Powering 120V AC corded lawn mower with litium battery

AntronXAntronX Solar Expert Posts: 462 ✭✭
I decided to power my Task Force 18" 12A 120V AC Lawn Mower with 20 lithium-polymer 5Ah cells in series for total of 74 V DC. I have many old Li-Po battery packs left over from my RC hobbies that are getting weak to run at 120 A continuous.

To my surprise, the mower ran idle at only 1.2 Amps and averaged 2 Amps while cutting lawn with occasional peaks of 6 A. It ran at slower speed which made it even quieter than usual, and as my neighbor pointed out, quieter than quiet house air conditioner unit. I ran it for one hour straight and the mower consumed only 153 Watt/hours to cut 2500 square feet of lawn. The battery pack had another 1.5 hours left in it. I could have finished mowing in half the time if I worked faster, but I had too much fun not dragging the cord behind me. I also talked with a neighbor for 5 minutes while having the mower left on next to me. We could easily hear each other without having to raise voice.

Then later I discovered that the blade was dull. So I sharpened it with small file and put Corrosion X on filed off area to hopefully keep it from rusting. I now want to see if sharper blade will improve cutting speed.

So now I need to build lithium battery management system and find suitable charger. Also I need to build PWM motor controller for gradually reducing motor speed at preset battery voltage to control battery's depth of discharge.

Comments

  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Powering 120V AC corded lawn mower with litium battery

    now this is different and interesting too. i am confused though as to you running an ac motor with dc batteries or am i missing something here? update this thread when you follow through will any upgrades or changes to your project as i'm interested.

    btw, bring it up my way and cut my grass too.:p
  • AntronXAntronX Solar Expert Posts: 462 ✭✭
    Re: Powering 120V AC corded lawn mower with litium battery

    Few pics of the contraption:
  • AntronXAntronX Solar Expert Posts: 462 ✭✭
    Re: Powering 120V AC corded lawn mower with litium battery
    niel wrote: »
    ...as to you running an ac motor with dc batteries...

    The motor is brushed DC motor, that may be series wound if I am correct. This way, it can run on either polarity in the same direction. So it runs directly on 120V AC just fine. Many household appliances use brushed DC motors, like coffee grinders, blenders, edge trimmers, chain saws.
  • AntronXAntronX Solar Expert Posts: 462 ✭✭
    Re: Powering 120V AC corded lawn mower with litium battery
    niel wrote: »
    btw, bring it up my way and cut my grass too.:p

    You should make one too, it's too much fun :D
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Powering 120V AC corded lawn mower with litium battery

    i never realized they used dc motors in them. my yard is too steep for the mower and is a bit on the small side so i won't attempt the mower as i use a weed whacker. it would be nice to try the batteries on it, but they make rechargeable weed whackers already. they need to make them better quality so i don't have to buy another one every season or 2. gas models are quality, but i'll stick to electric.
  • CaptTurboCaptTurbo Solar Expert Posts: 66 ✭✭✭✭
    Re: Powering 120V AC corded lawn mower with litium battery

    I hope this thread continues for a long time. I'm very much interested in a cordless electric mower. I have been looking at lots of them (online) but most of them are too heavy because of the lead acid batteries.

    One stands out because it's lighter weight from using a plastic deck (the Neuton CE6) but it only has a 19" deck and is pricey at $499.00

    I'm determined to go electric but I'm waiting to find a mower that hs better overall ergonomics. Lately I have been mowing with my 20" Gilmour manual reel mower. Gives a great cut if you don't mind making more then one pass in areas. The manual reel mower is incredibly light and easy to push. I would like to someday experience a high end one. I just bought a cheap one to play with and I certainly feel like I have gotten my moneys worth after using it for two years. It is still serving me pretty well.

    As I said I hope this thread has legs because it sure has my interest. I'm producing more powr from solar then I need and I would love to use some of the juice to mow the lawn! .
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