Introduction: How to Rebuild a Dewalt 14.4v Battery Pack

Picture of How to Rebuild a Dewalt 14.4v Battery Pack

$80 for a new battery pack.

$25 to build your own.

Plus bragging rights!!!

Step 1: Take Apart Battery Pack

Picture of Take Apart Battery Pack

remove the six screws that hold the pack together

carefully pull apart the two halves

take notes as to where things are and how they go back together

have a digital camera on hand for documenting dis-assembly

Step 2: Remove Battery "pack"

Picture of Remove Battery "pack"

carefully pull the battery pack out of the holder

Step 3: Document Everything

Picture of Document Everything

as you pull the battery "pack" apart

take pictures and draw pictures of how the 12 batteries are packed and connected so tightly

Step 4: Buy Replacement Batteries

Picture of Buy Replacement Batteries

Google 1.2v subC batteries

(1.2 * 12 = 14.4)

find your best price for 12 batteries

when you place your order make sure you have measured your battery cells and are getting the correct "physical" size

buy with or without tabs

without tabs is less expensive and the following steps will show you how to make your own tabs

Step 5: Diagram the Connections

Picture of Diagram the Connections

you will notice after folding and unfolding the string of batters

that the 12 batteries are wired in series pos-to-neg, neg-to-pos and so on

use the gummy insulator that you pried away from the top and bottom of the batteries to draw a template

then use a coin to complete the circles representing the batteries

draw a diagram looking at the batteries from the bottom

then draw a diagram of the batteries from the top

note each connection and how the battery tab is oriented

number the batteries on your diagram

while you are waiting on your new batteries to arrive in the mail

practice refolding the old battery string and placing it back into the holder


Step 6: Making Battery Tabs

Picture of Making Battery Tabs

the battery tabs, as you can see, need to be flexible

one very good source of material for making battery tabs is an old computer cable with an outer mesh

this is an old Firewire cable cut into small strips with the innards removed

the mesh can be squashed flat and take on solder very well

you will need eleven strips

cut extra just in case

put some flux on both ends and tin the ends with solder in preparation for soldering to your new batteries

Step 7: Preparing the New Batteries

Picture of Preparing the New Batteries

when your new batteries arrive, flux and tin both ends with solder

use a small iron with a nice large flat head

do not hold the iron on the battery for more than a second or two


try it again until the solder melts and adheres to the battery

wear eye protection and use common sense

common sense says "overheat . . . and BOOM!"

take your time tinning the ends

one or two seconds at a time

flux is a must!!

Step 8: Build Your New Battery Pack

Picture of Build Your New Battery Pack

arrange your new batteries on one of your template drawings

solder your homemade battery tabs to the batteries following your diagram for the bottom view

slowly, not overheating the batteries

sice you have tinned both the battery and the tab, soldering will go quickly

once you have the tabs on by following your "bottom view" drawing

flip the batteries over

set them on the gummy insulator you saved

and put the whole bundle in the battery holder

now solder the remainder of your tabs following your "top view" drawing

the first battery in the string of batteries has a special connector that is spot welded in place

use an old wood chisel to pry it away from the old battery, it pops off easily

tin that connector with flux and solder and solder it to you last new battery

the bottom of this battery may need a longer battery tab to get to the next battery in series

and the wire coming from this special connector goes to the last battery in your series of batteries

if you saved the gummy insulator from your earlier steps, place it on top of the batteries

otherwise cut a new template from some sort of nonconducting material and put it in place

now reassemble the two halves of your battery housing and screw them together

having total confidence in yourself drop your new battery pack into the charger

a steady red light means everything is good and the battery is charging

wait 5 minutes and try your drill

if all is good give it a full charge

but just to be safe . . . keep an eye out for smoke

Step 9: Charge Your New Battery Pack

Picture of Charge Your New Battery Pack

steady read light means all is good and the battery pack is charging

if you end up not calling the fire department

take yourself out for a beer

and brag about your experience!!


LegoSurvivor (author)2017-12-15

for step six just use a old 9v battery.

jdawe2 (author)2017-09-23

Just found this - THANK YOU! great idea. These darn batteries are hideously expensive. Also - found a decent price on replacement nicd's with tabs here at amazon:

Creamaster (author)2012-06-18

I haven't read through all these comments so apologies if I'm repeating someone.

I'm pretty sure you just destroyed every one of those new cells when you soldered them. You should always buy your batteries with the tabs soldered on - the extra expense is worth it. If you look closely you'll see the tabs get attached with a very small spot-weld or two to the battery cel. That's done with a machine that's very fast and doesn't heat the battery up. Your solder iron heats up the battery - even just as the solder and flux cool - that extra heat hurts the chemical makeup of the batteries and that shortens their life, if not destroying the battery right there and then.

