Refurbish a Makita 9.6 V NiCad Battery

Refurbish Makita 9.6 V NiCad Battery Makita 9.6 V NiCad Battery Refurbish-6095D Drill & Battery 9000
How to Refurbish Makita 9.6 V Battery

In this article I teach you how to refurbish a Makita 9.6 V NiCad Battery.  I have a beloved Makita 9.6V cordless drill and flashlight that have faithfully served me for over 20 years now and even though it doesn’t have all the bells and whistles (and power) that some of the new cordless drills have, I don’t intend on replacing them any time soon.  I was about ready to throw out this battery pack, which came with the drill back in 199x when I purchased it but the love of repairing, learning, and fixing overtook me so I decided to tear it open and see if I could install new 1.2 volt NiCad C battery cells.  I wrote about the process of opening up the case and removing the battery cells in the following article:

How to Disassemble a Makita 9.6V NiCad Battery Model 9000

After taking it all apart I decided I wanted to go ahead and replace the cells and refurbish it…

How to Refurbish a Makita 9.6 V NiCad Battery

Equipment Involved:

Tools Needed:

Parts Needed:

Step 1: Cut open the battery case

When I did this the first time I opened up the battery case along the the seam on the end.  Now that I’ve done one I suggest cutting it right in the middle of a cell so the part you cut off is like a “cap” on the end.  This will make it easier to disassemble the battery and eaiser to put the case back together and the cell itself will form part of the stability of the newly assembled battery:

Location to cut Makita 9.6 V NiCad battery case open
Where to cut the case open – 1 inch from the end

Here I am scoring a line 1 inch from the end to cut on:

Makita 9.6V NiCad Battery Marking Case For Cutting Open
Scoring a line to cut on 1 Inch from the end

I ran my Dremel pretty slow, at around 2,000 rpm:

Makita 9.6V NiCad Battery Run Dremel at 2000 RPM
Run Dremel at around 2,000 RPM

Here I’ve cut all the way around on the line:

Makita 9.6V NiCad Battery Case Cut
Cut all the way around, only as deep as the cardboard
Makita 9.6V NiCad Battery Case Cut and End Cap Off
The end cap will come right off

Step 2: Remove the old battery cells from the case

If you cut the case an inch from the end, like I show above, it will be VERY easy to remove the cells by hand–they should slide right out:

Makita 9.6V NiCad Battery Battery Cells Removed
The cells slid out in one piece

I wrote an entire article on how to disassemble this battery and you can read it here:

How to Disassemble Makita 9.6V NiCad Battery 9000

After I had the battery all disassembled I put together this diagram of all the parts and the polarity of the cells as they are arranged in the case:

How to Disassemble a Makita 9.6 V NiCad Battery
How to Disassemble a Makita 9.6 V NiCad Battery

Step 3: Remove the thermal switch

The thermal switch is spot-welded to the side of one of the end cells:

Thermal Switch Spot Weld Location
Location the Thermal Switch is Spot Welded on the End Battery Cell

Carefully pry it off the battery case.  I used a needle-nose pliers.  Pry up a bit and then adjust your grip on the tab so the tab doesn’t tear in half.  Here you can see I’ve pulled the tab completely free:

Thermal Switch Tab Pulled Free From Cell
Thermal switch tab has been pulled free from the cell

Once you have pulled the tab free you can use your needle-nose pliers to flatten the tab back out.

