Guides
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Coin battery size chart16 common lithium coin cells, CR1025 to CR2477: diameter, thickness, volts and each maker's typical capacity. Printable PDF. Button and watch battery size chartSilver oxide watch cells by number with their SR codes, and alkaline LR button cells: size, volts, capacity and each maker's codes. Printable PDF. Battery size chartAA, AAA, AAAA, C, D, N and 9V batteries, the 12 V A23 and A27, and the CR123A, CR2, CR-P2 and 2CR5 photo cells: size, volts and codes. Printable PDF. Battery voltage chartWhat a full, part-used and empty AA, AAA, 9V, coin, button, 18650 and 12 V deep-cycle battery reads, from the makers’ own figures. Printable PDF. 18650 battery sizeAn 18650 is a lithium-ion cell about 18 mm across and 65 mm long; Molicel's is 3.6 V. A 21700 is 21.7 x 70.2 mm. Protected cells and handling, in makers' words. Button battery safetyWhat to do if a button or coin battery is swallowed, which cells cause most serious cases, how to keep them from children, and what Reese's Law requires. How to clean a leaking batteryHow to clean up after an alkaline, NiMH or NiCd battery leaks, in Duracell's steps, what to do if it touches skin or eyes, and why batteries leak. Storing and throwing away batteriesHow long batteries keep and at what temperature, from the makers' sheets, and which ones EPA says stay out of the trash, with how to tape or bag them. How to change a key fob batteryThe steps car makers' own manuals share for changing a key fob battery, their warnings, and how to start a car when the key's battery is dead. What size power station for a CPAP?From ResMed’s own figures, the watt-hours an AirSense 10 needs for a night, with and without the humidifier, and ResMed’s and Philips’ battery advice. What size power station for a fridge?Turn the kWh a year on a fridge’s yellow EnergyGuide label into the watt-hours a day a power station must hold, with four ENERGY STAR models worked out. What size power station for camping?Add up a camping day’s watt-hours from each maker’s spec, for a 12 V fridge, Starlink and a CPAP, and the station that covers them. What size battery for an RV or camper?Turn a day’s watt-hours in an RV or camper into amp-hours at 12 V, Renogy’s way, and what Battle Born says lithium changes. What size UPS for a computer or router?Add up the watts on the UPS and multiply by 1.25, CyberPower’s rule, then check the UPS’s watt and VA ratings.