Does Ballast Resistor Affect Voltage Regulator?

87Itasca · March 18, 2018, 09:21 PM

Hi all,

'71 Dodge B300, 360.

We bypassed the ballast resistor (with a jumper) while doing the HEI conversion, per their instructions, and all is well with the ignition system, BUT the battery doesn't charge.

It has been a bit of an issue with this RV as long as I've known the owners. The alternator gauge alwaysc reads around 0, or as much as -20 or so with the lights on. It never indicates it is charging (never reads positive). The battery has never acted like it was low on charge, so it was never looked into.

Now, the LCD screen shows the battery voltage is at 12.5 volts (and in yellow), and it drops down further as you drive it, as one would expect if it wasn't charging. We swapped out the voltage regulator, and it was charging per our multimeter, but after a few minutes, it went back to discharging again.

Are we cooking these things with the jumper in place of the ballast resistor? Are aftermarket external regulators just junk? What am I missing here?

turbinebronze · March 19, 2018, 01:02 PM

The ballast resister has nothing to do with the charging system on a Chrysler product, unless someone did some rewiring! You should look at Dave's Place (web page). He has the wiring drawing for the basic Chrysler charging system. The link is on the right side of this page. It should help you out.
Just my 2 cents, Craig.

87Itasca · March 20, 2018, 01:04 PM

The wiring is all original, save for what was done on the ignition side, and replacing the old, partially melted alternator power wire. What AWG should this be? Old was a 12 awg (!!!) that was obviously overheated. We replaced with an 8 AWG, since its a 60A unit, and the wire is only run about 3'.

Thank you for the advice on Dave's page. He's an exceptional resource here. Looking at the circuit, nothing we have on ours differs from that, save the bypassed resistor. When we full field the alternator, the battery goes up to 16.X volts at idle, so it should be good. When it was working properly though, the alternator didn't start charging the battery until 900 RPMS or so. Sitting idling at 750, it wasn't spinning fast enough to charge.

Not sure where our issue lies. The fusible link is obviously good if the battery voltage increases when the alt is full fielded, and the alternator appears to be functional. I'd say its the regulator, but something seems to be killing them, unless they are just that poor of quality.

Don't know if it means anything, but measured the resistance between the two pins on the regulator, and the new ones read around 84 ohms, whereas the bad ones read quite a bit higher than that. IIRC 176 ohms or something to that effect. Might be a useless measurement, but it seems like something is going on internally with the used ones.

skloon · March 20, 2018, 02:31 PM

I remember something where the power from the ballast resistor went to the instrument panel, and if the alternator light isn't getting power you don't get any charge- I may be combining with some other car though

BamBam · March 20, 2018, 03:30 PM

I'm new to RV's but not Mopars. I'm not quite sure what the problem really is, but I hope this will help with the wiring. Disregard the Imperial in the title, this site deals with all Mopars, there's tons of Tech info. Good Luck
http://www.imperialclub.com/Repair/Electrical/charging.htm

DaveVA78Chieftain · March 20, 2018, 11:08 PM

Charging system description

Troubleshooting Procedures

Elandan2 · March 21, 2018, 08:19 AM

I have one question, does the unit have an electronic battery isolator? I know that on our unit, the ammeter does not work with that in the circuit. In fact, that was how I knew the isolator wasn't working one time, when the ammeter suddenly came back to life.

87Itasca · March 21, 2018, 10:52 AM

It does not have a battery isolator. Coach and chassis batteries are always connected. It surprised me too, but I've looked for one to no avail in times past.

Thank you Dave. I'll see what we come up with.

DaveVA78Chieftain · March 21, 2018, 01:08 PM

One note about that info. It is primarily for a electronic regulator configuration on a Class A Dodge chassis. If your 71 Class C Van chassis uses a mechanical regulator then there are different procedures.

turbinebronze · March 22, 2018, 01:12 PM

Maybe this will help? (I don't know if this link will work..)

https://www.allpar.com/photos/vimages/mopar-photos/electrickery/21.gif

87Itasca · March 23, 2018, 03:38 PM

Well, this is a new one. I think it might be because the alternator is only a 50/60A unit, and the fuel injection/electric fuel pump is using a good bit of reserve.

It does charge, but only from about 850-2100 RPMs. Over that (cruising), it does not. It starts to taper off to 13.1V at 2000 RPMS, then as they increase to 2400-3000 while at highway speeds, we are actually losing charge.

What gives?

Froggy1936 · March 23, 2018, 04:28 PM

Sounds like worn out brushes , Or loose stator wireing Frank

87Itasca · March 23, 2018, 04:51 PM

Alternator is a new unit, from Rockauto. Should have mentioned that, sorry. Alternator is about a year and a half old, but it has about 300 miles on it, tops.

Rickf1985 · March 23, 2018, 09:44 PM

How is the belt? How low in the pulley is the belt riding? It should be sitting flush with the top of the pulley. If it is sitting down inside it may be riding on the bottom of the groove and slipping without making any noise. It is very common to have a bad pulley on a unit that has had a slipping belt for a while. Once the load increases then the belt starts slipping and the voltage drops off.

87Itasca · March 26, 2018, 01:13 PM

Bingo!

Belt was loose enough to slip. Edges of the vee were nice and shiny too. Scuffed the inner walls of the pulley with some sandpaper, put a new (slightly shorter) belt on, then tensioned it properly. All is well on the road.

It still doesn't really put out at idle (12.5-12.7V), but as soon as you rev up over 1K it does fine. Maybe a smaller diamater pulley?

Rickf1985 · March 26, 2018, 10:51 PM

If it was slipping for that long you need a new pulley, no two ways about it. The inner profile of the old pulley will be worn out.

87Itasca · March 27, 2018, 01:15 PM

Alright, I'll add that to the next round of parts. Took it for a long drive yesterday and the replacement voltage regulator crapped out. Ran it at 15.0-15.5V until I got home. No damage, thankfully as the ECU and pump are good for up to 18V. Put another one in, and all is well...

Are any brands better than others? Seems these should last a good while before failing.

Rickf1985 · March 27, 2018, 04:10 PM

I guarantee the battery did NOT like that!!!! Are you reading these voltages from the dash gauge or a known good meter?

postman · March 28, 2018, 05:47 PM

Quote from: Rickf1985 on March 27, 2018, 04:10 PM
I guarantee the battery did NOT like that!!!! Are you reading these voltages from the dash gauge or a known good meter?

Rick1985 suppose it was a good gauge, is there a circuit you can interrupt to save the battery? Or do you remove the wire from the Alt. output stud making sure it doesnt ground? (to make it to a safe stop) Hm?

Rickf1985 · March 28, 2018, 09:00 PM

Pull the field wire off, no field current, no charge.

87Itasca · March 29, 2018, 12:20 PM

I was reading it directly off the battery terminals. Drove it for about 45 minutes. Battery doesn't seem to have been too upset by it. It was weak before, and it seems to be just as weak as it was before, lol.

I was concerned about the bulbs though. Don't seem to have lost any.

Rickf1985 · March 29, 2018, 02:02 PM

A weak battery can cause a lot of the issues you are mentioning! You need to get a good battery in there or you will be chasing your tail forever.