How can you calculate run time?

I made my first p60 drop-in, it has three settings, hi, medium and low.
I measured amperage at the tail cap.
I got 1.38 high, 0.42 medium, and 0.06 Low.

How long can I expect the light to run on each of the settings, assuming that I am using a quality 3100 mah 18650 battery?

Poppy said:

I made my first p60 drop-in, it has three settings, hi, medium and low.
I measured amperage at the tail cap.
I got 1.38 high, 0.42 medium, and 0.06 Low.

How long can I expect the light to run on each of the settings, assuming that I am using a quality 3100 mah 18650 battery?

Click to expand...

3100/1380 = 2.25 hours
3100/420 = 7.38 hours
3100/60 = 51.7 hours
This is assuming it is a regulated driver if unregulated runtimes could be considerably longer as the battery depletes and current and power input to it drops.

Thanks Lynx_Arc, I really appreciate your response. I had done the math like that, but wasn't sure if I could use the full 3100 mah, or if it needed to be cut to 50% or something like that due to the battery protection circuits.
Maybe I should have included that in the original post?

A quick search is often all you need to answer common questions like this. Use the Google search box under the CPF logo.

Google CPF for How can you calculate run time?

Cheers Norm

Poppy said:

Thanks Lynx_Arc, I really appreciate your response. I had done the math like that, but wasn't sure if I could use the full 3100 mah, or if it needed to be cut to 50% or something like that due to the battery protection circuits.
Maybe I should have included that in the original post?

Click to expand...

The protection circuit should only kick in when there is a dead short or the battery is nearly depleted I think. Depending on the circuit design of the light you should get full capacity I think such that the only limitation would be is the battery actually 3100mah or not as some manufacturers exaggerate capacity for sales purposes many test out actually lower than advertised.

Thanks Norm, honestly I didn't search this time (obviously... there are at least twenty people who asked the same question using similar words!) Many times in the past when I did a search, the words I used were so common they produced hundreds or thousands of hits. For example if I included 18650, I'd get over 32,000 hits.

I guess I need to read the thread on "how To Search on CPF"

I have to give your credit for all the time you spend on this forum. I'm a mod on another (non flashlight forum) and can truely appreciate your dedication.

Lynx_Arc, again... thanks for the followup post. I have some 3400 mah Eagletacs, and some lesser quality brand stuff, you know what I mean. Being able to do the math, gives me a good ball-park of what to expect out of a quality battery.

Thanks again :thumbsup: