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alternator vs generator controversy

O

olddog

Well-known Member
Trick question....
With a totally dead 6V battery/generator/regulator system,
how fast will you hafta tow the vehicle before it starts?
 
Too many possibilities the way you worded it but yes we all know a genny doesn't have to have a battery.

My first car was a 1955 Ford Custom. 272 automatic. 21mph and you could pull it in gear and she would crank. I coulden't count the number of times I was the pusher on a good hill running as fast as I could by the time she cranked before I got it. That was my first conversion.
 
I'm betting the dead battery will zap any power the genny could make and it will not have any power left to fire the ignition. Unless you have a magneto.
 
What kind of engine? Diesel? Gas? Gas with magneto? Gas with coil and distributor? If it's an older diesel, with mechanical fuel shut off, just tow it until it starts. Engine rpm while towing will depend on what gear it's in given a constant towing velocity. The higher the gear the slower the rpm. If it's a gasser with magneto, 1/4 turn of the engine could/should do it. If it's coil and distributor, better charge the battery first and plan on going only a short distance after it starts if the generator's not working. Your goal seems to be to just start the engine? And then what?
 
(quoted from post at 07:28:01 09/09/15) Trick question....
With a totally dead 6V battery/generator/regulator system,
how fast will you hafta tow the vehicle before it starts?
Click to expand...

Too many variables to correctly answer your question.
 
On a test bench, if you connect the field to the battery terminal it will charge. Just like a generator, it has residual magnetism. It may charge on a tractor too but may take a while. Never tried it.
 
If you disconnect the + terminal you might be able to start a gas tractor with a generator and once it is going reconnect the terminal. Seems like a waste of effort unless the battery is good but drained from leaving something on or draining it while trying to crank it. Are we talking theoretical or a practical problem where you are in a remote area with two tractors or a truck and a tractor? I would just borrow the battery and just parallel it after cranking. Otherwise there is insufficient information to go beyond this point.
 
I forgot to add that weather conditions apply and why you need to pull start the tractor in the first place.
You could of course harness 30 sled dogs or 150 cats.
 
Think dynamo...

I have worked on several small import tractors that use perm magnet low current dynamo style generators, and a simple external rectifier pack / charge regulator.

( yes.. no charge control via field control )
 
(quoted from post at 08:12:43 09/09/15) I'm betting the dead battery will zap any power the genny could make and it will not have any power left to fire the ignition. Unless you have a magneto.
Click to expand...

I'm betting you just made an incorrect statement. I've successfully tow started a tractor with a dead battery that had a dist.
 
When people say totally dead, completely dead or just dead do they mean not enough to turn over the starter or engage the solenoid. If you take the distributor off, use an insulator to break and close the points and it sparks, it ain't dead.
 
(quoted from post at 09:54:12 09/09/15)
(quoted from post at 08:12:43 09/09/15) I'm betting the dead battery will zap any power the genny could make and it will not have any power left to fire the ignition. Unless you have a magneto.
Click to expand...

I'm betting you just made an incorrect statement. I've successfully tow started a tractor with a dead battery that had a dist.
Click to expand...
hat makes more than one of us!
 

Did lots of mostly dead batteries when I was a kid.. so it works and works well. However if its a shorted battery, your screwed. But the normal sulfated battery, just a quick push and your going. We did it all the time. Some of the farm tractors needed long pulls to get the extremely low battery up a bit before they fired over, but again, if battery was not shorted, did it a bunch of times. Some tractors took almost a half mile before they started firing. But a friend, a rope and away you go.
 
Dead battry with a coil and generator and you can tow fast enough it should start. Now STONE dead you may not win. Alternator you are toast. They will not pick up like a genny. They need something like 7 or 8 volts and then they will charge like **** to the wall. The charger from wally world that costs $20.oo will desulfate your cells and I have saved a couple of batteries.
 

Do you really want to operate a generator or alternator maxed out continuously ? On the near dead short a dead battery loads an electrical system with.
Garages do a tidy business replacing alternators after operators jump start a total dead machine .
Put a 120V charger on that dead battery for a couple of hours before starting.
 
You know the op never said it was a tractor. I could be a boat for all we know or even an airplane. Sounds more like a 20 questions problem. Dead stick landing or hit the silk.

Just what kind of vehicle are we talking about? Bicycle?
 
Ok, Ok, OOOKKKKAAAYYYY!!!!
I didn't specify gas or diesel.
I was thinking gas with a TOTALLY dead battery.
Where does the regulator get current to pull itself in,
in order to feed the coil? There's no wrong answer.
 
(quoted from post at 16:29:32 09/09/15) Ok, Ok, OOOKKKKAAAYYYY!!!!
I didn't specify gas or diesel.
I was thinking gas with a TOTALLY dead battery.
Where does the regulator get current to pull itself in,
in order to feed the coil? There's no wrong answer.
Click to expand...
rom the generator, the same as if it had a charged battery.
 
Helped a friend unload a Farmall Cub from the trailer, that he had just bought.
It had been sitting for more than 5 years. I suggested they remove what gas was in the tank & carb and put fresh. They did. Suggested they charge up the 6V Batt. cuz it won't start with a dead batt. Didn't have a 6V charger. Gonna jump w/12V boost charger. I suggested they pull the wires off the regulator. They Did. Pulled the cap off the dist & bussed the points. Hooked wires back up to regulator.
No joy. So... they hooks onto the thing, and pulls it round and round his 5 acre field, till gas was running out of everywhere. No joy. By the sounds of the fan, they were pulling at least as fast as full bore speed.
Next day, set a charged 12V Bat. in there, unhooked to wires to regulator and Vroom!
 
