does anyone know if bosch batteries have over discharge cicuitry in them as I have a few of them around?
Surely it does not matter if BOTH the tool and the battery pack have the management stuff in them?
What I mean is if the tool shuts off on low voltage and the battery shuts off on low voltage, one of them will shut off on low voltage.
What you don't want is neither of them shutting off...
I have Milwaukee M18 packs here. The BMS PCB on one of them failed. I was able to go on Ali express and buy a replacement BMS board.
Indeed whole packs, minus the cells are availible - shell, BMS, buss connectors etc.
Third party packs are often poor as the cells are rubbish. Same with any cheap thing that uses 18650 li ion cells.
Laptops generally have really good cells, and the battery packs on them generally die because one single cell has gone bad. You can test the cells for capacity (extra equipment needed) and choose only the best - but again its pretty much always that one has died and all the rest are still great.
Swapping an individual bad cell may be solution for you. Or swapping the whole lot. Or getting an adapter plate as I really doubt that having two low volt protection systems will be an issue. But then you would likely need a new charger also.