Sub ohming safely

[the_hydeonian]

Call this a daft question, but I see loads of experienced vapers sub ohming on stacked mods ( batteries in series) going off ohms law this method doubles Volts, Amp draw and Wattage, surely that then becomes dangerous, can someone please help get my head straight on this, and to alleviate any worries i may cause the group, I haven't bought a stacked devise

 

[Anise]

I don't have a stacked device so I can't help you but I'm sure someone will come along with an answer for you.

 

[Baditude]

Perhaps a more correct term would be "multiple battery" devices that use different circuitry. There are basically two types, series and parallel, of circuits.

Series or "stacked" cells result in increased voltage output (8.4 volts), but the capacity (mAh) and amp limit remains the same as a single cell.

A parallel circuit results in increased capacity (2X) and amp limit (1.5X, not 2X), but voltage output remains the same as a single cell (4.2 volts).

Both are potentially dangerous if used incorrectly or misunderstood. Super sub-ohming with a stacked (series) mech mod is a misapplication and a bad idea.

For a more detailed explaination of each, click the below link:

UNREGULATED PARALLEL BOX MOD VS. UNREGULATED SERIES BOX MOD | VAPING BATTERY SAFETY

 

[Nate5700]

I guess we're talking unregulated mods. If that's the case, power output varies according to the square of the voltage. So if you put your batteries in series it doesn't double the power. It increases it by a factor of 4. In terms of current, it only doubles the current. P = I * V = I^2 * R = V^2 / R

What this means in terms of safety is that power output and current are going to increase with batteries in series, for the same coil. So if you're thinking that you can build a lower resistance coil and then put batteries in series to get more battery life, that is a Very Bad Idea.

Batteries in parallel have their own set of problems, namely that charge can flow from one to the other even when you aren't firing the mod.

Mech mods as a general concept scare the out of me. More batteries means more danger.

 

[Rossum]

Call this a daft question, but I see loads of experienced vapers sub ohming on stacked mods ( batteries in series) going off ohms law this method doubles Volts, Amp draw and Wattage, surely that then becomes dangerous, can someone please help get my head straight on this, and to alleviate any worries i may cause the group, I haven't bought a stacked devise

A stacked mech (or other unregulated device) requires different builds than a single-cell device. Keep the resistance high enough that you're not straining the cells' CDR even with a nominal 8.4V. Thing is, you don't need to build particularly low when you've got 8.4V to play with, because, as the previous poster stated, power increases with the square of the voltage.

 

[the_hydeonian]

Thanks for the lesson guys, so much to learn, think I'll stick to regulated at the minute, I have been studying ohms law and battery safety and would like to try a mech but it will be single battery lol. I like the look of the Tauren

 

[Baditude]

I see loads of experienced vapers sub ohming on stacked mods ( batteries in series) going off ohms law this method doubles Volts, Amp draw and Wattage, surely that then becomes dangerous.

There's no logical reason to super sub ohm with a stacked tube mechanical mod in this day and age, at least not safely. As everyone who has responded to your question has said, stacking batteries does not double the amp limit or capacity, they stay the same as if using a single cell. Users must still stay under the amp rating of a single cell.

If one battery shorts in a dual battery mod, the second battery is sure follow suit. Double the batteries, double the power of the bomb.

Back in the day before high wattage regulated mods became readily available, the only way to sub-ohm was to stack batteries in a mech. It wasn't particularly safe then, and it isn't particularly that much safer today. For folks that want to vape super subohm with dual/triple batteries they should use a higher wattage regulated mod. I realize that opinion will not be popular among that niche group, but I can live with that. Science wins over urban legend myths.

 

[sonicbomb]

Unregulated series or parallel, as long as you choose an appropriately high or low resistance you can achieve the same power output and overall runtime. Both examples below are for a two battery mods using Samsung 30Qs, the first in series the second in parallel.

