Craftsman 19.2v Battery Fix

by jdmorrisw

73K2318

Intro: Craftsman 19.2v Battery Fix

I bought two of these 19.2v lithium batteries for my Craftsman Drill on eBay and was very happy with their low weight and high power. The joy ended after only one or two recharges, as the batteries would no longer charge. The charger would show the fully charged green indicator light even though it had no charge. Worse, the company who sold them to me was no longer registered on eBay. It looked like a total loss. Out of curiosity I took one apart to see if I could figure out the problem. Nothing was obviously the problem as far as the circuit board was concerned. The thought occurred to me that the batteries might be good and could be charged with another charger. I simply removed the circuit board, verified that the batteries were connected in series and bought a universal laptop charger with multiple voltage settings. I soldered a couple of wires, reassembled the battery without the circuit board and charged it with the laptop battery charger. It worked fine. With the second battery, I took pictures so you can see the process.

STEP 1: Needed Tools and Accessories

#10 Torx bit and driver

Scratch awl

Needle nose pliers

Wire cutter

Wire stripper

Hot glue gun

Soldering iron

Soldering paste

Solder wick

Solder

Shrink tube

Small piece of black wire (about 4")

Universal multi output voltage laptop charger with 20v output option

Two small red and black insulated alligator clips

STEP 2: Open the Case

If you have a #10 security torx bit, use it to remove the 4 screws from the case. If you only have a normal torx bit, first use the scratch awl with enough pressure to break off the little pin in the middle of the screw head. You might have to come at it from several angles but it can be done. Then, you can remove the screws with the normal torx bit, pop the top off and remove the two plastic locking tabs.

STEP 3: Remove the Circuit Board

First, pry up the white plastic charge connector support so it is loose. Remove the 4 small screws holding down the circuit board. Cut the four thinner wires from the outer edge of the plastic battery holder (three red and one blue). Cut the black wire at the charger connector terminal, and also cut the blue and red wires (that are visible from the same side as the black wire) at the connector terminal. Do not cut the red wire that is opposite the black wire at the connector terminal, but rather cut it at the circuit board. Desolder the battery connector tab from the circuit board as shown. Pry the circuit board up from the tab you just desoldered and tilt up the circuit board. Cut the red wire from the bottom of the circuit board. Remove the sponge tape holding the thermal protector on one side of the battery case and remove the circuit board. Separate the charge connector stand from the circuit board.

STEP 4: Rebuild the Battery

Set the charge connector base back in its original position with the two pins in their respective holes. Use the glue gun to fill in the space and to attach the other two legs to the battery holder so it will stand firm. Strip the red wire from the charge connector and the other red wire from the battery pack. Place a piece of shrink tube over one wire, solder the two together and cover the joint with the shink tube. (I know. That's a duhh.) Find another piece of similar wire (black if possible) and solder one end to the charge connector where you cut the original black wire. Solder the other end to the tab on the battery pack that was desoldered from the circuit board. You are done with the inside work. Replace the spring tabs on the side of the case, snap the top back on, carefully aligning the charge connector terminals and replace the screws.

STEP 5: Build the Charger

I live in Mexico and bought my universal laptop battery charger on Mercadolibre.com for about $10 dollars. Yours may be different depending on where you live, but there are cheap universal laptop chargers (made for lithium batteries) readily available. The charger must have a 20v output position on the selector since these are 19.2v batteries. Mine fortunately came with a two pin connector wired to a multiconnector, so I simply cut the wires at the multi connector and put the red insulated clip on the positive side and the black clip on the negative side. Yours may be more complicated than that. The trick it to have the alligator clips on the output side with the positive and negative wires clearly identified. Check the wires with a voltmeter if in doubt about which is positive and which is negative.

When your charger is ready, make sure it is set for 20v output, connect the red, positive, clip to the positive terminal on the rounded side of the battery charge connector and the black, negative, clip to the negative terminal on the flat side of the battery charge connector. Let it charge for almost an hour and try it out!

STEP 6: Back to Work!


14 Comments

Dennis0912 1 year ago

This post should be removed from this site. Very dangerous to remove thecircuitboard from lithium batteries. This is the charge protection keeping the batteries from overheating and exploding. Remember the cell phone batteries exploding a few years ago. Yes this can be done easily but can't be done safely without an understanding of how lithium batteries work and there general characteristics like there tendency for exploding when exposed to heat either from overcharging or external sources.

jdmorrisw 1 year ago

Are you taking into consideration the use of a laptop lithium battery charger?

tytower 6 years ago

Nice thing about that is they are 18650 batteries . Each is nominal 3.7Volts with a recomended never charge over 4.2 Volts. So you want to be getting each cell to about 4Volts . They will go out of balance as they are connected in series to bump the voltage up .

So you will need to have a way to balance them from time to time.

Good stuff.

Dennis0912 1 year ago

While they are 18650 batteries powertool batteries use high discharge INR18650 cells with a nominal voltage of 3,6 that are capable of high drain and fast charge without overheating. They are capable of supplying up to 20amps of power compared to the normal ICR18650 cells that supply less than 1amp on average. Never remove the circuitboard from lithium batteries not only will you burn up the batteries but you risk an explosion. If you forget to unplug the charger.

tytower 6 years ago

Come to think of it . That's possibly why the battery would not charge initially. In that case I would have checked each cell to find the weak ones and charge each individually up to 4V then tried it again on the charger and used it.The circuit board was probably fine

tytower 6 years ago

Your circuit board probably refuses to charge below a set limit

I would also suggest you check each cell now because you don't appear to have done that yet and the low cell will still be relatively low.

Dennis0912 1 year ago

Ok that will work shortterm but you need the circuit board for balance and over and under charge protection. When your charger says the battery is full but it's odviously dead you have a connection problem between the battery and charger terminals. Test this with a multimeter if you show voltage while touching the negative terminals on the battery and the charge terminals you have a ground problem with a simple fix simply solder a wire between the battery terminal and charge terminals. This will fix your charging problem while keeping the circuit board intact with all the protections working..

rtsulliv 4 years ago

Where can I find a circuit diagram for the battery controls ?

jdmorrisw 4 years ago

Sorry, I can't help you there. Good luck.

EkaS21 4 years ago

I make this but why the battrey is very hot affter i make test drill some wood sir

EkaS21 4 years ago

Like this sir

jdmorrisw 4 years ago

Sorry, I'm not sure. I'm just handyman level, not expert. Yours is a little different from mine with that pink battery. I can't really see from the picture how it is connected. Wish I could help.

DIY Hacks and How Tos 6 years ago

Nice trick. I will definitely remember this if my drill ever starts to give me problems.