Sigelei Series safety

[Chrissar]

Hi I'm new to this forum, just wanted to check my understanding of battery/power/resistance issues.

I currently have a dual coil twisted 26g Kanthal build in my RDA reading 0.24 ohms on a Sigelei 100W+ (actually reads 0.2 on Sig as it doesn't provide the decimal point to the hundredth). My understanding is that i am OK to use two LG HE4s (20A maximum discharge) as the Sigelei runs these 'stacked' in series - thereby increasing the nominal available voltage to 7.4 volts and thus placing less stress on the battery by effectively reducing the required current (vaping at 70W) from 18.71A (single battery 3.7 nominal volts) to 10.51A.

Can anyone with experience in such things confirm this for me and put my mind at ease that I'm not stressing these batteries to much - i have noticed the mod get a little warm after some continued vaping - obviously i put it to one side and have let it rest - thought i should ask this question before firing it up again - (may put in a new slightly higher resistance build just to be on safe side).

Many thanks

 

[dave61]

Im curious about this myself

 

[martinelias]

In series the voltage doubles, the load and the mah remain the same.
In parallel, the voltage is the same but the load is divided in half and the mah doubles.
So 18.71a remains 18.71a in a series setup as the load does not split amongst the cells.

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[martinelias]

Oh, and you're fine with that setup. Those cells can handle that.

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[Chrissar]

Thank you very much for your reply and without wishing to call into question your advice can you explain why even steam engine tape calculator calculates a significantly lower ampege in terms of battery draw when combined voltage is taken into account? I have had a number of replies on another forum to this same question which seem to support the theory - there seems to be lots of differing opinions about this - thanks

 

[martinelias]

What numbers did you plug into the equation? I don't see where steam engine accounts for parallel or series setups.

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[Chrissar]

well i perhaps incorrectly assumed that when it asks for nominal voltage i would have to input this as the combined voltage across both batteries (7.4) as opposed to 3.7 - this then in turn brings the battery amp draw down significantly - am i way off with this?

 

[Chrissar]

....the inference here is not that the current is split across the two cells - i understand that this is not the case with a series configuration but that the extra voltage somehow compensates for a proportion of the battery amp draw - lowering the required draw across the board - certainly entering a higher voltage on steam engine seems to support this but perhaps this effect is not obtained by combining the voltage of two separate batteries in series?

 

[Chrissar]

....may be getting a little confused by nominal voltage and the actual voltage being used when firing at 70 watts - given that everyone seems to think this is fairly safe regardless with these batteries - ill wait until they're charged fire it and check the voltage - then try the calculations again.

 

[martinelias]

I think steam engine is for single cell applications. Could be wrong though. Also from some mild researching the manufacturer recommends 30a cells.

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[Chrissar]

Yeah i think it probably is - i suppose that I'm just assuming that if in series you add the voltage then this acts just the same as if you had a single cell that had that combined voltage itself???

 

[martinelias]

I tried it but when you do it the amps goes off the chain. No way that's accurate that way.

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[Chrissar]

Thanks for all the help - Ive found some Sony VTC5s from a place near me (good reason to think they're genuine) - think I'm going to order a few of them to be on the safe side - be really useful to get my head round this anyway though!

 

[NemesisVaper]

70W on a single cell regulated mod will draw around 16.7A on a fully charged battery. On a series regulated device it would draw half that, 8.4 A.

On a regulated device, the ohms of the build doesn't matter. All that counts toward amp draw is the wattage you've set and the voltage of the cells at the time you fire the mod.

On a regulated device, amp draw goes up as battery voltage drops, which is the exact opposite of what happens on a mech.

To calculate amp draw on a regulated device, divide the wattage you're using by the cell voltage. You'll need aa mod that shows actual battery voltage or a multimeter to find that out. Can't use the voltage shown on the screen as that's what the board is putting to the atty.

 

[Jon@LiionWholesale]

Your original thinking was actually correct, assuming I'm reading your post correctly that you're talking about a regulated mod. Putting batteries in series in a regulated device allows you to use the combined voltage, which once you do the calculations ends up meaning the amps are halved. 70W with two HE4's is very easy on the batteries since you're looking at about 10A each like you said.

Note that this is very different than a mechanical device, if you put batteries in series in a mechanical device your watts will exponentially increase and you will be putting a lot more stress on the battery, not less. That's probably where the confusion comes in.