Cheap drill battery pack

thingiverse

This is a battery pack for those cheap drills that were produced around 2003 - 2015. Einhell, Defort, Ferm, Challenge, Amtech, ProUser, Speedway, Workzone, Power-G, Boston, Draper, XU1, Trades Pro and Top Craft (maybe Mastercraft) made (or relabeled) them. Most of those drills aren't too bad, but the batteries suck. All of my standard 18V batteries (I have 4 of these machines with 6 battery packs) are on their last breath, so I decided to upgrade them to Li-Ion using 18650 cells. The files contain the original Sketchup file and the STL for printing. I usually draw stuff that's more functional than beautiful, so go wild on the design if you want to. :) I got about 8 hours print time at a very strong pace. With less agressive settings I imagine 10 - 12 hours would do the trick. Grtz Dustin Print Settings Printer: FixrBot 1.0 Rafts: Doesn't Matter Resolution: 300µm Infill: 85% Post-Printing Battery requirements You can use 4 or 8 18650 cells with up to 5 Ah at 14,8V. If you have a drill with a simular battery but a smaller voltage pack, you could wire it differently. 7,4V with 10Ah! or 11,1 V with 5Ah. (only 6 cells in this case) Stay away from the cheap china cells because they will give you a bad time. They are labeled 6,8Ah or more, but are not even 1Ah. That's fine, if you know what you are buying. Panasonic/LG/Sony is the way to go. Worn laptop batteries will do fine too and usually outperform brand new china cells. Assembly Put big washers (same size as the tubes if you can find them) inside the pipes for the battery and on the lid, insert M4 (16-20mm long) bolts (or whatever non-metric stuff you have to use) and tighten them with a M4 nut. Do this on the lid and the housing for the negative terminals. On the positive terminals leave out the big washer. Find suitable springs and drop them inside the tubes on the negative sides of the cells. Finding good springs is a bit of a challenge. Then make wires and put the top pack in series and the bottom pack in series. Make a bridge between the two 4S packs. Screw it down with another nut. Use good wiring. I use 2,5mm² hard copper wire. My drills can draw up to 15A of power. Screw the lid on the housing. Measure your voltages. If you run into trouble, check each cell. A spring might have made bad contact. Also check your polarity on the part that goes inside the machine. Usually it's marked on the machine or your old battery pack Run the positive and negative wire from the packs through the housing and up the part that goes inside the drill. Find metal plates that fit inside the contact. Solder them to your wires. I used hot glue to fix the plates in place Fit inside your machine. Li-Ion upgrade complete ! Stuff you'll need. 4 or 8 18650 cells Copper wire 8x big (18mm dia max) washer. 16x M4 bolt 16 or 20mm long (or whatever non-metric bolts that fit) 32x M4 nut Soldering iron Tin Plates for contacts Hot glue gun Multimeter Safety warnings Li-Ion cells are dangerous. Improper use can cause violent explosions or fire. Soldering can cause burns. WARNING : YOU CAN NOT CHARGE THIS PACK IN YOUR STANDARD CHARGER !!! The standard charger is made for Ni-Ca batteries and therefor not suitable for charging this pack. It will melt, burn or even explode! You have been warned. :) Charging I have a bunch of these cells lying around. I just replace them and recharge them with a normal 18650 charger. You can also use a LiPo-pack charger, set it to 4S2P and leave the batteries in. I might model a charger later on to hook up to my regulated power supply. Thoughts Well, in my search for replacement batteries i found so many brands who relabeled these machines... it would be interesting to find the original manufacturer, or where they copied this design from? Does anyone have a clue?