Jump to content

Recommended Posts

I am tryng to get my 50 Olds 88 on the road but have an issue charging the battery. I have replaced all the wiring under the hood and have cleaned the regulator points as described in the manual. Basically at fast idle the generator puts out roughly 6.5 volts (Chcked at regulator). When headlights are on it drops below 6v. At idle with all electic off it barely hits 6v and goes in the low 5v's with hedlights on.

So reving the engine increases output but never above 6.5v. At idle I can see the speed of my blinkers drops by half and speed up when I rev the engine.

The manual says if you have low output you can isloate to a generator problem if you ground the "F" terminal it should cause the generator to increase output. I tried several times but never saw an increase.. I checked the brushes which look good to me and checked to ensure the connections on the two wires from the generator were clean and tight.

Trying to avoid a trip to the shop to have the generator checked in case it's something simple.

Link to post
Share on other sites
  • 2 months later...

Hi. I am not a generator expert, so please take what I say with a grain of salt.

Did you try to "motor" your generator?. If you ground the case and touch power to one of the terminals, does the generator spin?? If not, there may be something wrong internally. (a generator is a motor "in reverse").

Next thing, if it does motor, see if a smaller diameter pulley is available. The smaller your pulley diameter, the faster the revolutions of your generator (which should help with idle and basic around town situations).

How about your voltage regulator... Generally it is an external regulator (especially for 6v). Did you "excite" your voltage regulator?? (I believe you have to briefly short terminals "F" to "I", but double check your manual) If you do not excite your voltage regulator, you will generally have problems with charging.

Also, in the voltage regulator, there are tabs that can be bent / adjusted to regulate the output of your generator. Once again, check your manual for specifics.

These are a few Ideas. I hope it helps you.


~Joe Ferrero

Link to post
Share on other sites
  • 4 weeks later...


My battery has stayed charged with no problems but yesterday both low beam filaments blew out on my drive home. I noticed my dash lights seemed a bit brighter than normal as well. The amp meter in my dash does not seem to work but I imagine the generator pushed out excessively high voltage. I did check my wiring and the low beam wire has 6 volts and it's a bit much to assume that my 2 month old headlights both decided to go out at exactly the same moment.

I have read the most common reason for voltage surge is a bad ground but I checked all my wires and they are tight and clean. Engine block has a ground strap to the firewall, ground cable from battery to engine seems good, positive connection between regulator and starter seems good. Not sure where to check now. When I got home, I put a meter on the batter with the car running and it never went over 6.5 volts as I turned various electrical components on and off.

Also, does anyone know where I can buy 6v volt gauge to mount under the dash?

Link to post
Share on other sites
Does anyone know where I can buy 6v volt gauge to mount under the dash?

A volts gauge is a volts gauge, is it not? I certainly would want one that reads more than 6 volts, in order to get a more accurate picture of what is actually going on. Ideal would be a 10 V gauge.

Link to post
Share on other sites

I think Dave is right, that a voltmeter will only read whatever voltage is going thru it. Most you'll find will read up to about 15V, which should work though I know sometime gauges are less accurate reading in the lower third of their scale.

Ray- agreed it is coincidental that both lamps burned out concurrently, but if these were new reproduction 6v headlamps they'd be suspect to begin with. For that matter really old 6v lamps might also have reached the end of their life.

Link to post
Share on other sites

Both headlamps burning out at the same time mean one thing . Too many volts. You should be able to get an inexpensive voltmeter at Radio Shack. As a temporary check it may be just as easy to hook up a VOM meter in a way that you could monitor it. Obviously you already have one if you check the voltage.

Link to post
Share on other sites

Headlight problem is interesting to say the least. As for the generator and your voltage readings, 6.5V is too low and usually indicates no charging at all. Your battery when sitting with engine off should read 6.4-6.5V and once engine is started and generator starts charging it should jump up above 7 volts. When you start the car and there is no increase in battery voltage, that is typically a no-charge situation. That could be cables/connections, generator or regulator. Feel free to contact with any questions.

Link to post
Share on other sites


Thanks for the info. I do have some questions....

I have been measuring voltage at the battery. While running I see about 6.5 volts as long as the engine is above idle. Battery is new. I have been running the car for a few months now and it always starts up and never seems low. I ordered a Radio Shack 0-10V meter I will install inside the car so I can monitor while driving.

1) Should I measure voltage at the Regulator instead of the battery terminal?

2) My + cable is new and the correct size for the car. Ground strap from battery to engine block is not new but looks good. It is heavy braided metal. It is a clamp style (universal) though so I think I should replace this as well.

