A battery can supply a current as high as its capacity rating. For example, a 1,000 mAh (1 Ah) battery can theoretically supply 1 A for one hour or 2 A for half an hour. The amount of current that a battery actually supplies depends on how quickly the device uses up the charge. Batteries are a vital part of many electronic devices, supplying the current that powers them. The amount of current a battery can supply is determined by. This is a great question and one that we get asked a lot. The answer, unfortunately, is not always black and white. There are a few things to consider when trying to determine if your battery is. Batteries come in all shapes and sizes, but when it comes to rating them, there is a standard set of criteria that is used. The most important factor in rating a battery is its capacity, which is measured in amp hours (Ah). This tells you. Assuming you have a 12V battery that is in good condition, it can supply up to 30 amps of current. The amount of current that a battery can provide depends on its sizeand capacity. A larger battery will be able to provide more.