Upgraded LiPo Lawnmower Now Has Plenty Of Juice

Back in 2010, [Dave] took a stand. He gave up his dependence on gasoline for his lawn mower, and bought a CubCadet CC500 48V lead acid powered electric lawnmower. Within two years, the batteries had already kicked the bucket. Unwilling to let go, he replaced half of the batteries, but that wasn’t enough. It now took him two charging cycles to mow his lawn once

Enough was enough. He had to replace the whole set — but this time, with LiPo.

As an avid lover of drones, he’s been using LiPo batteries for other things for quite a while. He did some calculations and figured he would only need about 10,000mAh at 48V for a 40 minute run time, which would still be a pretty pricey upgrade. So instead he started with 2 x 22.2V 5,200mAh packs instead ($200). As it turned out, that was more than enough.

The circuitry in the CubCadet was pretty straight forward, so it was almost a drop in replacement, minus the need to use a different charger. He added in a switch to flip between charging and mowing modes to allow him to use the LiPo charger without damaging anything.

Now all he needs to do is give it an Internet connection or maybe make it remote-controlled…

21 thoughts on “Upgraded LiPo Lawnmower Now Has Plenty Of Juice

  1. Lead acid batteries are fairly inefficient, so it’s not surprising that he gets away with less capacity.

    550 W translates to about 11 amps at 48 Volts – nominally – but several small PBA batteries in series can lose up to a a volt per amp of output, so when the motor is drawing 11 amps it would actually be averaging about 400 Watts and dropping down to 350 Watts when the battery is completely empty. You lose about 30% of the charge in use because of the high internal resistance.

    Furthermore, you aren’t supposed to use more than half the charge to keep a PBA battery healthy – that’s why it died in two years. The warranty is carefully calculated on the assumption that you will abuse the battery to death regardless of what it says in the small print in the user manual, so they don’t have to replace it.

      1. A push reel mower is the real win. Much less to go wrong than either gas or electric and even more environmentally friendly. Presumably, it could be made a reel mower with electric boost to power through tall grass, while still being way lower cost than electric only.

          1. I’m guessing you haven’t used one in a very long time, then. My Fiskers reel mower (http://amzn.com/B0045VL1OO) handles my yard quite well, even if I let it get a bit too long before going out. And my yard is the size of 55 king sized bedsheets… about a tenth of an acre, which I get done in about 45 minutes without too much sweat after edging and sweeping up.

            No gas, no oil, no noise, no charging, no cords, no sharpening blades.

        1. They work well on smooth lawns, but on the lumpy disaster that is my back yard, they do little other than slice the tops of the bumps and leave the grass in the hollows. This while requiring a back-breaking amount of pushing (pushing is fine over the few square metres of smooth lawn I have).

          It seems based on the comments here that the more affordable solution (possibly) would be to double the capacity of the PbA batteries and reduce the rate of discharge to a level where the batteries last longer. The problem would be getting twice the capacity in roughly the same space.

          1. Mine was really bumpy too. Look into “dressing” the lawn by raking in soil to the low spots. You can get bags of cheap top soil at the home center really cheap. If you spread it out over a few seasons, you can get really good results without killing off the turf in the low spots.

      2. Fossil fuels definitely don’t win when it comes to mowing an average lawn, especially since the mower has significant downtime to charge fully between weekly mowings. I am currently using a corded electric mower and it is so much faster to coil up an extension cord when I am done vs. having to get in the car, to drive to the gas station if I am out, or even maintain another ICE. My neighbors laugh at me when my extension cord gets stuck on a sprinkler, but then I get to laugh at them when they’re out there cussing about the pull-start not working. Al least I know mine will work every time. Then to going wireless with batteries solves any minor issues. It is much quieter, you’re not breathing exhaust, and having all of the other electric yard power tools makes plenty of sense too, especially blowers. I realize gas may still have it’s place for certain conditions or large properties, but the average Joe should go electric.

    1. So what sort of service life should one get with the new LiPo batteries? Also, how about a simple voltage converter from the AC mains? I’ve been using a plug-in mower for about the last 15 years though not everyone has outlets etc. to make that work.

  2. just got 5 years out of my lawnmower batteries. Well maybe 4 but I limped my way through last year doing half the lawn between charges. Just replaced with new sealed lead acid deep cycles. Just had to tear out the connections and make new terminal points for the new batteries. Cost 80 bucks to get it changed over and added 10ah of charge at the same time. woot!
    Don’t know if it’s cheaper than gas over the long run, but my wife can walk beside me and we can chat in a near normal voice while I’m mowing the lawn. I appreciate that. And I guess the warm fuzzies of no emissions are nice too… cept usually while i”m doing it the grill is fired up so maybe it’s really just a carbon offset.

    1. Any more information is appreciated. I am looking to make something like the story above, but remote control using a 24V Wheelchair rig. I have my eye on a cheap 24V mower sans battery and am thinking I should be able to power everything off of the same 24V power source. 60Ah sounds like the plan, please respond here with more info or PM me at https://hackaday.io/controlmypad

  3. Our troy-built 382cc has been consuming spark plugs faster than any other gas-engine equipment at home and especially during winter. The carbon build-up is really fast but the mower is still working great. What do you think is the problem? I haven’t had time bringing it to mechanic yet. The mower is 6 year old. Thank you

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.