Building a Li-ion battery out of cells from old MacBook Air laptops.
21 cells, three in parallel and 7 in series. This is to power my new used Worx Landroid WG795E, that had two bad lead acid batteries.
And I needed to get a new pair anyway. So I build that, using a 24volt 50A BMS.

[Affiliate Links]
Link – Cells from Li-ion macbook air :
Link – BMS 7S 24volt :
Link – Worx Landroid Robot LawnMower :
Even just 1$ a month, comes out to the same as Binge-watching all of my 500+ Videos every month.

My PlayHouse is a channel where i will show, what i am working on. I have this house, it is 168 Square Meters / 1808.3ftยฒ and it is full, of half-finished projects.

I love working with heating, insulation, Servers, computers, Datacenter, green power, alternative energy, solar, wind and more. It all costs, but I’m trying to get the most out of my money, and my time.



  1. Hi, how long is your mower mowing on the new and improved battery? How is the battery working after a few months? Thanks

  2. If it needs extra weight just stick a little tray or bowl for catnip on top. Cats from your neighbouhood will always volunteer then.
    Next put a webcam in the garden and publish the videos of the robot riding cats! :oD

  3. Nice green project!
    Hope that the original lawn mower charger lives up to its task, i think li-ion needs a different kind of charger, but then I could be wrong.

  4. Isn't chargers for CAD batteries different than Li-ion batteries? I want to change the batteries to li- ions in my compact drill but I thought I would need a different charger so I didn't do it.

  5. Very cool Morten, looking forward to the next video with the robot ๐Ÿ™‚

  6. Morten, you could glue sandpaper on the ramps of the charging station to give the wheels more grip. Thank you for making these videos!

  7. Im worried about having Li ion batteries in my house while i sleep.
    I could never leave them in the house for the weeks without me being there.

  8. I really love these videos that use solar/renewable power for things.
    You should really do more on them!

  9. 15:53 to swell, or to bloat is what the battery did โ€ฆto swallow happens when you drink water ๐Ÿ˜‰

  10. I think you might have two big problems. First the charger built into the mower dock will be set for lead acid voltages and will be way off when charging your pack. Next problem will be the mower voltage settings again will be set for lead-acid, This will mean the mower will think the battery is flat when its really not and will keep going back to charge itself. I wouldn't think there would be any options to change these settings on the mower solftware. This will be a big problem. So i would do two things. Take out the charger in the dock and replace it with a 10amp CC/CV boost converter set to 29.4volts, Using the exciting connections in the dock to make this easy. The mower should read the voltage and think its charging so that part is simple. However on the mower to stop it thinking the battery is always flat and going off to charge and not being able to change software settings for this the workaround will be to add another cell eg Change it from 7s3p to 8s3p. You can use a 10s bms for this as it will also work with 8s. The 8s3p will be a higher voltage and wont be too high that the mower wont run but will be high enough that the mower will think its got lots of charge. The only other way you could get around it is by using a 20amp boostconverter with a "lowvoltage cutoff" (very important) on your 7s pack. The 1500w boost convter models from ali will do this as they have the cutoff. This will mean you can set your battery voltage to a range the mower likes so the mower will keep running and when the boostconverter voltage drops on the battery it cuts off. However the only problem with using the boost converter idea as a workaround is that it will cut off and not have any warning to the mower so it wont be able to find its way home to the dock for charging but you could have two boost converters set at two different voltages one for the mowers working voltage and the secound set at the low voltage so when the first boost kicks off and the batt voltage drops to the limit and the secound one takes over the lower set voltage will make the mower turn around and go back to dock for charging. In some ways that might be easyer and be better then the 8s idea as it lets you use the complete battery charge by using the boost converter idea. The boost coverter is very efficient that shouldn't cause any problems.

  11. The red wires you used to parellel each pack together look far too small. The mower will draw more than 10amps at times. It will be great to know how many amps the mower draws when running but given its age it will be high.

  12. 27:28 that soundproof foam is not cheap. I just brought some off them for the server cabinets. 16 cost me around ยฃ22.

  13. What's the brand and specifications of the windmill? I like your approach to green power ๐Ÿ™‚ Are you going for a 100% off grid solution for your playhouse?

  14. Make it an extra ramp to the charging point but it cracked me up

  15. I believe those cells have aluminium tabs; I pulled some cells out of a chromebook, and if my memory serves me, to solder to them I had to resort to scraping off the oxide layer while wetted with phosphoric acid. I like the look of your 'damned mess', the more stuctural tape the better. And you could use the spare capacity and give the mower its own live streaming camera.

  16. Congratulations, now you have a fire hazard parked right next to your house, hope your insurance covers "made some batteries from scrap garbage".

    btw you counted capacity wrong

  17. Did you do a discharge capacity test on those lithium cells.
    I'm worried because Apple users are exactly the type of people to throw away a entire laptop just because the batteries are sagging.

  18. You should check the voltage on the power brick for the lawn mover, you could bypass it if it produces 12v

  19. Those MacBook batteries are lithium polymer not lithium ion right? Over discharge protection is a must.

  20. Excellent video…
    Also have some issues with my laptop it does not find the hard disk…
    Any suggestions would be appreciated….
    Is HP model with i5 procesor and abot 2-3 years old…
    Should I buy new hard drive or the whole laptop it was good for what I use it.?..

  21. Hi Morten ,
    That was a great video as usual:D but Iโ€™m a little bit worried about your batteries Maybe you should keep an eye on them because Iโ€™m pretty sure at least one of them will die in a short term ๐Ÿ™ I have done some testing on those batteries and they donโ€™t like at all to be discharge at more than an amp they became rather hot and by so dangerous I will suggest you to rather use some high drainage cells in your robot that will be more safe than those MacBook batteries :). Keep up the good vids and see you later ๐Ÿ˜€

  22. Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

  23. This says all what you think your time is worth.. My time for sure is more worth then 500kr per hour.

  24. I wonder if you could mount a solar panel on the robot itself? Could keep itself charged while it mowing.

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