Electric garden tractor puller questions???

supercub,

I've been pulling electric with JimDear2. We pulled for points this year, with Jim coming in 1st, and me in 2nd.

Jim is running an average size golf cart motor at 48 volts with 450A alltrax. We just built a P&S 144V/500A controller up upgrade it a bit for next year.

I'm running an ADC L91 motor with 450A alltrax. 60V system through the controller, with a controller bypass and 120V overdrive. That runs pretty sweet. Once I got it working well, I blew 3 batteries in 4 hooks, pulling about 400 amps. I can change batteries like the best NASCAR pit crew. I've since shelved the remaining 13ah hawkers and started picking up 16ah.

Have you been pulling gas? Jim has pulled for many years, and I'd been electric drag racing for almost a decade, so we paired up.


Darin

supercub

Darin beat me to answering you, I've been off making parts for our new battery. He covered a lot of good info to start.

Where are you located generally? We are in southeast Michigan.

I also believe you are going to need more voltage and amprage. I'm going to go into it in more detail below then Darin did. Even so you should have a ball. Lots of people will show intrest and finally the comments you get when going down the track are quite funny (no noise remember)

Unless you plan to use the tractor for general use you really don't need big, heavy, high amp hour batteries. Darin will be using 10 batteries that are about the size of motorcycle starter batteries. They are special (read expensive) 16 ah high discharge AGM's. (Mine are slightly bigger 24 ah versions). You might shop around and see what you can find like Optima red tops. For competition you want big output for a short period and light weight.

Even smaller starter batteries might work out since they are supposed to give big amps for a short period. I don't know for sure since I've never tried them. A hook in 0-13 class can last for 45 seconds to over a minute. So standard starter batteries may not cut it.

I've read of people who went to recycling yard and bought used batteries (those from big telcom back up systems or wheel chairs are a good selection) checked and charged them, kept the good ones resold the bad ones to the recycler at a slight loss, bought more and so on.

The batteries you want should be able to give massive amps while maintaining reasonable voltage under load.

You have to have a strong battery to make power (voltage times amps equals kilowatts (1000 watts), 750 kilowatts = 100 hp)

One way to think of it is the battery equals the engine in a gas powered vehicle and the electric motor and controller is closer to equaling the transmission.

Just like a gas vehicle, when you have big power (battery) then you have to have a transmission (motor/controller) that is able to use the power. Lots of power with a weak trans equals burnt and broken parts. Lots of trans (motor/controller) with weak power (battery) goes nowhere and is a waste of time and money.

I've been running 48 volts and just can't get enough wheel speed. Try your tractor out at 24 volts since that is the equippment you have and go with at least 2nd gear to start off. Remember the more load = more amps = more torque. The maximum torque your setup will produce is at 0 rpm.

I did well against the 0-13 horse real stock tractors.

The un-real stock (cheater) 0-13 and 16 horse stock altered tractors were more Darin's meat, once he got the 120V bypass done. He would get out real good then blow up a battery. Until that happened he was gold. The major reason to go to higher voltage is to keep the load (amprage = torque) down. With my little 6.7 inch motor and 48 volts the tractor would crawl down to inches per minute and keep going. All that torque breaks things. I blew up one stock differential carrier, (Darin's was welded) and I am now running a 2 piece carrier from a hydrostatic differential. Held up under 48 volts don't know about next year and 144 volts.

So here are some suggestions and things to watch out for;
1.) Join a pulling club if you haven't already and ask lots of questions. Remember the things they do to gas tractors to make them stronger will work for you as well.
2.) Remember you may make lots more torque at a slower speed then gas so you might be able to run a higher gear than equivalent gas tractor.
3.) Be very careful when on the throttle, if something in the drive line breaks the motor could overspeed and blow up the commutator. Series DC motors will run away if given high voltage/current with no load. Darin made a special control circuit that reads the setable shift light circuit in a aftermarket tachometer. This shuts off the power if the rpm exceeds what is set into the tach.
4.) Do lots of research, ask lots of questions, don't get flustered. Our first year was a disaster, we did everything wrong, our second year was spent getting it right, our third (next) year we are going to kill them.

Stay in touch, ask, I'll be watching this thread.
Jim

Supercub,

The easiest way to mount the motor is to remove the stock ICE and clutch, build a plate that will go between the frame rails, and drill the motor bolt pattern on the plate. You can put the motor anywhere the driveshaft will reach, but i moved mine as far rearward as I could. Bolted a sprocket to the drive shaft. Sprocket on the motor. Double roller chain to join the two. Plus added a support bearing for the driveshaft near the motor. I think this is the easiest mounting method.

A stock ICE turns 3600 I think on the governor.

