running battery powered tools using mains dc adapter

[Matty]

I'm not sure which section to put this thread but here goes. In the new workshop I'm building I will be using quite a lot of battery power tools. The mitre saw and table saw in particular will have quite permanent homes but will go on site with me too.

My question is is there a dummy battery available for Milwaukee M18 tools that has a 18v dc psu that I can plug into mains when they are on the bench?

 

[Myfordman]

Only a very beefy PSU and heavy duty leads will be able to run battery tools even if you could get an adaptor. You would almost certainly need a battery mounted close to the tool to give the low impedance source to start the tools and backed up with a charger.

 

[Nic Rhodes]

I don't know about Milwaukee M18 but I have this for my Festool sanders so is possible.

 

[Myfordman]

Interesting! Is that a standard festool offering of something you’ve put together yourself?

 

[Myfordman]

Just found my own answer. This is only available for festool sanders hinting at the difficulty of providing this functionality for all types of tool
The load of a sander is relatively benign compared to routers saws etc

 

[Doug71]

I'm think DeWalt do a mains adapter for their flex volt saws etc, always wondered why other manufacturer's don't do the same.

 

[TheUnicorn]

I'm think DeWalt do a mains adapter for their flex volt saws etc, always wondered why other manufacturer's don't do the same.

the sceptic in me thinks that adaptors would reduce the income from battery sales

 

[Sideways]

Consider that many routers are about 1kW and the latest brushless battery tools are capable of matching corded performance of nearly 2kW tools
Simply divide power by 18V and you could be wanting 50 to 100 Amps !

The Mirka Ceros sander is essentially a 20V brushless tool with about 350W (?) power.
It uses an external power supply brick to make 20V DC supply.
That's a big and expensive brick and it's nowhere near big enough for many powertools.

It would be a nice idea but it's a non starter, even for no other reason than the thickness of the power cable to carry those currents.

 

[Matty]

yeah I did think a of making a home made one but the psu would end up being really expensive so might as well buy a few more batteries

 

[Dabop]

I have a homemade one using a Meanwell PSU (the 24v ones can be 'turned down' to 20v with the trimpot next to the power LED)- but...
Yeah you need a pretty grunty one, depending on the tool, your PSU has to be able to handle the stall current of the motor- I use a 30A one I picked up for just over a hundred bucks Aussie about five years ago, runs my drills and circular saw as good as the batteries do (you do need a reasonably thick cable to not get voltage drop, I used 15A mains powercord from an old caravan extension cable) and an old DOA battery pack to use as the 'fake battery'- although you could easily get one of the 'battery pack adapters' found on ebay and the like (lets you use battery packs from different manufacturers) and use that as the basis of the 'battery plug'
I don't know why they don't make them, the battery powered machines are just as capable (if not more so) than many mains powered ones, and it is nice if you are working on the workshop to not have to be swapping out batteries all the time...

 

[Superduner]

There is a channel on YouTube called "The Post Apocalyptic Inventor". It's a German guy who fixes and renovates tools that he finds in scrapyards. One of his favourite fixes is doing exactly what you want to do.
You will be able to source the parts that he uses, or maybe even contact him to find out more details.

 

[Cooper]

There is a channel on YouTube called "The Post Apocalyptic Inventor". It's a German guy who fixes and renovates tools that he finds in scrapyards. One of his favourite fixes is doing exactly what you want to do.
You will be able to source the parts that he uses, or maybe even contact him to find out more details.

Thank you for recommending The Post Apocalyptic Inventor. I've just enjoyed watching a couple of clips. I wish I had his electronic knowledge. I'm always distressed when I see electronic equipment chucked away when its probably only a small element that has failed.

 

[Superduner]

IF I'm remembering correctly, the videos showing the use of an external power supply for cordless drills are the earlier ones.

 

[Spectric]

Consider that many routers are about 1kW and the latest brushless battery tools are capable of matching corded performance of nearly 2kW tools
Simply divide power by 18V and you could be wanting 50 to 100 Amps !

Not an issue when we had 12 volt tools as you could run them of a car battery, I had a nice AEG that had a duff battery that was not worth replacing so some wire and croc clips and a battery and away we went, still technically cordless. We seemed to have skipped 24 volt tools because they use two 18 volt batteries to deliver 36 volts.

 

[Sideways]

40 or 50 years ago when cordless was in it's infancy, Black and Decker marketed a battery powered drill that looked just like their corded stuff but had a six foot power cable that went into a remote lead acid battery pack with a shoulder strap.
I've never been able to find a photo on the web for that black and decker - it was waaay before the internet - but here's a press release from Bosch showing they also made a drill like that around the same time.
https://www.bosch-presse.de/presspo...ry-expertise-at-bosch-power-tools-200448.html

Lead acid batteries don't last long when you repeatedly run them down, but a luggable 18v power supply made from three 6V motorcycle batteries would work and say a 3 metre lead to a dummy battery to plug in the tool. Lead acid batteries will deliver the current needed.

 

[Bob008]

I'm think DeWalt do a mains adapter for their flex volt saws etc, always wondered why other manufacturer's don't do the same.

The dewalt 54v saws suffered big problems when using there own power adapter its a common problem