Simply Auto SB-CR1632 CR1632 3V Lithium Coin Cell Car Key BatteryThe Simply Auto CR1632 Battery is the thickest of the three 16mm coin cells, and that extra depth is the whole point of it. Where a key housing has the diameter of a 16mm cell but a little more room behind it, manufacturers specify the CR1632 rather than a thinner CR1616 or CR1620, because more lithium means more time between battery changes.A CR1632 battery is 3 volts. It is a lithium manganese dioxide coin cell measuring 16mm across and 3.2mm thick with pressure contact terminals. Lithium chemistry holds that 3V steady under load instead of tapering off gradually, so your remote keeps its range almost until the cell is spent, and an unopened battery keeps for up to 10 years in storage. It is CE, UKCA and RoHS compliant.Fitment is worth two seconds of care here. The CR1632, CR1620 and CR1616 all measure 16mm across and differ only in how deep they are, so they are genuinely hard to tell apart by eye once out of the packet. Read the code printed on the face of the old cell rather than guessing. A thinner cell will sit loose and lose contact; a thicker one will not seat properly and can strain the contacts. Note the orientation before you lift the old cell out and handle the new one by its edges.Beyond car key fob battery replacement, the CR1632 also powers watches, calculators, fitness trackers, glucometers, digital thermometers, small remotes and other compact electronics.If your key takes a different cell, the full Simply Auto car key battery range covers CR1616, CR1620, CR1220, CR2016, CR2025, CR2032, CR2430, CR2450 and the 23A, 27A and A76 alkalines.