Solder Slingin So and So - 6 Volt Electrical

[Whit Otis, 1188]

OK you electrical types, in the past year my 40 and 48 (both original 6 volt systems) quit charging.  Upon removal and examination of the generator, it was discovered that the armature became hot enough to sling the solder out of it.  I had the generator rebuilt, and my rebuilder supplied the replacement regulator as well.  The rebuilt generator and new regulator were tested in his shop, and properly polarized before re-installation.  When I asked the guys what causes a generator to become a solder slingin so and so here was the response:

If your generator has thrown solder out of the armature and the regulator is also bad, this is an indicator of a bad battery.  If a battery will not accept a charge, then the regulator attempts to supply a full charge at maximum rate.  The battery failing to accept the charge causes the regulator and generator to overheat to the point of slinging out the solder.  

How to tell if the battery is NOT accepting a charge.
A.  Hook up battery to a charger with good voltmeter
B.  Before turning on, set the charger for highest output for fastest charging (do not use trickle option if it has one).
C.  Observing the volt meter, turn on the charger.  The meter should immediately jump right up to a 9 or 10 volt charging rate if the battery is good.
D.  If the needle does not immediately jump to 9 or 10 volts, but rather climbs up very slowly or not at all, then the battery is not accepting a charge properly and youre heading for regulator/generator trouble.

Can one of you electrical experts out there confirm if the above is correct or not?  
Thanks, Whit Otis

[Doug Houston]

If a battery isnt accepting a charge, it wont draw the full output current of the charger, nor the generator. That usually indicates a sulphated battery. Overheating a generator can be caused by too much current being drawn from the generator. A bum battery will not usually do it. If the regulator is either set for  the wrong charging current regulation, or the voltage regulating relay is running the charging voltage too high, you can burn up a generaqtor that way,

A revealing test is to get a generator test meter,(often called a V-A-R) made for just that purpose, and see just what the regulator is doing to the generator in operation on the car. A 6 Volt system should run about 7.25 Volts, and regulate to no more than 30 amperes on earlier systems, and up to 45 amperes on later 6 Volt systems. The shop manual for the particular car will have those numbers.

Sounds to me like the regulator is running the generator to destruction.

[Joe G 12138]

I agree that there is most likely a regulator problem. The regulator usually has three coil and contact sets. One is the cutout relay, to keep your battery from draining when the car is not running. The second is a voltage cutout, to keep the voltage to the electrical system from going sky high at highway speeds. The third real is for limiting excess current, which can boil the water out of batteries or overheat lots of things...including generators and battery cables.

If your battery isnt getting cooked, another possibility to look for is a combination of problems. One that comes to mind is using a shorted condensor on the generator, but having it connected to the wrong terminal on the generator. (Field instead of armature).

Most 6 volt cars have ammeters. What does yours say when the car is shut down? Running? Idling?

[TJH 20664]

Not to distract from solving Whits problem.. Lets help him first but then... since we have so many experts here can someone explain further how regulators work?

Again Im no expert, so thats why Im asking....

The old ones were essentially a relay/buzzer werent they? They buzzedor switched at a given speed to change the voltage?  You could control the voltage by adjusting the pivot or the spring on the contact(s)?  I  remember hearing talk about if you were doing a budget 6 to 12 volt conversion you would change your battery and coil and just open the regulator and bend something till it was bout right.

Do newer solid state regulators work the same way by using an scr or transistor type of thing to switch the circut at a high speed to get the desiered voltage?

Maybe Im getting ahead of myself and should wait for the answer but I will ask or state my theory now anyway...

Diesel locomotives used to have DC motors in them because there wasnt a way to control AC on that scale? Same reason we had generators (DC) in our cars till solid state stuff came out when we switched to alternators (AC)?  The problem with trying to control AC with a electro-mechanical regulator is you have the AC frequency itself to contend with so it gets much more complicated to design a coil to respond the way you want it to?

Thanks,
TJH
StPaul/Mpls MN USA
73 Eldo convert

[Doug. Houston]

Early charging systems had a cutout relay on the generator, and that was all. If the generator wasnt running fast enough (at idle) to charge the battery, the cutout disconnected the generator from the battery. But, on a long haul, the generator overcharged the battery and either boiled it dry or burned up the generator armature. There was a third brush on the generator to adjust charge rate, and you adjusted it to conform to the needs of your battery. In the thirties, youd almost always see cars on the highway with headlights on, so as to divert generator output from the battery. Chevrolet had a position on the light switch that put a resistor in series with the generator field, to reduce charging current if needed. That way, you saved your headlights. If the car had a radio, the power switch for the radio by-passed that resistor when you turned on the radio.

In the mid-thirties, generator ragulators became increasingly more sophisticated, with voltage control and current control, using relays to do those duties as servo devices.As generator voltage would try to rise, the voltage relay would reduce field current, and maintain the desired voltage. Likewise, if the battery displayed a high charge, a current regulator relay functioned similarly, to regulate charge current to a preset level. I have heard of blacksmith tinkerers, hacking up regulators to convert them to higher charge voltages. This was popular with the 8 Volt advocates. They loved to replace headlights, burn up radios and dash instruments, plus who knows what else? Theyre smart people; just ask them.

