Questions regarding voltage drop

[GrayVaper]

I just received my first mech mod last night. It is an all copper Panzer clone called the Red Phoenix. It is all copper throughout except for the magnets in the firing button. This clone was reviewed by Twisted420 and he was amazed at the low voltage drop of .04 - .05 on a Kayfun 1 ohm build.
I installed an inline volt meter and got a battery read of 4.10v on a fresh Efest 2100 MaH 38amp 18650 battery. Then I attached my .3 ohm dual coil Mutation X build and my reading dropped to 3.56v for a difference of .54v. I know there must be a formula for the build vs voltage drop but I am not an electrical engineer.
can someone explain this all to me?

 

[Neunerball]

1.) an inline volt meter is not very accurately.
2.) a 0.3 Ohm coil sucks lots of power from the battery. Therefore, dropping the voltage rather fast.
3.) to get an accurate measurement, you should use a Volt/Multi meter, and measure directly at the mod's connection.

 

[Eric DeCastro]

that sounds about right anyway. on my .49ohm builds the battery sags from 4.2VDC to 3.4XXXVDC. on an 18350

 

[GrayVaper]

So this is normal then?

 

[Eric DeCastro]

normal battery sag. people have been using voltage drop incorrectly. voltage drop is across a component. what you are measuring is what is called loaded power. or voltage with a load on it.

so the older your battery gets the lower that voltage will get. voltage drop will never change unless the material the current is going through chemically changes.

 

[GrayVaper]

Good point. This is all Greek to me.