Confused at how my regulated mod RX2/3 is calculating displayed current

[arabdjin]

I understand Ohms law well (I'm an avionics engineer by day) and how it applies to mech and regulated mods. For regulated mods the Watts + battery voltage is what counts, however... all the calculations I see say take the set wattage and divide by the total battery level (at lowest value) to get the current draw. So setting my mod at 75W with a triple battery mod I should see:

75W / 9V = 8.33A

My mod (Reulaux RX 2/3) displays the current voltage AND current draw and at 75W I'm seing, 3.46V and a current draw of 20A.

Does anyone know how the current displayed on this mod is calculated?

Any help would be most appreciated!

 

[KenD]

I understand Ohms law well (I'm an avionics engineer by day) and how it applies to mech and regulated mods. For regulated mods the Watts + battery voltage is what counts, however... all the calculations I see say take the set wattage and divide by the total battery level (at lowest value) to get the current draw. So setting my mod at 75W with a triple battery mod I should see:

75W / 9V = 8.33A

My mod (Reulaux RX 2/3) displays the current voltage AND current draw and at 75W I'm seing, 3.46V and a current draw of 20A.

Does anyone know how the current displayed on this mod is calculated?

Any help would be most appreciated!

The current draw on the 2/3 (and pretty much all mods that have an amp display) display the current at the atomizer, not the battery. After the chip does its regulation. The volts shown is what the mod fires at to provide the set watts. So a regular ohms law calculation based on the resistance and that voltage is the basis of the calculation. Useless information really.

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[arabdjin]

The current draw on the 2/3 (and pretty much all mods that have an amp display) display the current at the atomizer, not the battery. After the chip does its regulation. The volts shown is what the mod fires at to provide the set watts. So a regular ohms law calculation based on the resistance and that voltage is the basis of the calculation. Useless information really.

Sent from my M7_PLUS using Tapatalk

Uselessindeed and connfusing. Where is the chip getting that displayed 20A reading if not from the batteries? Is my initial calculation more accurate then?

 

[Baditude]

I don't quite understand how regulated mods do their calculations, but perhaps this will help:

Calculating battery current draw for a regulated mod

How to Choose Your Batteries by DJLsp Vapes

 

[KenD]

Uselessindeed and connfusing. Where is the chip getting that displayed 20A reading if not from the batteries? Is my initial calculation more accurate then?

What's the resistance of your coil? If I remember correctly the Joyetech mods do the calculation based on the resistance and the voltage required to get to the set watts, as if it were an unregulated mod with the battery at that voltage (3.46 in your case). An ohms law calculation based on those variables. Honestly, I haven't given it that much thought as the displayed amps are totally useless, but that's more or less it.

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[KenD]

I don't quite understand how regulated mods do their calculations, but perhaps this will help:

Calculating battery current draw for a regulated mod

How to Choose Your Batteries by DJLsp Vapes

I've lost my faith in Daniel from DJlsb vapes a bit since he has repeatedly refused to acknowledge that 220w (the Smok mods he so adores) is simply too much for two 18650s.

In his answer to me he defends himself by saying that he simply adheres to Mooch's recommendations, but I seriously doubt that @Mooch says that 37 amps per battery is unproblematic for any 18650. I could be wrong of course, but in any case I think it's irresponsible for a reviewer to make it seem ok to exceed the cdr of batteries.

Edit: just rechecked Mooch's battery lists and there are a few batteries that he rates with a maximum vaping amps of 40. Still, Daniel should at the very least point out that such a high wattage as 220w is beyond the capability of most 18650s, identify the few batteries that can handle the current, and point out that even then the cdr is exceeded.

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[arabdjin]

What's the resistance of your coil? If I remember correctly the Joyetech mods do the calculation based on the resistance and the voltage required to get to the set watts, as if it were an unregulated mod with the battery at that voltage (3.46 in your case). An ohms law calculation based on those variables. Honestly, I haven't given it that much thought as the displayed amps are totally useless, but that's more or less it.

Sent from my M7_PLUS using Tapatalk

So the displayed voltage is 3.46V and the coil is 0.16 ohm. Using Ohm's law with these values gives 21.625A. I see around 20.2A being displayed.

Is the current an internal calculation or a reading at the output of the regulator? Can't see how 8.33A (based on the correct calculation for a triple batteries at 75W) becomes 21+ amps???

 

[KenD]

So the displayed voltage is 3.46V and the coil is 0.16 ohm. Using Ohm's law with these values gives 21.625A. I see around 20.2A being displayed.

Is the current an internal calculation or a reading at the output of the regulator? Can't see how 8.33A (based on the correct calculation for a triple batteries at 75W) becomes 21+ amps???

The input and output amps are completely separated, basically no relation to each other. You can't determine the amps at the battery by the readout at all. The calculation you had in the op was correct. For the amps at the atty, I don't know what exactly the mod is doing so that the amps aren't 20.2 but it's close enough to a regular "mech style" ohms law calculation for me to believe that's what it's doing.

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[arabdjin]

The input and output amps are completely separated, basically no relation to each other. You can't determine the amps at the battery by the readout at all. The calculation you had in the op was correct. For the amps at the atty, I don't know what exactly the mod is doing so that the amps aren't 20.2 but it's close enough to a regular "mech style" ohms law calculation for me to believe that's what it's doing.

Sent from my M7_PLUS using Tapatalk

Thanks buddy. I've emailed Wismec to see what they have to say and what they think of making the read out read the output from the batteries instead which I think will be more useful.

I'll post back what they say if they ever reply.