The alternator systems are voltage-only regulated. The regulators have circuitry in them with transistors or other solid state devices that sense system voltage and hold the field current to a level corresponding to the desired system voltage. In a 12 volt system, that voltage is about 14.5 volts.  

Ill try to answer the DC motor thing. The speed of a DC motor depends on the current it draws, If a voltage is varied upward, the motor goes faster, and has higher output. Speed control with a DC motor is smooth, from dead stop to full speed. This is ideal for elevators, streetcars, hoist motors and, indeed, traction motors for trains. The diesel engine drives a Dc generator, which feeds the traction motors that run the vehicle. Again, smooth speed control.

The speed of an AC motor is determined by the power frequency and the number of poles in the motor....and thats all. The more poles in the motor, the slower it runs. Frinstance, the synchronous speed of a 2 pole motor on 60 cycles is 3600 RPM. For a 4 pole motor, its 1800 RPM. An induction AC motor always runs a percentage slower than synchronous speed. Lets not get into why just now, but it does. If you need to vary the speed of an AC drive, youll use a variable transmission of some sort.

As far as generating devices go, the biggest reason that an alternator system is superior is that it charges at idle. The old DC generators didnt, and couldnt. You just have to know how to drive cars with DC generators  to keep your battery from running down.  

[Rhino 21150]

Usually the generator burns up because the load on it is too high. If your genny and regulator test okay off the car, the first thing to suspect is a shorted battery. If the battery is shorted internally it will never put out over four volts (one cell bad) or two volts (two cells bad) no matter how long you charge it. The battery tester that uses floating balls will tell you if you have a bad cell, read the instruction sheet. If the battery checks ok get an ammmeter and pull up the armature wire (engine OFF)and check the current flow when the engine is running. The ammeter goes between the armature terminal and the wire you pulled off. If the meter reads backward, turn the engine off, reverse the wires to the meter and try again. If it is over twenty five amps, recheck everything you have already tested!

[John Washburn]

Whit,

A couple of comments. You got great advise.

One handy little item, that will not fix the problem, but will stop the generator burn out. Is a fuse. In the old days you could buy a fuse that attached to the voltage regulator, so if the generator started to go, the fuse would blow first. I can show you how and what these look like when you stop by. These are hard to find but I may have a spare or two.

Second, I can lend you the correct SUN VAT machine to check out your system, with associated instructions, or we can see if we can come down and do this with you, and Old Bill.

But again the cheapest way, is to install a porcelain fuse. I think a lot of tractors used these also, so we might want to check with some of these old tractor guys.

The only time I had this happen, BF (before fuse), was when I had a 5 post voltage regulator rebuilt for my 37. Bad job, cooked the old generator very quickly.

John Washburn
Elizabeth, Colorado
CLC #1067

[Whit Otis 1188]

WOW!  Thanks for all the great info you guys.  It is amazing the amount of knowledge that resides in this hobby of ours... always an opportunity to learn great stuff.. thanks again.

[Philippe M. Ruel]

the biggest reason that an alternator system is superior is that it charges at idle. The old DC generators didnt, and couldnt.

They could as much as generators, but they could not bear high rpm because it would have burnt commutator bars and brushes. To work properly at high engine rpms they could not rotate much faster than the engine, so they featured large pulleys.
Alternators feature smaller pulleys to rotate much faster than engines and so they provide current even at low engine rpms. At high engine rpms they may rotate faster because they use slip rings instead of commutator bars.

[Doug Houston]

I hate rhubarbs, but Im gonna stand firm on this one.

Ill say it another way: For a given RPM, DC generators cannot quite charge, and a rectified alternator system can. If it were otherwise, explain why police cars, even before WWII were equipped with rectified alternator systems. Clue: THEY CHARGED AT IDLE. Those cars may stand for possibly an hour or more with lights and radios going, while at idle. There were high current DC machines made, but they dont charge at idle! Leece-Neville made those systems. The alternator waqs huge, as you might expect, and they had a big rectifier stack mounted under the hood. The big breakthrough came when Chrysler ws able to make a compact 30 amp 12 volt alterntor, and have pressed-in silicon rectifier diodes, supplied by Sarkes-Tarzian Corp., of Bloomington, Indiana. The rest of the industry had no choie but to follow.

As far as geting a better charge rate on our vintage cars, Delco did offer a slightly smaller generator pulley as an option, but it wasnt a solution to the problem; just a help. I have some on a couple of my cars.

[Bill Burton #19057]

As youre going through the system, be sure to check all the connections carefully.  One often ignored is the connection between the battery and the block at the block end.  If that is seriously corroded, everything else said will be caused.  Also, Ive seen screws too long used on the alternator connections that grounded against the fender or firewall.  That creates catastrophe and can be something not easily spotted.  Mundane and probably neither of these affects you, but just a thought.  Best wishes; Bill Burton