Probably you took about half the life span off these batteries.

This would all be fine if you're stuck and had to have a battery pack work right now, but if you're trying to save money, do it right.

Ch34pskate (author)Creamaster2017-01-25

Where do you pick up the batteries with the tabs on them already. I have wasted ~$40 trying to solder directly to the battery. One started smoking. Had a bucket of water to drop it in but it bubbled for about five more minutes. And I only hade the soldering iron on the battery for no more that five seconds.

Creamaster (author)Ch34pskate2017-02-06

Any reputable battery shop should be able to make them for you. Yellow Pages? Is that still a thing?

At any rate, spot-welding is almost instant.

If you're game, here's a video on how to make a spot-welder from an old microwave:

ksickafus (author)Creamaster2012-06-18

i don't have a welder

and, this site is for the DIY peeps who have duct tape and a paper clip

so, you gotta go with what you have

but, I am sure you are right about the battery life

the batteries I found did not have tabs

plus the tabs need to be in specific angle for this thing to fold back into the holder

but, if you have tabs and a welder . . . go for it!

geconi2o4 (author)ksickafus2017-01-06

Total novice here, if you just connected copper mesh between the battery tabs, could that work?....without adding too much resistance?

garver brown (author)2015-06-08

Based on everything that was explained and then all the comments, If you figure $20.00 an hour for labor its then cheaper to buy a new battery pack. Also test the batteries usually there is only one bad one in the bunch of old batteries.

How much do you get paid when you aren't working? I don't get paid anything, so doing things like this not only expand my mind and give me a sense of accomplishment, but also save money in the process. Also, this site is called Instructables, not buyables.

If i was to do this instructable i would'nt charge myself anything.

SueD32 (author)garver brown2016-01-20

I would rather pay myself $20 an hour than pay someone else to do something.

DaveP80 (author)2016-04-26

Would it work with 2200 mAH batteries instead of 1800?

Ion-ChristopherD (author)2015-03-22

MY BAD - that should be 300 WATT not 30. 150 on low, 300 on high. Two stage trigger.

BY ALL MEANS BUY TABBED BATTERIES. And yes, soldering can shorten the life of one or more of those batteries.

Ion-ChristopherD (author)2015-03-22

PROPER SOLDERING TECHNIQUE for batteries, 30 watt iron, flux paste, practice how to "tin" your parts before assembly - including the iron tip. Use a wet sponge to wipe the tip every time you solder, and fine garnet wet-dry sand paper to clean the tip every hour or so, and to prep the surface of things you want to solder. To tin, apply a spot of flux and make it boil, quickly feed some solder right at the junction (tip/part). The solder will spread into a thin, shiny film. Great! Lift the iron as soon as this occurs.

TIP for experts - cut about an inch of solder wire and use a needle nose pliar to roll it into a circle. Put that on top of the area you just tinned. Put your tinned wire braid on top of that. Now you won't need three hands. Proceed....

Now you put your tinned pieces together and hit them with the full 30 watts - they will melt the solder quickly. You SHOULD add a bit more solder from the roll (or see above(. Use a cheap holder - and you will be able to use two hands!

ilz19 (author)2015-03-14

great writeup. will give this a go.

russ_hensel (author)2015-02-05

Just a note to let you know I have added this to the collection: Cordless-Drill-Battery-Maintenance !


Take a look at a bunch of different/similar approaches to this project.

gezer2u (author)2012-06-17

Nice job with the instrucable!
Some things to clear up.

I know a thing or two about nicad and niMh batteries. I have soldered hundreds and hundreds of batteries. I have raced battery powered RC cars for many years. As in any racing everything counts and I battery powered RC cars, batteries are everything. For instance look up "worlds fast RC car" :)

That said, batteries won't explode from soldering them. Getting them too hot will affect the life and capacity. There is a vent in the pos. side that vents gas's as the cell charges. If it gets damaged then there is a possibility that it can explode.

I think the reason that the factory battery is spot welded is because it is faster then soldering.

araceliS (author)gezer2u2014-12-18

If the old batteries in your pack are NiCd (and they probably are) make sure you ask them if your charger is compatible with NiMh before you upgrade. It's been a little while since I worked at B+ but IIRC it was the rapid chargers that tended to be incompatible.

Also, an advertisement for Batteries Plus (even though the particular store I worked at sucks and doesn't deserve it): they can potentially rebuild tools that you'd think are way too old. I rebuilt a cordless drill before and didn't even have a removable battery pack (batteries built-in to the handle). The same guy also brought in an electric razor that he apparently never cleaned; I had the pleasure of cleaning out several decades worth of facial (I hope) hair before I could rebuild... so maybe don't do that.However, Its pretty dangerous.I bough a new one from this site. It is a great source for OEM chargers if you can find them.

ksickafus (author)gezer2u2012-06-25

correction . . batteries WILL explode! Read below. I was replacing a small CMOS computer button battery with no experience, little patience and a huge soldering gun.

