[OBeer-WAN-Kenobi]

Hi everyone,
I've decided to start a build thread here to chronicle my upcomming lawnmower build. I figured a lawnmower would be a great place to start.

Since this is my first EV I've got a lot of questions about the electricity end of things. I can machine, fabricate, and weld just about anything and have access to all of the equipment I'll need but I'm electrically challenged. I used to do car stereo's but this is a lot more complicated; at least to me.

I'm currently looking at a smaller forklift motor to power a riding lawnmower and plan to use either 36v or 48v depending on the size of the chasis of the free mower I'm getting (I haven't even seen it yet). I'd like to use seperate motors to run the blades to cirvumvent the inefficeincy of v-belts and also to make the deck easily removeable.

I think I basically understand how large a motor to use for the traction but I really don't know what to look for to run the blades. I also realize I'll probably need some sort of friction clutch between the blades and motor incase it hits something.

My secondary project is to build another mower deck that can be pulled behind or pushed in front of my electric golf cart. I don't have the cart yet, but it should be delivered next month. I'd like to be able to plug the deck right in to the golf cart and use the carts batteries to run it. I plan on putting an ATV winch on the front of the cart and will use that to lower and raise the mower deck (and a plow at a later date).

Anyway, that's enough for the first post. Any comments and help would be greatly appreciated.

 

[major]

My secondary project is to build another mower deck that can be pulled behind or pushed in front of my electric golf cart.

Hi again OBeer,

See post #7, http://www.diyelectriccar.com/forums/showthread.php?t=45125 There is not a separate forum here for electric tractors and/or mowers. But there have been quite a few threads and posts. Do a search on the site.

Regards,

major

 

[TX_Dj]

The way we've done it around here is to use one motor to replace the ICE, and retain the stock blade PTO.

Flip the switch and you can move or mow same as usual. Simple contactor controller with a DC circuit breaker rated at the amperage you want to set as your upper current limit.

This is the same way my electric push mower works, it has a 40A thermal breaker and a simple contactor controller. It came this way from the factory (black & decker).

 

[OBeer-WAN-Kenobi]

The way we've done it around here is to use one motor to replace the ICE, and retain the stock blade PTO.

Flip the switch and you can move or mow same as usual. Simple contactor controller with a DC circuit breaker rated at the amperage you want to set as your upper current limit.

This is the same way my electric push mower works, it has a 40A thermal breaker and a simple contactor controller. It came this way from the factory (black & decker).

I'm sorry, are you describing what you used to substitute for a controller or what you are using to stop the motor in an overload like running over an oak tree stump?

I did just purchase a small clark forklift for the motor and should be able to use the controller off of it as well as far as I know.

 

[OBeer-WAN-Kenobi]

Just a little update.
I got the forklift home tonight. The guy I bought it from had a bigger forklift and put in on my trailer for me but when I got it home I had to do it myself. Luckily it's a tilt trailer so I just pulled it off with a chain and my F-250.

The motor appears to be an ADC 6.7" but I haven't taken anything apart yet. Its hotter than the dickens out today so maybe ill rip into it tomorrow morning.

If anything interesting happens ill let you guys know.

 

[OBeer-WAN-Kenobi]

Another update,

I removed the traction motor and it is a Prestolite MGT. Thanks Major, for your information in the forklift motor thread.

I've also removed the hydraulic motor and this one is also a Prestolite MGT but just slightly smaller than the traction motor.

I'm still hoping for a little more info on these two motors; specifically the RPM and continuous power ratings. I'm having a hard time finding it out for myself. I did find out that Prestolite was bought by another corporation but I couldn't find any specs for these motors on their website.

Anyway, I took one of the motors apart and everything appears to be in good shape besides being dirty. The brushes were seized up a bit but a few gentle taps with the handle of a screwdriver and they loosened up and were sliding up and down like they're supposed to.

I'll be dropping the motors off at a local motor repair shop just to get cleaned and checked out but I don't think I'll need any actual repair done.

