21 Volt 4000 mah Replacement Battery Pack If the old light is just not what it used to be, maybe a new battery pack is in order.  These are the premium 4000 milliamphour battery packs we use in our box and belt lights.  Packs also available for belt lights and other voltages. Give us a call   or just send us an email.  No charge for installation, just send us your battery pack. Price for these 21 volt packs with a 3-year warranty are $120.00.