Run without Battery

[Stumpy]

Got a question about the charging system, follow me for a few minutes if you will. I know alternator based charging systems will produce enough power to at least idle a spark ignition motor. They'll usually stall if you give it some gas or turn on the lights.

Now my understanding here is fuzzy so correct me if I'm wrong but there are two problems with this. The main problem is that the battery acts as a damper for the alternator absorbing momentary stray charges in the system and without it these currents will fry most thing electrical such as the diodes in the alternator. This is especially true if the battery is disconnected while the alternator is making power. Even a dead battery provides some damping. The other problem is the alternator's output is controlled by an electromagnet who's voltage is varied by the voltage regulator. The regulator needs power from the battery before the alternator to start the alternator. Sometimes there's enough residual magnetism in the windings to allow it to self start but without a battery it can stall under load cutting off the power.

A simple tractor with a mechanically injected diesel that only uses electrical power for starting and running the lights should be able run without a battery by disabling the alternator to prevent it from frying the system. I could do this by removing the belt but if I understand the system correctly the key also disconnects the voltage regulator which should disable the alternator. Hook jumper cables up to a suitable battery/vehicle, turn the key on, get it started, flip the key off, remove jumper cables and drive away. And finally my question, has anyone tried this? Does anyone know of any reason why it wouldn't work? Once I've got the motor back together again I'll do some probing with the multimeter but I was curious if anyone else had tried it.

I'd like to try this because this thing will see intermittent use a best (hard on batteries), batteries are expensive, I've got high capacity battery in my truck, and the lights don't work anyway.

 

[B7100]

Why take the battery off,Iv'e run old dumpers on site for years by jumping dead battery and using with no issues.If you don't need anything electrical working then I can see no problem . If you run with out battery isolate just +ve lead.Your concern about damage to alternator,not sure but would it matter if diodes were damaged as the alternators only possible purpose would be to act as an idler for the water pump if one were fitted ?

 

[RDR]

Many years ago my 154 British Leyland slung the windings in the alternator. Since it starts well without the glowplugs I haven't bothered to replace it. I might have to charge the battery once a month. Sometimes only once in two months. I had a small EverStart battery that lasted in it for 5 years after 2 years in my race car. I always did a slow charge when it would need it. In your case just unhook the exciter wire to the alternator. If you have places you go with the tractor where you can't get to it with the truck, you will have to carry a battery to it to jump it.

 

[Orange Tractors]

You could just shut the key off, the engine will run just fine with out the elctrical circuit.

There is one slight problem with this idea-- your oil pressure light needs power to work. If you fit a mechanical guage, then I would have no problems with the idea. Other than jump starting tractors when the snow is blowing is a Royal PITA.

Robert

 

[bruceatlam]

The reason that the tractor stops running when you turn the key off is that the fuel solenoid closes and shuts off the fuel supply. You need power to keep the solenoid open. You don't need to have a good battery for that --- the generator/alternator will do that.

It should run fine without the battery, but it'll need the alternator. Back in the good old days B4 all the electronics in today's cars, we used to check the alternator by disconnecting the battery. If the engine continued to run, the alternator was good and supplying the voltage to keep the car running. If the engine quit, the alternator was bad. Same should apply to your tractor except your using the power to keep the fuel solenoid open rather than supply spark to the engine.

I think --------------------

 

[MagKarl]

The reason that the tractor stops running when you turn the key off is that the fuel solenoid closes and shuts off the fuel supply. You need power to keep the solenoid open. You don't need to have a good battery for that --- the generator/alternator will do that.

It should run fine without the battery, but it'll need the alternator. Back in the good old days B4 all the electronics in today's cars, we used to check the alternator by disconnecting the battery. If the engine continued to run, the alternator was good and supplying the voltage to keep the car running. If the engine quit, the alternator was bad. Same should apply to your tractor except your using the power to keep the fuel solenoid open rather than supply spark to the engine.

I think --------------------

He's got an L175, they didn't have computers and the fuel shutoff is manual. The older tractors don't shut down with the key, you have to pull the lever up by hand to cut the fuel.

