I am in need of some advice on these Model T generator systems. I have a 1926 model t Roadster and I noticed while running whether it's at a low or fast idle the ammeter in the car shows less then 5. My magneto system doesn't work so I run the car on battery. The only reason why I noticed this was because I noticed this morning as I went to start my car it sounds like a dying battery. Finally got it started and noticed like it didn't seem to be taking a charge. Im trying to figure out whether it could be a cut-out switch or generator problem. I'm a diesel mechanic so I have no problems with diagnosing, I just wanted to get a better understanding of these systems. Thank you.
I am assuming it is the original 6 volt system. Is the generator putting out voltage you may need to adjust the "Third Brush" or the cut-out switch may have gone south. Will the battery charge on a charger? "T's" generally don't use much power so for the ammeter to drop to less than 5 volts after running for a few minutes is normal. Check your connections on the battery and ignition switch it is probably something simple, Good luck
Forgot there is a "T" club in your area with lots of expertise contact info
Tin Lizzie Club of North Central Florida
c/o John Farr
2163 Callaway Drive
The Villages, FL 32162
Yes, it is the original 6v system. I usually drive the car about 20 miles per trip and today I did 40 miles. The gauge stayed on 5 or below....I have the battery on a charger right now to eliminate the battery.
I meant amps not volts, geeez my brain is melting today
Gotcha, no problem. I've had one of those days too
Would you happen to know which terminals I would put my meter on to test voltage coming out of the generator?
Even if the charge rate shows as 3 or 4 amps it should be enough to maintain the battery. How old is your battery?
Battery is from 2016. I've owned it new for 3 months. Just took it off the charger and it started the car fine. Still curious as to find out how to measure voltage at generator/cut out switch to determine if one of those are an issue.
Well, if your ammeter shows a charge of 3 or 4 amps, versus zero when the engine is off, there's your "voltage" check right there. If you like, you can test voltage from the generator terminal post to ground and from the cutout, where the battery wire connects, to ground.
I show 4-less amps while running from the gauge in the car. If I put my meter on the yellow/black wire at the generator and another lead on the bottom mounting screw I get almost 7v. If I put a meter lead on the yellow/black wire and go across the cut out switch to the stuff with the nut I barely get 2v. Does that make sense?
"I show 4-less amps while running from the gauge in the car."
I don't understand what you're trying to say here.
"If I put my meter on the yellow/black wire at the generator and another lead on the bottom mounting screw I get almost 7v."
That sounds encouraging. I assume you're getting that reading with the engine running? Is "almost 7V" more than what the battery alone shows after you charged it?
"If I put a meter lead on the yellow/black wire and go across the cut out switch to the stuff with the nut I barely get 2v. Does that make sense?"
Do you mean you checked across the cutout? You should not get a voltage drop across the cutout, which is what I think you're saying.
With the engine running the ammeter gauge that is on the dash of the car shows 4-less amps. No matter what the rpm is.
If you can picture standing on the passenger side of the car. You have the cutout switch on top of the generator. You have 2 ears that have screws that hold down the cutout switch. Then you have a stud with a nut that also mounts to the cutout switch.
With that said, if I take a meter and go from the yellow/black wire to one of the ears with a screw I show 7v.
If I measure across the cutout switch (yellow/black wire to the stud with the nut) I get 2v.
WHAT DOES "4-LESS AMPS" MEAN? Is it showing a positive 4 amps or a negative 4 amps? In other words, what side of zero is the needle when it shows 4 amps?
"...if I take a meter and go from the yellow/black wire to one of the ears with a screw I show 7v."
When you do that you're essentially measuring the battery voltage. If the voltage of the stand-alone, disconnected battery is the same 7V then your generator is doing nothing. But, if the battery voltage is say 6.3V, but you're checking 7V with the motor running, then the generator is putting out.
"If I measure across the cutout switch (yellow/black wire to the stud with the nut) I get 2v."
That means you show a voltage drop across the cutout. That shouldn't be. Measure the voltage from the "stud with nut" to ground, while the engine is running. What voltage is that?
My mistake, show 4-less amps on the positive side of the ammeter gauge inside the car.
The the voltage of the battery itself is 6.3v.
The voltage from the "stud with nut" to ground is 6.8 and rising the longer the engine runs.
