The Stovebolt Site Forums The Shop Area The Electrical Bay Charge start voltage

OK so lets get the dumb stuff out of the way. I have a 52 3100. It has a 55 235 in it. 4 speed manual truck trans, and an Alternator. With a solid state voltage regulator. The regulator is a replacement for the 67 C-20 that I also have. The alternator is also the same. They both are 12 volt systems, and it helps me keep my parts list manageable. Same head lights, same park lights , same brake lights, and so on. I can even change the radio from truck to truck if I want to. The battery sadly will not interchange. The posts are reversed. So there is that. Now to my question. The system has been stable for over 10 years. Now it won't charge with out a few high RPM rev cycles. What part is likely going bad? The alternators is internally rectified, and externally regulated. The Regulator is a direct replacement for the older mechanical version. 12 Volts of course. I don't mind changing them out, I just want to get some idea about the why. Thanks guys.
Steve Halverson.

Unplug the connector from the reg. Put a jumper on the connector from the blue wire to the red wire. Start the engine. The alt. should charge infinitely. If so & all connections are good then the trouble is most likely is the regulator. Don't run it long like this as you can burn out bulbs or electronic parts.
I put one of that type regulator on a Buick a few years ago & it didn't last very long.

George

Steve, First of all you are limiting yourself WAY too much for no reason. (manageable parts list, battery interchangeability) These are non issues in old truck life.

Since you have already made the jump from generator:
1. As your charging systems go bad, switch to internally regulated alternators and get rid of all the extra parts/wiring. Using an externally regulated alternator is half way to heaven.
2. Batteries are interchangeable for testing one vehicle or another. With jumper cables or longer cables. They don't need to be interchangeable if they are bad. You buy a new one.
3. If it takes revs now and didn't before. maybe your idle has dropped or you have some loose or corroded connections. Residual magnetism, which begins the charging at start up, is not used so much in 10si alternators. They use battery power to excite the alternator. I don't know what a DN style alternator uses. Make sure you have a good, load tested, 12.6V charged battery, first.

Delco 10si Alternator. si= system integrated= internally regulated. 3 wire hook up. Better to have one component for charging, not alternator and regulator with many connections/wires.

If there is a charging problem and connections are clean and tight, battery is good, then one component @ $55 free ship, 20 minutes and you are fixed. No testing required.
You can test, disassemble, clean and rebuild them with diodes and regulator for $15, but the delta is only $40/no DIY risk.

Let us know if you agree with suggestions or have questions. Glad to help.

Thanks for the tips. The truck came home with a lot of problems. In the beginning I had no Gen. And so I used what I had on hand. Thinking 12 Volts is 12 Volts so that was a part of what drove this. Now to be fair, the 52 is a daily, not a show truck. The setup has worked for 15 years with only one battery change. The other thing is the problem is new to me. Never had it happen before. The alt has let me do lots of grocery runs, and trips to the dump with little care about recharging on short trips. There is other things that have started to get wonky. So a new wire harness is next to install. Random is weird. No radio, and then it comes back. No brake lights, and they come back. The charging was just as strange. So the harness. But after 15 years, the Regulator was my first thought to explain the issues. More thoughts will come. I will try the jumper. If nothing else, I can learn what the solid state reg. does. And that might help understand the circuit they use. The regulators I worked with were little chips whit heat sinks. Good for 5 Volts but little amps. And they had heatsinks on them. At 35 amps that is another world indeed. Just trying to be smart and not just a parts changer. Harness this week and more to come. I will keep posting what the adventure is as time goes along. Thank to you both for the input. It is helpful.
Steve Halverson

Slow down Steve. The only problem you have stated is that you have to rev to get charge. I guess you know that from looking at ammeter. Not sure. You don't say that you have checked battery voltage during motor running and after a drive with motor off. You don't say you have a starting problem. So no real problem on your initial post.

Then you say radio goes off and on. Brake lights go off and on. Don't know how you know the brake lights are doing that?
Without wondering how the regulator works and understanding the circuit, can you tell us what specific problem you wish to fix?
You say you don't want to be a parts changer, then you say you are getting a new harness. THAT is a BIG part to change without letting us know exactly what you are trying to fix.
As I said, MAKE SURE your battery is good before doing anything else. Have it tested by someone who knows how to load test. You can just test the voltage yourself. Do those things and report back.

You need to know if battery is good/charged to 12.6V/being charged at ~14V.......by using a multimeter. Report results. One step at a time. The wonky stuff points to low battery. Battery going bad. Your tests will tell us if it's the battery or the charging system. But we don't know what the IT is. Where's the beef?

Jerry (Hotrod Lincoln) can fill you in on how the regulator works if that's what you want.

So your battery is 7 or 8 years old?

Intermittent electrical sounds like corrosion/rust on the grounds from battery to block and block to body. Check those first to ensure you've got solid grounds everywhere-especially as you mention that the rig had a lot of problems when you got it. It's not outside the realm of possibility that it's been grounding from block to chassis through the drivetrain all these years.

It's also the super cheapest and easiest first fix that could rule out a bunch of other, not so cheap and easy fixes.

Sorry for the delay. Life gets in the way.. Charging voltage was and is 14.5 VDC. that was not the issue. The random times from start to charge was. The problem was as suspected, a bad crimp on one wire. I found it after way too much time, but poking and picking is a good activity. The wire was from the sensing part. And it went to the regulator. It added resistance, and dropped voltage too low to excite the charge function. One crappy crimp and days were wasted. Been there and done that. The real question was the "why" and after that it was just simple trace 4 wires and find what was bad. Thanks to all for the inputs and the help. I still think that is the best part of this site.
Steve Halverson

Glad you found it. I once had an alternator wire break inside the insulation. From the outside everything looked great. The intermittent charge/no charge was impossible to find.

One day while it was running and I was checking connections and tugging on various wires, I pulled on one and the engine skipped. I found the culprit just by luck.