BOOM!! The battery exploded!

After changing my pants I made a mental note that IS ALWAYS in the back of my mind whenever I solder batteries ... eye protection, patience, slow as she goes, common sense, etc.

I have soldered hundreds since. No explosions, and all projects are still in working order.

Hec031 (author)gezer2u2012-06-18

I agree with this conclusion. The spot welding is simply a mass production process and not some kind of restriction on soldering. Many rechargeable batteries come with their metal tabs soldered since they are made by workers in developing countries.

Money says the batteries last just as long as the factory one or longer. Time will tell.

ksickafus (author)gezer2u2012-06-18

I've only exploded one battery while soldering . . .

wet my pants!

but, it was a small button battery for a computer CMOS.


and it took a very long while to explode by someone who didn't know what they were doing

that's why sites like this are nice

so . . . I agree

you are not going to explode the battery by soldering

a spot welder would be nice

but this is the duct tape solution for those who don't have one

Kenno79 (author)2014-10-17

Question - I am about to try this instructable on a DeWalt battery pack, same model as in this demo. I have found Sub-c batteries with a solder tail, isn't that the safe way to go about this issue with over heating and exploding batteries? And... should the batteries be Ni-Cd or Ni-MH?

Bill P (author)2014-09-07

An add-to for this hack. Harbor Freight Tools regularly has 14v-18v battery packs on sale for around $12. These battery packs contain the very same "C" and "Sub-C" cells found in most rechargeable packs. I have rebuild countless battery packs for everything from cordless screwdrivers to power saws from these units and I can tell you personally, you cannot beat the savings. I have also found the battery quality to be comparable to branded battery packs. Try one time and you'll be a believer.

falk (author)Bill P2014-09-30

I did a search, and they did indeed have an 18v battery pack you could gut for its cells. These are 1300-1500 mAh which are inferior to the 1800mAh cells you can get at Your call whether the savings are worth it.

I couldn't find any 14.4v packs, but maybe they come and go.

laurentiuvincze (author)2013-04-07

Good work !

Beanal (author)2013-03-28

Use a small screwdriver to pry out each of the12 NiCad cells from their battery compartment. Some are soldered as this provides a better connection and helps stop the cells from shorting. If they're soldered, heat a soldering iron and touch a soldered cell terminal with the soldering iron until the solder melts. Remove the soldering iron and quickly pry the cell away from the connection before the solder hardens. You must do this on all 12 cells.

boomchuck (author)2012-12-26

Thanks for creating this DIY! I have an 18v Coleman that came with two batteries that have since crapped out (after less than a year). Couldn't find replacement batteries. With this DIY I can now I can replace the innards of a perfectly good cordless drill.
I have one question, though. Should I get the 2900mAh or the 1600mAh sub-Cs? What's the difference?

boomchuck (author)2012-12-26

Thanks for creating this DIY! I have an 18v Coleman that came with two batteries that have since crapped out (after less than a year). Couldn't find replacement batteries. With this DIY I can now I can replace the innards of a perfectly good cordless drill.
I have one question, though. Should I get the 2900maH or the 1600maH sub-Cs? What's the difference?

RangerJ (author)2012-11-24

Two observations:
One - there is a good chance only a few of the batteries are bad. I have repaired battery packs by making two weak ones into one functional pack. This is accomplished by charging both and letting them sit for a day. Take them apart and measure voltage on each separate cell, marking it on them with a felt pen. If the cells are 1.2 volts, you are good. If 1.1, weak, and below that no good. Take the bad ones out and replace with good ones.
I have had success with Craftsman batteries in years past - I don't know if they are still the same or not.

Two - I have tried to repair DeWalt batteries and couldn't get the insulators off the top and bottom no matter what I did. At the best, I could break it into pieces and remove them. At the worst, they broke and still stuck to the cells.

Anybody got a solution to that problem???

gezer2u (author)2012-06-25

I was really refering to sub C batteries. Their size makes them a rather big heatsink making it a lot harder to over heat them to the point ofexploding. I have seen them explode from using a device called a battery zapper that uses a capacitor and high voltage to break up shorts in the battery thus lowering the resistince in the battery and increasing the voltage. They sound like a stick of dynamite! Lol

I think a button battery is different because It is very small and can over heat rather quickly. I wonder if the CMOS battery exploded because it is lithium. Lithium is a whole different thing.

I too agree that you need a soldering iron that is big enough to stay hot while soldering the battery. I was trying to make a short comment and figured someone else would say it. :)

joshua a.c. newman (author)2012-06-25

DeWalt battery packs are NiCd and not NiMh?

