modality - a method of therapy that involves physical or electrical therapeutic treatment. rehabilitation - the treatment of physical disabilities by massage and electrotherapy and exercises.
Alkaline AA batteries are rated 1.5 volts, while NiMH AA batteries are rated at 1.2 volts. NiMH generally refers to a battery being rechargeable and to the materials from which the battery is constructed.
Now count the batteries and multiply by battery voltage, 6 batteries times 6 volts equals a 36 volt system, and so on. You may only charge 12 at time with your charger, so you will have to remove a few battery to battery cables.