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Panzer T70E (Electric) Build Log


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#1 BowDown OFFLINE  

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Posted July 10, 2013 - 09:00 PM


Ok I believe I'm going to change directions a bit with my build. The gas engine is too large without frame stretch, and my lawn is small enough to mow via electric.

Which option would you go...

1) 3600rpm electric motor 12hp, not variable. T92 3sp w/reverse transmission off stock panzer drive. Belly mounted mower deck.

2) 3600rpm electric motor 5hp, variable for drive. 3600rpm electric motor 5hp not variable mounted to mower deck attached via 3-point hitch. Motor would swap between future attachments.


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Edited by BowDown, July 12, 2013 - 02:14 PM.

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#2 DH1 ONLINE  

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Posted July 10, 2013 - 09:04 PM

I think you will find that your biggest problem is going to be where to put the batteries.

1 - 12volt battery in not going to be enough, it will work but only for a short time, minutes.

I think to power the tractor and deck you will need 4 batteries.


Edited by DH1, July 10, 2013 - 09:10 PM.


#3 superaben OFFLINE  

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Posted July 10, 2013 - 09:25 PM

Have you considered golf cart style batteries and motors?  Is that even an option?

 

Ben W.


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#4 BowDown OFFLINE  

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Posted July 11, 2013 - 08:39 AM

I am aware of the power requirements, and the motor options. Was more looking for opinions on the setup options. Seems like 2 motors would be a more modular setup, but a single motor may be cheaper in the end.

 

Of course using multiple motors I could mount the drive motor by the rear axle, and the attachment motor on the attachment.

 

 

The golf cart battery/charging system is a good possibility, but the motors are not cost effective to use. The motors are designed to mount directly to the drive line and do not have a bearing on the connection end.



#5 JDBrian OFFLINE  

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Posted July 11, 2013 - 10:22 AM

A fixed speed motor that runs at full speed at it's rated voltage is easier to use on a hydrostatic tractor as it does not need any speed control system. On a geared tractor you would only have full speed in each gear which wouldn't be very versatile. A fixed speed motor would also work well on an attachment. Going to a 36 or 48 volt system allows more power without huge currents although a lot of current is still required. Large batteries, wires, contactors etc. can really take up a lot of space. I've thought about doing an electric or hybrid tractor myself but it's an expensive proposition and you need a large enough chassis to fit all the gear to do the job. Keep us posted on this as it's an interesting project.



#6 BowDown OFFLINE  

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Posted July 11, 2013 - 10:31 AM

Those are some good points.. I will mainly use the tractor for mowing so the engine will keep the rpm's at max for the mower deck in a transmission configuration... but it does make the idea of 2 motors a better option. That way the attachment can run at whatever rpm independent of the motor.

 

I was thinking 5-6hp for the drive motor, and 3-4hp for the attachment motor. Should be more than enough power right? Figure it's instant TQ, and from what I gather electric HP can be equated to double that of a gas HP?



#7 Cvans ONLINE  

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Posted July 11, 2013 - 10:51 AM

Roughly speaking and if my memory is correct I think an 5hp electric motor will do the same work as a 8hp gas engine. There are variables involved but I think this will get you close. 



#8 BowDown OFFLINE  

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Posted July 11, 2013 - 04:53 PM

Excellent. About what I thought.



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#9 BowDown OFFLINE  

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Posted July 11, 2013 - 05:13 PM

I may have scored a pair of 4hp 24v motors from a lift truck. :)



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#10 BowDown OFFLINE  

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Posted July 12, 2013 - 08:10 AM

Motors will be shipped Monday! Prbly be a couple weeks before I see them. :)



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#11 BowDown OFFLINE  

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Posted July 15, 2013 - 07:12 AM

$T2eC16RHJHkFFlyOpRf%29BRmninPETQ~~60_57

 

Here's a picture of the motors I got. They will prbly produce more power @ higher voltages.. but they are just about right @ 24v.

 

Thinking (4) of these batteries for power:

http://www.ebay.com/...984.m1423.l2649

 

 

Going to shop local for the batteries though. Shipping is crazy!



#12 BowDown OFFLINE  

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Posted July 15, 2013 - 08:16 AM

Kind of sucks I never got to ride around on my tractor before tearing it down (motor issues).

 

Anyway from what I gather typical mowing is usually done in the middle belt position? When the tractor is in the 'fast' belt position how fast is it? I'm thinking for transport purposes, not mowing.

 

I'm setting up the gearing based off stock for my new electric motors and was curious if I'm on the right track...

 

193 257 343

 

Those are the stock RPM's of the rear sprocket on a T70B. My max using a 14 tooth on the electric motor would be:

 

440

 

That's like 28% faster at full throttle.

 

 

My electric motor will be on a controller so I will have a vast range of speeds... and I was thinking of running it a bit hot on the speed end just for transport purposes.. but I really don't want to make the tractor too fast in the case of accidental WOT.

 

Any input is appreciated.



#13 DH1 ONLINE  

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Posted July 15, 2013 - 04:16 PM

Golf cart batteries are good for EV conversions, lots around.

On my electric tractor I find that driving around in top gear full speed it doesn't draw that much, but start going uphill or driving on grass, pulling something the amp draw goes up a lot.

I use 3rd gear of my 4 gears for most of what I do, 2nd for heavy work and 4th for driving down the road to the neighbors.

I have a 2hp - 36volt motor running at 36volts.

I have a 200 amp controller that has a 80amp continuous rating, the motor has a 45amp continuous rating and when I push it hard in 3rd or 4th, the motor does heat up.

IMO choosing a smaller controller that is within the motor amp specs is probably your best bet.


Edited by DH1, July 15, 2013 - 04:16 PM.


#14 BowDown OFFLINE  

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Posted July 15, 2013 - 05:02 PM

Thanks for the info. Given my motors are lower voltage I would imagine the amp draw would be higher at their almost 4hp rating. A 200A controller may be closer to spec + headroom.

Do you run attachments off the same electric motor?



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#15 DH1 ONLINE  

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Posted July 15, 2013 - 08:15 PM

No motor driven attachments, only things that can be pushed and pulled.

 

A 4hp motor running at 24volts would draw about 125amps

 

Volts X Amps = Watts

 

746 Watts = 1hp

 

I was looking at a 200 amp or a 300amp controller, the 300 would of given me more power, torque BUT pushing the motor even harder than the 200 does, so I selected the 200 in an attempt to protect the motor.

The 200 amp controller with enough battery power (amp/hrs) would burn out the motor if pushed hard enough, long enough.






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