Sometime this week I'll try to get all of the electronics out of the forklift before they get rained on too much. I was lucky enough to find a wiring diagram that someone had taped to one of the inside panels of the lift so that's good. Hopefully it will be enough to help me through.

ETA: I still have yet to figure out a good and safe way to keep the motor from over RPM if a belt breaks. If anyone has a good and cheap way of doing it, let me know. Oh, and suggestions for batteries and a charger would be great too. 36 volt system.

 

[Woodsmith]

ETA: I still have yet to figure out a good and safe way to keep the motor from over RPM if a belt breaks. If anyone has a good and cheap way of doing it, let me know.

If you have a chat with Jimdear2 he was mentioning to me a fix he has done using an aftermarket car tachometer with shift light.

I will need to add the same fix, eventually, to my tractor project.

 

[major]

I removed the traction motor and it is a Prestolite MGT. Thanks Major, for your information in the forklift motor thread.

I've also removed the hydraulic motor and this one is also a Prestolite MGT but just slightly smaller than the traction motor.

Hi OBeer,

The traction and pump motors are both Prestolite MGT type. This means that they both are of the same electromagnetic design. They had different numbers following the MGT, like 4011 and 4012. Those numbers specify the mechanical design. As you can see, one is a traction motor, 4 terminal (reversible) with an external shaft (likely). The pump motor is likely a unidirectional (2 terminal) motor with an internal shaft to mate to the pump. Likely the pump motor isn't going to be of much use to you. Except possibly for spare parts for the traction motor.

I'm not surprised you cannot find specs on the motors. These are not commodity products. They are specifically designed and manufactured for the OEM. I am familiar with them from a previous life. They were also used at 48 volts. When at 36 volts, IIRC, had a continuous rating of about 7 hp, maybe in the range of 2700 RPM. This is if they were ventilated with internal fan. At 48 volts, maybe up to 10 HP at 3600 RPM.* Overload capability is excellent. The brushes are about the same size as you will find in a 9 or 11 inch WarP motor. Should be no problem using controllers at 500A limit, or higher.

I'd be sure to keep your operational RPM below 5000; 4000 is better. Max tolerable is likely 6000. The pump motor may have had the standard Prestolite 4.5 degree advance for unidirectional motors. The traction motor would be on neutral. You can go higher on voltage but would have to advance it. And watch the RPM.

Good luck with them,

major

 

[OBeer-WAN-Kenobi]

Thanks again major.
Those ballpark specs should help alot.

Hi OBeer,

The traction and pump motors are both Prestolite MGT type. This means that they both are of the same electromagnetic design. They had different numbers following the MGT, like 4011 and 4012. Those numbers specify the mechanical design. As you can see, one is a traction motor, 4 terminal (reversible) with an external shaft (likely). The pump motor is likely a unidirectional (2 terminal) motor with an internal shaft to mate to the pump. Likely the pump motor isn't going to be of much use to you. Except possibly for spare parts for the traction motor.

Why would the pump motor not be of much use? (Remember the electrical/motor ignorance here....) I was thinking I could use this in another project where it would be powering a mower deck (not a whole tractor) similar to what you posted in another thread and plug in to my electric golf cart. You are correct that it has a female shaft, but that's not much of an issue. I could either use parts from the hydraulic pump to make it a male shaft or just machine something up. If it wouldn't work for some reason I'm not seeing here I could always keep the hydraulics and make a wood splitter or something out of the rest of the forklift pieces...LOL.

Does 2 terminal mean it should have 2 poles? The smaller motor has 4 poles and 8 brushes as well. I'm not at home now or I'd check the number of terminals as I've forgotten.

 

[major]

Why would the pump motor not be of much use? (Remember the electrical/motor ignorance here....) I was thinking I could use this in another project where it would be powering a mower deck (not a whole tractor) similar to what you posted in another thread and plug in to my electric golf cart. You are correct that it has a female shaft, but that's not much of an issue. I could either use parts from the hydraulic pump to make it a male shaft or just machine something up. If it wouldn't work for some reason I'm not seeing here I could always keep the hydraulics and make a wood splitter or something out of the rest of the forklift pieces...LOL.

