I have done some research on the internet about lithium ion and seen a lot other conversions here on instructables.
Step 1: Delete Your Original Battery Pack and Save the Connector.
it's easy to open up the pack, some torx screws and voila.
be safe and wear some gloves, pull off the pins and take off the big one on the left and 1 of the 2 others. You only need 2 pins.
I soldered wires on it, about 10cm but it's up to yours.
Step 2: Get Some 18650 Holders and 18650 Battery's
The battery's are more difficult, you need good ones. I gathered old makita battery's with error. There are always some good cells in it. To get 18v, use 5 of them and charge them up with a good li-ion charger. monitor them, after 3 days they should be above 4v, if not they are bad.
If you want t new ones search for good battery's with high drain. Makita is using 15A ones. On my multimeter, they are about 2100 mah
Solder the wires to make a 5 pack in series and connect the contacts.
the 3s holder is hard to get in, just push. the 2s is for on top.
Step 3: Close the Pack
Close the case and test your drill, happy and or not?
Step 4: Protect Your Pack
Also charging should be with a lithium ion charger, never use a ni-cd or ni-mh charger. Never use the original charger of the black and decker!
I am using an Imax B6 mini charger with crocodile clamps to charge the pack.
There is not much space left for a protection board, so I should change the pack without the holders. I will update this when my pcb/BMS is in the house.
I ordered a 20A high drain BMS with a higher 30a peak. The BMS also charge the pack and balance it.
I don't know if that BMS is working to well but I will let you know.
Step 5: Finally, Protected!
I bought an protection board this on
Rated at 20a continious discharge, I dont know for sure about the discharge rate of the battery cells, it are sony SE US18650V cells
I did find some info, that they are 20A discharge rated, another site says 15a discharge. So maybe it is better to find batteries that are 20A of higher rated for protection only.
I made a video:
As you can see, there is full power, and the drill is not stopping so far, but I cant stop it by hand. Maybe if its get stuck when drilling, large holes or something, I would like to see what happens. So just not finished this instructable yet.
Also the BMS does not fit in the battery case with the batteries in the holders. I have to make the batteries in the case without the holders, and have to solder the wires on to the batteries to make it fit.
Will be continued....
Step 6: Fitting It In
The BMS was not that small it could fit in it with 18650 holders.
I decided to lose the holders and put the batteries without it. I packed it somehow with electronical tape, and soldered nickel welding tape with flux on it. Maybe it is better to weld it on them, there are sevarel instructables here how to make a welding machine from an old microwave. But thats to much work for me, solder works, I used S39 (not that old acid but new one) and a gas soldering iron. First solder a drop on the battery with flux, then preheat the nickel strip a little bit, use pliers to hold, then push it on the battery with the iron till the solder melts.
I used double sided tape to fix the BMS , I taped the little nuts.
Funny that my charger says 282 m0hm resistance, while the original battery more than 999....
Project finished, battery works well, charging goes well, blower and drill work well!