Bosch 24V Makita CXT Battery Adapter

prusaprinters

I have an old 24V Bosch SDS Drill with a failed NiCad battery.  Rather than rebuilt the existing battery I designed an adapter to hold two 12V Makita CXT batteries.The pictures show an earlier design, this design brings out all the connections from the battery to allow a 3S BMS to be fitted for each battery.WARNING:  The Makita CXT batteries do not appear to have built in battery protection, hence you will destroy them if you over discharge them.  It is recommended that you fit 2 BMS as part of the build, one for each battery.1pcs 3S 20A Li ion Lithium Battery 18650 Charger PCB BMS Protection Board 12.6V Cell 59x20x3.4mm Module|Integrated Circuits| - AliExpressThe terminals are designed to take standard 6.25mm blade crimps, although these are an interference fit they should be glued in place with either a hot glue gun or epoxy.Wire the connections to the BMS and then wire the BMS outputs in series to give 24V.  I wired this in 1.0mm^2 wire.  The drill will draw 15-20A so make sure your wiring is suitably rated.WARNING:  The Makita batteries can output a significant amount of power, check your wiring carefully before connecting the batteries.The connection labelled T appears to be a thermistor for the battery, however this has not been tested and there is little information available on the build of these batteries.The battery holders are mounted using heat-set inserts.Brass Hot Melt Inset Nuts Heating Molding Copper Thread Inserts Nut SL type Double Twill Knurled Injection Brass Nut M2M3 100Pcs|Nuts| - AliExpressOther Hardware:4 x M3 x 8mm6 x M3 x 16mm6x M3 Hex nuts