Battery math question

[bombastinator]

so my brain is kinda fried atm and I’ve got a battery question my head is balking at. I’m kind of feeling like a noob here.

mod is ageis legend running in straight wattage mode

mod claims at rest with atomizer attached:

18w
1.98ohm
5.97v
0amp (of course)

atomizer is drawing at load (it’s SS): firing for a couple seconds. These numbers vary but do not exceed:

18w
2.4ohm
6.6v
2.7a

I want to do the math to figure out what my real draw is
I think I’m pretty safe running a pair of Samsung 30qs I’m not sure how safe though.
I’m also guessing I CANT run 35Es.

Anyone with working grey matter feeling bored and want to do me the favor of schooling me on the numbers?

 

[Punk In Drublic]

Current draw on the batteries with a regulated device = Watts/amount of cells/cell voltage/efficiency. Efficiency is unknown with many devices so for the sake of example we’ll use 90%. Current draw will be at it’s maximum at the devices cut off voltage. This is on average around 3.2 volts

So 18watts/2 batteries = 9

9/3.2volts/0.9 efficiency = a whopping 3.13 amps per cell. Better turn down that wattage!!

 

[Hawise]

Only the watts and the battery voltage under load matter. Unfortunately, the mod is probably displaying voltage to the coil rather than from the battery when under load, so we don't know what that is. However, since you're more concerned with what the battery can handle than what you're using right this instant, we need to use the low battery cutoff rather than your actual voltage anyway. I'll go with the standard cutoff of 3.2 v.

Amp draw per battery

= wattage / number of batteries / low voltage cutoff / efficiency
= 18 / 2/ 3.2/ 0.9
= 3.125 amps

So yes, it looks like you could use a pair of 35Es if you wanted to.

ETA: and @Punk In Drublic beat me to the Post button

 

[Punk In Drublic]

Looking at Mooch’s battery test’s, I am willing to bet the 30Q will still give you a longer run time despite the lower mAh ratting. Mooch doesn’t test the 30Q with a 5amp draw, but at 10 amps the 30Q better’s the 35E 5 amp curve in Amp Hours at a 3.2 volt cut off. Stick with the 30Q

 

[bombastinator]

Current draw on the batteries with a regulated device = Watts/amount of cells/cell voltage/efficiency. Efficiency is unknown with many devices so for the sake of example we’ll use 90%. Current draw will be at it’s maximum at the devices cut off voltage. This is on average around 3.2 volts

So 18watts/2 batteries = 9

9/3.2volts/0.9 efficiency = a whopping 3.13 amps per cell. Better turn down that wattage!!

.9 efficiency. There’s my brain fart. I knew there was a brain fart in there. I thought it was too good. Vaping monster DL @ 18w. Burns at 20. Something couldn’t be right. Thx! U rock!... wait... that’s not right either. Gnar. Brain is moving decimals on me. Maybe This gigantic coil garbage does work then.. and I shouldn’t even attempt to think things when my brain wants to turn off. This is why I don’t drink much. It simply isn’t necessary. All I need is a long day. Either this is just about the most efficient big cloud DL ever or something else is wrong. I’m going with something else is wrong. Anyway if my batteries are safe I’m gonna vape it and go to bed.

 

[Punk In Drublic]

Venturing into the unknown which is trying to assume what you are confused about. 0.9 efficiency is the device efficiency, not the coil efficiency. Don’t what defines coil efficiency given there are may subjective views on many different coils. I say if you are content with 18 watts with what ever coil(s) you are using then that’s all that matters.

So curious, what is this gigantic coil?