# Push mower conversion, not exactly an EV, but still fun...



## Zemmo (Sep 13, 2007)

Wow, thats a great little project! I have been wanting to do this exact thing my self. I already have a motor, I have been watching for junk mowers to take for free and convert.


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## RKM (Jun 9, 2008)

dimitri,

You continue to impress!

How does the 2500 rpm unloaded speed compare with the original ICE?

I don't know the blade length, but have calculated the tip velocity to be over 160 mph based on a 22" blade. This seems pretty fast. My riding mower tops out at a tip velocity of 110 mph. For safety sake, you might want to look into this. Great job though! Congrats.

Rob


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## TX_Dj (Jul 25, 2008)

Dimitri-

Looks great! Keep up the good work!

Not seeing something like this in the photo, but if you don't have it already I have to recommend to put a safety release at the push handle, perhaps in line with the master switch on your control box, so that if you release the handle, the blade will stop. This way you could activate the mower with the master switch that drives the contactor, and actually on/off the mower from the control position. Could come in handy if you hit something that stalls the blade, you could make it stop before it blows your fuse or overheats the motor.

Another recommendation, if necessary (depends on how fast the blade spins down) would be to use a double-position contactor where the "on" position routes battery to the motor, and the "off" position routes the motor to a resistor bank for dynamic braking of the motor so it will stop much faster, if that's a problem.

Always fun tinkering with things like this and improving the design. Keep us posted.


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## dimitri (May 16, 2008)

Yes, I had planned to install a microswitch at the handle in series with the main switch, this way both switches must be on to close contactor, thus providing better safety and better motor control. 

I haven't actually installed the microswitch yet, I'd like to see how the mower works first, but I will definitely do it later.

As for motor RPM relative to original RPM, it was just a guesstimate that 2500 RPM should be in same ballpark with ICE RPMs. I will not be running it without load, self propelling gear provides enough load even when there is no grass cutting going on. BTW, judging by how fast I have to walk behind it to keep up, RPMs must be pretty close to original


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## grose (Apr 30, 2008)

This is a project that I'm looking forward to also! I've just gathered up all the parts, and I have a "like new" mower deck.

I went with the 24V motor made by Briggs and Stratton. Also $150 shipped.


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## dimitri (May 16, 2008)

Well folks, I wanted to give everyone an update on my electric mower project. I have relatively large yard for a push mower, about 1/4 of acre covered by grass, although my wife and I are replacing it by various landscaping improvements, there is still a lot of grass to be cut. It used to take me about an hour with original ICE mower, including a run to a gas canister to refill the tank. Most of my neighbors use tractors, but I wanted an excersise and I was too cheap to buy a good tractor.

The one and only piece of advise for anyone considering similar conversion, STAY AWAY FROM STARTER BATTERIES  Those buggers only last 20 minutes per charge, so I had to split my lawn cutting into 3 phases with many hours of recharging in between, since I only have 12 V charger and have to charge one battery at a time.

I ordered 36 V scooter charger on Ebay, so I can charge whole pack at once, so that should work better. 

If I was to do it again, I would not buy those tractor batteries, I would go for scooter or wheelchair or UPS batteries, they are typically Deep Cycle and SLA or AGM types. It would cost a little more, but would work much better.


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## TX_Dj (Jul 25, 2008)

Ouch. Expensive lesson.

I use an 18Ah battery in my mower, which works great for me... but I have a small lawn. Despite that, Black & Decker claims up to 1/3 acre per charge, depending on lawn type and length.

These are just simple Yuasa SLA batteries, I don't think they're really even deep cycles... I never let them "get into the red" and rarely have to charge before I'm done mowing, though it happens if I let it get out of hand. Even still, the batteries have lasted about 5 years per set, despite the texas heat.

Maybe yours is draining faster because of the wider blade and self-propel?


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## 280z1975 (Oct 2, 2008)

I've got an electric mower ... it was my wife's cousin's, but then he moved into an apartment and it became ours. It's basically an old style push blade mower (you know those ones you can find for 2 dollars at a garage sale) but was built as an electric one (a lot of people here have tiny lawns, so there is a large market for electric (cord attatched) and battery powered mowers.

I don't know it's "range" as our 'lawn' is all of 15 feet by 25 feet ... but with our move to a larger house I can test it out more. The battery does seem quite resilent as I have run it several times between charges and usually keep it hooked up to a 500ma solar trickle charger to help keep it maintained (don't know if it helps much, but hey, I've got it). Best part is it can still work without the battery when pushed along.


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## Zemmo (Sep 13, 2007)

Do you happen to have any pictures of this mower. It sounds like the Reel Mower from your description. Thats the kind of mower I would like to convert to electric.


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## Doofus McFancyPants (Jul 10, 2008)

Awsome job.

