The Intellicharge i4 is a universal, automatic smart-charger compatible with almost all types of rechargeable batteries thus eliminating the need to own several chargers. Capable of charging 4 batteries simultaneously Each of the four battery slots monitors and charges independently Automatically identifies Li-ion, Ni-MH and Ni-Cd rechargeable batteries, including 26650/ 22650/18650/17670/18490/17500/17335/16340(RCR123)/ 14500/10440.Features three charging modes (CC, CV and Trickle Charge) Automatically detects battery status and selects the appropriate voltage and charge mode 3 Color LED displays charging progress for each battery Automatically stops charging when complete Features reverse polarity protection Designed for optimal heat dissipation Certified by both RoHS and CENo Spacer required!When charging a single battery in the I4, the charging current can reach as high as 750mA, which exceeds the current many Ni-MH/Ni-Cd AAA and 10440 Li-ion batteries can withstand. For this reason, under no circumstances should a single AAA or 10440 battery be charged on its own, as potential overheating, damage or even explosion may occur.Due to the aforementioned reasons, it is recommended that a minimum of two (2) AAA or 10440 rechargeable batteries are placed into the charging slots together. When charging two batteries in the I4, be sure to always place them in either slot 1 and 3 or slot 2 and 4.When charging different battery types simultaneously (for example, li-ion 26650 and AAA), always ensure solid contact is made between both sides of the battery and the charging slot’s metal contact points.