(quoted from post at 16:54:46 09/09/15) Helped a friend unload a Farmall Cub from the trailer, that he had just bought.
It had been sitting for more than 5 years. I suggested they remove what gas was in the tank & carb and put fresh. They did. Suggested they charge up the 6V Batt. cuz it won't start with a dead batt. Didn't have a 6V charger. Gonna jump w/12V boost charger. I suggested they pull the wires off the regulator. They Did. Pulled the cap off the dist & bussed the points. Hooked wires back up to regulator.
No joy. So... they hooks onto the thing, and pulls it round and round his 5 acre field, till gas was running out of everywhere. No joy. By the sounds of the fan, they were pulling at least as fast as full bore speed.
Next day, set a charged 12V Bat. in there, unhooked to wires to regulator and Vroom!
Click to expand...
ice story ending. I see no question, however.
 
Have started a good many cars & tractors in my 70 years;
just that far; to start with an ALMOST dead battery.
 
Trick question?
Plane crashes on the US/ Canadian border. Where do you bury the survivors?
 
I went to a consignment auction and one of the tractors was a Farmall M that they could not start. I had arrived early and I got to watch them pull the tractor all over the lot without a pop. When it came it's time on the auction block I bought it for $400. I started to load it on my trailer using my winch and after I got the thing about half on the winch quit. It wa a very warm day but I managed to finish loading it with a load binder and a lot of sweat.
After I arrived home I decided to put the battery from the now inoperable winch in the old M just to see what was the starting problem. I climbed on the old beast, pushed down on the starter button and it started right up and ran perfectly.
If the battery is totally dead you can not start the machine by pulling it as there is no way to excite the generator.
 
teddy52food wrote
From what I have read a DC generator will self excite because of residual magnetism in the field poles. The initial current formed must reinforce the field in the poles in order for any current to build. As the armature continues to spin emf builds up in it as long as the voltage in the armature exceeds the voltage drop across the windings of the field coils.
Hey it sounded ok when I read it.

I skipped some of the verbage to advance the plot.

I still think you have to remove the + terminal from the battery so that it does not sink the resulting emf. It would help if you had an electrolytic cap across the output. Once cranked you need a resistor in series to the battery to keep the engine running and slowly charge the battery or as said earlier the battery should be put on a charger back at the barn.

Also would there be much residual magnetism in tractor sitting in the field for five years as olddog said?

I guess you could point it North South and beat on it lightly for a few minutes with a tire iron.
Click to expand...
 
You still didn't tell us whether it was magneto ignition or coil and distributor. My old WD Allis would have started just fine with the crank if the battery was dead. The problem with your question was that you evidently thought most of us were mind readers which we're not and we can provide testimony from our ex-wives to prove that.
 
(quoted from post at 09:51:59 09/09/15) Dead battry with a coil and generator and you can tow fast enough it should start. Now STONE dead you may not win. Alternator you are toast. They will not pick up like a genny. They need something like 7 or 8 volts and then they will charge like **** to the wall. The charger from wally world that costs $20.oo will desulfate your cells and I have saved a couple of batteries.
Click to expand...

If your worried about that, just let it idle.. the gen or alternator will not put out full charge, but a much reduced charge level... so it will not over heat, A later gen also has a "current limiter" in the v-reg, so it will not over charge or the soldered wires will melt out of the commutator. So mid 50s on , your pretty safe and limited to a very safe level for very long periods of time. So with the current reg no problem... alternators will charge at high rates for long long long periods with out damage. Agreed that running it for months on a shorted cell battery will probably lead to an early failure, but it will take a while to get there.
 
(quoted from post at 19:08:22 09/09/15)
If the battery is totally dead you can not start the machine by pulling it as there is no way to excite the generator.
Click to expand...



Unlike alternators generators don't require electrical excitement to charge as they make their own excitement.
 
(quoted from post at 12:42:26 09/10/15)
(quoted from post at 19:08:22 09/09/15)
If the battery is totally dead you can not start the machine by pulling it as there is no way to excite the generator.
Click to expand...



Unlike alternators generators don't require electrical excitement to charge as they make their own excitement.
Click to expand...
im, I'm afraid that there are too many 'theorizers'/'over thinkers' in this thread instead of those of us who have simply done it. :roll:
 
A one wire Delco alternator doesn't need a battery to excite the fields to get it to start charging but as a safety precaution most regulators will not allow the field to ground unless there is voltage on the #2 terminal. Since the output terminal and the #2 terminal are tied together in the one wire regulator with no voltage on the output terminal the alternator will not start to charge.
 
(quoted from post at 16:45:58 09/10/15) A one wire Delco alternator doesn't need a battery to excite the fields to get it to start charging but as a safety precaution most regulators will not allow the field to ground unless there is voltage on the #2 terminal. Since the output terminal and the #2 terminal are tied together in the one wire regulator with no voltage on the output terminal the alternator will not start to charge.
Click to expand...

In a genny the field shoes have residual magnetism in them that allows the genny to charge when turning. The field circuit will show 3-4 volts with the regulator disconnected on an A type circuit.

In an alternator the rotor contains the residual magnetism which with a special regulator which feeds that residual magnetism back into the rotor windings makes the alternator charge without external excitation. I have modified a couple for slow speed tractor engines, the alternator being the Delco 10SI.

This is not done with the standard 1 wire alternator regulator. The regulator used is a D10AC used for the 10SI. It involves removing the diode trio and adding internal wiring to take AC voltage from the rectifier bridge and feeding the rotor from there which the regulator controls all internal.

I have one I did for my 830 Case diesel and it starts charging as soon as the engine is running , no rev up to initiate the charge.

Research he D10AC regulator online, you will se the regulators with internal jumpers.
 
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