The A76 battery is also referred to as “button” or “coin” cell battery because its size resembles a button. These batteries are small and round, measuring 11.6mm (0.457 inch) in diameter and 5.4mm (0.21 inch) thick. This battery is non-rechargeable. This battery is an alkaline battery using manganese dioxide chemical system, an economical alternative to silver oxide batteries. Generally, these miniature batteries are used in several small electronic devices like watches, cameras, calculators, toys.
Energizer makes the A76 battery with the following specifications:
You can see the battery is an alkaline battery from the Manganese Dioxide chemistry. The capacity of 150 mAh is on the higher end of these size batteries and should be expected from a brand name battery. Using a cutoff voltage of .9 volts, the capacity is calculated by voltage divided by load multiplied by running hours until the voltage reaches the cut off voltage. In this data sheet, it takes 900 hours at a 1.25 V drain with a 7.5K ohm load. Therefore, 1.25 / 7.5 * 900 = 150 mAh.
Equivalent Batteries to the A76
Energizer's A76 name is their own name for this battery, as they want their customers to keep buying replacements from their company. But this size of battery is a standard size battery available from many other companies and manufacturers including generic brands. To shop for generic versions of the A76 battery, look for batteries labeled as the AG13 or LR44 battery. AG13 and LR44 are much more common in the market and are available much cheaper, especially online.
As you can see from the voltage graph, the voltage continuously drops until it no longer provides enough voltage to operate a device. When used in lights, you might notice the lights getting dimmer and dimmer as the battery becomes weaker. It is important to note that for certain electronics that require a high voltage to operate, an A76 battery will seem to have a short life, when in fact it still has energy left in the battery cell. As an example, a device that can still function at .9 volts will run for 900 hours, but a device requiring 1.4 volts might stop after 200 hours. For those devices needing a high voltage, a battery with a silver oxide chemistry will work longer. Silver oxide button cells have a chemistry that maintains the nominal voltage longer which suddenly drops when the battery dies. The trade off is that they are more expensive due to the high cost of silver. Silver oxide versions of this size battery are labeled as SR44, 303, and 357 batteries