Picture of Hot Rodding a Power Drill Battery
So, your power drill battery dies. What now? Fork over 85 bucks for a new one? I don't think so. After searching high and low on the internet for a good price for a replacment battery I found the retail for my Black & Decker 14.4V to range from 35-85 dollars. Riiiight. Time to make your own!

At this point it would be good to mention you should really discharge the pack before you continue. Don't play with electricity unless you know what you are doing!

Step 1: Let's find out what is inside!

Picture of Let's find out what is inside!
I had a little brainstorm and decided to open this thing up and see what makes it tick. It's funny, I always thought there would be some mystical magical component of power tool batteries that justified the outrageous prices...you know, custom made or ethereal glowing lights or little elves or something. Turns out they are just a rip off.

Fortunately for me the internals were looking familiar, a simple set of "Sub C" rechargable NiCd cells from my RC car racing days. I used to build my own racing battery packs so I couldn't help applying that here.

I had visions of using batteries that power world championship RC cars and transform my moderately powered B&D into a drill that would make screws and yet-to-be-drilled holes tremble with unspeakable fear.

When you open the battery you'll need to save some plastic bits detailed below. Don't break them.

Battery bars are not needed, you can just cut up some tin or copper sheeting. Also, the cardboard tubes were for heat displacement and wear to prevent shorting, so you need to use them.

russ_hensel6 months ago

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

>> http://www.instructables.com/id/Cordless-Drill-Battery-Maintenance/

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

betterways1 year ago
This is Good to know stuff. How many other batteries have you taken apart? Are they all made up of common AA, AAA, C, D batteries? I just recently saw a tip that a six volt battery is filled with 30+ AAs. And if a rechargeable one is filled with rechargeable AAs, then you could get a great discount buying them that way.
That video has been round for years, and it's a fake. 6-volt lantern batteries really have just 4 Uber-large F (longer than a D) size cells in them. Pretty much all drill packs use sub-C size cells which means they're the same diameter as a C cell but shorter. Lithium-ion drill packs use 18650-size cylindrical cells that look like giant AAs in terms of proportions but are much fatter and longer. Same size that is used in laptop battery packs.
chrispook2 years ago
Hi, I've got a cheap 18V battery pack that stopped charging and I'd like to rebuild it according to your instructions. When I opened it up I found a polyfuse in the middle of all the cells labelled JRM A55, which had shorted out. Should I retain this or replace it?
If I uprate the cells will the original charger handle the power or do I need to look at a new charger too?
mickmnr3 years ago
Hi, I read a fair bit about this topic here as I'm interested in having a pack to run a few cordless tools I have (mainly old drills 12, 14 and 18 V. and a edge trimmer) I also found on the net a site "Rambo Battery" . I seem to understand that it is actually possible to have a "half cordless" tool (that is with a short lead from the pack / porta-pack to the tool, which I think would be fine in most situations). But I don't seem to see any provision for a charger for these contraptions!
I read that the tool does not care where the power comes from and I like the idea of Lithium (rechargeable type) batteries.
Where I live in Sydney Australia they don't seem to have any idea about such alternative ("they" are tools suppliers, Electric retailers, and even battery businesses, such as battery world)
Here in this thread, one get the impression that is rather easy (with some basic idea) to build such apparatus, but it makes me wonder; for instance I have a Black and Decker cordless drill only a few years old but that doesn't seem to have its original battery available anymore and with a battery replacement (mostly out of stock!) and for which there is a very tinny warning: "will not work with original charger"!
My father had an interesting saying "I'm not rich enough to buy cheap things"
I have tried similar "alternatives" with refilling my own printer cartridges, but eventually gave up the idea although it was indeed a cheaper option but at a cost although not monetary. I wonder if contemplating this battery power alternative falls in the same category.
Just the same the idea of a universal pack for cordless tool is indeed very attractive.

CATX205 years ago

Hi, my cordless tool uses 1.2ah sub c cells would this matter if i replace them with 2.0ah sub c cells or would this damage the tool?

mikej_w CATX203 years ago
A change in Ah - Amp-hour - and will not hurt your tool. If the cells fit, AND are the same chemistry AND are approximately the same voltage, you will be fine.

The biggest danger for the tool is to have too high a voltage, as in heavy use the motor may burn up.

