OT Electrical questions, tractor starting

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

John T

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.

• Air starters

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

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.

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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!

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!

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.

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