Formulas for runtime ect.

Hi.
I've noticed a few people on this forum use Excel for working out alot of electrical calculations.
I've just been introduced to Excel at work and am hoping to make more use of it other that speeds and feeds for machines.
Would anyone know of the whereabouts of a compilation of electrical formulas i could stick into Excel?(i have to learn how to get that working yet)

For eg. i would like to work out runtime of batteries at a certain current.
And also the right amount of voltage to use with a Fatman and xxxLEDs.
Ect.
I'm sure these are easy calculations for some -but they give me a headache as i'm pretty new to electronics

Thanks for any help.

Cheers
Dom

The first one you mentioned, you don't need excel to do it.

If your batteries have [X] Ah, and your bulb pull [Y] A, you will get [X/Y] hours runtime. In real life, you might want to draw 10 or 20% of that value.

However, if you want to learn excel and fiddle with it, a runtime formula would be great to start with. Just post if you need any help getting started.

Thanks Winny -i'll see how i do with the excel on that one.

Cheers
Dom