The other problem is with the charger. Your charger is very specific to battery chemistry. Each chemistry has it's own needs. NiCd is the simplest to charge. Hydride batteries are more complicated to charge, and a Nicad charger will charge them but they will have a shorter than desired battery life.
Lithium cells are great, but they need a precision charger. The voltage per cell is much higher, so you could possibly put in fewer of them, with larger Ah to get better battery life per volume.

You could possibly replace the guts of an existing charger with an off the shelf charger from the R/C market to take advantage of these cells.

Oh. The simple answer is just to keep the voltage sane. > Ah won't harm the tool.
Murch773 years ago
I get a kick out of all the RC car products... I thought the exact same thing when I opened up my drill battery!! I have some 3300 Mah NiMH matched cells from an attempt of getting back into racing that are just sitting in storage... They're going to need some attention first, but I might build some "hot rod" batteries!!
arpruss4 years ago
I wonder if using Wire Glue would work for the tabs? I don't know how well it stands up to the temperatures batteries reach.
motor1374 years ago
I have built approximately 6/7 battery packs using the solder method. I typically dope and tin both contacts. I buy about half of my subC cells with the tabs to reducing the amount ofhard soldering.

I have done a fair amount of soldering in my day and have been cautious about overheating the cells, although Ihave messed up few. Never had one explode or anything.

Hears the deal, recently was at Battery Plus and we all know that they pack batteries with a spot welder. I was explaining how and what I was doing and he said he was a fireman and he knew of someone that had a cell explode and burned up his house... He said it was extremely dangerous to do without a spot welder. He would do them for $$$. Now was this a scare tactic or what??? I have a case of SubC cells sitting in the garage wondering?? hmmm comments please. Oh I am using a temperature controlled soldering pen sith a flat screwdriver type end.
archer6817j (author)  motor1374 years ago
That sounds like a scare tactic :) Like I said in another response, RC enthusiasts have been doing this for decades. Just don't overheat the cells :) Any tool, used incorrectly, can lead to injury. Just be smart!
motor1374 years ago
ok, been building my packs witha Weller Solder Station, pen. I can adjust the temp and the tip,usually used the screwdriver blade tip. Any idea what temp you think is ideal?
archer6817j (author)  motor1374 years ago
The short answer is that you should use the "right" temperature :) It's best to solder batteries hot and fast. You don't want to apply heat for a long time and "soak" the battery.
tallman20094 years ago
These instructions to rebuild a battery will work, but there are some serious issues with it. Number 1 - you should not solder on the cell terminals. Soldering on cell terminals will ruin the cell and greatly shorten its life. That is why you see spot welds on the original tabs connecting the cells together. You should buy cells with tabs already spot welded on for rebuilding batteries. You also need to be concerned about adding height to the cells with solder etc. so the case will close.
You also need to test the connections as you go so you don't end up with shorted cells or wrong connections. If you want to build a battery superior to the original battery that will run any tool at any voltage, check out the Rambo Battery. The Rambo Battery kit is simple to build and it allows you to run your tools at a few volts over the tool voltage - 14.4 volt tool running at 18 volts for example. You will really enjoy the extra power and speed you get. You can also configure a Rambo Battery using NiMH cells rather than NiCD cells for much more power.
archer6817j (author)  tallman20094 years ago
First, "Number 1 - you should not solder on the cell terminals. Soldering on cell terminals will ruin the cell and greatly shorten its life."

This is absolutely false. If you "overheat" the cells you can damage them, but people have been building high-performance racing batteries for RC for decades by soldering on battery bars.

Second, this sounds like a product advertisement and I'm tempted to flag it as such.
reddnekk4 years ago
Need some advice. I have every 18v. tool Ryobi ever built--bot first ones in 1993, and they still work fine. But the batteries--have about a 9mo life if used heavily; price has gone from$20 to almost $50 in the past couple of years. So had about 8 bad batteries on hand. Now Harbor Freight 18v. batteriest are dirt cheap--have paid as low as $6. So first took guts out of Ryobi battery, replaced them with guts out of Harbor Freight battery. Finally woke up, and now just take the top stem part off the Ryobi, do the same to the Harbor Freight battery, then connect the wires from the Ryobi to the battery pack in the HF, and glue (and tape) the Ryobi top to the HF bottom. Am using the Ryobi chargers (have six) which have a trickle charge and a fuse inside, and so far everything seems to work OK. Now, am I doing something I shouldn't? Am I risking fire or tool damage? Need to know, because am now working on plugin adapter for these tools so can run them on house current.