We must re-use the battery terminals, the thermistor, and the thermal switch and the are spot-welded to the old batteries.  You will need to keep track of where they were attached and we need to re-attach them in a location that allows them to fit into the black plastic piece that fits on the end.  Carefully pry them off the old batteries.  Here is the location where the positive and negative terminals are spot welded:

Spot Welds of Positive and Negative Terminals
Location of the positive and negative terminal spot welds

The thermal switch is spot welded on the side of one of the end cells:

Thermal Switch Spot Weld Location
Location the Thermal Switch is Spot Welded on the End Battery Cell

Here I have pulled the spot-welded thermal switch free from the side of the battery:

Makita 9.6 V NiCad Battery Refurbish-Thermal Switch Spot Weld Removed
Thermal Switch is pulled free from the battery

Step 4: Remove the thermistor

The thermistor is spot-welded in similar fashion to how the thermal switch is attached, on the other side of the same cell:

Location of thermistor spot welded tab
Location of thermistor spot welded tab
Thermistor spot welded tab removed from the cell
Thermistor spot welded tab removed from the cell

Step 5: Remove the negative battery terminal/connector

We are going to do one battery at a time to keep track of what goes where and we’ll start with the negative end.  Carefully pry the metal battery terminal tab off the negative end of the battery (NOT the button end) from the places it is spot welded.  In the series of three pictures you can see me carefully prying the (negative) battery terminal free:

Makita 9.6 V NiCad Battery Refurbish-Removing Battery Terminal Step 1
Time to remove the negative battery terminal
Makita 9.6 V NiCad Battery Refurbish-Removing Battery Terminal Step 2
Grab as close as you can to the battery with your needle-nose piers
Makita 9.6 V NiCad Battery Refurbish-Removing Battery Terminal Step 3
The battery terminal is free and ready to be re-used

Step 6: Prepare the first new NiCad cell for the negative battery terminal connection.

We need to transfer the negative battery terminal piece you just removed to the first new NiCad battery.  The replacement batteries have tabs on both ends and we don’t want a tab on the very end.  The way I removed the tab is to use my Dremel tool and cutting disk and make a slight score on the tab that allows it to break easily when you bend it.  If you buy the Tenergy batteries I link above you will be working with the red (negative) end:

Makita 9.6 V NiCad Battery Refurbish-Tab Scored By Dremel
The tab has been scored by the Dremel cutting disk and will break off easily
Makita 9.6 V NiCad Battery Refurbish-Tab Cut Off
The tab broken off

Step 7: Insert the negative end of the new battery into the end bracket and mark where the terminal should be soldered.

Everything needs to line up closely for it to fit back together so the best way I found was to insert the first new battery into the end bracket (note the polarity), place the negative terminal where it goes in the end bracket, and mark the location it should be soldered.

Important Note: It is critical how you have the battery oriented when you mark where the battery terminal is going to be soldered.  The new battery tabs cannot be on the side that touches the case, they must be in the valley, like this:

Makita 9.6 V NiCad Battery Refurbish-Tab Location Diagram
NiCad Cell Tab orientation diagram

One thing I’ll note is that you shouldn’t use permanent marker to mark the location (as I did in the picture below) because the flux you are about to put on the metal will smear the ink everywhere and you won’t be able to see your mark.  Mark the location by scratching it with the point of a pocket knife:

Makita 9.6 V NiCad Battery Refurbish-Marking Location of Negative Terminal
Mark the location to solder the negative battery connector to the new cell

Step 8: Prepare the pieces to be soldered

Because you want to avoid heating up the battery any longer than necessary we want to make it easy for the solder to stick.  You can ease your soldering by the following:

  • Sand or scratch with the tip of a knife the metal where it connects
  • Apply flux to both sides of the metal that are being soldered together

Scratching/sanding battery end:

Makita 9.6 V NiCad Battery Refurbish-Battery End Scratched Up For Soldering
I scratched the area to be soldered with my knife
Makita 9.6 V NiCad Battery Refurbish-Apply Flux Before Soldering
Apply flux to both parts before soldering

 

Step 9: Clamp everything in place and solder the tab in place

You cannot use your hands because everything is going to get hot when you solder this joint so you need to use clamps.  I used my extra set of hands tool, my 6″ clamps, and quick grips to hold everything right where I wanted it as you can see below:

Makita 9.6 V NiCad Battery Refurbish-Soldering Clamp Setup
My clamped up setup–ready to solder

A good setup is key for getting a good soldered connection:

Makita 9.6 V NiCad Battery Refurbish-Negative Terminal Soldered in Place
The negative terminal soldered in place

Step 10: Prepare to solder the thermal switch in place.