I am actually planning on something simular for my first conversion project. I figure this will allow me to see if i can aquior the skills to feal confidant that i can actually complete a EV conversion.

I have a mower already that i am using - so i am going to keep my eyes open this fall for any "yardsale specials" as well as Spring time for people who have dead mowers after winter. we have a small yard ( compared to the 2 acres i grew up on) takes me 30 - 40 minutes to cut it now with a push mower. I think this is easily convertable. Plus if i can convert it all pretty cheap - it will pass the Finantial Test ( the wife).

i have seen some of the web pages on conversions of mowers - looks basic - Motor - batteries - safety switches.

Would you be willing to provide a quick electrical diagram of your connections and equipment? will help me make sure i am thinking of all the correct items needed.

Steve


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## 280z1975 (Oct 2, 2008)

Sorry for the delay, but here are pictures of my mower (as requested earlier)

It's a Gardena ... saw some other electric mowers at the garden center today, but they were all corded, not battery powered. One was very similar to this one where it can be used as a normal mower or with electrical assist.

Sadly this is my only "EV" ...


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## TX_Dj (Jul 25, 2008)

280z1975 said:


> Sadly this is my only "EV" ...


No need to be sad about that. It's been said that one lawn mowing with a standard ICE mower is about equivalent in pollutant output as driving 100 miles in a modern emissions-controlled mid-size sedan.

If that's the case, and if we figure I've used my cordless electric mower approximately once a week for approximately 30 weeks per year for 10 years, that means I've eliminated as much as 30,000 miles worth of emissions. Give or take.


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## 280z1975 (Oct 2, 2008)

I'm glad to know that my lawn mower is polluting much less ...

On a side note I calculated the fuel efficiency of my 2.0 diesel van yesterday (for use with a cycling touring business we have) and it was getting 13.3km/L (7.5L/100km ... strange thing is our "fuel efficient" small Ford Fiesta with 1.1L engine get's only 14.5km/L (6.9L/100km). Of course it's from 1991 and our van is new. I really thought the little, light car would be more efficient) And with the price differance between gas and diesel here it's cheaper to run the van! ... still neither is close to an EV and the Fiesta will be traded in for an EV scooter/moped in a couple of months once my wife switches jobs.

-Gregg-


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## dimitri (May 16, 2008)

I thought I'd post an update to this ancient thread.

Its been 2 seasons since I converted my push mower to electric, using 3 12V starter batteries from riding mowers. Clearly those batteries were not up for the task, sagging voltage, stalling motor, 15 minutes of runtime, etc. I had the mower parked for a while due to dead batteries, but always wanted to put LiFePo4 cells on it to give it a new life.

Recently we did a big landscaping project around the house and in the process we removed a lot of grass, so instead of paying the lawn service I decided to invest in a good battery for my electric mower and cut remaining lawn myself.

So, I got 12 TS40AH cells, grouped in 3 12V packs, replacing old lead acid batteries.

WHAT A DIFFERENCE!!!! The mower runs like a tank, I have to keep up with it. No stalling, no sag, it cuts thru tall grass easily, and I cut entire remaining lawn in one shot, without having to stop for a recharge, woohoo 

I know its pretty damn expensive investment to put LiFePo4 pack on a mower, but I figured it will pay for itself over the years since I will not pay for service or gas anymore and the battery will last like 100 years or so  running less than 50 cycles a year.

I used to have 60 amp fuse on the mower, but it blew when motor stalled in the tall grass, so I put 80 amp fuse on it now. When cutting thru heavy patch I measured 70 Amps at 36V, so 2.5kW or 3.3HP. This kind of load is rare, most of the time it runs around 30-40 amps, so the pack can run for an hour at around 1C load. It takes me 40 minutes to cut the lawn, so the pack is within good operating range and should outlast the mower or the house whichever comes first


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## Tinodesis (May 4, 2008)

Very cool, dimitri!

I have been thinking about a weed eater with a backpack for the batteries.


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## onesojourner (May 6, 2008)

what do you have for a controller on there. I am considering doing the same thing to mine.


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## dimitri (May 16, 2008)

onesojourner said:


> what do you have for a controller on there. I am considering doing the same thing to mine.


No need for controller, just a 100Amp continuous duty solenoid with 12V coil, feeding from the first 12V battery in the pack using the flip switch to power the coil. 80Amp fuse is series between the solenoid and the motor. That's all there is to it.


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## TX_Dj (Jul 25, 2008)

Yup exactly. I mean, the only benefit you'd really gain from having a controller on a mower like this is some form of current limitation rather than a fuse... but, the components are all rated within his 80A fuse, and he won't hit that limitation except in a dire situation. Flip the switch and mow. That's how mine works too.