There is a voltage regulator being sold by the vendors. If you have a voltage regulator on the generator, you would have a higher amp charge rate after using the starter and then it would drop down to a low rate after the battery is fully charged. When you turn on the lights the ammeter would read close to zero but not discharge.
If you have the cutout or the diode cutout, the rate of charge would be the same whenever the engine is running except that it would drop to near zero at idle. If the third brush is set to 5 amps you would continue to charge at 5 amps as long as the car is moving along. But when you turn on the lights it might drop to a few amps discharge. You can set the third brush moving it toward the engine if you drive with the lights on most of the time. Set it so the charge rate would be zero with the lights on. In the summer when the days are long, you can set it to 5 amps or less if you drive often for longer distances.
When the battery is old sometimes it does not take many amps to fully charge it and it also won't take many amps to discharge it. I find that the typical battery lasts from 4-5 years.
O.K., sounds like your generator is putting out. It may just be that you need to adjust the charge rate.
Hate to belabor the point, but please tell me, how does "4-less amps" differ from "4 amps"?
It ranges from 4 to 0. Headlights on while running drops to 10 on the discharge. How do I adjust the charge rate? I'm new to Model T'a. This one was left to me from my great grandfather and I got it running after it has been sitting 8+ years.
I'm a little worried about the cut-out. If you with the engine OFF measure from the terminal on the generator (the one the cut out connects to) and to the mounting screw on the cut out and read ANYTHING, then your cut-out is not shutting off the generator to battery, and draining your battery. If you have a regulator cut out, be careful what you do around it, you can 'fry" the electronics in it.
I think you need to get a fellow model T person out there to help you straighten this out--it's difficult to 'splian via the forum!
DO NOT ADJUST ANYTHING. It all sounds normal for a T that is generally not driven at night. I understood Jerry's question so I didn't get in here until you answered it. 4 amps of charge is PERFECT for a car with a diode cutout and the voltage reading of 7V when the engine running is perfect too. Whoever setup the charging system set it up correctly for a daytime driven T. If you drive at night you can drive for awhile with the 10 amp discharge and not have to panic since your battery has a lot of reserve. If you DO drive at night for longer trips than just home from the grocery store, then consider getting a Voltage Regulator to put on your T because only then can you safely set the charge rate up to 15 amps to carry the headlights when you turn them on with the confidence that the VR will reduce the charge rate back to a very low amount once you turn the lights off. Please understand that I am the maker of the Voltage Regulator and also a maker of diode type cutouts. I think you have a diode cutout on your car right now and it is all working OK - you don't need to be charging the battery after each drive unless you are driving at night with the setup as it is. It will be very harmful to the battery AND the generator to set the charge rate higher than what it is now and then use that higher rate with a cutout while driving during the day. Please trust me and do NOT do anything to the generator or its third brush adjustment until you understand more about how the Model T electrical system works. It is fine the way it is at least until we understand your driving habits.
The battery voltage will not immediately drop from 7V to 6.3 when the engine stops unless the battery is really discharged or defective. It will generally take awhile (hour or more) to drift back down from the charge voltage to the normal open circuit voltage of 6.35 for a fully charged battery. Right after charging by any method the battery voltage will be higher than "normal" resting open circuit voltage near 6.3V.
If you measure voltages with a digital meter you very likely will get strange readings from it when the motor is running since digital meters are HATED by your Model T so it retaliates by giving you screwball readings when you use them. Use an analog meter that has reasonable accuracy and you won't get fooled into thinking something is wrong when it isn't. I could give you a long technical reason why digital meters are interfered with by the T ignition system but it is just easier to say your T doesn't like those kinda meters. It is older than you so respect its old age and rejection of modern technology as fair warning to not use those devices for taking readings My high end $$$$$ fluke digital meters don't read correctly on my T either.
I will not adjust anything. I typically drive it 2-3 saturdays a month with my wife. We've had some cold nights here in FL and I had to do some work on the car so I haven't attempted to crank in about a month. Then I went to crank it on Sunday and it would barely turn the starter over. The battery cutoff switch on the floor board was off. I did charge the battery on a charger today, but before then I was having to jumpstart the car.
So with everything y'all are saying, my charging system is fine?
Just read my last post. Let me clarify. I had to do some work on the car so it sat for over a month. During that time my battery cut off switch on the floor board was off. We've had a couple of cold nights here in Fl, and I'm not sure if that impacted my battery at all. On Sunday I finally got my car back together and went to crank it and it barely turned over. Didn't think much of it and it finally started.
