Note: CR/BR (Lithium) battery types are 3.0 Volts. This mistake in the handbook appears across several different models of Casio solar calculators. The handbook is wrong! The replacement for the National GR927 is the 399 silver oxide battery and not If you are replacing a National GR927 battery in a Casio calculator please note that your calculator handbook is likely to say that Watch battery suffixes read our All About Watch Batteries write up. You shouldĬheck that your application will not be affected by the slight increase in battery voltage which will result in using a silver oxide watch batteryįor further information about watch batteries their chemistry, numbering, watch battery prefixes and Duracell D309/393PK - 1.5V Silver Oxide Watch Battery Duracell Duracell D309/393PK - 1.5V Silver Oxide Watch Battery Write a Review You May Also Like. Mercury watch batteries are no longer manufactured so your only alternative is to use a silver oxide watch battery of the same size. The battery numbers in blue text are links to more information on the particular battery and will take you to a page where you will be able to order the battery. AG & SG AWI Bulova Citizen Duracell Renata Seiko Timex Maxell National Panasonic Sony Toshiba Varta Vinnic 301 11.6 x 4.20. To remove the back cover first turn the watch over and locate the small depress. Energizer Eveready Rayovac Maximum Dimensions (MM) DIA x HT (IN) DIA x HT I.E.C. Watch battery, even if the sizes are comparable. You will need case back opener, a small screwdriver and a case back closer.1. Note, that the lithium watch batteries, or button cells, are 3 volts, not 1.5 volts and cannot be substituted for a 1.5 volt silver oxide watch battery or alkaline This will give you an idea of which watch battery to choose if you do not have a watch battery cross reference number to match the battery against. The Watch Battery Cross Reference table can be sorted by watch battery size, either by selecting the watch battery diameter, or the watch battery thickness Numbers as used by various different watch battery manufacturers. The Watch Battery Cross Reference Table below gives all Watch Battery sizes and their equivalent replacement watch battery reference