Bosch 18V Battery Adapter

thingiverse

This is a battery adapter for Bosch 18V Litium battery packs to supply e.g. a TS100 soldering iron. Tested with Bosch Pro Core 18V battery, but possibly compatible with other Bosch 18V batteries. In addition to the buit-in charge state monitor my design includes a switchable voltmeter to check the battery voltage and avoid deep discharge. To save power you may switch the voltmeter off when not required for voltage monitoring. The switch does not interrupt the external load. The (+) and (-) connectors are marked on the battery. Caution: - Exclusively use the genuine Bosch battery charger! Never charge the battery through this adapter. The battery may catch fire or even explode. This adapater completely ignores the temperature sensor accessible via the middle contacts. The temperature sensor is a safety device used by the genuine Bosch charger during charging and by the Bosch tools during discharging. - Drawing too much current from the battery pack or a short-circuit will lead to fire and/or explosion! I have no profund knowledge of the maximum allowable current. It may be around 10A, but this is just an assumption and possibly dependent on the size and version of the battery pack. I could not find any official Bosch maximum current data. Again this adapter completely ignores the the temperature sensor used by genuine Bosch tools to sense dangerous battery temperatures. You are using this adapter at your own risk. - There is no battery discharge protection in the battery pack to avoid discharging the battery below a safe minimum and subsequently become dangerously unstable while being recharged. Such protection circuits may be located in the Bosch tools. So it is up to you to stop discharging before the safe minimum voltage level is underrun. After an underrun the charger may refuse to load the battery or the battery may explode during charging. The safe absolute minimum voltage per 20V pack may be around 5 x 2.5 = 12.5V, but please do not call me to account for this figure. If the voltage falls below this value you should stop using the battery and dispose of it. During use the voltage will remain high for a long time and then drop quickly, so watch out and disconnect the battery in time. - Disconnect the adapter from the battery when not in use in order to prevent accidental short circuits. - Using this adapter may void the warranty of your Bosch battery pack. - Do not hand this adapter over to persons who are not fully aware of all of these points. To make the cable strain relief work as intended, the width of the circular cable trench must tightly match the cable diameter (current default is 3.5 mm) in order to create some friction. You may have to modify the parameter "d_cable" in the OpenSCAD source file and re-create the .stl file to match your cable: - Download and install OpenSCAD from openscad.org - Open the .scad file in OpenSCAD - Modify the value of the "d_cable" variable according to your cable's diameter - Render with "Design/Render" - Export with "File/Export" - Feed the exported file to your slicer and print The three sheet metal screws are of the 2.9 x 9.5 mm (DIN 7981-C-H) type. The AMP contacts are the red or (preferably) the blue 6.3 mm (0.25") type. The voltmeter is the XH-028 V4.0 type supplied e.g. by the Ebay vendor moore_estates: https://www.ebay.ch/itm/164877631255 I suggest to secure and isolate the red and black voltmeter wires with a drop of hot glue at the voltmeter wire soldering points against a possible short circuit in case the wires break at the solder point. The switch has a 12 x 12 mm footprint. The contacts are 5.08 (0.2") apart. Various manufacturing variants with these dimensions may fit. When using a differing voltmeter or a switch with differing dimensions you will have to modify the voltmeter() and pushbutton() modules in the supplied .scad file. Upon rendering, these two modules are being subtracted (via OpenSCAD difference()) from the cover in order to create the necessary cutouts. So modifying the two modules will automatically provide a fitting cover .stl file. Changeing the distance between the two mounting holes of the voltmeter (currently 28.5 mm) will require further modifications. See also my Ferrex (Aldi) 20V Battery Adapter: https://www.thingiverse.com/thing:4885569/edit TODO: Next big thing would be to integrate an automotive flat fuse. Probably one day ...