3) I have a 10g wire used as my engine to cowl ground. Should I get the correct strap or should this be fine?

4) I cleaned the points with a small file in the regulator and set gap to factory spec. I don't have anything handy to put a load on the generator outside just turning all the electrical components on. Is it possible to set the regulator effectively without that? When I adjusted for voltage it did not seem to do anything.

5) The brushes in the generator look fine to me but I do see some sparking out the back (I.e. the spark actually jumps outside the generator housing occasionally.). Is this normal or the sign of a problem?

I guess I should just take this all to a professional to have them look at it but I'm trying to do all the work I can myself, not to mention I am way over budget. Any suggestions or advice is more than welcome. I do have the 1949 Olds 88 shop manual which goes into a fair amount of detail on the charging system but this is not an area I have much experience in.

Link to post
Share on other sites

Have been following this thread and just read your last msg. I am no expert, by any means. At the same time, I do feel I know enough to safely say that "sparks jumping outside the generator housing occasionally" is most definitely not normal, be it a 6 or 12 volt system. good move on the 0-10 V meter.

Link to post
Share on other sites

I did some more detailed testing last night and things seem normal to me. Before I started I turned the headlights and blower fan on for about 10 minutes to discharge the battery a little.

Test 1 - Engine rpm 1,200+. No load. All electrical components turned off.

Initial voltage reading at Bat connection of regulator was in the high 7v area. Flirted with 8v

After a few minutes of running it reduced to about 7.5v

Test 2 - Engine rpm at 600. No load

Voltage reading dropped to about 6.5v to 6.8v

Test 3 - Engine rpm 1,200 with load. High beam lights and blower fan on high

Voltage reading dropped to 6.5v

Test 4 Engine rpm 600 with load

Voltage reading dropped to 6v

At no time did I see any spiking or radical changes in voltage. Raising the rpm raised the voltage accordingly. Under full load the system could maintain a charge of 6.5v+ but could not really keep up at idle which I believe is normal for a generator. So my question is "Do I have a charging problem?" Also, what could I check to explain why both of my low beam bulbs burnt out at the same time?

Link to post
Share on other sites
  • 3 months later...

Another silly question... I replaced the regulator with a new one. It seems to take about 10 to 15 minutes before I see any charging after a cold start. The manual talks about a warm up period of 15 minutes before you run any tests on the regulator/charging system. When I start the car cold I get no charge at all. Volt meter stays around 6. Raising engine speed does nothing. After the engine is warm and seemingly the under hod temperature reaches a certain level, the battery gets a charge around 7 volts and plenty of amps. Increasing the load by turning on lights or blower fan or high beams does not seem to do anything to get the charging process started. It just seems to be temperature. Is this normal?

Link to post
Share on other sites
  • 7 months later...

Need to find out what your generator is putting out, Volts or amps?

1. Buy a cigarette lighter plug in, for making some accessory to run from the cig lighter. Just the ends that plugs into the lighter, it will, or should have two wires coming out. Those two wires are what a person would wire to what ever they wanted to run power....

2. A multi-meter....The red is the hot wire, black of course is negative....Using the cig lighter plug you just bought, use the center probe on the positive or red wire of your multi meter, and the black of course is the ground....

3. Run your car, plug in the cig plug, connect the multi meter, and WA LA!!! you will get what your voltage reading is....Speed up the accelerator, and see if your voltage also increases.

4. Go back to idle, and turn on the head lights, watch the volt meter and see if it decreases. Speed up and see if the voltage also increases to accept the increased load.....(right off the top of my head, I can't tell you what the amp ratings of the head lights are) If the voltage regulator is working properly, you will see the increase as the need for more voltage is needed. This all can be a one man operation and done from inside the car. In the garage, or observed driving...(But do it when there isn't much traffic around, your eyes are supposed to be on the road)

Normal 6 volt is 6.5 volts static...7.4 at normal charging rate at temp. Charging rate may be + - .2

Normal amp charging about 45 amps

Multi meter = a mechanics next best friend

I might add, if your lights go dim as you're just idling, then chances are you battery is about to go ka-putz....If they go bright as you increase your engine speed, to kick in the generator, then the generator is what is producing the volts...A generator is for replacing the voltage in a battery.....Look at what the amp rating of the battery is...This is what that battery should maintain, for????say 3 hours, without being charged.....If you turn on your lights, and they are dim, before you even start the car, then that will pretty much tell you you've got a low battery....The problem might just be a old battery and not the generator....

Old Codger

Edited by Old Codger (see edit history)
Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Create New...