ElectroFrank (author)2012-06-21

Another trick I use:
Take a cheap RC model battery pack with compatible voltage and capacity, and fit about a four foot lead to the power tool terminals with a matching plug.

Then I can just drop the battery pack in my pocket, and conveniently use the power tool with much less weight in my hand.

Then also, with an appropriate socket fitted, run it from my car battery charger when in my workshop.

ksickafus (author)ElectroFrank2012-06-25


ElectroFrank (author)ksickafus2012-06-25

Thanks !
I forgot to say: when running a battery power tool from a car battery charger, only if it is a compatible voltage ! 

If the car battery charger is a slightly lower voltage, the tool will run a bit slow.

If its a higher voltage, the tool runs faster, but give it regular breaks to cool down or it will overheat !

jamesvs400a (author)2012-06-17

will have to make an instructable when i re-build my battery pack for my drills. not going to be as simple as yours though. (lithium batteries with cutoff circuit/custom charger.

note that the fast charger is what kills the batteries. best thing you could do is redesign the charger. got an ozitto 20.4V drill that slow charges then cuts off power to the battery pack when charged to prevent overcharging. batteries have lost capacity from new but still has heaps of torque after 8 years. makita nicad drill and both battery packs are fancy paper weights. :)

ksickafus (author)jamesvs400a2012-06-25

waiting . . .

Wildrat (author)2012-06-17

This is a good instructable, unlike instructables to cook cake in a microwave or how to make a sweater for your gerbil out of an old sock. Good Work!

ksickafus (author)Wildrat2012-06-25


ksickafus (author)2012-06-25

good comment

enivels11962 (author)2012-06-17

If the battery is no longer very functional, there may be only one or two cells that are bad. Before replacing all cells test each to see which are deficient. Replace only those that are defective and no longer hold a charge. Cheaper yet.

ksickafus (author)enivels119622012-06-25

cheaper yes? But for all the work in this project why not change all 12 and just keep the "old" good ones for some other project?

Wildrat (author)enivels119622012-06-17

Your idea may save a couple of bucks and be a good idea in a pinch, the problem is you do not know how much capacity is left in the used batteries unless you you discharge them with a known load for the required time. If you have it apart and ordering batteries go ahead and replace them all, not unless of course you build a simple capacity tester. Your idea will work if your stuck or funds limited.

papagun (author)2012-06-17

It has been my experience that soldering heat devastates the cells. That's why they should be spot welded rather than soldered. The battery will work for a short time after this sort f repair, but the heated cells will die pretty quickly... certainly the battery will not last as long as a commercially repaired or spot welded one.

sconner1 (author)papagun2012-06-22

My personal experience would support this.
Unfortunately, Not many of us have access to an ultrasonic welder.

ksickafus (author)sconner12012-06-25

that's why you are on this site . . it's for people who have duct tape and paper clips

sconner1 (author)2012-06-22

Just a thought. One could use fine sandpaper to Clean the surfaces to let the flux do it's job quicker and easier with less heat transfer.

ksickafus (author)sconner12012-06-25

yup! I used my Dremmel(sp?) wire brush to "skuff" up the battery ends. After tinning the ends of everything, soldering was quick!! The drill works great. And. I have only charged it once since doing this. Holding charge very well. Just the experience was worth $25, even if I shortened the battery life. Without a spot welder you gotta go with what you have!!

Ricardo da Vinci (author)2012-06-17

Hi! I'm really glad I saw this, although I had worked out most of it myself, the heat question I had not anticipated. I was told by a seller on Ebay that usually, not all the cells in a pack go, and to test each one before replacing the lot?
I have about four of these in pieces, and I feel the cheapest way is to find a cheap one, and replace the string as a whole, eg, looking at Ni-cd 18v pack, I see a replacement power pack for only £7.80 on Ebay, so I'm going to buy it and try to re-fit it in a different case as an experiment, this would be far cheaper than buying all the individual cells, as they are at least £1 each!

Moving onto the heat question, I have seen low temperature solder for sale, but haven't tried it yet. Any ideas?

I'll report any findings!

In accordance with the "be nice" policy, "You are all a wonderful group of intelligent, handsome, fair and fastidious people and it brings me the greatest pleasure to interact with you,

Love and Kisses, Hugs and Blessings!!!"

Richard Lakin-Inzunza

just do it! and let us know how the LT solder works!


but I thought

if I am going to go through all of this

why not just replace all 12 cells?

in my case

I didn't get a good reading from any of my cells anyways

do all 12 is my advice

About This Instructable



Bio: Karl Sickafus @ FB
More by ksickafus:How to rebuild a Dewalt 14.4v battery pack
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