The Electric MTD

this build started as with me having an old mtd frame with a knocking 12hp briggs. a bit later after i got this tractor i bought a roper rt12 without the engine, but i did get the starter/generator. so i combined the starter with the old mtd frame and hoocked up a giant 12v 75 AH battery to it.

this is what it looked like.





yes it worked. not it was not great at all... the old starter was tired and it just couldnot keap up with what it needed to provide.

soooo i got a bigger better and more powerfull continuous duty motor.
the starter gave out about half an horse power. (yes i made a post on facebook saying it was 1 hp but i found out it is not) and if i used it for any amount of time it would overheat, its just a starter after all. the new motor is a confirmed 2.25 hp continuous with peaks up to 9hp. before the tractor would barely get me going, but  now its faster than my gas powered one and it had a massive amount of torque.

the new motor requires 90V DC and about 20amps so i had to get a string of 8 12 volt batteries to make it work. i am using eight 12volt 12AH in series for 96volts DC. (the small overvoltage it not going to damage anything). i found a 125amps 120V DC breaker and im using it as a switch for now. i am going to desing and build a circuit that adjust the speed of the motor according to the position of a foot pedal (like a gas trottle).   i have 2 sets of the 8 batteries the tractor requires and one smaller set, so i can put one on the charger while im using the other ones, this way i can use the tractor continuously if i need to.


this is what it looks like now.

starting to build something to hold all the batteries after a very succesfull test run

the new motor. its out of a treadmill, yes its weird i know, when the guy asked what i wanted to know with it he did not get what i was telling him lol

motor mounts, they are reinforced now

supports for the battery tray



battery test fit, perfect !


i will try to get some footage of it running and doing some work soon.
i still have to build a charger to charge all the batteries at once because i can only charge them in pack of 4 with my 48v charger...
any questions or comment go ahead !


Please forget my grammar mistakes, i speak french haha...

Neat setup! Treadmill motor should be pretty reliable I would think. I'm not real great with electrical stuff, but your saying the treadmill had the DC motor and some sort of converter from 110v AC current? I'm interested to know what sort of run time your going to get out of this. I'm planning a project where I was going to run 6-8 lead acid car batteries in parallel (so I would still have 12 volts) and run a 1hp or so electric motor. The reason I want to stay with 12v is because I will have other electric motors and lights running from the same system and I don't want to get complicated with switching back and forth or separate battery banks. It would be nice to get a couple hours out of it at least (at relatively low loads). Keep us updated!

Dang this is a cool build, and unique. What are your plans for it? Just ride around 'stock' or...

in the last few days i installed a voltemeter, and a voltage converter. now i have the main battery pack voltage wich is 96 volts and the secondary 24volts. the 24volts is used to power the tailights, the voltemeter and the motor cooling fan.




the switch (a 125a dc breaker)

i had too add a spring to the idler for the back belt because the motor spins couter clockwise. without the second spring the belt would slip.

i dipped the voltage converter in hot glue to seal them from the elements, i could have used silicone but i needed a non water based one and i dont have any.



the motor and a small 24v fan to cool it a little.

i used a stainless steel mesh filter in front of the fan so crap doesnt get in.

these are my two 28 volt battery pack, they are connected with an anderson 50Amps connector, this makes it easy to hook up my charger to them. i glued the 2 pack of 4 batteries together to make it easier to take the battery packs out.

this is a small voltemeter i installed. this way i can see when the batteries are empty.

craftsmancole wrote:

Dang this is a cool build, and unique. What are your plans for it? Just ride around 'stock' or...

well yes for this one its just going to be a machine to ride around, i use it alot because i live in a city and people just complain if i use gas powered tractors for anything else than plowing/blowing the snow or mowing. i want to leave the city but im living with my parents and im not leavin till i finish school. i am seaching for a better more power full motor, to make a mud mower, i found a couple of options, the best one wet is an old electric forklift motor, these are just awesome they are so powerfull some people use them to make diy electric cars. at this point im just wondering if itf going to blow the tranny, with this much torque it could very well happen lol. ill have to see.