Now that you have the negative connector soldered to the end of the first battery you can feed it into place in the end bracket and see where the thermal switch needs to be connected.  Mark the side of the battery for where the solder connection will be because you will need to remove the plastic battery case to expose the side of the battery.  IMPORTANT NOTE: the side of the battery is the negative terminal of the battery.  DO NOT short the positive and negative or you could burn yourself or possibly explode a battery.  Here I am marking the location:

Makita 9.6 V NiCad Battery Refurbish-Marking Thermal Switch Solder Location
Marking where the thermal switch will be soldered

Cut the plastic case away and sand/scratch the surface to prepare for soldering:

Makita 9.6 V NiCad Battery Refurbish-Battery Case Cut Away and Sanded
Cut off the plastic case where the switch will be soldered

Step 11: Prepare to solder the thermistor in place.

With the battery in the end bracket mark the location where the thermistor should be soldered and mark where to cut away the plastic case wrapper just like you did in Step 10 for the thermal switch:

Makita 9.6 V NiCad Battery Refurbish-Marking Thermistor Solder Location
Mark where to cut away the battery case for the thermistor tab
Makita 9.6 V NiCad Battery Refurbish-Battery Case Cut Away for Thermistor
Plastic case wrapper cut away to solder thermistor

I recommend sanding the area where you’ll solder, I had not done that yet when I took the picture above.

Step 12: Clamp and solder the thermistor in place.

Clamp everything in place so nothing moves, sand all surfaces to be soldered, apply flux to both sides of the joint, and solder them in place.  Here’s my clamp setup for soldering the thermistor:

Makita 9.6 V NiCad Battery Refurbish-Thermistor Clamped For Soldering
The thermistor tab clamped in place
Makita 9.6 V NiCad Battery Refurbish-Thermistor Soldered in Place
Thermistor soldered in place

Here’s another look at the thermistor soldered in place, with the clamps taken off:

Makita 9.6 V NiCad Battery Refurbish-Thermistor Soldered in Place 2
Another view of the thermistor soldered in place

Step 13: Clamp and solder the thermal switch in place.

I had a harder time figuring out how to hold this solder joint tight.  Here’s my clamping setup for this soldering joint:

Makita 9.6 V NiCad Battery Refurbish-Thermal Switch Clamped For Soldering
Clamping setup for soldering the thermal switch tab
Makita 9.6 V NiCad Battery Refurbish-Thermal Switch Soldered in Place
Thermal switch soldered in place

I wasn’t real crazy about the solder joint I achieved above but this isn’t a high current connection so it just has to have good electrical connectivity.  One thing I’ll note is not to worry about melting the plastic battery case wrap–it doesn’t hurt anything.

Step 14: Remove the positive battery connector/terminal

Pry it off just like you did the negative one:

Makita 9.6 V NiCad Battery Refurbish-Positive Battery Terminal to Be Removed
Remove the positive battery terminal

Step 15: Prepare the new NiCad cell for the battery terminal

Cut off the tab from the positive end of one of the batteries just like you did in Step 6 except doing it on the positive end instead:

Makita 9.6 V NiCad Battery Refurbish-Positive Tab Removed Off New Battery
Cut the tab off the positive end of a new NiCad cell

Insert the new cell into the end bracket, positive end first (button end) and mark where the positive connector should be soldered.  Just like in Step 7, make sure you pick the opposite side to run the tab down and orient it as diagrammed below or your cells will never fit back into the original battery case:

Makita 9.6 V NiCad Battery Refurbish-Tab Location Diagram
NiCad Cell Tab orientation diagram

