I've dozens of drills over the years, well not quite . I think it's pot luck on the cheaper ones. I got a 8V black and decker of car boot, it is still good and the same battery. My present new one is 18V makita with one 4 amp/hour battery, this is ,so far , a very good bit of kit but not cheap. If you are not using the drill for profesional jobs I would suggest getting just one battery, they seem to last longer this way.