Just drove my just finished off-frame full restoration 55 1st 250 miles to Northern Michigan for proper winter storage. Along the way I noticed a few bugs that need to be addressed. The first and most concerning is the high voltage(19.4) I am seeing at the battery when at anything but idle rpms. When at idle the amp gauge is in the middle and the voltage is at 14.5. As soon as I raise the rpms the amp gauge goes to D (discharge) and the battery voltage jumps to 19.4 which is concerning and probably unsafe.
Any ides as to the culprit and where to start my trouble shooting? I should add that we upgraded to 12v system and went to a alternator.
This forum has been great in helping me solve the many mysteries along this journey.
First of all, welcome to Stovebolt, where the inmates are running the asylum! Do you have a generator, or an alternator as a charging system? That voltage is WAY too high- - - -it will fry the battery in short order unless that problem is corrected. Charging system voltage against a fully charged battery should be no higher than 14.5-14.7, lower if the battery is slightly discharged. It also appears that the ammeter might be connected backwards- - - -which is a very simple fix once the high voltage problem is addressed. Help us out with a few more details about the electrical system, and one of the resident spark chasers should he able to help you sort things out. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Since the truck is up in northern Michigan I could not snap a quality image so I had to capture this image from a video of the engine's first run. Not knowing much about it looks like 3-wire to me.
The other thing to note is that the battery/voltage/alternator tester I'm using only indicates a good alternator (green light on tester-photo in first post) when the engine is at idle and the battery voltage is 14.5.
That's a 10-SI alternator with an internal regulator. If it's producing that kind of voltage, the regulator is shorted out and needs to be replaced. It's running full field coil current with no way to control the voltage. Disconnect the big battery charge wire at the back of the alternator NOW- - - - - -before you blow up the battery!
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
10/4 on the concern and disconnect of battery. Can't imagine with a newly re-built engine and only 250 miles on her why that would be. Can't say I'm very happy. The first shop that worked on my truck (and they could not finish my truck while taking on new projects - not good so I pulled the pulled the project from them) had sent the engine out for the re-build so I'm probably left with only internet review comments as my only form of complaint.
Since I have the latitude to buy it here (SE Michigan) and take it north (where truck is stored) do you have a recommendation as to the amp output and 3 wire vs 1? I plan to do the swap over the holidays.
I should have added the only electrical loads are AM radio, heater blower, head lights, front running lights, rear license plate light, turn signals, gauge lights, starter.
Pistol Pete, I would visit A and L parts and purchase a new, not reman, Delco alternator, you can probably take the other one in to them as a core refund.
1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy
A "new" "Delco" alternator will still be made in some third world sweatshop. The name got sold some time ago, sort of like "Craftsman" and a few others. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Amazon 2114 alternator is a good choice. I've used it several times. It's a rebuilt 10si designed for "three" wire. Output has no association with if it's wired as one or "three" wire. Don't be lured by hype or clones. Don't be lured by "One wire alternators". The 10si can be wired either way. All this info from us is assuming all is wired properly, battery is not being funky/sulfated, your meter is not faulty, or a pulley ratio thing.
We will help you wire the 2114 when you are ready. It's very easy.
What is the voltage across battery posts with motor not running?
Last edited by bartamos; 12/22/20247:40 AM. Reason: clarification
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn
I was advising buying new as compared to a re-man due to the high failure rate of recent re-man parts. The parts store I mentioned is an independent long time business, hopefully with some old school knowledge behind the counter. Is there a different brand that you recommend?
1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy
Quick way to see if the ammeter is wired backwards or not.
Turn on the key, but do not start the engine. Note where the ammeter needle is pointing. Turn on headlights. If the needle moves towards C the meter is wired backwards.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
Guys, you have all been most helpful here. When I concluded my test, the voltage across the battery had dropped to 13.2v and I have to assume it continued to drop back to 12.8 as everything is brand new and I have no starting issues. I'll take a new voltage reading upon my return to northern Michigan (were the truck is) over the holidays. Since I was not involved with any of my truck's wiring I can't be sure that it is correct. Sounds like the best plan for me is to study up on the correct wiring for my alternator and start there before junk the alternator installed with the engine rebuild.
The odds against someone getting things right the first time with an aftermarket wiring harness are pretty high. Few, if any of them are period-correct, as the prevailing (wrong) opinion is if you use an original-type dash mounted ammeter, all your kids will be born naked! Few, if any of the new harnesses even come with the proper wiring in place to support an ammeter. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
