Well, there are two of us.
I also have this charger and I know what needs to be done to make it work, but it's not that simple.
First, a warning. If you have a package of 10 li-ion cells, connecting it directly to the charger will not be of much use. It is enough for one cell to charge faster, exceed the voltage of 4.2 V and it will be over. I know this from experience, because I use a Makita 10.8 V charger (a package of three cells in a row) and at the beginning I connected the cells without protection. Li-ion cells from power tool batteries have a built-in protection against overcharging, but most of the available cells (e.g. 18x65 laptop cells) do not have such protection. So you have to get a balancer, which will not only equalize the capacity of the batteries, but also will not allow you to overcharge individual cells.
But how to start the charger.
The third pin is an output to some thermistor that disconnects charging when the battery temperature increases. In the case of Makita, I took this device from a used battery and the charger charges me a package with 5 times greater capacity than the company's one (of course with an attached balancer).
Now I have built a battery with 50 36 V li-ion cells to drive the motor in the bicycle wheel and I would like to use the charger mentioned in the post. My battery has a total capacity of 11 Ah.
I have to buy a balancer (for 12 cells it costs about PLN 280) and start the charger.
Unfortunately, it is difficult to get a used battery for this charger.
