Convert cheap battery drills to mains elec (UK)

[quintain]

I have 2-3 cheapo battery drills where the battery is dead,
I wish to convert them to UK corded use for bench use purposes I.E, screwdriver, small dia' drilling and such.
Has any one successfully done this at low cost and if so how.
BTW I am aware that YouTube have examples but I prefer to rely on sensible advice.

 

[dzj]

I heard people use a PC power supply, but haven't tried it myself.
Something that'll give you 12 or 18V and a lot of Amps in any case.

 

[Fitzroy]

I’ve just built myself a hot wire cutter which demands low volts and c. 5 amps. The easiest way to get this turned out to be batteries. I did eventually wrangle something together from an old transformer but the trouble was getting the amps. There was an old dc power supply on gumtree near me but it’s max amps was 2.

Looking at the tech specs for some of these tools they pull 200-300watts which at 18v is 10-15amps. I think it’ll be tricky to build/buy something that’ll supply that sort of current draw cheaply.

 

[clogs]

I used a battery off my truck in an emergency....18v Hitachi.....got the job finished then just binned it/them and bought the latest model.....actually gave the combi drill set away to somebody with decent batteries...
why BOTHER....plenty of cheap mains corded drill's about....
even Lidil, Aldi do such stuff....

 

[quintain]

Thanks to every one so far.
Clogs: I don't like just throwing things away---pls send some sunshine to NW Cumbria UK
DZJ: I do have a couple of v old desktop computers I will think about your idea BUT I am concerned about dust-proofing the PC power source

 

[Sandyn]

What voltage are the units? 12V is a lot easier than 18V. A good 18V drill may require possibly 300-500W peak power, around 20A-30A. If your drill is that kind of power and you want full capability, you will need a suitably powerful PSU. They are available, at 12V. A computer PSU's and Amazon have some examples of 12V 30A supplies so it's just a case of a bit of engineering. Some battery chargers can be used, as a 12V supply. Others need 12V present to enable them.
I think it would be a lot of messing around when drills are so cheap now, but if it's a interesting challenge to you, it is possible. I haven't looked at any of the youtube videos, so not sure what techniques they use.

There are many options. First thing is to establish what voltage and current you really need. You can reduce the current to the drill, but the torque will reduce, just as it does when the battery goes flat. A quick check..... You can get laptop supplies, which are 19V/7.5A. That would power a 18V drill. You will find a suitable supply if you search, but you need to know what you are looking for.

If you just plan to use the drills for small scale stuff, there are lots of I.T. power modules available at 12V and 18V(19V), just try to find the highest rating for what you are willing to pay. You may have some suitable module already?

 

[Vann]

I had contemplated using a car battery to power my 12v drill - but never got around to it. Could even go so far as to run a 12v circuit near the bench with several sockets...

My tuppence worth.

Cheers, Vann.

 

[Superduner]

I know you said that you had looked at YouTube, but take a look at "The Post Apocalyptic inventor". He's a German guy who rescues stuff from scrapyards and gets it into working condition.
Converting battery tools to mains is one of his "things". He certainly seems to know what he is talking about, and explains everything really well.

 

[xy mosian]

I killed a car battery charger trying to drive battery drill. I can see advantages in your idea, for me the lower noise level is a bonus. That and, as you say, reducing waste.

I would agree with the above, there are power supplies available, on the web of course, which can provide lots of current. Otherwise buffer a car battery charger with a battery, that way is less likely to kill the charger.

xy

 

[artie]

I too had a few battryless drill/drivers around but I couldn't bring myself to spend money to end up with a less versatile tool.

I considered a attaching a cheaper battery made from individual cells which could be carried and connected by a short cable, for portability.

But again, the cost of cells and time to connect etc made me think , in the long run a proper replacement battery is the most cost effective.

 

[Limey Lurker]

"You can reduce the current to the drill, but the torque will reduce, just as it does when the battery goes flat." Isn't it the case that the drill will demand whatever current it needs, and the PSU must be capable of supplying that current? Unless the PSU is choke controlled.

 

[HamsterJam]

I would be tempted to carefully dismantle the battery pack and remove the cells then either fit a power supply in the empty space or run a cable from the battery pack to an external power supply. This means just the battery pack is modified and not the drill.
For safety’s sake, please fit a fuse to the output of any power supply (especially high current sources like a car battery) and dispose of any redundant cells properly.

 

[quintain]

What voltage are the units? 12V is a lot easier than 18V. A good 18V drill may require possibly 300-500W peak power, around 20A-30A. If your drill is that kind of power and you want full capability, you will need a suitably powerful PSU. They are available, at 12V. A computer PSU's and Amazon have some examples of 12V 30A supplies so it's just a case of a bit of engineering. Some battery chargers can be used, as a 12V supply. Others need 12V present to enable them.
I think it would be a lot of messing around when drills are so cheap now, but if it's a interesting challenge to you, it is possible. I haven't looked at any of the youtube videos, so not sure what techniques they use.

There are many options. First thing is to establish what voltage and current you really need. You can reduce the current to the drill, but the torque will reduce, just as it does when the battery goes flat. A quick check..... You can get laptop supplies, which are 19V/7.5A. That would power a 18V drill. You will find a suitable supply if you search, but you need to know what you are looking for.

If you just plan to use the drills for small scale stuff, there are lots of I.T. power modules available at 12V and 18V(19V), just try to find the highest rating for what you are willing to pay. You may have some suitable module already?

