• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Help/advice please re replacing a power tool NiCd battery pack with a DC transformer


New Member
I am new to this forum and would appreciate your help and advice. Please tell me if I am in the wrong forum and/or the topic is not relevant.
In this case, I would also appreciate if you point me to the right direction/forum.
My question is that I am not going to replace the battery packs of this power tool with very expensive replacements and/or batteries.
So, I would like to get a transformer which could supply the required power and the torque
The power tool in question is a 14.4 V/ 2.0Ah impact driver.
I am afraid I have forgotten how to calculate the correct rating of the transformer [I could do it about 50 years ago...]
As I am in the UK, the AC voltage is 240. So, what rating of a transformer should I think about/purchase/build?


Well-Known Member
Most Helpful Member
The battery may have two amp hour capacity - but the tool load current could be anything, lower or (more probably) higher than 2A.

How long does (or did) it work continuously for, at full load, on a single charge? That should give an approximation of the load current to base things on..

As another approach - 14.4V implies a 12 cell NiCd battery pack.
That has a voltage range almost 18V immediately off charge down to 12V dead flat.

It would cost roughly £14 for four, good quality 2.5AH 18650 lithium cells - which would likely work OK & may even fit in holders in the original casing? They give a voltage range well within the original NiCD range, so should be totally compatible.

You would need either a separate cell charger and remove them from the holder, or build them in (using cells with solder tags), with a four cell protection & balance board, then use a suitable external four cell charger.

Example BMS with balance, rated for power tools:


Well-Known Member
If you use the tool by your automobile, evaluate hooking it to its car battery with alligator cables to see if it performs to your satisfaction.
For true portable, check if a bunch of 18650 cells can be made into a pack, in the original housing/contacts, but you will need to work on the charging scheme.
A 240VAC to 14V/2A+ adapter from mains may be dissapointing. Try one if in your means.
If you are willing to drag an adapter to 240VAC everywhere you use the tool; you may be willing to trade the drag with a motorcycle battery; about the same bulk.
Original battery packs are a shame of price gouging and deserve out of the box views.

dr pepper

Well-Known Member
Most Helpful Member
A car battery charger would also probably work, you just need a reliable means to connect to it.

Latest threads

EE World Online Articles