DIY: Lithium Battery to NiCd Power Tool (With Simple Adapter)




This time I’ll show you how to make an adapter, which allow you to use lithium ion batteries at old NiCd or NiMH batteries powered cordless power tools.

How I did it - you can check by looking DIY video or you can follow up instructions bellow.

For this project you will need:


Super glue

Covered polystyrene sheet

Some wires

Old NiCd battery housing

Wood screew

Epoxy glue


Soldering iron

Screw driver

Utility knife

Drill and bits

Rotarty tool

Sand papter 280 grit

Step 1: The Idea

One day I was looking at those two cordless power tools on my workbench, and just been thinking, that will be very nice to get rid of old, heavy and small capacity NiCd battery by replacing it with lithium battery pack from Bosch impact driver. From electric side it’s totally possible, because both power tools are operating at same voltage - 18V.

There’s need to make an adapter which will have same form and connectors like impact driver at one side, and at other side - flush surface. This surface will be glued at a top part of old NiCd battery housing.

I have a spare NiCd battery housing from previous build - so I’ll use it.
First - cut of unnecessary plastic parts to get flat surface.

Step 2: 3D Printed Adapter

The easiest way to make an adapter is to use 3D printer and just print it. I don’t have one, but I asked mine friend to help me, so that’s how it looks. For those who have possibility to use 3D printer, here is a link, where you could download project files:

Bosch battery model for 3D printing:

Step 3: Material

Any way, most of you don’t have 3D printer, so I’ll show another method. As main material I used
4 mm Iroplast SB board. This is some kind of polystyrene with covered both sheet surface. It’s lightweight and it’s very easy to work with it.

Step 4: Rough Adapter Shape

Here is what left after cutting and glueing sheet on sheet to get rough adapter shape.
Battery sits and holds very well.

Step 5: Connection Terminals

Next - I made battery connection terminals. I used spring clips from same NiCd battery. Cut two holes in adapter body and slide terminals in. Bend and with rotary tool cut them in proper size.

Step 6: In Progress With Terminals

Connected two power wires to positive and negative terminals. Added some glue in gaps between terminals and adapter body to secure them in place.

Cut additional layer to cover terminals and wires. With fast drying super glue, glued last sheet in place.

Step 7: Adapter Fixing Point

Made a hole in battery top part and used it as a template to mark and drill a hole in power tool body. In this hole will be screwed wood screw, which will hold an adapter in place. Also made a bigger hole in adapter body, which allow me to put and screw wood screw directly to power tool handle.

Step 8: Soldering and Glueing

Soldered power wires to old battery connector.

With two components epoxy glue, glued both parts in place. Sanded plastic surface to get stronger joint. Clamped and left to dry. Also added some glue to fix connector in place.

Step 9: Finishing

Glue dried, so it’s time for final check. Looks, that everything is ok.
Marked lithium battery out line and with utility knife shaped to final adapter form. Sprayed some black paint to get more aesthetic look.

Step 10: Finished Product

And here it is - finished product. Of course, this is not 3D printed adapter quality, but I think it came pretty nice and compact as possible too. Plus it weighs almost nothing.

Step 11: Fixing in Place and Conclusion

Connected adapter to power tool and with wood screw secured adapter in place.

And it works. With this adapter and lithium battery pack I’ll get a lot of advantages, like: fast battery charge, bigger battery capacity, state of charge indicator, reduced power tool weight. Plus I no need more to have few different battery chargers for different power tools batteries. Using idea this adapter, I could use only one charger and one type of batteries for all my cordless power tools, even for oldest.



    • Sew Tough Challenge

      Sew Tough Challenge
    • Paint Challenge

      Paint Challenge
    • Backyard Contest

      Backyard Contest

    16 Discussions


    Question 10 months ago

    would your friend 3d-print two plates for me? At a nominal fee please??


    1 year ago

    Nice job! I am thinking of doing the same. Now i have tried an einhel 18v lion battery on a 18v bosch tool and works fine. The bosch connector has 3 contacts, (+),(-) and a third, but the einhell battery only has (+) and (-). I suppose the third contact is some kind of regulator, sensor, protection circuit. If I buy a lion battery with 3 contacts, and solder them respectibely, will this work and also be safe not to decharge too much or overheat? thank you


    2 years ago

    I don't know, but I've got some tools that I would like to keep one of them to use, because I'm cheap and don't care to pony up for a new cordless jigsaw. So I'm going to try this, don't know where to get that material, but I've got some plexi laying around that I'll use.


