The basic rule receiving a replacement battery is that it requires to have the same voltage as the original. An 18V drill cannot managed with a 12V battery. It can only operate on a 18V battery. One other thing is this the physical packaging associated with a battery could be different from company to company. A 12V Ryobi battery probably doesn’t fit within a 12V Makita cordless drill unless the car battery has value of getting physical element. So make sure the replacement battery looks your as aged one anyone order they. Also, if you want for new one’s battery in the same voltage rating via the same company, find out that battery technology is changing fast. An 18V lithium-ion battery has different physical packaging than only a NiCad 18V battery.