Does 2 terminal mean it should have 2 poles? The smaller motor has 4 poles and 8 brushes as well. I'm not at home now or I'd check the number of terminals as I've forgotten.

I was speaking mainly about the shaft on the pump motor. Internal splines or tang drives are unusable for most guys. However, if you can figure it out or use it with the pump, more power to you

Both the MGT motors are basically the same size, 7.2 inch diameter with 5 inch cores and 2 inch comms. One may look larger due to the flange or something. They are both 4 pole (magnetic poles) motors. For wound field DC motors, 4 terminals are required for reversible motors (traction) but only 2 terminals for unidirectional motors (pump motors).

 

[OBeer-WAN-Kenobi]

Thanks major, I understand now. Yeah, Machining/Fab no problem. Electricity=uhmmmm..... LOL

If you have a chat with Jimdear2 he was mentioning to me a fix he has done using an aftermarket car tachometer with shift light.

I will need to add the same fix, eventually, to my tractor project.

That sounds like a good idea to me and fairly inexpensive too. You could take out the shift light and rig it to a relay to throw out a contactor or something right?

I'll PM Jimdear2 and see what he has to say. Thanks!

 

[OBeer-WAN-Kenobi]

Brought my motors down to the local motor guy to get cleaned up and checked out. When talking to him on the phone he was worried about running them continuously but after seeing them, and calling them monsters, he wasn't too worried about powering a paultry lawn mower.

Probably going to pick up the donor tractor tonight or tomorrow night. I've got to swipe a trailer from one of my friends.

I've started thinking about batteries now. Any suggestions for reasonably priced....er...cheap batteries that will do the trick? I'm still planning on 36 volts and conservatively, I'm guessing the thing will probably draw about 50amps continuous (with the deck engaged). It will probably be a little less but I'm not so good with the calculations. My target is to mow for at least 1 hour before hitting 50% DOD.

If someone would help me out with the calcs and make sure I'm not off too much here that would be great!

Thanks again!

 

[TX_Dj]

I'm sorry, are you describing what you used to substitute for a controller or what you are using to stop the motor in an overload like running over an oak tree stump?

I did just purchase a small clark forklift for the motor and should be able to use the controller off of it as well as far as I know.

My point is there's really not a reason for a controller in this application. The transmission sets the speed the mower moves at, so all you really need is a "big on/off switch" to turn the motor on and off.

That's what we've done in the past, and what I've seen in lots of other mower conversions.

 

[Woodsmith]

I've started thinking about batteries now. Any suggestions for reasonably priced....er...cheap batteries that will do the trick?
Thanks again!

I got my batteries for my tractor gifted to me from Simon Rafferty on the forum.

He went to a local scrap yard and tested all their Optima red tops. He bought them for £3 each with a sell back of £2 each. I reckon £1 per battery is pretty good.

That may be a way to go, at least initially, to get things moving and tested before you decide what to invest more money in if you find it necessary.

 

[OBeer-WAN-Kenobi]

I got my batteries for my tractor gifted to me from Simon Rafferty on the forum.

He went to a local scrap yard and tested all their Optima red tops. He bought them for £3 each with a sell back of £2 each. I reckon £1 per battery is pretty good.

That may be a way to go, at least initially, to get things moving and tested before you decide what to invest more money in if you find it necessary.

That sounds like pretty good advice to me and the way I'd like to go to start off. That is if I can find a scrapyard around here that has old batterys they're willing to part with. But I don't know where to find some £. I only have $, so I might be screwed....

Seriously, though, what's the best way to test batteries that I may find? Is there a prefered method/Tester? Been doing a lot of reading here but still pretty ignorant on quite a few electrical matters.

I'd also like to get everyones thoughts on which new FLA batteries would offer me the best bang for the buck in my application. That way I've got something lined up for later. I'm still entertaining 6v and 12v options, though the 6v would depend a lot on the footprint of the battery.

