Are ac/dc battery chargers interchangeable if the plug fits the item and input output are the same

Question

My hedge trimmer has not done a lot of work, came with 2 batteries 18V but neither will charge, thinking its the charger but can I use another from a cordless vac or such?

Answer 1

Chargers are interchangeable if the have the same voltages and polarities. You need a 20VDC charger to charge a 18V rechargeable battery. Cant be too low or too high.