Then today I went to drive it to work to show some of my fellow workers, and I had to jumpstart it to get it to start. And by jumpstart I mean I took a 12v battery , set it in the trunk and hood up jumper cables. Then I drove it 20miles to work and I went to leave this afternoon and it wouldn't start again.
I got home and put my battery on charge and started to test my charging system.
If the car sits for long periods you'll have to charge the battery periodically. 6 V batteries doesn't live forever - sometimes just 4-5 years when not used all the time and sometimes shorter if not kept charged all the time. Maybe you need a new battery?
Still working on getting my T up and running, so my comment is based on my WWII jeep which is also 6v negative ground system. Our club members always leave a battery maintiner on their batteries while not in use. Even if it's only a few weeks, on a new battery, they just seem to discharge somewhere and the ground connections need to be perfect or it turns over very slowly and sounds like a weak battery.
The maintainer just puts out enough charge to wake the battery up and not overcharge it or get it warm. There is one on my jeep right now. They come with connections that mount permanently on the battery to go to a quick disconnect terminal that hangs out my headlight. When not in use, I tuck it out of sight and no one knows it is there. I plan on doing the same with my T and run the terminal out between the body and chassis somewhere out of sight.
Sounds good. Thank you all for your input! I think I will get myself a battery maintainer since I don't drive it everyday and go from there. Thank you all again!
Those battery cutoff switches are big trouble. They typically are not capable of carrying full current to the starter. The contacts are typically brass plated steel which corrodes over time and causes resistance which leads to an undercharged battery and even worse performance of the starter. You would be doing yourself a big favor by eliminating it.
Lead acid batteries can last 10 years if you keep them charged all the time. They can last less than a year if they are allowed to go dead once month. I don't recommend trickle chargers because they often are cheap and unreliable. A good automatic battery charger installed on your car for a day once a month will keep your battery in great shape.
I agree with all of what Royce had to say. I would add just one general statement related to his disconnect switch comment.
Voltage is simply electrical pressure. A 6 volt system therefore has HALF the electrical pressure of a 12 volt system. That in turn means a 6 volt system has TWICE the sensitivity to resistance resulting from corrosion (the battery cutoff switch Royce mentioned) loose/corroded terminals at the battery and anywhere else in the circuit.
A quick check for suspect battery terminals when you are confident the battery is in good condition is to turn the headlights on and then hit the start button. If the headlights go very dim or completely off when attempting to crank the engine then the battery terminals need to be checked/cleaned.
The extra sensitivity of a 6 volt system to resistance I mentioned explains in part at least their undeserved reputation.
Ditch the battery disconnect switch. If you answered my phone for a month you would have no doubt about that. They do nothing but cause trouble and very likely the slow cranking could be part of the problems it may be adding to your car.
So about 15 years ago I was having trouble with my Tudor having enough power to turn the starter. New battery, 6 volt, new 00 cable positive and ground, rebuilt starter. I was jump beside my self & very frustrated. So I took all the cables off cleaned the area for the ground til I got to shiny metal, hooked everything back up,no change. At this point I just about had given up. Took the starter out, checked it to see if the shaft was bent,nope. So I walked away from it for about 2 weeks. During the last week I called Fun Projects to place an order for some non related items and spoke to John. A few minutes into the conversation I mention to John about my frustration with the electrical problems I was having & during the conversation I mentioned that I had a safety switch in the system to prevent a possible fire if anything went wrong while I was gone. John said take the cutoff out of the system and said they were notorious for causing problems. Well I knew John was wrong because this was a high dollar switch. Not some cheap foreign made junk. The call ended and I thought about the conversation for about another week while still trying to get the starter to work. Finally I just decided to bypass the switch by simply connecting the two end cables together with with a bolt & nut just to prove it was not the switch. Long story short sometimes you need to listen to people who know what there doing. I'd like to tell you that after all that the T still was slow in turning over but I can't, after connecting the ends the starter magically had plenty of power to crank the engine. I still have the cutoff switch because the Scot in me tells me I'll find a use for it sometime in the future.
When I gave up fixing my original starter switch, I bought a new one. This switch worked but the engine always cranked slowly and the battery had to be fully charged for it to work well enough to start the car. I bought another new starter switch from Lang's and it looks exactly like the other one but this switch works as it should. The car usually starts as soon as I hit the switch.