Won't show charge

[ttraut@unlockit]

My amp guage won't show a charge (but will show discharge so I believe the guage works).

I figured it might be the alternator and took it in to get checked; they said it had a short so I replaced it. Same thing.

I figured the voltage regulator might be the culprit so I replace it; same thing.

What do I check next?

The car's a 69 Roadrunner; 383; electronic ignition and has been running this set-up for about a year without problems. No recent work on the electrical system.

Help?!

Terry

[creative1]

not really much info to work with here, but i assume you went to a chain store (like autozone or car quest) and got a rebuilt alternator. my experience with these rebuilt units is that you get a usable unit one time in three.

the first thing to do is to get a voltmeter and measure the battery voltage with the engine off. should be around 13 volts... give or take a couple of tenths... then start the engine and measure the battery voltage again. should go to something like 15-18 volts. hopefully not 18, but it could go that high. if there is no increase in voltage, the alternator is not charging. if this is the case, take it back and have them test it. if it was purchased at a chain store, it will likely have a "lifetime warranty" and they will replace it if it is bad. if it isnt bad, then you will know the problem lies elsewhere.

i have seen ammeters that wouldnt show much of a charge unless there was a really heavy load on the system or the battery was discharged pretty good, but i doubt if this is the case, cause you wouldnt have posted if this was a 'normal condition'. other causes of no charge are broken wires... bad connections, and it is possible that you have 2 defunct regulators, though not likely. unlike alternators, regulators are not easily rebuildable, and are new units when sold.

[23T]

Check the wiring make sure no cracks, good clean connections, ckeck to be sure you have every thing grounded good

[dave571]

I agree with creative one, that you need to check the voltage to see if the system is charging.

I think he's a little hihg on the values. A charged battery should have an open circuit voltage of about 12.5 to 12.8. You shouldn't see values of 13 or higher, unless you just took it off the charger.

Running, it should be 13.6 to 14.6 without worrying unless it goes above 15 volts. (but that is overcharge, and doesn't seem to be your problem)

So first verify that it does or does not charge. (with the voltage check)
I assume you're using the single field wire alternator. If it's not charging, pull off the small field wire, and check it with a voltmeter or test light. It should be system voltage, as if the regulator is working, it will try to go full field, if the voltage is too low. If you have a very low voltage there, then go to the regulator. The input terminal on the regulator should have system voltage on it when the key is turned on.

I've found in the past, that a lot of the time there is a voltage drop, prior to this location, and the regulator doesn't work properly. (6 volts on the system wire instead of 12) It can't do it's job, if it doesn't have correct voltage.

Can be caused by corrosion, or a broken wire, ect. I think if do some searched of the threads you may find a diagram of the circuit. It may help to find the fault.

[dave571]

ps. Don sells a fully electronic regulator for the early style alternator.

It's a bolt in, NO WIRING MODS, and it looks just like the one you take out.

check it out at his site
www.4secondsflat.com

click on the little picture of the regulator, and then you get you get the details.

28 buck plus shipping, I think..

[ttraut@unlockit]

Thanks for the guidance!

First of all, Dave's comment about single field made me go back to the alternator and check the connections. The one with the eye connector is obviously correct since it is held on by the one and only nut. After closer inspection, I found TWO blade type connectors and connected my female connector to the OTHER one. Now when I step on the gas, the ammeter shows a slight charge.

Engine off = 12.7 volts
Engine idling (900rpm) = 12.5 volts
Engine at 2000rpm = 13.2 volts

Thanks, Dave, for the Don connection on the regulator. Even though I just bought a voltage regulator ($41!), I STILL think I'll order one from Don.

Terry

[creative1]

tried this earlier... but explorer crashed

ok... all mopar alternators have 3 terminals on the back!!! the big one is output... then there are 2 field terminals. now for the tricky part...

early mopar alternators had one brush on the field grounded to the alternator frame. these were used with a BLACK relay type regulator... kinda cubical looking thing. basically, it allowed one of two different voltages to flow to the field: full battery voltage for the high charge rate (battery discharged or heavy load... full alternator capacity) and some lesser voltage for low charge (battery at or near full charge or light load).

later alternators have neither brush grounded, these use the solid state (electronic) regulator, which applies full battery voltage to the alternator any time the ignition is on, and regulate the output by controlling the flow of current to ground, after it has gone through the field.

the later style alternator CAN be used with the earlier style voltage regulator. just pick a field terminal and make a jumper wire to connect it to ground... the engine block, alternator mount bracket, or a right rear fender bolt if you have the wire... lol... then connect the other terminal to the wire that comes from the field terminal on the regulator.

if you get the late style brushes, and put them in the early style alternator (no need to disassemble the alternator) you can convert the old style alternator to the late style.

where the hell they come up with this "one wire" sh*t i dunno... it aint a mopar! there is, i hear, on some of the newer vehicles (2000(?) and newer) a 'denso' (nippon-denso(?)) alternator that may be a TRUE one wire alternator. a TRUE one wire alternator has the regulator mounted internally. want one of those, GET A CHEVY or a FORD!!!. then when that $6 regulator goes south, you can go to autozone and fork out $60 for a rebuilt alternator, cause they aint gonna tell you that you can buy the regulator seperately. they will also charge you $14 for that $6 regulator, unless you piss 'em off... then it will be $21... lol. i could write a book about my experiences at autozone... none of them are positive. $18.95 ror a set of edelbrock metering rods... my a$$!

wanna REALLY piss 'em off? take a perfectly good old style ford alternator, and a perfectly good old style gm voltage regulator, and marry them on a 1959 mga!... then take THAT to them and try to get parts... roflmao. it WILL work, and it will work well. those parts is parts, and they dont care where the volts come from as long as they are volts.

[ehostler]

The regualtor that Don sells is no better than the one that you can get at the local parts store. The one from the local parts store is also solide state on the inside, now days.

The new Denso Alt still uses a dual field setup. It is NOT internally regulated. the PCM is the regulator on the newer MOPARs. Only GM style alts are internally regulated.

If you are running a dual field alt in an older system (pre '70) then you definately need to ground one of the fields leads out of the alt.