 

[Stumpy]

Exactly my tractor just keeps right on chugging with the key off. Except there is actually no way to shut off the fuel short of running the tank dry. No manual valve off the tank or anything. The knob on dash is the compression release.

Robert I've got a few suitable oil pressure gauges lying around it's just a matter of plumbing so it's visible from the seat. I wouldn't want to run without an oil pressure indicator either.

RDR that's part of the reason I was considering the idea, there is no where in my yard I can't get really get to with my truck and most of the yard is a hill so I should be able to bump start it if I stall it. I'll probably put a battery in it eventually but I've already run up against my budget just putting it back together.

 

[Orange Tractors]

Hey Stumpy,

I though of a reason not to do this today-- the fan is electric in the L175. You might be alright in the winter, plowing snow, but I wouldn't do it anyother time.

My L175 can get very hot when mowing tall grass in the summer.

Speaking of plowing snow, we are supposed to get 1-3" of the white stuff tonight.

Since that isn't enough to plow, my daughter's car decided to break one of the rear lower control arms while she was backing out of the driveway this evening. This allowed the back left tire to turn bending the trailing arm, and steering her into the fence.

Guess what Dad gets to do tomorrow.....

Robert

 

[Stumpy]

Uhg that sounds like a fun one. I blew both brake circuits at once on my Accord when I was 17 and had to drive the remaining 3 miles home by downshifting and using the ebrake. The rear line popped right above the gas tank and when we took it down found out it was almost rusted through. Isn't it rewarding being your own mechanic?

That's interesting Robert because my L175 uses a straight mechanical fan. Heck it doesn't even have a thermal clutch, it runs at pulley speed all the time. The parts diagrams I've got shows my setup too. Perhaps someone added an electric fan to yours to prevent overheating/give it a pseudo thermostat?

If I can ever figure out a way to do it cheaply I'd like to add a thermostat and water pump to this thing and give it an automotive style full circulation cooling system complete with a bypass for faster warmups. I have my doubts the lack of thermostat and always on fan will ever let it come up to temperature in the winter. A water pump would solve the overheating problem too.

The problem I've run into is I can't find a water pump that doesn't have it's inlet and outlet going straight into the block. It'd be easiest to plumb the pump in at the lower radiator hose and stick the thermostat and bypass tube on the upper hose. For that I'd need a water pump with hose fittings. Only thing I've found are electric universal water pumps that they want far too much for. I'll keep looking but one mess at a time, I've got to get it running first.

 

[Orange Tractors]

Isn't it rewarding being your own mechanic?

Yes it is. I don't mind doing mechanic work, when I don't have to do it, in other words, as a hobby. I don't like it when it has to be done right now.

I did get the parts ordered, and it is supposed to be in the low fifties this weekend; so I get to drive her to school and work until I get the car fixed.

That's interesting Robert because my L175 uses a straight mechanical fan. Heck it doesn't even have a thermal clutch, it runs at pulley speed all the time. The parts diagrams I've got shows my setup too. Perhaps someone added an electric fan to yours to prevent overheating/give it a pseudo thermostat?

I think it is factory, at least it looks that way to me. I am pretty sure others on here have L175's that have the electric fan too.

I did look at the .pdf manual I have, it shows the mechanical fan also. Curious. Maybe Vic can tell us if there are two versions.

Robert

 

[skeets]

An old trucker I use to know once said that if they lost a battery in the ld diesel trucks once the motor was started they would put the battery leads in to a bucket of sand and as long as you didnt shut down you were good to go,, I have no idea what the bucket of sand was about but there ya go,,,, Sometimes old school is a good thing

 

[Stumpy]

Old school is certainly a good thing. The amount of knowledge lost between generations astounds me. The only trick is deciding whether what the old school decided was cool was actually cool.

I'm sure the sand was just to isolate the leads and prevent shorting. It was probably just the positive lead too. Again though I'm not sure that would prevent the alternator burning itself out. If those trucks used a dynamo then I don't know. Depends on the design of the charging system.

 

[skeets]

I dont know stumpy but I think may be the sand was there to load the system down a little bit maybe to keep from over charging and burning it up. There would be some current flow through the sand I think not much but just a bit and if it was damp, well more,, I dont know Im just guessing