How to Check for Current Draw in Batteries
- 1). Check the label on the device your battery powers to ascertain the milliamps hours (mAh). This is the amount of current your device uses per hour to operate. Make a note of the mAh figure.
- 2). Check the label on the battery you use to power your device. Practically all rechargeable batteries indicate the mAh of a fully charged battery. Nonrechargeable batteries do not always indicate the mAh, but if you go to the battery manufacturer's website, you can usually find the information based on the size and type of battery you are using. Make a note of the figure.
- 3). Divide the mAh you noted from the battery label by the mAh you noted on the electrical device's label using a calculator. Multiply the result by sixty to tell you the number of minutes you can draw current from your battery to power the device. For example, if the battery indicates the mAh is 2,000 and the electrical device says 500 mAh, 2,000 divided by 500 equals 4, multiplied by 60 equals 240 minutes, or 4 hours.
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