The Stovebolt Site Forums The Shop Area The Electrical Bay Generator not Charging Battery Fully

Hi guys! My grandpa's 1951 Chevy has the original 6V system, and I believe even the original voltage regulator. It's an Echlin with an adjusting acrew in increase/decrease the voltage. The screw is set to max voltage and the battery is fairly new. The generator charges the battery enough to start the engine and run all accessories (the headlights are super bright, although the running lights are pretty dim). The issue at hand is the battery isn't getting fully charged. I can charge the battery manually with a 10 amp charger, and when I start the truck, the battery has a lot more power and turns the motor over at almost lightning speed compared to how it turns over when only the generator has charged it.
I have two 1940s/50s era tractors with 6V systems, and none of them have the issue. They all charge the battery just as well as a battery charger. I guess first I need to hook a voltmeter on to different points in the system and see what I'm getting out of the generator, then the VR? Does that sound like a good starting point?
Any advice appreciated! I'm not too good with electrical systems, so word responses accordingly, please.

This may sound stupid, do you have a 6V or 12V battery? Just a quick thought. A 12V battery will turn your starter faster (i.e. Lighting speed)

It's a 6V, for sure. It's the same battery I was talking about above...only difference is if the generator charges it or the 10 amp battery charger.

Have you polarized/repolarized the generator?

http://chevy.oldcarmanualproject.com/shop/1948_51truck/51ctsm1218.htm

http://chevy.oldcarmanualproject.com/shop/1948_51truck/51ctsm1213.htm

I have never polarized the generator on this truck. My understanding was if it wasn't polarized, it wouldn't charge at all? Since it's been charging some (and I can always see the needle on the amp meter jump up when I apply throttle) I didn't think to try that.

Edit: I was just reading those links you posted, and read the part about the radio by-pass condensers. I will have to check and see if mine are connected in the wrong spots. I know those things seem to be everywhere on this truck...one on the generator, one on the VR, one by the distributor, etc.

If you read what I posted: have you followed those instructions and polarized/re[polarized your regulator/generator every-time/any-time you disconnect/remove/replace the generator and voltage regulator.

Why not just do it now - it cannot hurt, and, it might solve your problem?

If you read what I posted: have you followed those instructions and polarized your generator every-time/any-time you disconnect/remove/replace the generator and voltage regulator.

Why not just do it now - it cannot hurt, and, it might solve your problem?
http://fergusontractors.org/nfs/wp-content/uploads/technical-articles/Polarizing-a-Generator.pdf (about tractors, but pertains to our trucks with generators/volatge-regulators).

Here are noise suppressor/suppression instructions for 47-55st Chevrolet trucks.

I've never had either the generator or VR disconnected, so I never polarized it. I will try that, and cleaning the contacts inside the VR, after reading the links you posted. Thanks!

First, before you do anything else, measure the voltage at the battery posts with the engine running at fast idle- - - - -around 2000 RPM or so. If the voltage regulator is adjusted properly the voltage against a fully charged battery will be around 7.25-7.5 volts. Anything under 7 volts is too low. Those external-adjustable regulators are just about worthless- - - -nothing beats an original equipment Delco regulator with clean points and proper adjustment.
Jerry

I will try that. I guess the VR isn't original then. Looks old enough, I thought it was. I might look into a replacement if I can't get the voltage up.
Off topic, but how do you tell the engine RPM on these engines without a tachometer in the cab?

Just listen to it and turn the idle speed screw clockwise to increase the RPM. When the engine sounds like it does when it's running down the road in high gear, it's about right to check the voltage. Generators don't get anywhere close to full output at idle speed.
Jerry

Finally got the time to go mess with it today. Battery went bad on me a week or so ago, and just now got a new one. I tested the voltage with my voltmeter, and on the new battery it showed a strong 6V sitting. Before doing anything else, I unhooked a condenser which was hooked to the FIELD terminal on the generator (Because I learned it was a "no-no" from the previously posted links). Started it up and increased the RPM. First it stayed at 6, then gradually crept to 7, and crept some more to 8 volts and stayed there as long as I applied throttle. I thought maybe it was just recharging what I used up when starting the motor. Went for a drive, about 2 miles, under 30 mph. When I got home it was still showing 8 V with throttle applied, and 7 with no throttle.
If it overcharges, I may turn the regulator screw down a bit, but if not I guess I won't worry about it.

8 volts is a little high, which could cause the battery plates to warp or the water level in the cells to drop too quickly. I'd suggest dropping the regulator setting just a little, but remember that when you install the cover after making the adjustment, the voltage will drop slightly due to better magnetic conduction of the steel cover. Adjust the voltage at the battery posts cruise RPM to about 7.7 or so with the cover removed, and it should drop to about 7.5 with the cover on.
Jerry

Remember, my regulator is the old Echlin external adjustable type. Has a little screw protruding through the cover, so no need to remove it I don't think.
I got to thinking...grandpa used to run an 8V battery in this truck, so maybe that's why it's turned up.

Running an 8 volt battery was a common “Farmer” fix back in the day. While not the best solution it did serve its purpose. Turn it down just a hair and call it good. Remember, Smalltown Weekend next Saturday!

An 8v battery was a classic "farmer" repair - quick and easy, and "get 'er done". Moreover, many tractors used 8v batteries, so they were on-site-"solutions".

I'd be willing to bet that the starting problems that were solved by that 8v solution were often due to bad battery cables/connections, especially the ground cables/straps, and incorrect gauge 12v replacement cables/straps..

To keep an 8V battery charged properly, the regulator had to be set to 9.25 volts or so. That was rough on bulbs, particularly headlights. Very few 8V conversions got set up properly, and the ones that did had problems with burned-out bulbs and short point life..
Jerry

Just a thought on how I determined if my generator was working; I would check the battery voltage before a drive, then when I got back, I would check it again. As long as the voltage was higher on the post drive check, I figured the battery was being charged. The variable readings on my amp gauge had me wondering if I was getting a good charge or not.

Lee.

If a battery is being charged properly there will be a heavy surge of current as the load of running the starter is recovered. That means the ammeter will show full deflection or close to it and the charging system voltage will be somewhat low. The state of charge of the battery controls the voltage, at least until full charge is reached. As the battery approaches full charge, the terminal voltage goes up and the charge current (ammeter needle deflection) goes down. The right way to check for full charge is by measuring the voltage at the battery posts (not the terminal connectors) after a drive, with the engine running at a fast idle. A 6V battery should indicate 7.5 volts at that time. A 12V battery will show 14.5 volts or slightly more. Checking terminal voltage with the engine off is not a good way to assess charging system performance.
Jerry