How to calculate runtimes?

I have a drop-in that does the following in its three modes:

150ma low, 1000ma medium, and up to 2.8a on high.

How can I figure out the approximate runtimes for this drop-in, based on a 18650 (3100) cell? Thanks.

Your battery has a capacity of 3100 mAh (milli Ampere hours). The current draw of the driver is expressed in Amperes or milli Amps (mA). Such as 2800 mA, 1000 mA, and 150 mA.

If you divide the mAh by the mA you'll be left with just h (hours). So...

3100 mAh / 2800 mA = 1.1 hours (1:06)
3100 mAh / 1000 mA = 3.1 hours

But this is a simplistic overview and there are other factors regarding batteries which complicate the whole calculation.

Hopefully you can run a burn test and see if these numbers are close.

You will often find your question can be answered by doing a quick search of the forum, using the google search box at the top of the page.

Norm

You mean there's a flashlight that Selfbuilt hasn't done a review and runtime test on? Impossible!

MRTdiver, thanks for the information. Very helpful.

Norm, I did a very cursory search and didn't see anything, though certainly I could have dug around more.