I replaced my batts (3rd time since new) this season with a brand new pair from BatteriesPlus and took the blade into the shop and got it the sharpest it's been in the last handful of seasons; then I took it out and mowed the weeds that were getting up to a foot or so tall after the heavy rains this past spring. Never choked or bogged once, never left even so much as a blade standing in the swath. I think this season I should be able to get back to using it as a mulching mower again, rather than discharge-only.

I paid about double what a cheap ICE mower would cost me when I bought this new 12 years ago, and I've replaced the batts 3x each time for just under the cost of a cheap ICE mower. No oil, no gas, no maintenance (other than blade grinding and occasional batt swaps) and total cost of ownership (minus negligable power requirements during charging) and this puppy has cost me all of $60/year to own and operate. I'd pay about that much for one or two cuts from a lawn service.


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## Inkidu (May 7, 2010)

Nice conversion dimitri. 

My B&D cordless mower always seems underpowered.

It would be nice to do a conversion with some more power.

My mower never gave the best looking results but all the other 

benefits made it worth while i.e. low maintenance, low noise, instant on/off etc..

Just replaced my 30lb old batteries with 7lb 15Ah pouches LiFePO4. ($400)

Painful ($) but it will be quite some time before they will need replaced.

And the whole mower is easily pushed and I can easily pick the mower

up with no problem. (Can get it to my lower lawn with ease)

I would encourage anyone to do a conversion like dimitri 

Once you go electric you will wonder why you ever use those smelly, noisy,

and expensive gas burners.


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## onesojourner (May 6, 2008)

I am seriously considering converting my mower. I am sick and tired of messing with the ice. Every year I have problems. 

Right now the mower has 5hp motor on it. I usually run it at about half power. This is not a self propelled model. I am looking at roughly 1 hp motors. Does that sound about right?


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## onesojourner (May 6, 2008)

could you post up a wiring diagram?


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## Inkidu (May 7, 2010)

This is around the size motor that is on my black and decker.

http://www.3rivers.net/~cmac/motors/ast-3132-01.htm

Although mine always seemed a little underpowered but it is light.

Probably better cheaper solutions but at least it gives you an idea.

This one does have a shaft and mount that might work/fit well. 

Hope this helps and good luck.


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## TX_Dj (Jul 25, 2008)

Mine is a B&D mower as well, though the older version of what Inkidu showed.

Something rated around 1HP continuous would probably work, roughly following standard rules of thumb.

Mine will probably need new brushes in a season or two. Oh the horrors!


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## dimitri (May 16, 2008)

It depends on how tall the grass gets and how sharp the blade is, also whether you mulch or just discharge. Mine is mulching and when I cut tall grass it gets over its 2hp rating, so anything less than 2hp would stall.

That motor linked above seems as the minimum, IMHO. You might be able to overvolt it a little, but it will stress it more and it might get too hot, depending on how long you run it without cooling off.


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## TX_Dj (Jul 25, 2008)

Good point dimitri. The type of grass and how tall it is vs how short you want it is a big factor. 

One thing I've learned in ~12 years of cordless electric mowing is that you should never, and I mean NEVER, let the grass get too long between mowing.

If you have a light grass that doesn't take much effort to cut, you'll do OK with lower powered motors, but if you have a heavier, thicker grass (say, St. Augustine) AND you're mulching that, you'll need something with more guts.

The great thing about DIY conversions of any "vehicle" to electric... you get to build it to suit YOUR needs.


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## onesojourner (May 6, 2008)

I am still trying to find a good price on a used motor. If any of you have any ideas let me know.


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## onesojourner (May 6, 2008)

here are a few sites for examples:

http://www.appropedia.org/Solar_Charged_Lawnmower

http://www.builditsolar.com/Projects/Vehicles/LeeMower.htm

http://www.arttec.net/Solar_Mower/1_Remove_Motor/Engine.htm


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## TX_Dj (Jul 25, 2008)

I like the one in the second link, that setup is very similar to what's inside the B&D, though the B&D has an integral charger circuit. The B&D uses a simple switch to turn on/off the load, with a combination deadman handle and lever start (hold the handle in, push the lever forward, and it engages the switch, release the deadman handle and it releases the switch).

As Lee points out in his article, the analog meters aren't great on the mower, which is what I suspected. I have analog meters on my scooter, and the needles fluctuate wildly with every vibration and bump, but I still prefer to have them over not having them. 

The B&D has a simple SOC meter, mounted parallel to the deck, it varies very little due to vibration and bumps, but mounting gauges on angle, especially up on the handle could be problematic.

I encourage anyone to do such a project. After 12 years of cordless electric mowing you couldn't pay me to go back to gas. Even if you gave me the latest and greatest riding mower (completely unnecessary on my yard) I would convert it to electric before using it.


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## Inkidu (May 7, 2010)

Great links.