chenxinghao6 years ago
What type of screw drivers did you use to losen the screws and open the case? My Craftsman 19.2 volt battery seems to require a special tool similar to torax but there is a little dot in the middle that is preventing any tool to get in to the spot.
You need "security" fastener bits. Harbor Freight has them for pretty cheap - http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=91310 or http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=93388

Unfortunately there are quite a few slightly different bits and if you don't have the right bit you quite often can't get the fastener out.
Deguacas allen4 years ago
When all else fails, use a dremel with a small cutting blade (carefully!) to cut a slot on the head of the screws, then use a reglur flat blade screwdriver
A trick I learned from a buddy who works on arcade machines told me to take a screwdriver, put it against that little post and wack the end with a small mallet/hammer. It breaks the pin out and allows you to use a standard bit for removal. Apparently, he does this so often that he carries a mallet around.

Gotta love those "Fine Adjustment" tools.
putnamcs5 years ago
Great Instructable. I too was frustrated with the cost of replacement batteries (for me it was my Craftsman drill). I didn't go all the way to 'hot rod' my battery pack, but your Instructable gave me the confidence to tear into it, find the dead cell, replace it and get my drill back from the dead. My battery cost $4.58, locally, at a store called Batteries+. That was the entire cost of the repair. One cell and solder I had on hand. Bravo. Thanks for taking the time to document this Instructable.
Can you please tell me how to identify the dead cell ?
Thanks !
matroska5 years ago
Protip: Did you know you could do the same thing with laptop batteries? Ha! Except, in laptop batteries it's a less common battery type, normaly the 18650. If you have some dead laptop batteries, try and open them. You will notice batteries that will look like AAs but that are longer. Once you identified the battery type (again, usually 18650) you can find a place to order new ones online and replace the old cells.
wrksnfx5 years ago
If your skills at soldering has you trembling there are places like http://www.batteriesplus.com/ that if you take in your dead pack they will take it apart and see how it's put together and build you a new battery bundle my brother did this with his Vietnam issued metal detector.
sharlston5 years ago
you will not be able to get shocked by a drill battery
This is the place where you're most likely to screw it up. I avoided the problem by buying the batteries with solder tabs already attached.
Poppy#16 years ago
Can I use Nimh batteries instead of Nicd? I am trying this with a Dewalt 18v battery pack.
syruss Poppy#15 years ago
make sure ur charger will charge both Nimh and Nicd batteries
Poppy#1 syruss5 years ago
Thanks, I have pretty much given up on this. It can be done easily enough though and by the time I add the cost of batteries, I have found that I can buy replacement refurbed powertool batteries for about the same. It was fun to do though and easy. Thanks for the help.
irishjim686 years ago
You could always VERY CAREFULLY drill out the post in the middle of the fastener, then use an "Easy Out" to get it out of the hole and replace it with a phillips screw of the same size.
eight8 years ago
Hey archer6817j,

Now this is a real instructable.

1. It is a genuine project
2. It justifies the time it takes
3. It saves money and the planet.
4. It is well documented.
5. You have included relevant links.
6. It gets eight's approval. (The sticker is in the mail, mate !)

Here are a few thoughts n the project and various comments/questions...

I use RUSTEX (35% phosphoric acid) for tinning wires and metal tabs when soldering. It is cheap and can be used for pacifying rust on cars and steel.

You can buy very wide heat shrink tubing to hold packs together.

NiCd cells can dump much more current in a split second than NiMh.

NiMh needs a special charger.
If you use a NiCd charger it will work to a point... but you wont get the depth of charge and neither Charge or Batteries will last long.

The biggest "D size" cells I can find locally have 9Ah capacity. (9000 mAh)
These wont fit in this project, but man -o- man what a charge life :)

Many older laptops used a "A" cell ( 2.0 Ah or 2.2 Ah ).
"A" cells are same length but bigger Diameter than "AA" cells.
Since "AA" cells now have 2.6Ah capacity, you can make lighter packs when rebuilding.

FYI, Duracell make 1.0Ah "AAA" NiMh.
I have been quite busy modding various torches and other items with these smaller cells.