mr.modified wrote:

Neat setup! Treadmill motor should be pretty reliable I would think. I'm not real great with electrical stuff, but your saying the treadmill had the DC motor and some sort of converter from 110v AC current?

yes the treadmill had a AC to DC power converter and then  it had a circuit that would maintain a constant se speed.

mr.modified wrote:

I'm interested to know what sort of run time your going to get out of this.

it really depands on what im doing, if im running it as hard as i can with alot of heavy accelerations, it lasts about 50 minutes, if im just idling around about 2 hours.

mr.modified wrote:

I'm planning a project where I was going to run 6-8 lead acid car batteries in parallel (so I would still have 12 volts) and run a 1hp or so electric motor. The reason I want to stay with 12v is because I will have other electric motors and lights running from the same system and I don't want to get complicated with switching back and forth or separate battery banks. It would be nice to get a couple hours out of it at least (at relatively low loads). Keep us updated!

yes having a battery pack voltage of 12volts is really usefull, but it means that if you are going to pull way more amps than a higher voltage system, for example 1 hp is 746watts (in the real world its more like 800 watts) of electrical energy and 746 watts at 12 volts is 62amps. but if you have a high voltage system, like mine it uses alot less amps so your components are cheaper and last ways longer, my motor is 2.25hp so 2.25*746=1679 watts so at 90volts its 1679/90=19 amps and at 12 volts 1679/12=140 amps. less amperage is better for your batteries too. for your project if you use car batteries you will get about an hour of running time per battery. because 1hp at 12 volts is 62amps and car batteries usually have about 65amps hours of capacity. but be aware that using car batteries like deep cicle batteries will kill them pretty fast. you should check for old golf kart batteries or something like that.

50 minutes of hard use is impressive for that bettery not taking up all that much room. I expected a lot less.

are you going to have a series of relays/solinoids like a golf kart, sot you dont just have a on and off for speed

Caddy_V3 wrote:

are you going to have a series of relays/solinoids like a golf kart, sot you dont just have a on and off for speed

no, this system is way too lossy, it wastes alot of power, so i would get worse runtime, and its not really possible for my application since the voltage is so high. but i will use something to regulate the rpms of the motor, i need to make the circuit, it will use a pwm controller, (in theory is 100% efficient) to control the power going to the motor.
and i dont just have the on and off for speed i still have the mtd varydrive going to the transaxle.

mr.modified wrote:

50 minutes of hard use is impressive for that bettery not taking up all that much room. I expected a lot less.

yes i know its impressive but its still 71 pounds of batteries.
i am thinking about making a circuit to have regen braking the varidrive already makes it possible in the mechanical department, i just need to make the circuitry.

i started to build a rear bumper/second battery tray. i get twice the run time now, i also have more weight on the back wheels so ill slip less in winter.

[img=https://2img.net/h/s18.postimg.cc/o1x2dw7hh/IMG_20161004_192334.jpg]

[img=https://2img.net/h/s18.postimg.cc/5l2nn2rj9/IMG_20161004_192458.jpg]

i still have to reinforce it,paint it and add a lowered hitch to hoockup to normal small trailers.

i almost finished the rear bumper i still want to put some sort of recovery hooks, just some point to attach a tow strap and mount my taillight back.

the hitch is super strong, i just have to find a way to drill a 3/4inch hole to put a hitch ball on it...







now this does make it abit back heavy so i need to make a front bumper to hopefully somewhat couteract this.

its been a long time since i worked on this thing. i took the batteries out for winter and i blew the motor a couple months ago. i need to get some new brushes, but i may just swap a more powerful 3.5 hp electric motor in it.
i also need to fix all the steering because its really loose. right now its burried in snow so i wont be able to get working on this thing anytime soon, but i will be upgrading this thing this summer.

heres some pics i took before winter.






i am in the process of editing the videos i took explaining this thing but i wont be done soon lol.