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-   -   EcoRider - riding lawn mower electric conversion (https://ecorenovator.org/forum/showthread.php?t=161)

Daox 05-19-09 09:58 PM

As promised, at least one pic (sorry, been car shopping for other people lately). This is the new shunt and ammeter. Meter courtsey of Ben Nelson and shunt courtsey of Tom G! Thanks guys!

http://ecorenovator.org/pictures/ecorider042.JPG

MetroMPG 05-20-09 07:48 AM

Nice. I love the old-fashioned look of that shunt.

wyatt 05-20-09 10:26 AM

Quote:

Originally Posted by Daox (Post 3070)
Well, no luck at the truck stop unfortunately. I guess semis don't use deep cycles, but just normal starting batteries.

You may have better luck at an RV dealer, or anywhere they sell solar or wind power installers. If I remember correctly that's where some others have gotten deep cycle batteries for alternator deletes.

Tango Charlie 05-26-09 08:29 AM

Boats use deep cycle batteries. Check with your local friendly marina.

Hugh Jim Bissel 05-26-09 06:36 PM

Quote:

Originally Posted by Daox (Post 2465)
I've also been looking at voltmeters for the mower....I'm also looking into a way to monitor each battery so I know if there is a weak one...

In his build thread MetroMPG installed this gauge. With it you can see which batteries are going out before they actually die. YouTube - #6) Project ForkenSwift electric car: LED battery gauge

He mentioned the builder had a schematic and parts list, but I didn't see a link to them.

Edit: was reading more in the Forkenswift conversion thread, saw a link to evconvert.com and took a look to see what was there. What a crazy random happenstance: the top blog article is part two of how to build the previously mentioned meter! So here you go:

Part 1

Part 2

Daox 05-27-09 07:16 AM

Yep, that was the circuit I was planning on making. I then sent those schematics over to an electronics knowledgeable friend who is part of the local EV build club. He is thinking about making a batch of them to sell. So, I'm kind of waiting on him.

Daox 05-31-09 03:57 PM

ITS ALIVE!!! :D

I've been working on the mower all day and I just got back from my first trip around the yard! Oh yes, I had a big ol EV grin on my face!

I mounted the motor up with the new pullies on it. I had one deep cycle laying around and one starting battery. So, I pulled the battery out of the Paseo to make three batteries. The deep cycle got shoved in the steering column box and the other two got strapped to the sides. I wired it all up with the ammeter and shunt, and used a digital multimeter to keep an eye on the voltage.

Here is the setup:
http://ecorenovator.org/pictures/ecorider043.JPG

http://ecorenovator.org/pictures/ecorider044.JPG

http://ecorenovator.org/pictures/ecorider045.JPG


Unfortunately, I didn't hook the drive belt up correctly, so there was a quite a bit of belt slippage. I'm looking into fixing that as I type this.

I did get some good numbers though. Just having the motor on and spinning the transmission draws about 25 amps. Oddly enough, putting it in gear and driving around takes just above 25 amps once you start moving. Until you're up to speed it takes a tiny bit more, but not much. However, once I dropped the mower deck and engaged the blades the amperage shot up to about 100! As the blades increased in speed and leveled off, the amperage dropped back down to about 75. This is higher than I was hoping, but I'm also hoping that the slipping belt has something to do with it. If the mower is going to draw 75 amps, I'm going to need some decent sized batteries to make sure I can mow the entire lawn all at once.

I also thought it would be nice to show a video at least of it starting up. Its a bit loud only because everything on the mower rattles. You never notice this when you have an engine roaring though!

YouTube - ecorider start up

MetroMPG 05-31-09 04:07 PM

75 amps! What a hog! :D

Congrats on the successful first test drive.

MetroMPG 05-31-09 04:10 PM

Are the figures for driving on the grass, or on the driveway ?

Daox 05-31-09 04:12 PM

I drove on the grass, cutting it, in first gear.

MetroMPG 05-31-09 04:36 PM

Very cool. More video! :)

Daox 05-31-09 06:03 PM

Haha, in due time.

The starting batteries don't last very long at all. But, I did get a second run in today with the belt adjusted right. Unfortuantely, it increase amp draw. :( So, I'm estimating a constant draw of ~100 amps. This is a bit disheartening. I'm going to have to rethink the battery arrangement. Ideally, I think I need a full hour of charge to do the entire yard. So, either I need to mow the grass in 2 or more cycles, get massive batteries, or up the voltage with another battery... Ideas are welcome.

