The main reason I had this idea was to be able to use more batteries for a longer lasting power supply. Is there a formula I could use to determine roughly how long my batteries will last with specified LED's at certain voltages? I assume Amps are the current, and not volts as I previously mis-stated. And most LED's are rated for 20v30 or so milli-amps or mAh, or at least I think that's how it was abreviated. Depending on how many LED's I had, and what amperage they drew power from, and then depending on my batteries and how many amps, or amperes I think they are also called, then I should be able to figure out roughly how long my batteries would last.
Sorry for my ramblings, but it helps me think. A basic formula would probably be something like Amps/power draw = Time or something like that? Please, feel free to correct me if I'm wrong. Just, logically thinking, that seems like it would work. But its entirely possible I left something out, possibly resistance of the wires, though that's probably not much. But putting a resistor in the circuit might change the formula too... hmm, many things to compensate for lol.
Again, sorry for my wall of text. But I prefer to learn things instead of just having someone hand me the answer.
LEDs have a supply voltage that varies with the colour (red has the smallest, and then up the rainbow towards blue it gets larger, symbol for voltage is U, unit is volt, short V) and a supply current (usually around 20 mA in standard LEDs, symbol is I, unit is ampere or short A).
Any unit can be varied with SI-prefixes (nano, milli, kilo, giga, etc., these all stand for a specific power of 10,
see here). (But don't use them on your feet and inches please, only use them with
SI units 
)
Every battery has a charge that is measured in Ah (marketing usually dictates writing the value down in mAh, because 1000 mAh sounds better than 1 Ah, despite being exactly the same). What the value means is that the battery can provide a current of one ampere for one hour. Or half an ampere for two hours and so forth... you get the idea. The formula you need here is Q=I*t (Q being the charge in As or Ah for a time t in the respective unit), which can be rearranged to t=Q/I, so one 20 mA LED will last around 50 hours on a 1000 Ah battery.
However, keep in mind that the battery voltage will not stay constant during that time. It usually starts out slightly above the nominal voltage (1.5V per cell for alkalines, 1.2 V for NiMH), then stays somewhat constant for a while and then, when little charge is remaining, drops steeply. That means that you might not be able to make use of the full charge if the voltage drops below whatever voltage you need. LEDs will work with a voltage slightly below the one they're rated for, but that has a huge impact on light output. If there is a datasheet for the specific battery you want to use, it will probably contain a discharge diagram that plots voltage against charge, you can use that to determine how much is really usable.
Also keep in mind that it's not a good idea to draw large currents from a battery, they usually don't like that.
Some other formulas that might come in handy are U=R*I (R being the resistance in ohms, short Ω) and P=U*I (P being power in watts, short W). The former is Ohm's law and is used to calculate that resistor.
The resistance of wires is negligible,
if the diameter is large enough. You can look the resistance per length up somewhere as well. But don't break your head over a few ohms.
Just thought I'd go fishing with this idea. I have a few 8.4 volt, 5000 mAh batteries left from when I was in my R/C phase. I'd thought of putting two of them together for 16v, like my Traxxas E-Maxx uses.
What do you guys think about that as a power source for the entire suit?
What do you need 16.8 V for?