Method A.
Put two batteries in series for 24V into your controller. You could add two strings in parallel. Depends on how big your batteries are. You can probably afford the weight. Do you know the weight class they pull, or is it open?

Method B.
Put two batteries in series for 24V into your controller. If the 200A controller is maxing out, you can add a contactor(relay) to bypass the controller, and put more amps to the motor. This will increase max torque, if your gearing will pull more torque from the motor.


Method C.
Put two batteries in series for 24V into your controller. If the 200A controller is maxing out, you can add a contactor(relay) to bypass the controller, and put more amps to the motor. This will increase max torque, if your gearing will pull more torque from the motor. You can also add a contactor to add a resistor (big wire) to bypass some of the field current in the motor, which will boost the motor speed, while losing torque, which will cause the motor to pull more amps. This is a bit like having a higher transmission gear.

Method D.
Put two batteries in series for 24V into your controller. Add two strings in parallel. The two strings are wired in parallel with each other through contactors. Add a contactor that will remove the controller from the circuit. Another contactor allows the two strings to be configured in series. This boosts your voltage to 48V. At higher voltage, the motor will draw high amps, and deliver high HP.


Many many options. And you can start with method A, see how you like it. Probably put some decent effort into your motor mounting method, and you can use the same plate to mount different motors down the road with another set of mounting holes.


Go nutts!

Darin

supercub910 said:

Do you think 4 standard 12v golfcart batteries wired series parallel to 24v will be enough power or should i add a few more? Also i could change my sprockets to increase rpm going into the gearbox...ex.[ motor turning 2500-3000 whatever the "sweet spot" is and have the gearbox input around 5000]??? Not really sure about my set up but its all about having a good time and my little boy is a tractor fanatic and he loves to go to the show-and-pulls so if nothing else im just doing it for his enjoyment. THAT AND CONFUSING ******** IS SOOOOOOOOOO MUCH FUN!!!!! I will try to post up some pics of last years "competition" so you all can see what im talking about.

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supercub 910,

You might review the build thread I posted when building my cub.

http://www.diyelectriccar.com/forums/showthread.php?t=28942

Four 12 volt golf club batteries should be sufficient to get you started. I cant see you running 4 golf cart floodies flat in a single pull

For tractor speed right now just run the highest gear the tractor will pull. I don't know how much torque your setup can generate, but I doubt you can overpower the stock 3rd gear. You need to get as much speed as possible in the firt few feet. Then just let the motor grind away until the tractor stops.

IMPORTANT NOTE: A stalled electric motor is basically a DEAD SHORT. you will burn up the motor if you don't back off off the throttle as soon as the tractor comes to a stop.

I assume you are running without a clutch (if not why not), so all you need to do is apply throttle and let er rip. Get the tractor moving as fast as possible then let the motor load down, the more load, the more amps you'll pull, the more torque you will pull untill you reach the lmit of your equippment.

You mention changing sprockets on a Cub Cadet. Are you adding something? Cubs don't have sprockets,

I recommend you attach your motor directly to the drive shaft with a coupler. Make sure the drive shaft is supported at the front with either a solid coupleing to the motor or with a pillow block bearing.

By the way be carefull with that ******* stuff. A lot of people consider me one.

The sprockets im speaking of are in my driveline...my cub is a 1961 model which is "the original" cub and which is completely unique to the other cub series. It came with a solid frame and mounting pad for the motor...basically one big flat area to mount the motor with a slot in which the clutch belt ran through to underneath the frame to a driveshaft which went to the gearbox. I was going to mount the motor on top of the frame and run a single 40 diamond chain down through the slot to a heavy duty driveshaft i fabricated along with those pillowblocks you mentioned and the driveshaft will attach to the gearbox. I only did this to keep from cutting up an "original"cub which later on i may decide to restore? But the 1961 cubs are susposed to have the strongest transaxles and frames even though they came with the smallest kohler motors. They are basically like a minature tractor. If i enjoy this project my next one will be one less rare and i wont mind cutting it up!!! As far as the ******* thing goes I dont know how ******** from michigan act but the ones we have are the ones Jeff Foxworthy speaks of. Kinda like a bunch of Joe Dirts running around!!! It makes for a fun time!!!

supercub910 said:

They pull before the big tractors and no one really rags anyone......most everybody there are just good ol country folks and most everyone enjoys the little tractors, especially the kids. No one really has any kind of majorly modified puller....mostly just flashed out mowers but it is still lots of fun.

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Super,

That's the way it used to be with us, every one having fun.

Then we started getting 100 and more pullers at a pull which slowed the start of the farm tractors, Then guy's (being guys) started modifying and building hot rods.

Now when guys show up with $10,000 50 cube and turbo diesels garden tractors and V8 mini rods you would be supprised how stressful it can get.

Thats one reason I got away from the ICE stuff.

Jim