I forgot to take a picture of this step when I had the new cell in the end bracket but you can review what we’re doing by going back to Step 7 if you want.  Here you can see I’ve marked the location with marker and then I followed it up by scratching in the mark with my knife so it doesn’t get washed away by the flux:

Makita 9.6 V NiCad Battery Refurbish-Location Marked to Solder Positive Connector
Positive terminal location marked

Step 16: Solder the positive connector in place

Sand the surfaces, apply flux to both sides, and then clamp everything in place:

Makita 9.6 V NiCad Battery Refurbish-Clamping Arrangement for Soldering Positive Connector
How I clamped everything in place to solder the positive connector

Here’s my solder joint:

Makita 9.6 V NiCad Battery Refurbish-Positive Terminal Soldered in Place
Positive terminal soldered in place

Step 17: Insert the cell with the positive terminal into place in the end bracket

You’ll need to bend the positive and negative terminals a bit to get everything to fit.  I had to trim off part of the plastic end bracket too, because my solder was running into it and the cell wouldn’t go all the way in.  Here’s what it should look like from the thermal switch side:

Makita 9.6 V NiCad Battery Refurbish-First Two Cells in Place-Thermal Switch Side
Thermal Switch Side

And the thermistor side:

Makita 9.6 V NiCad Battery Refurbish-First Two Cells in Place-Thermistor Side
Thermistor Side

Step 18: Use some clear tape to tape the cells together

This will help hold everything together for you:

Makita 9.6 V NiCad Battery Refurbish-Fist Two Cells Taped Together
Put a wrap of clear tape around the first two cells

Step 19:  Solder the next three cells in series starting on the positive end

You will always be connecting the positive end of one battery to the negative end of the other.  Put the two cells together, remove the tab heat shrink, sand where they’ll contact each other, bend the tabs so that when the cells are put together that the tabs press together, apply flux, clamp them together, and solder into place:

Makita 9.6 V NiCad Battery Refurbish-Third Cell Clamped For Soldering
Clamp the third cell in place and solder the tabs together
Makita 9.6 V NiCad Battery Refurbish-Third Cell Soldered
The third cell is soldered
Makita 9.6 V NiCad Battery Refurbish-Fourth Cell Clamped For Soldering
Fourth cell clamped in place and ready to be soldered
Makita 9.6 V NiCad Battery Refurbish-Fourth Cell Soldered
Fourth cell’s tab soldered
Makita 9.6 V NiCad Battery Refurbish-Fourth Cell Clamped For Soldering
Fourth cell clamped in place and ready to be soldered
Makita 9.6 V NiCad Battery Refurbish-Fifth Cell Soldered
The fifth cell is soldered, one row is done

Step 20: Finish soldering the last three cells in series

I won’t show every picture because they are all the same but keep soldering cells together, connecting positive to negative end until you have all three done:

Makita 9.6 V NiCad Battery Refurbish-Eighth Cell Soldered
Two rows of four soldered together

Step 21: Cut off the end tabs and prepare them for bridging the cells

To make both rows of cells add up to 9.6 volts we need to solder together the ends of both rows.  Unfortunately the tabs do not line up so we cannot use them to bridge the cells they way they are oriented.  Cut off the tabs like we have been doing:

Makita 9.6 V NiCad Battery Refurbish-Score both End Tabs
Score the tabs with your Dremel and cutting wheel

Straighten out the tabs and sand both sides:

Makita 9.6 V NiCad Battery Refurbish-Tabs Straightened and Sanded
Straighten and sand both sides of the tabs

Step 22: Solder the two end cells together.

