26650 Batteries For Sub-ohm In Mech Mod - Current Drain Questions

[1am7h30n3]

Very interesting! I'm sitting here scratching my head trying to make sense of it all. Yes I assumed those two values, just theoretical values for now (I am definitely going to go get myself a multimeter)

Ok, so this is how I broke it down:

Known values:
EMF = Battery resting voltage
Rload = The atty/coil resistance

Calculated Values:
Vload = Voltage measured at atty while firing
Rinternal = Mod and battery internal resistance
Iload = Current in circuit under load
Pcoil = Power at coil while firing

Formulas for calculated values:
Vload = (EMF x Rload) / (Rload + Rinternal)
Rinternal = (Rload x (EMF - Vload))/Vload

Sample Situation
================
Assume:
EMF = 4.2V (freshly charged)
Rload = 0.156 ohm

Solving for Vload:
Vload = (EMF x Rload) / (Rload + Rinternal)
Vload = (4.2 x 0.156) / (0.156 + 0.1)
Vload = 0.6552 / 0.256
Vload = 2.5594 V

Solving for Rinternal:
Rinternal = (Rload x (EMF - Vload)) / Vload
Rinternal = (0.156 x (4.2 - 2.5594)) / 2.5594
Rinternal = 0.2559336 / 2.5594
Rinternal = 0.099 Ohm

Proposal (Here there is some discrepancy, and I'm not sure why)
========
Iload = EMF / (Rinternal + Rload) (I = V / R)
Iload = 4.2 / (0.099 + 0.156)
Iload = 16,47 Amps (!)

Pcoil = Iload x Vload (W = Amps x Voltage) -> Here I assumed that Amps is Amperage under load, and Voltage is voltage under load
Pcoil = 16,47 x 2.5594
Pcoil = 42,154 W


How did you get to this calculation?: power = I x I x R = 15 x 15 x 0.156 = 35.1W.

I think we are on the same track there, the only difference is when you assumed a lower internal resistance than I did, you wound up with more current and also more power to your coil. I calculated my Rload to be the minimum Rload possible without exceeding 15A, you chose the same Rload as I did, but with a lower assumed internal resistance.

And then the power calculation will work out as well (with a different power result for your case, once you have calculated your min Rload to not exceed 15A). Of course, I'm not suggesting that we actually build these coils, 15A is right on the safe limit, this is all theoretical for me at this point...