Sorry for a long post... Lots to say : )
Ian01 eight8 years ago
This is an A cell, big and rectangular
eight Ian018 years ago
No mate. An "A" cell is like an "AA" cell but slightly larger diameter. I got mine from an early (Pentium 3) laptop power pack.
For anyone still reading, that is NOT. an A cell. It is an 18650 cell. Look it up.
Wow... I said that 2 years ago.
Mud Stuffin6 years ago
Exactly the same kind of drill that just died on me. Thanks for the info!
dlfynrdr7 years ago
If you mess up and overheat the batteries while soldering them together, how obvious is the results? Does the thing blow up in your hands, or do you just find out you can't charge the sucker? Or is there a quick way to tell with a multi-meter?
archer6817j (author)  dlfynrdr7 years ago
Excelent question and I have no idea. I would imagine a minor overheat would harm the battery internally and if you had a major overheat it might rupture. You should try to get the joint soldered in the first go. If you mess up and have to try again it's best to let the battery cool off a bit. My rule is if it's too hot to touch then it's too hot.
archer, how easy is it to get the top battery out of the casing without breaking it. I am trying to re-do a DeWalt 18v drill/powertool battery and would appreciate any info that will keep a klutz (me) from busting everything.
archer6817j (author)  Poppy#16 years ago
I think my battery was just held together by three screws. There might be some glue involved. Caution is advised since the plastic the battery case is made of is probably brittle and will crack/break if you do too much prying.
I think I will be able to unsolder the gizmo from the batteries. The tabs they have on them are pretty long and I can pull the battery part way out of the fitting charging thing, but I am guessing that I will be able to unsolder it and remove the 1 battery and replace it that way and then solder the tabs to the pack of batteries after that. Will let you know. Thanks for the answer so quickly.
The batteries are welded to those tabs. It is a special two prong spot welder. The prongs look like two black pencils with wires going to a transformer. You can however use batteries with the tabs already attached. This makes the connection easy to soldier
Thanks for the input. My problem seems that I cannot get the soldering gun hot enough. I kind of gave up on it and gave it to my son (the Mechanic, Computer guy in the family) to see if he can make it work for me.
You can also try a metallic epoxy. Not sure on who would have it but I have used it to fix brushes in dc motors. This item is usually found in a electronic surplus store.
Thanks, will see if I can that around here. Thanks again.
Poppy#16 years ago
From what I have been able to find out NiCd batts will have a much longer life than the NiMh type. Also, in my searching I have managed to get myself on some lists that all want to sell me stuff or want me to buy a franchise etc etc. So be careful when you are traipsing around the net for info. As you can probably tell from my incessent whining here I am new to this, so any help or tips or comments will be appreciated.
NiMH batteries also can not charge properly in a parallel setups.
Fixerdad6 years ago
Sorry to be a wet blanket, but I've found that a lot of battery packs are glued together. Take your time prying them apart. The one's I've tried only had glue in strategic spots but it was still a pain.
Poppy#16 years ago
I have been having a hard time finding Nicd batteries of the Sub C 2000 Mah at a reasonable price. I would appreciate any direction that anyone could give me on this search. Most of the places I have looked at want 2.50 on up per battery and that is in quantities of 50 or more. Also from what I have been able to find out the Nicd batteries will have a longer life span than the Nimh batteries. Thanks in advance. Jim
joetmari6 years ago
Has anyone opened a panasonic 12V battery?
xad6 years ago
What would happen if you used 1.2v AA size batteries instead of SC? My drill has 1.2v SCs rated at 2100mah - i have AA's that have the same specs. What is the difference between the SC and AA version? The mah rating and voltage seem the same.
Derin7 years ago
sub-c?man even my aa rechargeables are 2700mah
fegundez18 years ago
this is killer.i had thought this was so but hadent the time to try it,it looks the same for phones etc.how do you tell if the replacements arnt going to burn up the windings etc?
I actualy just did this with the battery for my iBook but going from 8 Li-ion cells to 12 NiMh cells reduced the capacity from 4000 to 1800mah but should give a longer battery lifetime overall. the replacement cells he used have the same voltage but an increased capacity. since it is the drill and not the battery that decides how much current to use this can't damage the drill. great job btw I like those battery bars I used bits of wire that I ripped out of a computer psu for mine.
ho do you drop the maH and have longer battery time? ug. me cunfuzed
archer6817j (author)  technodude927 years ago
Beats me. mAh is not a direct measure of a battery's capacity, but it's generally used to reflect the "ammount" of charge a battery can hold.

