# ICE push mower conversion



## PStechPaul (May 1, 2012)

You might do well with a treadmill motor which is usually 90 VDC and about 2 HP, which should be enough for push mower with 18" deck (it would probably be plenty for a 22" deck). Here is a 2.5 HP 6750 RPM 130 VDC motor that should work OK at a lower voltage such as 60-72 volts at about 3000 RPM which is about right for a mower. 

http://www.ebay.com/itm/270654887583

You could use six 12V 12Ah SLAs which would cost about $140 and would give 864 Wh or enough for 1/2 hour or even 1 hour of light mowing. Weight is about 72 pounds so not really ideal for steep hills. Here is a good source:

http://www.ebay.com/itm/UPG-6-Pack-WKA12-12F2-Genuine-12-volt-12ah-Battery-Electronics-/120948284954

You might not even need a variable speed motor controller, but those are available for less than $50.

http://www.ebay.com/itm/PWM-DC-20V-...Adjuster-Controller-24V-36V-48V-/181004140412

You can use LiFePO4 but you would need smaller cells than most EVs, and you will need a BMS and special charger. Cost for a 1kWh pack would be at least $500 to $800. I'm looking into some cheap cylindrical cells of Li-Ion and even NiMH which may be as low as $200-$300, but the SLAs may be safer and appropriate for a lawnmower.


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## Drinkholder (Jan 19, 2013)

Thanks PStechPaul! Great info 

How do you think that style of motor would run at 48 volts?

The SLAs would be preferable but like you say weight may be an issue on hilly terrain with 6 on board. If I could keep it down to 4 SLAs that would be great.


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## PStechPaul (May 1, 2012)

I think PM DC motors run at half speed with half the voltage, but they also may be limited to lower torque, which might give you only 1/4 power. A 90V treadmill motor will probably be OK at 48V but the 130V motor advertised might not give you enough power (and the speed may also be a problem). I think lawnmowers run at about 3600 RPM so you want to match that fairly closely to get the best results. So maybe 60 volts would be best, where the 6750 RPM 130V motor should run at about 3115 RPM.

Otherwise you will need to search for lower voltage motors. You can use a 12V or 24V motor with 48V battery pack with a controller. But for 1 HP (about right for a small mower) you will need 62 amps at 12V and 31 amps at 24V.

I found a few that might work:
http://www.ebay.com/itm/Ohio-Motor-...c-Motor-C-481512X7595A-INV-8575-/400363788323
http://www.ebay.com/itm/24-Volt-DC-Drive-Motor-ev-/281052606989

Electric scooter, golf cart, and wheelchair motors might be a good option:
http://www.ebay.com/itm/Unite-1000W48V-DC-Electric-Motor-MY1020-with-Mounting-Bracket-/300829169954
http://www.ebay.com/itm/EZ-GO-Golf-Cart-part-36-volt-Electric-Motor-USED-/330861490960
http://www.ebay.com/itm/EZ-GO-Golf-...r-EZ-GO-Textron-by-GE-2-HP-USED-/230910006932

It might be possible to use an AC motor along with a power inverter. I have found some that work on 24V:
http://www.ebay.com/itm/170949382136

It is not really designed for motors, so you may need to use a much larger one. However, I was able to modify a similar unit to bring out the internal 270 VDC which is enough for a 3 phase VFD. It may seem crazy, but I would actually suggest something like this, with a small VFD, and a 1 HP 3 phase motor, and the parts cost (except batteries) will be less than $200.

Good luck!


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## rochesterricer (Jan 5, 2011)

Don't they sell motor kits for mower conversions on ebay? I thought I remembered reading about that when I created a similar thread months ago.


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## PStechPaul (May 1, 2012)

You can buy a battery powered electric mower for $150, new:
http://www.ebay.com/itm/CLEARANCE-S...geable-LawnMower-Electric-Mower-/251133573253

You might consider a corded version, which you can often get cheap or even free:
http://www.ebay.com/itm/vintage-electric-lawn-mower-/181065855466

I'm not sure what type of motor they have. It may even be a universal type, as found in electric tools, which will run on AC or DC. You'd have to use enough batteries to get 100VDC or so, or you might even look at rewinding the motor for lower voltage.

I still like the idea of an AC induction motor, even a single phase. You can buy them for cheap, or even get them free from an HVAC service company's dumpster, where I got several large (1/4-3/4 HP) fan motors that I rewound. They also needed the bearings cleaned and lubed, since bearing failure is common in such usage. I have used a 2000 watt Harbor Freight inverter to run a 1/2 HP sump pump from a single 12V battery, so that is a possible option.


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## rochesterricer (Jan 5, 2011)

People have had success converting corded mowers using packs of less than 100 volts. You can see examples in my thread:

http://www.diyelectriccar.com/forums/showthread.php?t=71432


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## PStechPaul (May 1, 2012)

Good information in your thread from last March. I think that's about when I joined. If you dare to trust the "Ultra-Fire" Li-Ion cells from Hong Kong, you can get 30 of them for $60 including $2 shipping, and if they are true to spec you will have 111 VDC at 4.5 Ah which should handle a corded mower which I think draw about 5-6 amps at 120V for about 3/4 HP.

http://www.ebay.com/itm/lot-of-1865...-Rechargeable-battery-UltraFire-/180973630103

Of course, you should have a BMS and various means of protection for these cells since they may live up to their name. I hope to have my cell BMS system prototype working soon, but it will cost about $3/cell even as a DIY project. But that's not bad for $90 since it will keep the cells balanced and you should be able to use a simple charger with about 140 VDC from rectified line voltage and a 50 ohm 100W resistor which should charge the cells at about 1 amp when they are low (3V/cell = 90V), and it will taper down to 280 mA at end of charge (4.2V/cell = 126V). Should charge the pack overnight.


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## Drinkholder (Jan 19, 2013)

Thanks for all the helpful info and links, great stuff.


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## Drinkholder (Jan 19, 2013)

I will post some pictures once I have the mower up and running


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