MetroMPG 05-31-09 08:32 PM

Well, golf cart batteries are designed to deliver 70 amps for an hour. I'm sure I've read that several times on the EVDL.

The ones in the ForkenSwift are rated ~225 Ah. Of course that rating is probably at the 20 hour rate. Not sure how close to 100% depth of discharge you get with 70A for an hour, but it's probably getting close. Or you could just do the math... the Peukert number for lead acid is out there.

bennelson 05-31-09 09:30 PM

Very Cool!

Now we gotta weld up a battery rack for you!

Seems a shame not to do something with that tailshaft though.....


PS - An ElecTrak was ruthlessly snatched out from under me by another buyer. Grrrrr.

I'll just let Doax be the guinea pig before I convert my Simplicity..

Daox 05-31-09 09:31 PM

Ben told me I can get 100Ah group 24 deep cycles at the local farm store for ~$70 a piece. Not too bad and that would keep me going for a half hour. I'd prefer not to cycle them past 50%. That would allow me to get half the yard done. I'd rather do that than cycle them all the way down. Just weighing my options.

Higgy 06-01-09 09:11 AM

Good job Daox!

MetroMPG 06-01-09 09:48 AM

I'm curious how you operate the mower with an ON/OFF contactor the way it's set up now? EG how do you get in / out of gear / shift gears, etc.

Daox 06-01-09 10:20 AM

Yeah, that part needs to be tweaked yet. Currently, the drive belt is too short, so I have no clutch. I have to turn it on in gear. If I want to change gears, I power off, change gears, and power back on. In the future, I'll have a working clutch so I don't have to turn off to switch gears. I'll also have brakes then!

MetroMPG 06-01-09 10:36 AM

So the clutch is a tensioner arrangement on the drive belt ?

Daox 06-01-09 10:50 AM

Yup, exactly.

Tango Charlie 06-01-09 12:51 PM

Good stuff, Daox!
Sounds like a good excuse to take a break while mowing the yard. :)

Hugh Jim Bissel 06-03-09 02:20 AM

Quote:

Originally Posted by Daox (Post 3147)
I'll also have brakes then!

Brakes? Ya don't need no steenking brakes! Thats why its got a bumper! :thumbup:

In other news, the mow in 2 cycles sounds like a good plan until you figure out what you want to change. It looks like 1/2 at a time was your original plan/hope anyway. But if you decide to go for broke, Sydney or the bush; then you could pull a small trailer with batteries in it perhaps, or (hard to tell from the camara angles) looks like there's room to hang a battery (or two?) from either side of the frame, over top the mower deck, just in front of the rear wheels; this assumes your legs rest in a position thats high enough to clear them.

Daox 06-03-09 06:39 AM

After thinking a while, I have a few ideas.

1) Rebuild the mowing deck. It just seems to be sucking up way too much power. Clean up the bearings, repack them, adjust anything that needs it and tighten it all up. Heck, the thing is almost 40 years old! Sure can't hurt. :)

2) Play with voltage. Possibly go to 48V. I'm not really sure I want to do this though.

3) Like Jim said, tow a trailer with batteries. The previous owners of my house were kind enough to leave me one actually, so this isn't a bad idea! But, this wouldn't allow me to use it for other things like yard work... trade offs, whatcha gonna do?

4) ? Still thinking. :)

jwxr7 06-04-09 11:21 AM

Nice work so far!

It seems V-belts aren't the best for efficiency. You could try cogged v-belts. I think they are less lossy because they bend nicer around smaller pulleys. I was able to use one on the deck (the belt under the cover running the spindles) of my simplicity like yours.

Hugh Jim Bissel 06-04-09 08:40 PM

Quote:

Originally Posted by Daox (Post 3190)
...But, this wouldn't allow me to use it for other things like yard work...

How is the trailer set up, is there "wasted space" that batteries could go? For example there's a small landscaping trailer (prob 3x6) at work that has the bed completely over top of the tires. This leaves close to a foot to hang batteries underneath.

Could you put the batteries in the bed of the trailer and put a platform over top to use the trailer for other stuff too? or down both sides and leave the middle and on top of the batteries?