I taped both rows of cells as tightly together as I could so they are where I want them when I solder the ends together:

Makita 9.6 V NiCad Battery Refurbish-Rows Taped Together
Put a wrap of tape around the two rows to hold them tightly together

This is the goal, to have the tabs soldered in place as seen here:

Makita 9.6 V NiCad Battery Refurbish-The Goal--Cells Bridged
This is where I want the tabs soldered

It is a bit tricky to clamp the batteries still and hold the tabs in place for soldering.  I ended up clamping one tab in place and soldering it to the battery first:

Makita 9.6 V NiCad Battery Refurbish-End Tab Clamped in Place
Bend the tab to fit tight, clamp, and solder in place

Then I soldered the two tabs together:

Makita 9.6 V NiCad Battery Refurbish-Solder the two tabs together
Solder the two tabs together

And then solder the other end to the other battery cell.  I forgot to take a picture of that.  Here’s what you’ll have when you are done:

Makita 9.6 V NiCad Battery Refurbish-Cells All Soldered Together
Here’s the view from the thermistor side
Makita 9.6 V NiCad Battery Refurbish-Cells All Soldered Together-Thermal Switch Side
The view from the thermal switch side

Step 23: Check the voltage of your new battery pack.

When you are done if you measure the voltage with your multimeter you should get right around 9.6 volts if you measure the voltage between the battery terminals on the end.  Caution: Be careful not to bridge the two battery connections together with the leads of your multimeter.  I got 10 volts, which is just perfect for fresh batteries:

Makita 9.6 V NiCad Battery Refurbish-Newly Soldered Battery Measures 10 Volts
The new battery measures 10 volts–perfect!

Step 24: Glue the thermistor in place

The thermistor wiring was glued to the side of one of the cells so I used my hot glue gun and glued it back in place:

Makita 9.6 V NiCad Battery Refurbish-Thermistor Wiring Glued in Place
Hot glue the thermistor wiring in place

Step 25: Insert the battery cells into the case.

Take note of the orientation of the connections on the end so they line up when you insert the batteries into the case:

Makita 9.6 V NiCad Battery Refurbish-Battery Connector Alignment
Make sure to insert the battery correctly into the case

Carefully slide the cells in:

Makita 9.6 V NiCad Battery Refurbish-Inserting the Cells into the Case 1
Carefully insert the bracket end in first, oriented correctly

You can hold the case and push down on a hard surface to push them in.

Makita 9.6 V NiCad Battery Refurbish-Inserting the Cells into the Case 2
They are a tight fit

The cells should go all the way in until the terminals show up in their openings and the top is flush:

Makita 9.6 V NiCad Battery Refurbish-Cells All The Way In
The terminals should go all the way up into their openings

Here’s a look at my refurbished battery (left) by a factory battery.  As you can see below, the right terminal (on the left battery) doesn’t quite line up perfectly with the hole but I used a heavy knife and moved it into place.

Makita 9.6 V NiCad Battery Refurbish-End View of Refurbished by Original
Comparison between my refurbished (left) and an original battery (right)

Step 26: Prepare the end cap for reassembly

If you follow the instructions I give above, you will need to still Dremel out these the fins on the inside end of the end cap:

Makita 9.6V NiCad Battery End Cap Dremeled
Dremel out the fins inside the end of the cap

I learned a lot by doing this the first time and just had cut the end off.  Because we are soldering our own cells together and the tabs add length to all the batteries, this makes them just a tad bit too long.  This forced me to use a Dremel tool to cut out the structure inside the end:

Makita 9.6 V NiCad Battery Refurbish-Dremel Structure Off End Cap
I had to remove the two ridges from the end cap with a Dremel
Makita 9.6 V NiCad Battery Refurbish-Dremelling Structure Off End Cap
Here I’m cutting off the tabs that are in the way

Now we have some more room:

Makita 9.6 V NiCad Battery Refurbish-End Cap Cleaned Up
End cap cleaned up

I decided that before I do anything semi-permanent I ought to test the pack out and it worked perfectly:

Makita 9.6 V NiCad Battery Refurbish-Testing Battery Pack Out
Testing the battery out in my flashlight

It was hard to get out and I had to tap it on the table to get the battery to come out (because the tabs on the end cap are important for removing the battery from the tool).