To share my own experience, I have had this mower for 13 years. There was

a recall on the mower and I sent it in to get serviced "free of charge"

I put it that way because even though I said "don't do anything that costs 

me money" they still replace the rubber back part of the deck and few other things.

I bitched and they gave me a "discount". Such is life. But this is the 

reason I went the route that I did i.e. replaced batteries with expensive ones.

The electronics were replaced and the few odds and ends so basically I have 

a new mower that will last for many years to come.

Side note.

There is a lot of beneficial ideas that could carrier over to potential 

ev buyers/diy with a battery powered mower.

1) You could have something that works just as well or in some ways better.

2) You have something that needs much less service.

3) Its potential cheaper.

4) Much less polluting.(noise especially for me) Sat morning mowers !!!

5) You can do this diy.

6) Could get consumers used to the idea of something battery powered.

6) Why pay the pump?

7) You could update and improve a mower or car with an outdated battery.

Hope this helps.

This might help also. I have never order from this company but they do

have free shipping within the USA for package app. (batt. and charger)

and this would be a clean setup with a warranty.

http://elitepowersolutions.com/products/product_info.php?cPath=26_31&products_id=81


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## TX_Dj (Jul 25, 2008)

Interesting. I thought your version of the mower came out years after mine, I've had mine since 97 or 98, about as long as you. The inside of the deck cover on yours looks identical to mine, but yours seems to use a different "handle control" than mine does. I'll have to snap some pics for comparison.


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## Inkidu (May 7, 2010)

TX_Dj said:


> Interesting. I thought your version of the mower came out years after mine, I've had mine since 97 or 98, about as long as you. The inside of the deck cover on yours looks identical to mine, but yours seems to use a different "handle control" than mine does. I'll have to snap some pics for comparison.


I'm fairly sure about the mower being 13 years old. My mower(cmm1000) fell 

into the range of the recall #'s. My understanding was that it was essentially 

updated to the cmm1200 mower. That update/recall replaced the "handle 

control". They replaced the whole handle. 

This could be something that is helpful though.(considering that easily 

useful/adaptable motors seem to be harder to find and expensive)

1) Find an old B&D mower that falls within the recall #'s

2) Take it to a certified repair center and tell them 3 or 4 times not to 

charge you any money. (granted if it needs something then replace it)

3) Use the updated/repaired mower and replace the probably dead

lead acid batteries with LiFePO4 batteries.

Result 

You have a mower that will last for many years. 

Another bit of advice.

Unlike ev or ebikes, you essentially know after the first few times that

the combination of motor and batteries work i.e. always essentially the 

same amount of grass to cut.

My hope is with the 15Ah pack ( replaces 17Ah lead acid) that if I 

charge after each time I mow I will never have a problem.(check 

at the beginning and end of every season with a multimeter for balance)

I set my meanwell charger (PB-360-24 no PFC) to a lower 28.0v (28/8=3.5)

http://www.meanwell.com/search/pb-360/default.htm

Hope this helps.


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## TX_Dj (Jul 25, 2008)

Hmm. recall. Interesting. Since they replaced the handle setup, I wonder if that was part of the recall. I have an issue with mine now where it seems to stick in the run position even after the deadman lever has been released AND the start lever returns to off position. I have to tug the cable housing to get it to shut off. That just started this season, haven't sorted it yet.


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## Inkidu (May 7, 2010)

Here is the link.

http://www.blackanddecker.com/CustomerCenter/recalls/Recall-CMM1000.aspx

As the one link mentions 75% electronic problems. (unneeded electronics??)

Hope this helps.


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## TX_Dj (Jul 25, 2008)

Interesting. Mine is CMM1000 Type 3. Well, it says something about electrical component overheating. It's been good to me so far; rather than do a recall process on it, I will just gut out the original stuff and retrofit with my own. I did consider upgrading it to 36v this season, maybe now I have an excuse to.


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## greif (Jun 26, 2010)

what's the cable that goes to the front wheel?


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## dimitri (May 16, 2008)

greif said:


> what's the cable that goes to the front wheel?


I assume this question was toward my mower? Its a feature that original gas mower had, not related to conversion. There is a lever on the handle connecting to the lock bar on the front wheel to lock it in straight position and prevent the mower from turning. I suppose it was meant to help you mow a straight line if you had a few beers before or during lawn mowing


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## onesojourner (May 6, 2008)

well after doing some research I gave up on converting my mower. I found a black and decker cmm1200 for 150 bucks. some old lady had it. She said she only used it 3 times and then bought a riding mower. 

If I were going to convert mine I would not get anything that spun less than 3000rpm. If any one finds a motor that can do that for a reasonable cost let us know.


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## TX_Dj (Jul 25, 2008)

Can't go wrong with the B&D if you find one at the right price. Can't say enough good things about mine, and with all this rain I've had lately, it will be getting a workout soon.


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