Powering 19v DC motor.

[John Morton]

I built a lightweight lawn mower to make it easier for me to continue mowing at 84 years. I don't have a multimeter but the motor came from a hand-held cleaner so I expect it to be around 19/24v. I can't find a power unit online, anywhere. Sellers use 'power cord' 'adapter' and 'charger' to mean the same thing which doesn't help. I have a 12v power unit @ a mere 800mw but, as expected, the drag from the grass stalls the motor. Options are, of course, to use a step down transformer but this would be a bit cumbersome. Or, I could buy a 19v rechargeable battery. Any suggestions?

 

[Andy™]

motor is probably too small so no matter what voltage / power you put it, its not going to work. bit like putting a chainsaw engine into your car and being surprised it won't do 60mph

 

[Geoff1946]

I assume the cleaner which donated the motor gave you the 19volts rating(?) Did it state a wattage?

BTW. Aldi were recently selling some long handled grass clippers which use their 12volt tool battery .
The actual tool was only about £15 I think, but battery and charger cost rather more.

OR could this help ? https://www.amazon.co.uk/Cordless-S...373637919-B0D4J2XWLW-&hvexpln=74&gad_source=1

 

[Phoenix]

Most laptop chargers are about that, most would probably be underpowered, but one from a gaming end laptop might be alright - Technology moves on at such a pace and laptops are limited in terms of upgradability, so you might be able to find one at a tip possibly?

The other idea, is if you can find an old beefy wirewound transformer from halogen downlights from when they first became poopular 30 ish years ago, then if added an appropiatly rated bridge rectifier and some smoothing capacitors then that would end up right ballpark ish, calculates at 17v dc from 12v ac, however its likely to be a bit more if most of the time you are not loading it to max, just remember to fuse it appropriatly, otherwise with a stalled motor it would probably start cooking it and the cable. You could use a a polyfuse https://www.ebay.co.uk/itm/144872358890 rather than one that actually blows, just remember when they are latched into the fault condition, they do run warm so they need to be mounted in free air away from other stuff

 

[Richard-the-Ninth]

John Morton, you can buy a 19.5v power supply for £19 Click me, but I have to agree with Andy, that the motor will have hardly any torque, but will make a good fan.
I too have found an electric grass trimmer Click me (This will be cheaper than buying all the parts to make one.)

 

[John Morton]

John Morton, you can buy a 19.5v power supply for £19 Click me, but I have to agree with Andy, that the motor will have hardly any torque, but will make a good fan.
I too have found an electric grass trimmer Click me (This will be cheaper than buying all the parts to make one.)

That looks like a charger, Richard, thanks. The one I bought wouldn't turn the motor, possibly because they deliver in a trickle? After Googling for a week, on and off, I failed to source a 19v power unit. Looks like they don't exist. I set out to make it with stuff I already have, apart from the plastic sieve (riddle). I don't expect to be able to push the device or thrust it straight into thick grass but with careful handling I expect it to be worthwhile, despite its limitations. I'm currently searching for a cordless power drill, spares or repair, with working battery and charger.

 

[binky]

I'm currently searching for a cordless power drill, spares or repair, with working battery and charger.

Have a look at Ryobi, or Lidl / Aldi

 

[Richard-the-Ninth]

I'm currently searching for a cordless power drill, spares or repair, with working battery and charger.

Good luck with that one. If the battery and charger are still working and the tool failed (Drill, grinder, saw etc) will they not just buy a new bare* tool ?

I just looked on ebay there are lots of cheap (£30) NEW battery drills (and charger etc) But that is it, they are all cheap, which means quality is............

I admire what you are trying to do, but I believe it will cost you more in the long run than to buy an extending / long reach grass cutter, but good luck, and please keep us posted.

*bare means you can buy just the tool, no battery or charger Click me for examples.

 

[John Morton]

Have a look at Ryobi, or Lidl / Aldi

Aldi have recently discontinued their machine.

Good luck with that one. If the battery and charger are still working and the tool failed (Drill, grinder, saw etc) will they not just buy a new bare* tool ?

I just looked on ebay there are lots of cheap (£30) NEW battery drills (and charger etc) But that is it, they are all cheap, which means quality is............

I admire what you are trying to do, but I believe it will cost you more in the long run than to buy an extending / long reach grass cutter, but good luck, and please keep us posted.

*bare means you can buy just the tool, no battery or charger Click me for examples.

The problem is that the existing cutters resemble strimmers and it's difficult to maintain an even cut. I watched my neighbour using one and I wasn't impressed. My 'gadget' operates like a hover mower. I have given the blades an angle of incidence like a propeller.

 

[binky]

Aldi have recently discontinued their machine.

The problem is that the existing cutters resemble strimmers and it's difficult to maintain an even cut. I watched my neighbour using one and I wasn't impressed. My 'gadget' operates like a hover mower. I have given the blades an angle of incidence like a propeller.

I was thinking more about cheap drills and batteries you could cannablise.

Maintaining an even cut with a stirmmer is almost impossible - Ive tried that

 

[John Morton]

This is a courtesy post since people kindly offered advice and I was asked to provide updates. The mowing season now over, the urgency has gone for a while. Also, I'm reluctant to buy a perfectly good cordless drill and butcher it to make something that is predicted not to work. I'm also dubious about cordless batteries, their life expectancy and the need to charge them. Sometimes it's necessary to dash out and do the lawns at short notice so I'm thinking of a step up or step down transformer, since 18/24v power units appear not to exist. Thanks all and speak later.