Or have the smaller batteries onboard to pull the landscaping trailer, and make/buy/scavenge a second trailer thats just a frame for all the batteries you need for mowing. Then, if one set of batteries isn't enough to do the lawn, you could eventually set up 2 battery trailers and swap halfway through...

Daox 06-08-09 03:30 PM

I don't think there is much room to spare in the trailer. Its a pretty narrow, all metal trailer. I'll take a look at it again though. I've never used it.

Daox 06-08-09 03:42 PM

I finally got to bring the mower to the Milwaukee electric car club's EV build day. I got another member to come to my house and pick it up with a trailer to bring it down to the build day.

I talked with the guys about my problems and we all agreed the deck should be looked at. So, we removed it and found that at least two of the three spindles bearings that should be replaced.

We got the deck off the mower, and tipped it up to get a better look at the bottom to see what kind of adjustments I had. One of the guys thought I could adjust the drive belt so I might not need a new one. He adjusted it and thinks it might work just fine now.

http://ecorenovator.org/pictures/ecorider046.jpg




With the deck off, I set about taking it apart. I took the top covers off and found tons of grass clippings stuff around the pulleys and belt. It was a real mess. This picture is after I cleaned a good deal of it all up already.

http://ecorenovator.org/pictures/ecorider047.jpg



Another good idea that one of the guys there had was to get a cogged belt for the deck. The cogged belts can more easily bend around tight radii and thus less power will be spent. This should lower my amperage at least a bit.

http://ecorenovator.org/pictures/ecorider048.jpg



After it was all said and done, the entire deck was take apart. I have the bearings and will be stopping by a local bearing shop to find something to replace them with.

http://ecorenovator.org/pictures/ecorider050.jpg



There was also much talk about battery configuration of the mower. I mentioned that I had run it at 36V and it pulled 100A. The pulleys are a bit large at that voltage. If I went lower, the pulleys would be sized pretty much perfectly, so 24V is kind of looking like what I am going to go to. One of our members works at a golf course, so I am going to contact him and see what the possibility is of me getting four 8V batteries.

I also cut a few more slots for the motor into the frame. Unfortunately, my bolt circle is off, and the right side bolt is going to be a small notch in the frame rather than a slotted hole. Oh well, I think 5 bolts will hold! :)

http://ecorenovator.org/pictures/ecorider049.jpg

MetroMPG 06-08-09 03:56 PM

Quote:

I mentioned that I had run it at 36V and it pulled 100A. The pulleys are a bit large at that voltage. If I went lower, the pulleys would be sized pretty much perfectly, so 24V is kind of looking like what I am going to go to.
Can you explain what you mean here? Are things turning too fast at 36v because of the pulley size? How did that conclusion get made?

Daox 06-08-09 04:01 PM

The motor is rated for 3200rpm @ 24V. At 36V, the motor will spin proportionally faster, so 4800 rpm. I sized my pulleys the same as the original gas engine. According to reading and talking with people, most small engines run 2500-3400 rpm (feel free to correct me here, I haven't got anything incredibly solid). So, if I drop back down to 24V, I should be right in that range. Otherwise, I am going to need smaller pulleys to get the drive and mower deck speeds back down.

cgates30 06-09-09 07:00 PM

Great thread. This is exactly what I'd like to with my Yard Bug mower. It's a sit over the motor rig with room for a grass catcher under the seat too. I'd like to put the batteries where the bag would normally sit.

It looks like my system is a 2 belt system, one belt driving the blade and the other driving the transmission. So, if I can swap the gas engine with an electric motor (and the motor rpm is similar to the gas engine) then it seems like it could be a nice conversion. I'm also assuming I don't need a motor controller since speed is normally zero to slow. I'm not really familiar with contactors, but my understanding is they're a physical connection in the line completing the circuit between the battery and motor.

I need to find a good source for a 24-48 V motor that spins in the 3500-5000 rpm range. I figure I'll also look for 2-4 deep cycle 12 V batteries, contactors and cables. Installing the batteries shouldn't be a problem since I need to build a tray that sits over the deck/under the seat.

Would a golf cart motor be a good candidate?

Am I missing something, or would this work? A motor controller would be nice so I can vary speed, but then my blade speed would vary too. 2 motors would be nice, but then things start getting hard to write off under the 'hobby' budget.