Thanks again!

ETA: got the tractor home tonight but didn't have a trailer. Something kind of funny about a manufacturing engineer and a mechanical engineer loading a lawn tractor into the back of a truck with nothing but a rachet strap and no ramps...... let the engineer jokes fly!

 

[Woodsmith]

That sounds like pretty good advice to me and the way I'd like to go to start off. That is if I can find a scrapyard around here that has old batterys they're willing to part with. But I don't know where to find some £. I only have $, so I might be screwed....

Seriously, though, what's the best way to test batteries that I may find? Is there a prefered method/Tester? Been doing a lot of reading here but still pretty ignorant on quite a few electrical matters.

I'd also like to get everyones thoughts on which new FLA batteries would offer me the best bang for the buck in my application. That way I've got something lined up for later. I'm still entertaining 6v and 12v options, though the 6v would depend a lot on the footprint of the battery.

Thanks again!

ETA: got the tractor home tonight but didn't have a trailer. Something kind of funny about a manufacturing engineer and a mechanical engineer loading a lawn tractor into the back of a truck with nothing but a rachet strap and no ramps...... let the engineer jokes fly!

Where there is a will, there is a way.
I have loaded using all manner of bits of equipment, it is part of the fun.

Batteries can be tested with a battery load tester that places a large load on the battery and shows the sag.
It is a quick way of testing a fully charged starting battery. The breaker may have one of their own so worth checking before buying/borrowing one.

At the breakers you would want to look for sealed batteries that have come out of crashed or damaged cars. More chance of the battery being good when the car went to be broken.
Unsealed ones may have lost some electrolite in transit and ones from rusted out old wrecks may not have been looked after and may be the failing part that lead the car to be broken.

To many breakers the batteries are only worth the lead recycling cost as they can not really sell them on as usable.

Ultimately, you test all the best looking ones and then make an offer for the ones that seem to have a good reading.

I'd recommend negotiating the price in $ as the exchange rate to £ wouldn't be cost effective.

 

[OBeer-WAN-Kenobi]

Thanks woodsmith.... but does that mean that I'd have to charge these batteries first before testing them? That would take a while.....


Another small update. The donor forklift has an EV-100 control in it and had a handy wiring diagram taped inside one of the panels. I searched this forum and am still having a hard time getting more info on this control though I did find a thread where it was mentioned, that thread was mostly for the EV-1 control. Any of you guys got some good info?

 

[sjc]

My point is there's really not a reason for a controller in this application. The transmission sets the speed the mower moves at, so all you really need is a "big on/off switch" to turn the motor on and off.

That's what we've done in the past, and what I've seen in lots of other mower conversions.

I'm not arguing with you, since you've done it and it works, but I have a question: what load is there on the motor when the switch is on but the transmission is in neutral? I'm concerned about overspeed if the motor has full current but no load.

 

[Woodsmith]

Thanks woodsmith.... but does that mean that I'd have to charge these batteries first before testing them? That would take a while.....

No need. If the battery is dead or low at the breakers then assume it has been left discharged for too long and ignore it.
Only bother with the ones that are still holding the full, or nearly full, charge that they came in with.

 

[OBeer-WAN-Kenobi]

No need. If the battery is dead or low at the breakers then assume it has been left discharged for too long and ignore it.
Only bother with the ones that are still holding the full, or nearly full, charge that they came in with.

Cool. Thanks!

Another update. I've finished taking off the ICE, electrics and some body panels that were in my way on the mower.

I'm really thinking about using the hydraulic motor from the forklift now instead of the traction motor. This lawnmower has a transmission so it's kind of a waste to put a bidirectional motor on it. I'll keep thinking about it. Both the hydraulic and the traction motor appear to be the same size so that shouldn't figure into it at least.

I've attached some pictures for once, hopefully they come out ok. All I've got right now is my cell camera.

P.S. Don't mind the dog, he's a ham....