Step 27: Use tape or some kind of adhesive to re-affix the end

This step will differ for most of you if you follow my suggestions and learn from my mistakes.  When I did this the second time and cut the case an inch from the end I was able to simply use packing tape to attach the end.  I used my quick-grip to squeeze it all together and then put a round of clear packing tape on it:

Makita 9.6V NiCad Battery Taping The Case Together
Tape the case together

Here’s what I had to do to put this thing back together the first time I did this repair (and it didn’t turn out bad though).  Test how things are going to fit first:

Makita 9.6 V NiCad Battery Refurbish-Testing Fit of End Cap
Testing the fit of the end cap–it’s gonna be tight

I planned to use a clamp to smash it all together tightly so I figured it would work if I used epoxy.  Mix some 5-minute epoxy.

Makita 9.6 V NiCad Battery Refurbish-5-Minute Epoxy
5-Minute Epoxy

I’ve found that a split shim works great for mixing and applying epoxy (much better than a popsicle stick because they are flat and thin on the end):

Makita 9.6 V NiCad Battery Refurbish-Shim Stir Stick
A split shim makes a good stir stick

Make sure to mix it good:

Makita 9.6 V NiCad Battery Refurbish-Epoxy Mixed
Mix the 2 parts thoroughly

Apply a healthy amount to the end cap:

Makita 9.6 V NiCad Battery Refurbish-Epoxy Applied to End Cap
Apply a bunch to the end cap

Put the cap on and watch out for it to go everywhere (I planned on that though):

Makita 9.6 V NiCad Battery Refurbish-Cap on With Epoxy
Carefully apply the end cap to the battery

Put a wrap of packing tape around it to control the flow:

Makita 9.6 V NiCad Battery Refurbish-Control Flow with Packing Tape
Use packing tape to control the flow

Step 28: Clamp it all back together tight

Clamp it with the glue end down to hold it all together and to squeeze the cap onto the end tight:

Makita 9.6 V NiCad Battery Refurbish-Clamp Glue End Down
Clamp with the glue end down

I have a heavy duty bar magnet mounted above my desk that I use to store tools while I’m working (to get them out of the way and keep them accessible) and it worked great to hold the clamp while it dried:

Makita 9.6 V NiCad Battery Refurbish-Clamp Held By Magnet Bar
I used my mounted bar magnet to hold the clamp
Makita 9.6 V NiCad Battery Refurbish-Close-up of Glued End
A closer look

Step 29: Wait for the epoxy to set

I let the epoxy set for 2 1/2 hours before I took the tape off and then this was what I was left with:

Makita 9.6 V NiCad Battery Refurbish-Epoxy Dry Tape Off
The unfinished result with the tape off

Step 30: Clean up the excess epoxy with a knife

Be careful because there is plenty of opportunity to drive a knife into your thumb while doing this but clean up the excess epoxy around the end.  It turned out really nicely when I was done:

Makita 9.6 V NiCad Battery Refurbish-Epoxy Cleaned Up
Epoxy cleaned up with a sharp knife

And the battery fits great into my drill:

Makita 9.6 V NiCad Battery Refurbish-Refurbished Battery in Drill
Battery fits perfectly!

This repair was a lot of fun!  Let me know in the comments if you refurbish yours!

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6 Comments

  • Great post but can’t you buy them on eBay for $10.00 already refurbished? What am I missing?

    • Yes, you are completely correct, that’s why I wrote the following in the introduction of the article: “I was about ready to throw out this battery pack, which came with the drill back in 199x when I purchased it but the love of repairing, learning, and fixing overtook me so I decided to tear it open and see if I could install new 1.2 volt NiCad C battery cells.

    • Thanks for your question. The individual cells are exactly the same as the replacements I prescribe in the parts list at the top of this article, and as described in the listing:
      Makita Replacement Battery Cells.
      Product Link: Makita Battery Cells

      Does this give you the information you need?

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