electric conversion

[GERRY]

Hi iwas wonderinging has anyone converted a dexta to electric, ihave been thinking about this
for awhile now, as ihave aback end and after reading a bit on it it seem a 12hp electric motor
unit would give about the same power as the diesel equvilent, i would like to hear if anyone has any ideas
on this, Regards Gerry

[Bensdexta]

Hi iwas wonderinging has anyone converted a dexta to electric, ihave been thinking about this
for awhile now, as ihave aback end and after reading a bit on it it seem a 12hp electric motor
unit would give about the same power as the diesel equvilent, i would like to hear if anyone has any ideas
on this,

How do you arrive at a figure of 12hp? Power tests on the Dexta pto have demonstrated nearly 32hp?

[super6954]

Hi iwas wonderinging has anyone converted a dexta to electric, ihave been thinking about this
for awhile now, as ihave aback end and after reading a bit on it it seem a 12hp electric motor
unit would give about the same power as the diesel equvilent, i would like to hear if anyone has any ideas
on this,

How do you arrive at a figure of 12hp? Power tests on the Dexta pto have demonstrated nearly 32hp?

If I am right in my thinking with what Gerry has said a gas or diesel engine horse power and an electrical motor horse power are not the same thing. when I worked on a grain farm we had petrol engined augers with 20 - 25 hp and an electric motor auger the same size . i am sure that motor was a lot smaller than 25 hp on 3 phase electric maybe 10 hp from memory. Im guessing that the electric tractor would be gutless over the diesel engine as the electric auger was over the petrol one. also unless it had a big generator attached it would have limited range and quit when the plug came out of the wall when the extension lead got pulled tight. . Unless you are thinking of a battery motor from a forklift or milk float
Regards Robert

[Brian]

Horsepower is not really the answer. I always used the example of a car engine of 55 hp and a tractor engine of 40 hp. The tractor would pull far more because it relied on torque. However John Deere seem to be trying a "Hi-Bred" tractor with an electric motor assist.

I do not think a 12hp motor would be powerful enough without gearing down to a very slow speed but I hope I am wrong.

I could convert Dotty to electric and have a wind turbine installed on her bonnet! Think of the saving on petrol!

[Bensdexta]

Power is power! Mathematically equal to (force x linear speed) or for a rotating shaft (eg pto) (torque x rotational speed).

So if we halve the power, but keep the same torque by gearing, then we half the speed. So yes our 12hp Dexta will be rather slow! Nevermind the problems with the extension lead!

[super6954]

I guess I was kinda on the right line then when I said it would be useless . I guess Gerry would maybe better finding a perkins 6 cylinder and use up his spare parts . I'am sadly not a real fan of the Dexter, Majors rule here but would rather see it live on like that, or get restored to original than him send it to Japan and it come back as a Toyota
Regards Robert

[Brian]

I have seen one very nicely done and all chromed up, it had a Perkins V8 from a combine. There are some bodged 6 cylinder fittings in Majors and Dextas running around.

Like you Robert, I like to see them original and in use.

[GERRY]

hope i diddnt upset anyone just been googling electric tractors , someboy
it seems in the states has put a electric motor into a farm tractor , along with the other
bits an bobs an has aworking tractor, and can plough pull trailer ect,not to the standered of the diesel
but if one wasnt using the tractor only for the light bit of work it would save on oil and diesel no engine rebuilding
no fumes noise ect ect,other than the back end, going by his site the motor taking that 746watts is = to one hp
and the motor is if i have understood it correctly puts out about 60,000tatts , now this may be with what they call a controller or something it would be around 32/34hp, this with charging the batterys at about 50p a charge is worth a look at, All ideas welcome good bad or indifferent GERRY

[Bensdexta]

hope i diddnt upset anyone just been googling electric tractors , someboy
it seems in the states has put a electric motor into a farm tractor , along with the other
bits an bobs an has aworking tractor, and can plough pull trailer ect,not to the standered of the diesel
but if one wasnt using the tractor only for the light bit of work it would save on oil and diesel no engine rebuilding
no fumes noise ect ect,other than the back end, going by his site the motor taking that 746watts is = to one hp
and the motor is if i have understood it correctly puts out about 60,000tatts , now this may be with what they call a controller or something it would be around 32/34hp, this with charging the batterys at about 50p a charge is worth a look at, All ideas welcome good bad or indifferent GERRY

An electric tractor is entirely feasible but...

Suppose we wanted our Dexta to deliver 20hp for an hour, from one charge of the batteries. How many batteries would we need?

20hp is about 15kW. So we need to store 15kWhr of electrical energy. Using lead acid batteries, we can store ~40Whr/kg, so we'll need 375kg of batteries, that's over 1/3tonne. Then after an hour we'll have to go home for a recharge. Lead acid batteries don't like being run down, so they probably won't last long and they're not that cheap either. In practice we're probably going to need upwards of 1/2tonne of batteries. There are higher performance batteries, but they are more expensive. So the orginal Dexta has some advantages

[Brian]

I believe the John Deere uses the diesel engine to drive a generator that powers a motor to give extra boost at times of peak loadings.

There have been electric milk floats, factory tugs and electric cars over the years. Our streets are full of electric buggies and battery design is changing. The fuel cell has developed more over the years since Allis first put them in a tractor back in te 1970's. So it is not a bad idea.

The problem is energy storage as Ben says. Maybe Ford are once again on the right lines with the Hydrogen powered tractor, but from what I remember of hydrogen production in school, there are a few problems there too.

Regarding your point on pollution Gerry, is electricity any cleaner than diesel?

It has to be generated by burning fossil fuels or by nuclear power and these have their disadvantages. Its a bit like moving all the "dirty" manufacturing to China and India then saying that we are reducing pollution.

Back in my youth we were told that every car, train, tractor and truck would be driven by a small nuclear power cell and we would have unlimited energy.

[russelm]

Not hard to calculate.

If a Dexta is say 32 flywheel horse power at 2000 rpm (an example) then that equates to a torque of 84 Nm.

Given that 1 hp is 735 watts we can assume we would need a motor that can provide at least 23Kw of shaft power at 2000rpm, this will need a greater input power due to motor losses.

Thats much less than what a Nissan Leaf will give you (electric motors have a nice wide torque curve and the leaf has an 80Kw motor).

So if you have 10K lying around for the batteries, controller and motor then go for it.

Interestingly, hydrogen production as it exists today is bad news because most of it is created from natural gas!

[brownsmule]

Pardon the color (Persian Orange); but Allis-Chalmers built a electric motor (20 hp DC) about 1958 powered by no less than Fuel Cells.

I don't know how to post a link however if you google Allis-Chalmers fuel cell tractor there is a nice short video that is interesting. Now the question would be how to get the electricity on board to power the DC motor. The DC motor and controls should be cheap enough however the electrical side might be expensive. Maybe look into parting out a electric forklift for the motor, controller, battery and charger.

IMHO, I like the sound & power of the Diesel Engine

brownsmule

1961 Dexta
196X Super Major

[Dandy Dave]

Here you are. Dandy Dave!

http://www.youtube.com/watch?v=eON30MjT8fU