Worx Replacement Battery, Voltage Meter and Mounted Hangers

It took me a long while to get the design where I wanted and get the bugs out that I found. Some things you should know first. I have repaired many battery types over the years, but this is my first battery from scratch. I used salvaged batteries that tested around 1.1 and 1.2ah. This is a low-capacity battery for light work for tools that do not draw high current. This is for my two thrift store finds, a light and a small pressure washer. The light would only come on for a few seconds and go off. I discovered it needed a 10K ohm resistor strapped from the negative side to the connector beside it to solve the problem. The battery does have a BMS board to properly charge the battery through a DC connector on the front of the battery. I am using a 24V 1A wall charger. There is no way for sure to tell when the battery is fully charged but the BMS will cut off charging at a full point. I made the meter to periodically check the voltage. Initially I left it on the battery while charging and checked it from time to time. At one point it exceeded 23 volts, and I unplugged the battery. It immediately showed 20.8 volts which was acceptable. I plugged it back in without the meter for a while and it did not charge beyond 20.8 volts which is probably around the cutoff volt. I would not recommend leaving the meter on while charging. With the meter across the contacts, it might throw off the BMS and overcharge the battery. Do Not charge with a Worx charger.

Parts Needed for Battery:

• (5) 18650 lithium cells
• five cell BMS charge board (Amazon - 5S 15A 18V 21V Lithium Battery Protection Board)
• 10K ohm resistor, ¼ to ½ watt
• DC input connector 5.5 x 2.1mm (Amazon - HiLetgo 10pcs DC Power Supply Jack Socket Female Panel Mount Connector 3-Pin 5.5 x 2.1mm)
• (3) 6mm or ¼" female blade connector
• 24V  1 to 2A DC power supply, 5.5 x 2.1mm
• (4) 4mm screws, 16 to 24mm long
• wire and hot glue

Assembly:

Alternate batteries into holders. You can use the BMS plate and rubber bands to keep them aligned. Attach all batteries as a unit. They can be hot glued together for stability. Use some type of insulator around positive post to prevent any chance of shorting. The DC connector is three terminals. Center connector is positive, visually seen for soldering. The negative is the solder terminal in the middle. It will not show conductivity from outer case to terminal unless it is plugged in. Terminal opposite from positive is not used. Solder suitable length of wire to reach across board. The BMS board has solder pins sticking from thr bottom. Clip the pins close to the board and test fit into printed BMS plate. Solder BMS plug strip to batteries according to voltages marked on board. The next steps are done with the live battery, be cautious. The DC charge connector wires go to positive on the board at the BMS plug and negative on the other end of the board (two hole). From the one hole on the BMS board, solder a wire to negative pole of the battery pack (shown as green wire). 

The top section. Insert a tool fully into top part. Insert already crimped and soldered terminal wires into socket slot and push onto tools blades. Make the negative side up with 10K resistor as a set beforehand. Once all three are seated hot glue them in place. This will give you alignment for any tool. The two large wires from the battery top section. I used black and white only because they were handy. The white is the negative going to the two-hole BMS board. The black wire, positive, solders onto the 20-volt side of the battery pack. Insert spacer, battery pack, BMS plate into bottom housing. Align BMS plate with battery holders and hot glue together. Set BMS board into plate and hot glue down. Move wires around and flatten while setting top onto box. Once aligned use the four screws to attach top. The box has preformed threaded holes. 

Printing: I used generic black and white PLA, Creality Burnt Orange PLA. Everything printed 0.20 layer, 3 walls, 20% infill, top only needs support everywhere.

Parts Needed for Meter:

• Display (Amazon - Mini Digital DC Voltmeter 0.28 Inch 2 Wire 2.5V-30V)
• (2) 6mm or ¼" male blade connector
• (2) 4mm x 12 screws
• hot glue

Meter Assembly:

Solder the meter wires to the blade terminals. Hook display meter to known battery or power source value and adjust small potentiometer on display meter to calibrate. As in the battery assembly, the meter base needs to be slid onto the battery to insert the blade terminals. Due to the tool blade being thicker, the male blade will fit loose. Once fully inserted, hot glue them in place. Insert meter into top housing (snug fit). Hot glue in place. Any squish needs to be trimmed to allow meter to be fully seated. Curl wires into cavity and set top on base and secure with two 4mm x 12 screws. If the display does not light up or is intermittent, slightly twist blade terminals to get a tighter connection.

Printing: I used generic black PLA, Creality Burnt Orange PLA. Everything printed 0.20 layer, 3 walls, 20% infill, base needs support everywhere.

Holders:

I designed the mounting holes to use drywall screws. The battery mount does not work with OEM batteries due to tolerances. The replacement battery will fit tight onto the tools.

Printing: I used Creality Burnt Orange PLA. Everything printed 0.20 layer, 3 walls, 20% infill, both holders need support everywhere.