I have a slew of Makita 18v Tool batteries and was considering other ways in which they might be repurposed. I know the Makita range of BL18XXB batteries from teardowns on the internet uses internal circuitry for balancing, temperature sensing, over-discharge etc but they also sell two adapters that I decided might be a better method of accessing the power rather than just using a 'dumb' contact plate.
One adapter provides two USB ports, another (126655-4 Battery Holder) designed to run a cooling jacket, converts to a barrel jack that I assumed output something around the 12v the fans would need.
I ordered one but after hooking it up to the multimeter, and then a PC fan, can't get it to work, it blinks the power led but doesn't stay on. Doing my own teardown I'm surprised by the amount of internal circuitry for what I might have expected was a glorified voltage divider. The same can be said of the internal circuitry of the other adapter.
Does anyone have any idea what these adapters might be doing? I always understood the smarts of Makita's battery protection systems were in the batteries and not the tools so I was trying to work out what might be preventing the adapter from staying on. I didn't think there could be a DC 'protocol' over the barrel jack coming from the jacket to confirm the adapter was plugged in to a legitimate accessory so I wondered if it might be some sort of load/resistance detection? Does that sound feasible and without access to the jacket are there any suggestions for how I might test for that, or get around it?
Thanks in advance for any help.
It does have a USB (shown) and the wiring you see leads to daughter board with buttons and leds. You can cycle three fan speeds which I assume are output voltages not PWM. Label says 14.4V/18V followed by a solid over dashed line, which I gather indicates an output DC range.
Found an instructable (https://www.instructables.com/Making-a-Over-Discharge-Protection-for-Makita-Batt/) that indicates the battery doesn't internally have over-discharge protection and communicates instead via a third pin with the tool to prevent over discharge. This pin is present on the power tools I own but neither of the adapters (nor the work light I have) use it.