How Long Will a Device Drawing 8mA Last on a 12V Battery? Learn the Answer Here!

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SUMMARY

A device drawing 8 mA will last approximately 3.125 hours on a 12V battery with a capacity of 25mAh. The calculation is straightforward: dividing the battery capacity (25mAh) by the device's current draw (8mA) yields the duration. The discussion clarifies that the voltage remains consistent throughout the problem, and there is no known 12V watch battery available, as most watch batteries operate at 1.5 volts.

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How long will a device drawing 8 mA last on a 12 v bat that has a 25mAh?


25/8 = 3.125 hours?
 
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You got it.

- Warren
 
is there a bat as small as a watch bat that can produce that much mAh at 12v?
 
Not that I know of.

- Warren
 
what is ur mAH for watch bat?
 
Hell if I know, but I've never seen a 12V watch battery. Most battery chemistries in use today are 1.5 volts or so -- they'd have to pack 8 cells into that watch battery package to get 12V, and I don't think it's been done.

- Warren
 
Electrical current and pressure

david90 said:
How long will a device drawing 8 mA last on a 12 v bat that has a 25mAh?
Voltage is electrical pressure, and it is analogous to water pressure. We don't need to know what the voltage is to answer this; we just need to know that it is considered consistent throughout the problem. The question should be stated as:How long will a device drawing 8 mA at a particular given voltage last on a battery that has a capacity of 25mAh at the same given voltage?.



25/8 = 3.125 hours?
Yes, if the question is stated as I corrected above.
 

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