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I know that I should be able to address this problem but as I age I get more and more grey matter in the head blocking out what I should know.
1949 Chevy, 235 inch and 12 volt system. Starter is still 6 volt. Otherwise stock. Went to start the truck yesterday and ran the battery down quite quickly. Let it sit for half a day and it started up right away so drove it a few miles. This morning it started easily. At idle the metre reads less than 12 volts and at RPM it went to about 12.8 volts.
I know that a 12 volt battery should produce about 13+ volts when running. I am puzzled whether it is my generator or the battery. The battery case is spotless and the terminals are cleaned every 6 months.
I can take it to a local FLAPS and ask them to check the battery but they have a habit of saying its bad and sell you a new one regardless of the condition.
Any body who can offer me suggestions/ideas/help would be a blessing.
Bill

Do you connect a Battery Maintainer when parked...especially over extended periods...winter layup, etc. If not I would highly recommend investing in one they are relatively inexpensive and provide extended life. But by all means have it load tested @ your local FLAPS. Just a quick voltage check doesn't prove the strength of the battery.

Thanks. No I do not have a Battery Maintainer. The truck is started up and run around the block a few times during winter months.
I just checked again and after having sat for 3 hours the voltage reads less than 12. If at higher RPM it only gets up to about 12.8.
I do have a high quality master cut off switch under the seat and I do not think it contributed to the problem. I have had it in place for about 5 years and turn it off each time the truck gets parked in the garage.

“Voltage reads less than 12”, would be of concern to me. Get the battery load tested. 🛠

Was just talking to the only reliable auto electric shop in town and says I should be getting about 14 volts when its running and after running I am still not getting 12.6 which is the norm. I'll start with a battery load test and if need be take the generator in next. Could also be the voltage regulator.
Unfortunately its Friday and they are closed until Monday.

Got a daily driver? Is it 12 volt? Switch in the daily driver battery and check your voltage. It’s free and you can do it in your drive way.

The battery doesn't produce 13 volts, the charging system produces the voltage. Sounds like your charging system needs checked out.

I have a digital voltmeter that plugs into the cigar lighter; cost less than $20 thru amazon. At idle, the voltage is about 12.2 and the ammeter is showing a slight discharge. At fast idle, the voltage is over 13 volts and the ammeter is showing a slight charge. Speed up and the voltage goes over 14 volts.

I think 55shaker is correct - charging system needs to be looked at. There are instructions posted in the forums here on how to do it.

Good idea about using the daily driver battery. but my daily driver battery has said terminals only. At one point I disconnected the battery terminals just to insure they were clean. I clean them regularly so it was a shot in the dark. I noted the voltage before disconnect was 11 something, close to 12 volts. While the battery was disconnected I put the meter on it and could see the voltage drop. When I reconnected it was down to 11 volts.
If the voltage was dropping while disconnected it must be the battery not being able to hold a charge and not the generator/voltage regulator or a bad ground.

Certainly sounds like a bad battery, but since the voltage reads only slightly over 12V with the engine running, there is also likely an issue with the charging system, as others have suggested (V reg or generator). The voltage should read about 14-14.5V at fast idle. Spec on the '56 V reg, as a point of reference, was 14.5V. Load test the battery and check or have checked the charging system, as others have said. The charging system isn't ruled out as an issue based on the info you provided.

A single lead-acid battery cell produces approximately 2.1 volts when fully charged. Stack six of them in series, and a fully-charged "12 volt" battery will show an open circuit voltage of 12.6. Does that sound familiar? If your battery will pass a load test (no, there's NO substitute for a proper load test) - - - - -find somebody who can test and repair your charging system. Like the motto Sun Electric Co. used to put on all their test equipment- - - -"We test, not guess!"
Jerry

He's a hard sell...Jerry.