That is, a battery with more mAh can store more usable charge = longer life given that it is used in the same device...in my understanding.
He seems to be under the impression that NiMH batteries have a longer "life," i.e., more usable charge cycles, than Li-ion batteries. As a matter of fact, this could become true if the Li batteries are not well taken care of. Many laptop batteries are neglected by being left in the warm temperatures of the laptop on ...well, your lap. Plugging in your laptop to keep the Li-ion battery topped off can also lower its number of lifetime cycles. Under these circumstances, NiMH batteries are more suited for "set 'em and forget 'em." Aside from that, however, Li-ions are superior for lifetime if one simply takes care of them.
dlfynrdr7 years ago
I've seen about a dozen posts arguing about wether or not you can use your old NiCad charger after you've suped up to NiMh. Let's just assume for a minute that it is a bad idea. (The thing blows up and the world market crashes for example) Does anyone have a diagram for building your own charger? Or will the charger they sell for use on the Big Wheel trucks kids ride around on work? I don't know about you guys but I can't affor one of those $80 universal "charge everything and the horse you rode in on" chargers.
archer6817j (author)  dlfynrdr7 years ago
80 bucks sounds awfully cheap to me for a universal charger. At that price I'd be skeptical if it was a good one. It's especially cheap if you consider the price of OEM batteries. Where can I get one? I'd get one in a flash. The chargers for my RC cars are at least a couple of hundred...or at least they were when I bought them ages ago.
Derin dlfynrdr7 years ago
i dont want to be mean but here goes: he upgraded to nicd and the original was nicd so the charger can be used with the battery only it would take longer to charge
I'm going to give this a go with my Hilti drill battery thats died, I was quoted over $230 au for a replacement, have nothing to loose but hundreds to save thanks mate :)
Ibanezfoo7 years ago
This is a great instructable! I've used this same method for these types of packs, cordless phone packs, and other things. You'd be surprised how many of these seemingly proprietary battery packs are just filled with standard AA/AAA/C/D type nicads and nimh batteries.
mikesty8 years ago
Nice, but how do I tin the ends of the battery?
archer6817j (author)  mikesty8 years ago
I guess I should have taken some photos of that. I forget sometimes...well okay, a lot of the time. Basically you put a little glob of paste-tyep flux on the end of the battery. Flux helps the solder flow evenley instead of forming a big glob. I like to flux the tip of my iron as well and then melt a little droplet of solder to the iron. Quickly move to the battery terminal and as it develops enough heat the solder will flow from the iron onto the terminal. Remove the iron immediately to avoid over heating. The same technique can be applied when soldering the bars. Flux the end of the bar, place it on top of the tinned terminal. Put a drop on the end of your iron and heat the top of the bar. The solder will flow down through the hole in the bar and onto the top of the battery when the heat is "just right." Remove the iron and hold the bar in place till the solder turns from shiny to dull. It will take a few seconds to cool and solidify.
Would it be possible to use a "heat sink" to prevent heat issues? We always had to use heat sinks when soldering delicate chips & such - just an aligator clip without teeth.
How powerful was the soldering iron you used here? My soldering weapon of choice is the ColdHeatPro; do you have any idea of how that would perform here?
archer6817j (author)  Liquidhypnotic7 years ago
You will need a powerful soldering iron...probably one of the gun type, dual heat beasties.
I think you'll need something more powerful than a ColdHeat iron.
LarryB8 years ago
Sorry, I'm so cheap, most NiCad cells fail from internal short circuit caused by conductive threads that build internally, check the web for "zapping" the bad cells and recharge, even if you don't fix it for long, the remaining OK cells can be used to replaced really bad cells in another power pack. These sub "C"s are pretty common. I also rewired a failed battery pack to an external 12V 7.2Amphour gel cell. So now it is "semi-cordless". The drill was less than 12 volts, 9.6? but it works fine at 12 volts DC and I've got plenty of battery capacity with a 6 foot leash.
I get loads of old 9.6v drills at the dump. They work much better on 12v. I usually stick on a cigarette lighter pluggy cord from a dead spotlight or car vac, or some such, and use it in the van, until: a; I lose it under a pile of junk, b; the motor packs it, or c; the van's alternator goes for a poop, and I can't get the *%% bolt out to replace the bugger...
If I wasn't so lazy, I'd take a couple or three 6v gell cells, stick 'em to a tool belt and wire a dill to that. (oops, I mean a drill, dang this keyboard..) Maybe even do two and have real badass holsters and so on; do some quick draw screwin' and drillin'...
Ian01 LarryB8 years ago
Here is an instructable for zapping batteries with a welder:

Also see The ZAP-Adaptor by Tony van Roon, a cicuit to zap batteries.
Here is a patent for "Process and apparatus for nickel-cadmium battery revival," a guide for restoring batteries, and battery FAQ.
If i do this i would get 3500mah ((Nickel Medel Hydrate)) batteries. Nickle metal hydrate batteries are great, because they dont have the memory effect as NiCad (nickel cadium) batteries do, therefore you can charge them up without being completely run down so you have full battery power when you need it!
Nickel Metal Hydride Nickel Cadmium Is you airsoft charger designed for NiMH?
If you pulled out NiCD, then the charger is probably a NiCD only charger. Trying to charge NiMH batteries with a NiCD charger is not a good idea.
Eh. But i have a airsoft SMART charger (has aligator clips) you could put the positave to positave, negitave to negitave. and charge it fully. (The smart charger automaticly turns off charging when the battery it 100% full) :-D
samspock8 years ago
Some black and decker outlet stores have 9.6volt slide type battery packs for $1.98. I bought a bunch of them. They have 8 cells each and are physically the same size as the 12 volt slide packs. Just put in the missing two cells and shave off the 9.6v tab on the top an you can use them in 12volt tools. You can also use the cells to repair other packs. I fixed two of my 13.2 volt stem packs using these. They are so cheap since they only made 2 drills for them and don't sell them anymore.
DanYHKim8 years ago
I tried something like this to rebuild a NiCd battery pack for an old laptop computer. I found that tinning the battery terminals was made easier by scraping a small patch of the metal with a knife right before applying the flux. The rough spot made a better seat for the solder, and I probably scraped off a layer of oxide as well.
russtang8 years ago
Weird, I did almost the exact same thing last weekend for my Black and Decker drill :0. Refreshed both my dead nicad packs. I started with pre-made drill packs from harbor freight (item 90712). Disassembled them and had to rewire 3 or 4 cells to fit the same form-factor. I just cut the battery straps in the middle and re-soldered them in their new locations. Re-used the B&D case and connector. The replacements are 1000mAh nicad cells, and are lighter than the original so I assume they are smaller capacity (forgot to check the bottom of the B&D firestorm pack). But for $12.50 for 2 packs (on sale), I couldn't go wrong! Russ
chuckr448 years ago
I don't understand the issue with soldering here. It's easy. Just use a solder gun or soldering iron, not a flame-based torch like you would with plumbing. I solder LEDs and resistors this way all the time with no failures.
You should really spot weld the battery packs instead of soldering. I think there is an instructable somewhere about building a capacitor bank for welding battery cells. Heating the cells hot enough to to get solder to stick to them can damage the batteries. I thought about doing this for one of my batteries, but I really didn't want to blow $30 on batteries that I might damage soldering. I ended up buying a new drill.
archer6817j (author)  benjamenjohnson8 years ago
Do you have a link for that? I'm pretty lazy...especially since my battery is done. It is true that overheating your battery will kill it. However, custom battery builders for RC pretty much always solder packs together so it can be done. I've made dozens of battery packs and never had one fail. Most of those were with batteries that cost about ten bucks a cell.
OK so it's not an instructable but here's the link.
bmake8 years ago
If you were to use Nimh batteries would you be able to use the Nicad charger?
vatosupreme8 years ago
Someone Just told me that you can freeze these and then thaw them out and you could rechage them. Anyone able to verify or refute?
BrianH8 years ago
I did this a while ago with a craftsman drill.
Another Drill Mod
The most significant feedbacks that I got were:

1. Be sure that you have a fusable link to protect from short circuit damage. (I re-used the one from the original pack)

2. Batteries that come with solder tabs have the advantage of reducing the heat that will the cell will subject to while soldering. (Excess heat on the cell could possibly cause the vent seal to fail prematurely).

3. Ensure that the charger is appropriate for the new batteries. (I am still using the old charger - I did the math, and the NiMh batteries need a much longer charge using the old charger than the nicads did. )

I had great success with mine.
rdy4trvl8 years ago
Great Instructable! I'm curious how you opened the plastic housing - looks like there may be screws. Anyone with a Makita (model # 1233) that figures it out - please let me know...or I'll post if I do.
archer6817j (author)  rdy4trvl8 years ago
My pack is just held together with five screws. The Makita packs might be harder to get appart.

The other problem with the stick type Makita packs is actually soldering the batteries end to end since you can't use battery bars.

Try Googling "assemble battery pack" or something similar. I found a guy who shows you how to direct solder two batteries together.