    2 years ago


    I present the following with no malicious intent and in the spirit of constructivity.

    I often have difficulty understanding what it is people making contributions to forum conversations are trying to say because the syntax, grammar, spelling, and punctuation in use is so poor. It is difficult "work" determining what it is that participants are trying to say from what it is that they have actually written. and posted. Please, in the future, focus your thoughts, use correct nomenclature, eliminate jargon (be explicit--when presenting new ideas, assume that the reader has no prior knowledge of the subject matter in which you are giving instruction or offering anecdotal experiences--that is the essence of instruction), use spell check, use an English composition writing style guide, an PROOF READ your comments prior to hitting that "Post Comment" button.

    Many posts are laborious and painful to read and I must question the content and usefulness of the post if the thought being conveyed is not is not clear and concise, or is inarticulately presented. I am certain that I run the risk of missing out on some very valuable instructional insights because I am unable to follow some posts as they are written, and, therefore, unwilling to read them. As a metaphore, were I taking instruction in economics and the instructor could not (or chose not to) present his lessons concisely and clearly, I would have to question whether the content of his lessons were of any value--even if the instructor otherwise SEEMED to have great insight on the subject.

    Posts, if not clearly and concisely written, are a waste of time.


    2 years ago

    Good idea but I am not 100% sure but these Bosch batteries do no have temperature or deep-discharge protection in them, you could damage these batteries especially if you use then for "always on" application tools or lights. Temperature should not be an issue with normal load. Deep discharge should be done at 2.7 volt/cell, in this case 13.5V.


    2 years ago

    Hey how about a nice string of Christmas light lite by a rechargeable lithium battery. My new older house has no outside electricity? but we do have a few lithium batteries around.


    2 years ago

    let's see there are really only 2 tools sets out there that still use the old NiCd batteries Ryboi and Dewalt. Ryboi new ion batteries will fit in the old tools so what the point in making one for that.

    Then you have dewalt they sell a converter that does this. The converter is around $35-$40 depending on your store then you have to buy the 20v max batteries and charger or you spend about $150 where you get the converter charger and 2 batteries.

    - - - now I know what you are thing you cannot put a 20v battery into an 18v drill normally that is true. But you have to look at the fine print there. The battery tells you it is a 20v MAX. What that MAX means the initial(when you pull the trigger) voltage will be 20v then it will drop down and lvl off at 18v. Sorry guys if you bought the dewalt 20v max system and were thinking you were getting more powerful tool. You are not it has the same motor as the 18v do.

    With these two tool sets that are really the only ones that are still selling NiCd batteries and everyone else runs on ion batteries. And these two compainies sell a reasonably priced converters I really don't see the point in trying to make this converter.


    NEVER MIX CHARGERS NiCd charge differently then ion batteries. Unless you want to see your rechargeable battery look like last years hover boards DONT DO IT. You can cause a fire or explosion. At that point you and your family can be killed. Not to mention that your house can burn to the ground.


    2 years ago

    I would caution people not to fool with mixing chargers. Li ion batteries have very high energy density, and when they are not properly handled, extremely violent fires can happen. This, I assume, is why there are much more warnings on batteries and chargers these days, and they should be heeded.

    This why overzealous warnings, such as OSHA warnings of eye protection for opening a bread bag twistee, desensitize people from more-likely and real dangers.


    2 years ago

    Aside all other issues, I surmised that Ni-Cd are still used as new battery-selection-type by manufacturers because of its ability to deliver high current. I'd do, however, see drills with Li ion batteries, which I would assume are in the high current range.


    2 years ago

    You did a great job on this instructable, however, Ryobi makes Li-Ion batteries for these tools already.

    1 reply

    Reply 2 years ago

    yep, New lithium Ryobi batteries will work in the old NiCd tools, just have to get a new charger. and the new charger will charge both types of batteries.

    this instructable is good for showing how to make a cross-brand adapter.


    2 years ago

    The foam board is a nice idea. Thanks.