Instructables - Makita 18v LXT Lithium ion Battery-Repair

I have just had my Instructables on how to replace the control board on Makita Lithium-Ion batteries accepted  for there Tools Contest.  Please take a look by following the link below and vote by clicking on the vote tab on the right hand side if you wish!

Makita 18v LXT Lithium-ion Battery Repair

Makita 18v LXT Battery - Repair Eight Months On

This post is just a quick update.  Its been about eight months since I repaired my first Makita Li-lon batteries.  I have been careful to let repaired batteries to cool down fully before charging and where ever possible not to fully discharge them but so far there have been no failures of any of the repaired ones.  

I have however had a couple more batteries fail, as an experiment I sent them to the Makita Service Centre. Even though they were out of warranty, one by a couple of month and one by nearly a year, they sent me replacement within a couple of days at no charge.  I future this will be my first port of call and only if this fails will I attempt to repair them myself.

I do however have several failed battery packs that I had already taken apart with the intention of repair, so are not candidates for sending to Makita.  Due to being unable to source replacement control boards, i had put these to one side and had even concidered using the good cells for another project. Thankfully I once again have a supplier of them who has stock and have ordered several, so will soon be back repairing batteries.

Makita 18v LXT Battery - Repair

So as I mentioned in my previous post I have purchased a replacement control board from Ebay for my Makita 18v Li-Ion LXT batteries.  This weekend I finally had enough time to have go at fitting it and whilst it is not just a plug in affair I would say anyone with a multi meter and a half decent soldering iron should be able to do this.

I was lucky and had a battery that had ok cells but a faulty control board so I decided to try repairing this one first. The control board came with ok instructions on how to fit but they don't explain everything, this may be because it can be used with all of the models of 18v LXT battery Makita have made.  Providing you have a bit of common sense you should be ok.

So apart from the soldering you might expect you also have to cut away a lot plastic and that's assuming you are lucky like me and don't need to replace any cells.  If you do spot welding to the cells is the best way to go, as if you solder you risk overheating.

As I had previously got the battery pack out of the case the first thing to do was remove the existing pcb and cut away the plastic pcb support etc as per the instruction.  I opted to cut the nickel contacts instead of desoldering. Fitting the pcb and soldering the wires to the contacts was simple although I had to break out my larger soldering iron.  By far the hardest part was getting the covers back on this took a little fettling of the plastic to get it to fit.

Next came the moment of truth, I put the battery on a charger and it charged ok.  I then discharged the battery using my circular saw and once again recharged the battery and that also worked ok.  Needless to say I will need to let it go through a few more cycles before I am confident enough to call it a success but all in all things are looking good!