Daox 06-10-09 07:30 AM

Welcome to ER cgates30. Your setup would be very similar to mine being a two belt system. I suggest you start your own thread and post up some pics and we can work out any kinks and questions you have. :)

A golf cart motor may be good, but from my ebaying, they usually don't have an end on one side since they mount up to a transmission or differential. This means you'd have to make your own which is really not easy unless you have access to metalworking machinery.

You're right, a controller would be nice but is totally unnecessary once you size your pulleys right.

cgates30 06-10-09 08:54 AM

pulleys
 
I'm hoping the pulleys don't need to be replaced. My idea is if the motor speed is +/- 20% of the gas engine speed then everything should scale accordingly.

Will do on the thread, just need to get some pics, etc.
Thanks

Daox 06-11-09 10:59 AM

Well, I stopped at the local bearing place last night. I walked in, told them what the bearings were for and was asked if I wanted the imported ones, or nice ones. After a pretty short discussion, I ended up going all out and getting the very nice sealed Timken bearings. The guy basically assured me that they'd never go bad. So, $120 later, I have 6 new bearings to pound into the mower bearing carriers. This puts the total project cost at right around $160. That includes the pulleys and bolts/washers.

I'll get pics when I start the work which will hopefully happen this weekend. I really want to hook it all up and see if it made any difference. I also want to hook it up @ 24V and see what kind of amperage it pulls since that puts my rpms back in line with what they're supposed to be. That should give me a much more accurate idea of what my amperage would be if I decided to stay at 36V with properly sized pulleys.

Daox 06-17-09 07:54 PM

Tonight was a quick job. I got all the spindles together and degreased them since the new bearings are fully sealed. Then, I sharpened the blades. They weren't horrible, but they definitely weren't sharp.

Daox 06-23-09 06:17 AM

This past weekend was another build day. Unfortunately, I forgot my camera again! I did get the whole deck put back together. It just needs a new belt and then it needs to be put back on the tractor. After that, I need to load test it once again and figure out my battery setup.

Here is a picture of the new/old bearings.

http://ecorenovator.org/pictures/ecorider051.JPG

Tango Charlie 06-23-09 10:05 AM

Quote:

Originally Posted by Daox (Post 3307)
...Unfortunately, I forgot my camera again! ...

D'oh! That's grounds for a lynching, mister! Ha ha!
Good to see the project progressing, anyway. :thumbup:

Daox 06-23-09 02:08 PM

Well, I could argue that this really isn't part of the conversion, just part of owning a 40 year old mower! :)

Daox 08-03-09 11:40 AM

I finally picked up a new mower deck belt last night. I have no idea why it took this long. I've gone out to work on the mower several times since the last update only to think 'DOH, I need a belt!' By the time the next day rolled around, I had forgotten about it and thus it never got done. So, reassembly will be underway very soon.

Daox 08-04-09 08:55 AM

Its almost all back together. I need to stop on the way home and pickup another new belt. The motor must have moved forward a bit compared to the gas engine, so I need a longer drive belt.

Daox 08-06-09 09:30 AM

Test number two went off last night. I lowered the voltage and only used two batteries instead of three. Oddly enough, my amperage was lower than with three batteries (which is opposite of what it should have been). My guess is that the lower motor rpm really helped out. At 36 volts (3 batteries) the motor spins 1.5 times as fast as 24 volts (2 batteries) since rpm is proportional to voltage. At 24 volts, my motor rpm is much more in line with what was intended for the mower. The result was driving around still took 20-25A, but the mowing deck only took another 25A! This is HALF the amperage of the last test. It seems that the deck rebuild and proper pulley sizing really works out well. I am very excited about this!

The next step is to procure some actual deep cycle batteries. My power died off insanely fast because I just used two semi-dead staring batteries. One trip around the house and they were already puking on me. The local battery store has some group 24 deep cycles for $70 which seems pretty reasonable. I'll have to look into what else they have too. I might want to go with something larger. I'd ideally like a 1 hr run time. At 50A, I would get about 40 minutes of run time since you don't want to cycle batteries beyond 50% to retain good life. The alternative is to go back to 36 volts, but resize my pulleys. This theoretically would drop my amperage down to ~33A. This would (again theoretically) give me right around an hour of run time and maybe a bit more because of the peukert effect. So, 36 volts is looking like the way to go.


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