The Li-Ion battery system is compatible with all Nightsun two- and three-beam lights. The battery is an 84-watt-hour rechargeable Lithium-Ion (Li-Ion) water bottle style. This is being offered as an upgrade option on new systems, or as a replacement retrofit for all Nightsun two- and three-beam systems currently in use. Included with the Li-Ion battery package is a Boost/Regulator which provides constant, steady, whiter and brighter light output. An overnight "plug and forget" charger is also included.