Cordless Drill Hacking

[T3sl4co1l]

Yay, my corded cordless drill is cordless again!



If you don't recognize that, it's a Horrible Fright special, $20 cordless drill, originally with NiCd battery (long since deceased -- overheated and overcharged, because the charger is literally an AC adapter, diode and LED).

Well, instead of giving up on it, I soldered wires onto the battery terminals, and used it as a corded drill, within reach of my bench supply.  (Amazingly, the chintzy speed controller -- a MOSFET, an SO-8, and a few chip resistors and "////" region on the PCB emulating a potentiometer -- is able to suck down quite a lot of current, enough to brown out my beefy supply!)

Somewhat more recently, I built a 12-24 to 18V converter box for it.  This is based on my LED flashlight (written up elsewhere on here ), with extensive but fairly straightforward mods to adapt it to a much more powerful output stage (50V 40A peak switching, versus the original design's 10V 5A), in a Ćuk converter.

https://www.seventransistorlabs.com/Images/CukHack1.jpg

Also, it feels nice to finally spell Ćuk correctly here.

So, I happened to have a 12V gel cell handy, and needed a cordless use tonight.  So, I put two and two together.  That was tonight's story.

Tim

[JS]

Is it really cordless???

I'm about to do a similar thing but with 18650 batteries, I have 2 cordless drills and one screwdriver. One of the drills is serving fine with a car lighter adaptor, mostly on the boat but I still want it back to cordless and I wanted them to have no outside cords when using them as cordless. They will probably end much lighter than the NiCd versions of themselves.

JS

[Monkeh]

I applaud your ingenuity, but that's a horror show. Please go treat yourself to something better.

[T3sl4co1l]

I'm about to do a similar thing but with 18650 batteries, I have 2 cordless drills and one screwdriver. One of the drills is serving fine with a car lighter adaptor, mostly on the boat but I still want it back to cordless and I wanted them to have no outside cords when using them as cordless. They will probably end much lighter than the NiCd versions of themselves.

4 or 6 x 18650s would fit in the old battery pack, which I've thought about doing as well.  Don't really have a good way to weld cells together though (hmm..).  Will definitely be lighter!

I applaud your ingenuity, but that's a horror show. Please go treat yourself to something better.

Nah, I use it so little, it's not worth getting anything fancier.  Plus, the converter was a nice weekend project to keep my designing and hacking sharp.  Still impressed I packed everything into that little box!

Tim

[JS]

I have a few microwave transformers on my bin, planning to use one to make a spot welder for this kind of things...

JS

[Gyro]

Personally, I'd pick the SLA over 185650s for a lash-up too. Less chance of a *Bang* for your buck if you screw it up! Probably greater chance of magic smoke though (I think I'd put a fuse on one of the SLA terminals).

[KL27x]

Don't really have a good way to weld cells together though (hmm..).  Will definitely be lighter!

You don't need a welder. A regular soldering iron will work just fine. Put a fat tip on it, set it to dang hot, then get fast on/off. I like to tack the cells together with hot snot, first, solder the wires, and then perhaps even wrap the whole shebang in a few wraps of saran wrap and packing tape before stuffing it in w/e the end game is. If you want to get fancypants, you can wire each cell to a header/connector for balancing if/when needed. I do this with 30 AWG wire, since this doesn't need to be a high current deal.

But unless you already have a pile of 18650's on hand, I would suggest you first shop for a ready made LiPo RC pack. The prices have really come down a lot in the last 5 years. This saves a ton of work. They come in insane charge/discharge rates. And most of them come with multipin connectors for access to individual cells.

The greatest thing about li ion cells is they hold charge, unlike lead acid and nicd. So you will never have to charge the drill before using it. Only after you're done.

One drawback is li ion don't live as long when stored at high temp. I don't leave my li ion tools in the garage or car.

 

[T3sl4co1l]

I've actually had quite good life from lead acid, speaking of -- not that I've got much charge into or out of it, but I've got a marine deep cycle here for high current loads that's four or so years old.  My car's battery is about as old, and was starting to die this winter, but it came back with a nice long float charge.

Tim

[xavier60]

I bought a replacement drill for less than what it was going to cost to replace the burnt out motor controller in my old Makita DHP481.
 I had a go at making the old drill useful again by building a controller for it using a PIC16F88.
I originally thought that 25 amps would be enough, end up having to set the current limit to 60 amps for it to have a useful amount of power.
 It ended up working so well that the old drill has become my go to drill, mainly because I have programmed it to soft start and to shut down very quickly when the bit gets stuck rather than trying to break my wrist.
The DirectFETs in the original controller are IRF6613.
 