1.00 ohm coil - 8.4 volts - 8.4 amp = 70 watts (11.1 watt hours)
0.25 ohm coil - 4.2 volts - 18.8 amps = 70 watts (11.1 watt hours)



On a multi-battery regulated device because the batteries are separated from the atomizer by the regulator chip, the battery configuration series or parallel does not matter. Though series is usually chosen as it is more efficient.

 

[Rossum]

Unregulated series or parallel, as long as you choose an appropriately high or low resistance you can achieve the same power output and overall runtime. Both examples below are for a two battery mods using Samsung 30Qs, the first in series the second in parallel.

1.00 ohm coil - 8.4 volts - 8.4 amp = 70 watts (11.1 watt hours)
0.25 ohm coil - 4.2 volts - 18.8 amps = 70 watts (11.1 watt hours)



On a multi-battery regulated device because the batteries are separated from the atomizer by the regulator chip, the battery configuration series or parallel does not matter. Though series is usually chosen as it is more efficient.

In principle it is correct that that you can get the same amount of power from a set of batteries no matter whether they are in series or in parallel.

But in practice, series is more efficient in a mech or unregulated mod too, because the losses in the mod itself (which will be proportional to the square of the current flow) will be less.

Look at modern cordless tools. The have commonly have battery packs consisting of 3 to 5 cells. Those cells are in series, not in parallel. The reason for this is the same, to reduce the losses between the battery pack and motor in the tool.

 

[stols001]

You can also get a two battery series regulated mod, I have a DNA mod that's like that. It's rating wattage wise is lower but runtime is longer.

However, if I were going to "super sub0hm" (not quite sure how low that means) I would look for a regulated parallel mod, and maybe a 2700 series battery if you can find one that you can actually pick up) or a three battery parallel 18650 mod if you are going to be using this all day. Make sure the battery ratings (check Mooch's blog if unsure but you seem to have an idea of what you are doing) unless you only want to "super Sub0hm at home and can switch out various batterie frequently.

What resistance do you plan to use and what wattage?

Anna

 

[sonicbomb]

In principle it is correct that that you can get the same amount of power from a set of batteries no matter whether they are in series or in parallel.
But in practice, series is more efficient in a mech or unregulated mod too, because the losses in the mod itself (which will be proportional to the square of the current flow) will be less.

I knew that, but chose not to mention it in the context of the OP.
But thanks for pointing it out.

 

[KenD]

However, if I were going to "super sub0hm" (not quite sure how low that means) I would look for a regulated parallel mod, and maybe a 2700 series battery if you can find one that you can actually pick up) or a three battery parallel 18650 mod if you are going to be using this all day. Make sure the battery ratings (check Mooch's blog if unsure but you seem to have an idea of what you are doing) unless you only want to "super Sub0hm at home and can switch out various batterie frequently.

What resistance do you plan to use and what wattage?

Anna

The vast majority of regulated multiple-battery mods are series. It'll be very difficult to find a multiple-battery parallel mod. Two-battery DNA75 and 75c mods are the only ones I can think of that would fit the bill.

Sent from my Thor E using Tapatalk

 

[OldBatty]

1.00 ohm coil - 8.4 volts - 8.4 amp = 70 watts (11.1 watt hours)
0.25 ohm coil - 4.2 volts - 18.8 amps = 70 watts (11.1 watt hours)

Possible typo, should the 18.8 amps be 16.8? Can not get the math to work in both directions with 18.8.

In my case since I use a 1.65 ohm coil at 4.2 volts so would need a whopping 6.6 ohm coil to duplicate my wattage at 8.4 volts. This explains why my Noisy Cricket has been gathering dust for over a year

 

[stols001]

Two-battery DNA75 and 75c mods are the only ones I can think of that would fit the bill.

Yes, I have one and one that's not that popular, but I like it

Anna

 

[sonicbomb]

Possible typo, should the 18.8 amps be 16.8? Can not get the math to work in both directions with 18.8.

Yes typo. Sorry for the inaccuracy and thanks for catching that.