Ohm's Law question

[Loxley]

So until now I've been using charts and batteries based on what I've been told and researched to be safe. However now I'm trying to do the calculations myself and learn it.

I know Resistance = Voltage divided by Current (R= V/I)

So I'm looking at the Smurf batteries (Samsung 18650)

2500 mah
4.2v (after a fresh charge)


trying to solve for the resistance

4.2/2.5 I get 1.68 as the resistance.

Does that mean it's only safe to vape at 1.68ohms? From what I hear about the batteries the "safe to vape" zone should be much lower then that. Can anyone tell me what I'm doing wrong? What step am I missing?

 

[Hoosier]

Simply? Ohms law has nothing to do with charge capacity of a power source. So plugging milliamp hours into it does not result in any usable result.

You will need to know the safe discharge rating for the battery which will be an "I" you can use. Sometimes this is given as a "C" rating which is multiplied by the mAh to arrive at the actual amperage of discharge. Sometimes it is given as "amps" which is perfect. And what you really want is the constant discharge rating, and to be perfectly safe, use 80% of that for your calculations. (This will give you a safety factor of 1.2 which should cover variances in the manufacturing process and usage.) Be very leery of "surge" or "peak" discharge current ratings as those are only useful for a specific short duration and the specific duration is seldom given.

Hopefully you can get a more useful result now..