Running garden tools on 40-60V DC instead of 120VAC?

If there is permanent magnet inside, then yes for wearing.

I would get an AC inverter. 48V DC to 120V AC can charge an EV as well.

tirsdag den 25. maj 2021 kl. 01.02.09 UTC+2 skrev Joerg:

bite the bullet and buy a battery trimmer that runs on the same type of battery as your other tools

or something like this,

There are 2 problems with that. The motor needs to spin fast enough so the fan in it cools it off. The other that may or may not be a factor is that brushes are selected for a current density. That is the ammount of current determins the size of the brushes and too little is almost as bad as too much current as to the wear of the brushes.

Also, DC tends to create spark and heat. That's why Edison beat Tesla (the guy, not the car).

Well, i need 6 of them running in parallel, and with external electron tanks. So, it's easier to build from scratch.

It probably doesn't matter a damn in the end. If you really want to play it safe with what's likely a disposable tool anyways, reverse the polarity every battery charge so you get even brush wear. Just don't go too slow, or you'll overheat the motor- too much current, not enough cooling from whatever tiny fan is in there. Like with any appliance, there's not a single part in there that's overdesigned or built to do more than just get the job done.

All that nonsense sound far more complex than a f****ng extension cord, but hey, have fun. You're in the electrocution danger zone at 40-60 volts too. You won't be letting go of a DC tool running off some weird battery pack wrapped around your leg and arm.

You're going to spend as much time and money trying to make a battery... a commodity product that you can buy COTS mated to a specific trimmer.

Personally, I prefer long cords as they can meet many needs and eliminate the need for batteries (that fail and might not have sufficient charge for the work you've set out to do, TODAY!) as well as keeping fuel on hand (for gas powered devices).

Battery powered power-washer? Jackhammer? Air compressor?

It's the other way round, I think you'll find - Tesla's AC beat Edison's DC.

If you go much higher in voltage using DC on equipment designed for AC, then the on/off switch may arc for quite a while each time you turn it off, especially with an inductive field coil in series, and even more so at higher currents, like if you stall the motor and really want to turn it off. Same applies to fuses, if it has any. Perhaps 53V is still ok. Otherwise, a device that makes the current go to zero periodically (like an inverter) might help to extinguish any arc.

Oh, yes. Of course.

It's several tools and that would cost a bundle. My other battery tools are 21V Li-Ion and that's too weak for serious yard work. 2-3 of that in series, other story, then it works. I want to avoid having to nurse yet anoter battery system.

That would require also buying a big 12V battery and soon you are out north of $400 just for getting rid of extension cords. Nah.

I'll have to make those batteries anyhow for ham radio activities (SOTA or summits on the air). Got an old iWorx weed trimmer that has shot 18V NiCd batteries. I want to rework those into 16V (4S) Li-Ion, taking a slight power hit, and with a very small linear post regulator also use them for portable radio gear in the field. Now if I could use three of these in series to drive my other 120VAC garden tools that would be sweet. I've tried and it works, just not sure if that's ok for the motors longterm.

You probably don't have a property with steep rocky slopes and lots of prickly agave plants that latch on to extension cords like shark teeth.

And then it won't start, carburetor gunked up because of the #%^&@!! California gas. Plus if those run, you are breathing in 2-cycle exhaust for hours which can't be healthy. That's what I definitely don't want anymore.

Except for the jackhammer they make those. Too wimpy for me though.

Yes, good point. Though it does spin almost as fast as with 120VAC, just doesn't have as much power and bogs down easier, so I have to avoid larger branches.

I have a lot of 230VAC hand tools I brought over from Europe and I've used them extensively on 120VAC for decades now. Hammer drill, angle grinder, jig saw and such. No problems. The motors actually become less hot than they did on 230VAC plus they don't scream as much.

I just don't know whether DC would also be ok over the long run.

The peak current is 2A on 53VDC and 4A on 120VAC. If too little current causes issues that would be a problem but the current fluctuates anyhow all the time depending on what is being trimmed. Cutting ground cover barely raises the current, big sappy bushes do.

Edison failed to make cars and didn't have Bitcoin :-)

Now that is a good idea!

I've used 230VAC tools on 120VAC for decades, never any problems.

I'd carry them in a backpack but all well insulated and safe. I also never do such works when it's wet outside. Yes, making those packs and the chargers is a lot of work but I have to do that anyhow for portable ham radio purposes. The only extra work would be connecting three of them in series. And ok, I'd have to add in a reverse polarity Schottky diode each but that's easy.

Good point. Might have to add in a TVS across the motor connection.

But if you do that, label it and change the mains connector to something else, in case someone plugs it into a wall socket!

I've seen pictures of some electric cars from >100 years ago, with Edison NiFe batteries in them. IIRC some were still working, as those batteries are quite robust.

Or just leave it alone. It sounds like this guy can fix a switch if he has to.

Just use a large enough TVS so it's ok on 120VAC. The switch must be rated to take sparks in the 200-300V range. On DC it'll arc a bit longer but I am not one of those guys who is constantly clicking the trigger. Like the guy in a neighbor yard yesterday who constantly revved his gas chain saw. Its clucth can't last long that way.