some point, you can always set the idle RPM wherever you like.

[Jack B]

Check the alternator connections and the battery connections. Check, means remove, clean and tighten. Copper oxide (oxidation) on a connector creates a high resistance. I am not sure on the G3, but, the G2 had an inline fuse running out of the alternator harness, that could be another point to check. When you start out at 12 volts, it does not take much of a termination issue (high resistance) to get a pronounced voltage drop.