Thank Sandyn
I never thought about laptop power supply.
I am a hoarder and I just 'dug out' my 15++yr old P106 Toshiba laptop.
Power supply is 240v to 15 v with 5a.
This may be a little small but it is only gathering dust at present.
I'll give it a try.

Thanks again, Regards, Richard.

 

[Cozzer]

Thank Sandyn
I never thought about laptop power supply.
I am a hoarder and I just 'dug out' my 15++yr old P106 Toshiba laptop.
Power supply is 240v to 15 v with 5a.
This may be a little small but it is only gathering dust at present.
I'll give it a try.

Thanks again, Regards, Richard.

Shame it hadn't been a Dell.
IIRC, their laptop power "chargers" use 19.5v with 6.7A.

 

[mikej460]

I bought an excellent Dewalt DAB radio that runs on 18v Li-on batteries and is very useful when working outside but it does tie up a battery which lasts 2 days then needs a recharge so then I'm two batteries down. So I thought I would get hold of a duff 1.5AHr battery and convert it to mains for the shop and still use the good batteries when outside - easy peasy or so I thought. I had an old 18v laptop adapter so connected it up to the correct pins on the radio but it wouldn't power on. I then measured out each pin on a fully charged battery and found one of the charge (C3) pins was 3.5V so I figured I needed to put 3.5V on this pin. I've since bought a cheap step down pcb on Amazon and will be soldering it up inside the 1.5Ahr battery case. If that doesn't work I will give in, sell it and buy the newer model that works off mains and battery

 

[HamsterJam]

I bought an excellent Dewalt DAB radio that runs on 18v Li-on batteries and is very useful when working outside but it does tie up a battery which lasts 2 days then needs a recharge so then I'm two batteries down. So I thought I would get hold of a duff 1.5AHr battery and convert it to mains for the shop and still use the good batteries when outside - easy peasy or so I thought. I had an old 18v laptop adapter so connected it up to the correct pins on the radio but it wouldn't power on. I then measured out each pin on a fully charged battery and found one of the charge (C3) pins was 3.5V so I figured I needed to put 3.5V on this pin. I've since bought a cheap step down pcb on Amazon and will be soldering it up inside the 1.5Ahr battery case. If that doesn't work I will give in, sell it and buy the newer model that works off mains and battery

I think the ‘C’ pins allow access to each cell individually within the battery for balancing the charge across the cells during charging. The 3.5v you measured is likely to be across a single cell which are actually 3.6v each. (18v pack has 5 cells or 5 pairs of cells for bigger capacities).
However although it is theoretically possible, it seems surprising to me that the radio directly access individual cells as this risks unbalancing the battery.
Have you checked this pin actually has a contact in the radio?

Also some power supplies will not work properly when too lightly loaded and/or require a signal from the charge circuit in the laptop before they deliver the charge. Might be worth checking your laptop power unit is giving out 18v with the radio connected.

Finally, is there an ID pin and does that have a connection in the radio?
This is used by the chargers and tools to identify the battery pack and the radio might be checking for the right type of battery.

 

[mikej460]

Have you checked this pin actually has a contact in the radio?

Yes it is connected to the radio circuit

Also some power supplies will not work properly when too lightly loaded and/or require a signal from the charge circuit in the laptop before they deliver the charge. Might be worth checking your laptop power unit is giving out 18v with the radio connected.

Yes it is, I tested it with the radio disassembled but connected

 

[okeydokey]

I know this answer is way different to the rest but why not simply use a corded drill? No hassle and it works every time.
You can get them 2nd hand Gumtree FridayAd Ebay quite cheaply.

 

[Sandyn]

You can reduce the current to the drill, but the torque will reduce, just as it does when the battery goes flat." Isn't it the case that the drill will demand whatever current it needs, and the PSU must be capable of supplying that current? Unless the PSU is choke controlled.

I think you may be misunderstanding what I was meaning. It probably wasn't clear. What I meant was you can use an under rated PSU( current) to drive a drill, as you say, if you load the drill, the current will increase until you reach the limit of the power source, then the voltage will start reducing as the power source loses regulation, but it really depends on how current limiting is done. It could be foldback current limiting,in which case the voltage will be maintained and the current reduced until it goes into shutdown.
You will still get some quite usable torque from the drill.

 

[BigBertie]

I have 2-3 cheapo battery drills where the battery is dead,
I wish to convert them to UK corded use for bench use purposes I.E, screwdriver, small dia' drilling and such.
Has any one successfully done this at low cost and if so how.
BTW I am aware that YouTube have examples but I prefer to rely on sensible advice.

I have 2-3 cheapo battery drills where the battery is dead,
I wish to convert them to UK corded use for bench use purposes I.E, screwdriver, small dia' drilling and such.
Has any one successfully done this at low cost and if so how.
BTW I am aware that YouTube have examples but I prefer to rely on sensible advice.

I have done precisely this with an old Metabo drill. I bought a 12v power supply from Amazon….rated at 40A I think…not very expensive and I use it to power other things as well. I removed the cells from a dead battery and cut the top off, connected the terminals to a cable which then links to the power supply via an in line plug and socket so that the supply can be used for other things. It works perfectly. I have a miniature metalworking lathe and I use the drill to quickly move the carriage from one end of the bed to the other. There was and is nothing wrong with the drill and it’s great to continue using it. Let me know if you’d like more specific details and pictures and I’ll sort them out. …Psthe power supply cost £18