OT Electrical questions, tractor starting

[KYfarm]

how come tractors or really anything that starts from a battery don't come with some sort of disconnect and a transformer so that in cold weather you can throw the switch so the batteries are not connected to the starter, plug in a 110v cord to a transformer mounted on the tractor somewhere and your engine starter would then work off of the 110v supply (transformed down to 12volt).

Wouldn't this be very simple for an engineer type to create and work wonderfully for starting in cold weather?

 

[IaGary]

Thats a good idea but costly.

A heavy duty battery charger will do about the same thing and you can use it on all your equipment without having to buy one for every piece of equipment.

Just my thoughts.

Gary

 

[LarrySTN]

You most likely don't have a circut that will carry the load to direct start a tractor in cold weather. Not the mention a transformer that would carry the load would be very very expensive and very heavy. Large tractors would need 10,000 - 15,000 watts.

 

[rustyfarmall]

If you have 110 volts available where the tractor is parked, just install an engine heater. A warm engine will nearly always start, and a warm engine will receive less wear being started in cold weather than an engine that is ice cold. There are also battery chargers that have a "boost" feature, which will usually give enough of a boost to instantly start a tractor with a dead battery.

 

[Joe(TX)]

The transformer idea is sometimes called a battery charger.

 

[Bill in IL]

I like the idea but you would have to have a 120 volt starter to make it feasable.

Think of the welder you have in your shop and how heavy it is its probably only like 200 amps and has a loaded voltage of 20 volts or something like that. An engine starter would have to be almost twice as large to supply the amount of contious current at 12 volts to a starter.

 

[Bob M]

Could work in theory. But think about this….

An electric starter requires a LOT of instantaneous power in order to start an engine. Even on a small gas tractor you are talking something 3,000 watts or so. Bigger gas engines and diesels require much more power – 10 - 20 kilowatts and higher.

Supplying this amount of power from a 120 volt line brings up several problems. (For the following discussion Let’s assume a starter draws 3,000 watts):

1 – A 3,000 watt transformer with a 12 volt secondary is not cheap. Nor is it exactly small – figure about the size of large lunchbox. Locating and adequately protecting (weatherproofing) the transformer on a tractor would be problematic.

2 – Factoring in internal losses, the transformer will require about 3,500 watts input from the 120 volt line. That works out to a 30 amp draw. This is NOT available from your normal residential or farm branch circuit!

3 – You would need a HEAVY cord to supply the transformer. A minimum of #10 would be required. If any substantial cord length was necessary an even bigger #8 cord would be necessary. (Have you priced #8-3 SJO cord lately?!!) Of course special receptacles and cord connectors would be required also.

4 – If your tractor is parked (or stalls/quits) too distant from your high capacity 120 volt circuit, your gonna need the battery ANYWAY to get it started again.

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Bottom line is it’s a lot more cost effective to let battery(s) provide the burst of power necessary to crank up a tractor engine!

 

[rrlund]

Kind of off the subject,but similar. Oliver had a hydraulic starter for the fleetline tractors back in the 50s. They had a hand pump that pumped up the pressure,then you just engaged it to start the motor. It was installed on the diesels exported to jungle countries where moisture raised hob on the electrical system. They had no lights,no generator,no wiring of any kind.

 

[Rob in Ore]

Great question! Seemed to me like a good idea...until I read the answers below
Now I learned something already today and I haven't had breakfast yet.

 

[Mike M]

My snowblower allready has that ? 110V electric starter and a pull rope for back up. 10HP tehcumse

Likely not enough amps available to start large engines ?

Some big rigs had air starters. If your air leaked off then you could jump from another truck by using an air hose.

 

[greygoat]

Some Vietnam era helicopters had a hydraulic
starting system. Later ones may still have it.
The hydraulic system charged an accumulator to
"store" hydraulic pressure (energy ?)A solinoid
valve directed pressure to a hydraulic motor to
start the engine. If the accumulator was discharged it could be pumped up by a hand pump.

 

[Bob M]

In one of my old Detroit Diesel service manuals it describes a similar non-electric starter for their -53 and -71 series diesels.

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The starter itself was a small hydraulic motor. It was supplied by a high pressure (3,000 psi?)hydraulic accumulator plumbed thru a quick-acting hydraulic valve.

To start the engine you'd manually engage the starter pinion into the flywheel, then trip the hydraulic valve. The starter would then spin the engine FAST (600 - 800 RPM as I recall) giving a nice, quick start.

A tiny hydraulic pump driven off one of the cam/balance shafts automatically pumped the accumulator back up once the engine started.

There also was a hand-operated pump (sorta like a hydraulic jack pump) that could be used to repressurize an empty accumulator. However I suspect hand pumping up an empty accumulator back to starting pressure was a somewhat exhausting and time consuming exercise!

 

[Janicholson]

The way to do it is with a capacitor bank. THis could be charged while the trasctor is in the shed, or while it is out working. They have no temperature related issues, and they are powerful. A "bank" of 15 volt capacitors could be charged by a slow charger, then plugged into the tractor electrical system with a high amp plug and jack to allow the disconnect to be easy.

General Electric Dash9 CW44 Locomotives (the big Locos now on the Rails) use capacitor start systems for 6000 hp diesel engines. They start at all temperatures. JimN

 

[Janicholson]

Air starters are also common in industry. JimN
Air starters

 

[rrlund]

Sounds like the same setup as the Oliver. Probably built by the same supplier.

 

[dlplost]

Lets see..... 1 amp 120v ac to charge big capacitor to give 12v dc at 600 amps?

DOH, you allready have a "capacitor", its called a "BATTERY", how about a trickle charger to charge your battery? No diff than the capacitor start idea...

I did that for years with My 8n till I replaced my dead generator. One summer I even had one of those 12v Voltswagon solar panels taped to the hood to keep the batt up when it sat outside.

 

[John T]

Its one of those things that can work in theory but not very practical or economically feasible. Say a starter draws 500 amps at 12 volts DC = 6000 watts. At 120 volts thats 50 amps assuming an AC starter motor hugeeeeeeee enough for such a high torque requirement and many more initial start up load amps.....If you wanna leave the DC starting motor you have to rectify the AC and thats more inefficiency and heat losses..... Its more efficient to use a storge battery and then charge it up over a longer time which is what you already have. Crankcase and/or coolant heaters and big honkin battery chargers coupled with your own storage battery is a more efficient use of AC power to start your DC tractor......

John T

 

[KYfarm]

Thanks everyone, now I see why it wouldn't work. I figured there must be real good reasons why it wouldn't otherwise it was to simple for it not to have been implemented long time ago.