# Electronic – How to calculate average power consumption in mAh

batteriescurrentpower

I'm working on a device that sleeps for most of the time and occasionally wakes up and takes some sensor readings. This device will be battery powered so I'm trying to calculate how long it will run on a 2,000 mAh battery. A typical hour of application looks like this: It's easy for me to calculate how long each stage would take by itself (for example sleep could run for (2,000 mAh/.05 mA) = 40,000 hours) but I'm confused on how I would calculate every stage together and get an accurate calculation of how long the battery would last.

Thanks!

how I would calculate every stage together

Using $$1 \text{ mAh} = 1 \text{ mA} \cdot 3600 \text{ sec}$$

you can calculate the average as:

$$0.05 \text{ mA} \cdot 3473 \text{ sec} + 56 \text{ mA} \cdot 120 \text{ sec} + 0.44 \text{ mA} \cdot 6 \text{ sec} = 1.9 \text{ mAh}$$

get an accurate calculation of how long the battery would last

You can only use the number above to make a crude estimation how long the battery will last.
One reason is that for a high amperage the battery life will be shorter than the product mA times supply time.
Another reason is that the battery will self discharge.