Has anyone ran 20V cordless tools at 24V?

[CONSIDERABLE SHOUTING]

I've got some random orphaned 20V tools and battery packs meant to run 24V that I could power them with- I feel like it should be just fine, but I wanted to see if someone has done this before.

 

[amberwolf]

If the tools have no electronics in them, just brushed motors, you can run them at whatever voltage you like, up to the point the mechanical stuff breaks. 20v to 24v is about 20% increase in speed, so probably ok for most things.

Really high voltage increases could break stuff:

Brushed motors have commutators that can disintegrate (grenade) from overspeed, but it takes a fair bit over normal speeds to do this. Some are marked with an RPM limit, many are not.

Gearing (in drills, etc) may be plastic and not handle really high speeds, or the torque increase that happens from all this. (I broke the clutch in a Ryobi hand drill even though the voltage wasn't really much higher, but it allowed enough higher torque it couldn't take it).

Grinders / disc cutters might spin the media too fast and cause them to explode; circular saws too.

But as long as the voltage increase is minimal, and no electronics are involved, it's unlikely to cause failures.


If there are electronics, such as speed controllers or brushless motor controllers, then those have to be able to handle the higher voltage *and* the turn on/off spikes that happen from the motors, and/or their sometimes wildly changing speeds under load during use. Some of these just can't take it.

 

[Bgt2u]

I agree with amberwolf. 20v upped to 24v is only a 2% increase, which is minor over volting. Just make sure to stop using the tool, if it starts to get abnormally hot, let it cool down, and you will be fine.

 

[amberwolf]

20v upped to 24v is only a 2% increase,

I'm terrible at math, but I'm pretty sure it's 20%.

It's still significant overvolting, but for brushed motors it's normally tolerable, depending on design and conditions.

2% would only be 20.4v.

 

[Bgt2u]

I'm terrible at math, but I'm pretty sure it's 20%.

It's still significant overvolting, but for brushed motors it's normally tolerable, depending on design and conditions.

2% would only be 20.4v.

Wow, l am so sorry, you are correct, my mistake (l took calculus in high school, but have now switched to calculator....,lol). No seriously, that was just a dumb mistake on my part. Other than that, l stand by my original reply.

 

[scianiac]

Depending how new the tools are they may or may not have electronics (brushless tools will of course), and even then they may still take that amount of over voltage. Tools like circular saws normally just have a switch as they have no speed control, drills and such have speed control and that is electronic in newer tools. Also you have to remember the voltages written on the side of both mean very little, they are just rounded values from the pack voltage and sometimes pretty far off. You can guess those based on the chemistry of the original batteries for each tool.

 

[CONSIDERABLE SHOUTING]

If the tools have no electronics in them, just brushed motors, you can run them at whatever voltage you like, up to the point the mechanical stuff breaks. 20v to 24v is about 20% increase in speed, so probably ok for most things.

Really high voltage increases could break stuff:

Brushed motors have commutators that can disintegrate (grenade) from overspeed, but it takes a fair bit over normal speeds to do this. Some are marked with an RPM limit, many are not.

Gearing (in drills, etc) may be plastic and not handle really high speeds, or the torque increase that happens from all this. (I broke the clutch in a Ryobi hand drill even though the voltage wasn't really much higher, but it allowed enough higher torque it couldn't take it).

Grinders / disc cutters might spin the media too fast and cause them to explode; circular saws too.

But as long as the voltage increase is minimal, and no electronics are involved, it's unlikely to cause failures.


If there are electronics, such as speed controllers or brushless motor controllers, then those have to be able to handle the higher voltage *and* the turn on/off spikes that happen from the motors, and/or their sometimes wildly changing speeds under load during use. Some of these just can't take it.

Hm, so a lot of "it could possibly" without getting to the brushless techs. Also worth it to say, that common 5S batteries that this would replace rarely even sit at 20v, though most chargers rarely get those cells above 4.1v.
I'll do some testing first. The nicest tool I have is a hedge trimmer from Worx that had it's battery stolen- that one could possibly not appreciate the over-volting. The small chainsaw is brushed so it'll "just" run faster but like you said, it might not be able to handle it. Perhaps there's a way I can lower the voltage just for the tools- I have a 24v motor and could use 24v inverters, so keeping it at that voltage would be preferable.

 

[iventilation]

I think the other parts are not designed for such voltages and in the long run it can affect the service life! idk, what you think? Its 20 % more

 

[eee291]

Worth a watch

 

[CONSIDERABLE SHOUTING]

Worth a watch

SHHHSHHHHH dont tell them who inspired me! I wanted it to be a secret

 

[spinningmagnets]

Most older cordless tools are brushed simply because it's cheaper to build them that way.

The "20V" labeled tools are 5S, so we would call them "18V" nominal, its just marketing.

I suspect they will work just fine at 24V.

 

[docw009]

I burned up a Black & Decker 18V drill running it on a 36V bike battery, thru a long cord, I had hoped that since it was a rushed motior with a rheostat trigger, I could feather the power to the motor, but it overheated,

 

[amberwolf]

Probably from the commutator/brush arcing, which is a lot worse at double the design voltage.

(and if it overspeeds it can even grenade the commutator segments, which typically lockup the motor as the pieces jam it from rotating, if they are kept contained inside the motor shell).