Sedgey has enough information now.
He’ll figure it out now.
A friend of mine recently went through the same trepidation’s recently. Turned out to be he was chasing two rabbits up 2 different trees.
Two of the four recently new batteries wouldn’t hold a charge and the alternator was bad.
Carl

One of two batteries I load tested at Homecoming flunked the test. In any electrical system, the absolute first thing that needs to be done is to determine that the battery is capable of accepting and holding a charge and performing the proper current delivery when under a starting load. If it can't do both those things, tinkering with the charging system is premature. The battery is the heart of a good charging system, and nothing works right if it's not up to the job at hand.
Jerry

The final update until after I visit the electrical shop.
This morning with the battery connected and the motor not running the meter read 11.7 volts. I did not try to start the truck. Four hours since it still showed 11.7 volts and when I tried to start the truck (cold) it ran the battery down. I have removed it and Monday I will take it to the best electrical shop in town to start the investigation. This shop does everything automotive electrical and I have a lot of faith in them.
Bill

Went to the shop this morning. Fellow asked if it was charged and I said only about 11.5 volts. He put his voltmeter on and found 11.8v.
Then he put on the load and the voltage dropped to 5 volts. It was the battery he says so I bought a new which I am trying to install but the hold down bracket goes right over the post location. Trying to move the threaded uprights ahead but its tough as there is not much room to swing a big hammer.
Once its in I'll let you all know.
I don't know if batteries are getting heavier or I am getting weaker.

Went to the shop this morning. Fellow asked if it was charged and I said only about 11.5 volts. He put his voltmeter on and found 11.8v.
Then he put on the load and the voltage dropped to 5 volts. It was the battery he says so I bought a new which I am trying to install but the hold down bracket goes right over the post location. Trying to move the threaded uprights ahead but its tough as there is not much room to swing a big hammer.
Once its in I'll let you all know.
I don't know if batteries are getting heavier or I am getting weaker.



"Sedgewick"
1949 Chevy 1/2-Ton
1989 Caprice

Don't hammer on the threaded rods- - - -slip a piece of pipe over them and lever them around to whatever position you need. Was there a problem with the other battery? Maybe your seller needs to give you the right battery- - - - -not whatever he's got on hand.
Jerry

"Hammer" was only a turn of phrase! Spent the afternoon trying to solve this issue. For some reason the terminal posts are very close to the edge of the battery unit. If and when I figure out how to secure it it appears the battery cable terminals will sit on the hold down clamp. Although this battery does not have side terminals I think the case is the same as if it had seeing the posts are so close to the edge!
The other battery was dead. When a lod was put on it the voltage showed 5v.

Cut a disc from a piece of plastic or leather and slip it over the battery post to prevent the terminal clamp from contacting the hold down. There are also plastic hold-down frames that will definitely prevent shorts. The positive cable is the only one that can cause a problem- - - -it doesn't matter if the ground cable comes into contact with the hold-down.
Jerry

I was using one of those four-sided battery hold downs previously. That is the terminal contact point I was concerned about. I have since moved the threaded rods further outboard and substituted the old hold down with a piece of flat steel stock in which I drilled two holes for the rods. This very secure and well clear of the positive terminal.
The only problem is because the rods are leaning out from vertical the flat stock does not lay flat and only one edge contacts the battery case. Don't want it to act like and knife and I was thinking of elongating the holes in the steel stock or getting some round Stock. The round may be a bit of overkill.
Thanks to everyone for listening to my whine and helping me out.
Bill

Hey Bill,
You didn't sound whiny at all. Good luck to you with this.
Carl

I like Jerry's plastic/leather suggestion.

I would use those with with these anti-corrosion impregnated felt "washers". These seem expensive, but the photo shows rings with a "cut-out" to allow them to be used with different diameter terminal posts. Some sets do not have that feature.

I now use the felt washers (alone) with a 6-volt Optima battery in my 1954 trucks. The rings isolate/insulate the cable ends from the VERY CLOSE battery cover/retainer. No corrosion or shorts in over 10 years.

Good ideas, thank you. The relocated threaded rods allows me much more clearance from the terminals so I am good. I did however cover the flat steel stock hold-down bar with a piece of bicycle inner tube (same as use on my tailgate chains) basically I guess for a cool look!

I also had problems with the four sided hold down, I was very worried about how close it was to the positive cable. I cut a piece of aluminum square tubing, and drilled holes for the hold down rods, but before I put it in I covered it with three coats of liquid rubber, sort of like the dip used to coat tool handles. Seems to work pretty well.

Tim