You can take them apart and try to find the bad cell with a meter. It's typically the cell that goes into the charger first as that one tends to get baked by heat and heat kills a battery. A lot of hassle, I just look for battery sales and I've mostly stuck to Ryobi. When Home Depot has a sale on them, they can be pretty good. Every once in a while you catch their batteries on clearance. They used to have a pretty good price during black friday, they used to have the drill and battery for $30, but the last few years the price has gone up so it's not so good anymore, just have 4-5 drills sitting around just because I bought the kit to get the extra battery.