calculators on the net

[Ron Dickey]

I have found several types.

this site offers A calculation for Battery time before dead with usage.
at same site offers a calculator for interior volume offers shapes much like many trailer designs. made for boats
http://www.digiboat.com.au/info/calculators.htm

need any kind of calculator go here at very bottom of site is Electrical.
http://www.martindalecenter.com/Calculators.html

maybe I will put this on general site as well for those who never look here.
or maybe mike might like to add one to links.