[Piggzy]

I also have a DHP481 I'm pretty sure I have a problem with my main board. I was wondering if you could give me a list of parts you use to fix the circuit board. Please and think you

[daniel444]

lol,  same thing happen to me  , i bout the drill like 13 years ago , it had three dewalt ni-cad batteries they didn't last even a 1/4 of the mechanical life of the drill , they may have sold me old batteries i dont know , couldnt be bothered doing a lithium conversion on them

i used an xt-60 connector on the cable

[bson]

I applaud your ingenuity, but that's a horror show. Please go treat yourself to something better.

I dunno, sometimes something is so heroically winged with string and tape that you can't stop now! 

[magic]

My father made a dual role cordless/corded drill: one dead battery pack has been gutted and converted to power plug.

[xavier60]

I also have a DHP481 I'm pretty sure I have a problem with my main board. I was wondering if you could give me a list of parts you use to fix the circuit board. Please and think you

Hi, it was a complex project that I didn't document  very well. I didn't actually repair the original controller, I built a replacement.
I think that a replacement controller was priced about $200. It is permanently wired to the stator.

[lorik199]

I bought a replacement drill for less than what it was going to cost to replace the burnt out motor controller in my old Makita DHP481.
 I had a go at making the old drill useful again by building a controller for it using a PIC16F88.
I originally thought that 25 amps would be enough, end up having to set the current limit to 60 amps for it to have a useful amount of power.
 It ended up working so well that the old drill has become my go to drill, mainly because I have programmed it to soft start and to shut down very quickly when the bit gets stuck rather than trying to break my wrist.
The DirectFETs in the original controller are IRF6613.

Hello xavier, could you maybe post the schematic/source code?

[xavier60]

I bought a replacement drill for less than what it was going to cost to replace the burnt out motor controller in my old Makita DHP481.
 I had a go at making the old drill useful again by building a controller for it using a PIC16F88.
I originally thought that 25 amps would be enough, end up having to set the current limit to 60 amps for it to have a useful amount of power.
 It ended up working so well that the old drill has become my go to drill, mainly because I have programmed it to soft start and to shut down very quickly when the bit gets stuck rather than trying to break my wrist.
The DirectFETs in the original controller are IRF6613.

Hello xavier, could you maybe post the schematic/source code?

I could but rather not. It's very poorly documented and the drill's performances is well below original. It was a rushed weekend project just to restore some usefulness to a dead drill. It will take countless posts to fill in the gaps.
What are you intending to do?

[lorik199]

I also had an DHP481 and I want to restore it.
I've bought several chinese knock-off controllers from aliexpress but all failed.
With the increased popularity of brushless drills this project could be a gold mine for all, saving a lot of drills from being thrown away.
I would really apreciate any documentation, it could be a good starting point for a maybe improved version.
 

[xavier60]

OK, in that case my design is totally unsuitable for use in a salable product.

[lorik199]

OK, in that case my design is totally unsuitable for use in a salable product.

I don't intend to transform this into an commercial project and sell it, it's main purpose would be to help other hobbysts to repair their drills.
My main goal is to repair mine, but if in the process I could help others why not.
Do you use the hall sensors for feedback or only back emf?

[JoanBS]

Why is it that every time I read a thread that Seven Transistor Labs is involved, it asks me for my digital ID certificate?

[nonius_]

Well cover me in eggs and flour and bake me for 15 minutes.... I thought I was the only one who was cheap enough to convert an old cordless drill into a corded one. Seems many more people have had this idea. Great minds think alike

I love the old 7.2V Makita drills, they fit my hand wonderfully and can reach small places. But the batteries are expensive and nowadays sadly NiMH, as opposed to the original NiCd. So I made a few modified battery-packs: removed the guts and added a cord. The cord connects to a small tool tote that contains a 12V/7Ah gel cell and a fuse (plus a car cigarette lighter connector for other 12V uses, 'just in case'). With that 12V battery, the drill has become a *much* more powerful and I can drill a whole day without recharging. The slight overvoltage hasn't harmed the drill yet, over the past 15 years. If it does, I'll switch to another drill.... these 7.2V drills are cheap and plentiful as no one else seems to want them anymore.

The power connector is XLR.

These drills have a permanent place under the woodworking bench, they're the first drills I reach for when I need a hole that can't be made with the brace-and-bit or an egg-beater style hand drill.

I've also made another tote, with a few LED-lamps, to light wherever I'm working (am in the middle of a large home reconstruction project). Love that one too. Both are wired the same so I can use the Makita drills on the lamp as well, if needed.

(I've also converted a 14.4 Makita to Lithium (the orange battery pack), but don't use that drill much - I very much prefer these 7.2V drills for daily use and ease of recharge. I've also rebuilt quite a few of the 7.2V battery packs and use one of the drills with those. But in practice, the 7.2V converted ones are my favourite)

This thread brought a great smile to my face - great to see I'm not alone!

[lorik199]

I use the Hall sensor RPS into pins 11,12,13 on the PIC16F88.

Ok, a few more things to clarify:
1. do you used and special op-amp? or any generic one
2. what power mosfets did you choose?
3. 6.2V for powering the microcontroller seems to look like a typo, but i seen the reference divider used for 7805. I there a reason for increased voltage?
4.the attached snip from the schematic it's just an equivalent for the mosfet driver with 2n7002 for power fets?

I would be grateful if you could post the source code and PCB so I could build a prototype .

Thank you!

[elektryk]

There are some ready made BLDC controllers on Ali, I haven't tried it, but may be worth.

[xavier60]

There are some ready made BLDC controllers on Ali, I haven't tried it, but may be worth.

With stator and everything else.
https://www.aliexpress.com/item/1005007806340322.html?spm=a2g0o.productlist.main.1.64a045bdB1YsXy&algo_pvid=936ff873-7b65-4498-8ee8-51fd193a297c&algo_exp_id=936ff873-7b65-4498-8ee8-51fd193a297c-0&pdp_ext_f=%7B"order"%3A"28"%2C"eval"%3A"1"%7D&pdp_npi=4%40dis%21AUD%2127.79%2127.79%21%21%21126.66%21126.66%21%402101e07217467764632576453e646d%2112000042264772744%21sea%21AU%21130254308%21X&curPageLogUid=L0CNW9ECgBIx&utparam-url=scene%3Asearch%7Cquery_from%3A

[lorik199]

There are some ready made BLDC controllers on Ali, I haven't tried it, but may be worth.

With stator and everything else.
https://www.aliexpress.com/item/1005007806340322.html?spm=a2g0o.productlist.main.1.64a045bdB1YsXy&algo_pvid=936ff873-7b65-4498-8ee8-51fd193a297c&algo_exp_id=936ff873-7b65-4498-8ee8-51fd193a297c-0&pdp_ext_f=%7B"order"%3A"28"%2C"eval"%3A"1"%7D&pdp_npi=4%40dis%21AUD%2127.79%2127.79%21%21%21126.66%21126.66%21%402101e07217467764632576453e646d%2112000042264772744%21sea%21AU%21130254308%21X&curPageLogUid=L0CNW9ECgBIx&utparam-url=scene%3Asearch%7Cquery_from%3A

I tried those two controllers, they burned in a second
https://www.aliexpress.com/item/1005005647465100.html?spm=a2g0o.productlist.main.40.6fc874250ikhfH&algo_pvid=73e46733-8e23-47ea-8d69-e3cce3e90632&algo_exp_id=73e46733-8e23-47ea-8d69-e3cce3e90632-39&pdp_ext_f=%7B%22order%22%3A%221%22%2C%22eval%22%3A%221%22%7D&pdp_npi=4%40dis%21RON%2193.81%2191.93%21%21%21145.42%21142.51%21%402103894417470411618462912e17c1%2112000046385635481%21sea%21RO%212338764483%21X&curPageLogUid=EC7nD8ZhiJVz&utparam-url=scene%3Asearch%7Cquery_from%3A
https://www.aliexpress.com/item/1005007512494150.html?spm=a2g0o.productlist.main.18.6fc874250ikhfH&algo_pvid=73e46733-8e23-47ea-8d69-e3cce3e90632&algo_exp_id=73e46733-8e23-47ea-8d69-e3cce3e90632-17&pdp_ext_f=%7B%22order%22%3A%2219%22%2C%22eval%22%3A%221%22%7D&pdp_npi=4%40dis%21RON%2167.97%2123.79%21%21%21105.36%2136.88%21%402103894417470411618462912e17c1%2112000041081263016%21sea%21RO%212338764483%21X&curPageLogUid=1XhZrJRXVQeh&utparam-url=scene%3Asearch%7Cquery_from%3A