# Am i Safe ? Shaun's Guide to Battery Drain



## shaunnadan (2/2/16)

As a follow up article to http://www.ecigssa.co.za/shauns-guide-to-battery-safety.t17245/ I have decided to go into a bit more detail in regards to battery drain.


a common question I get asked is "I have this coil on that battery and I’m firing at these watts, am I safe?" then I go out, get the calculator, plug in all of the values and return with an answer. 


*So how do I do it ?*

start by going to the Battery drain page on Steam-engine.org
http://www.steam-engine.org/batt.asp

select the mod type : regulated or unregulated 
enter in your atomizer resistance
select your battery from the presents (if it’s not there then you would need to manually enter in your battery specifications)

then compare your current value in the battery drain section to the amp limit. the amp limit headroom will tell you how much headroom you have before stressing out your batteries (the preferred amount is 20%)

if your amp limit headroom value is in the negative then your battery drain is higher than how much your battery can take!


all done 


*Important side note !*

steam-engine does not take into account multiple battery configurations. what this means is that if you have a mod with more than 1 battery you will need to manipulate the calculations manually. 


*if you have a parallel mod >*
a parallel mod will double your amperage and mah. the voltage will stay the same


*if you have a series mod >*
a series mod will double your voltage. the amperage and mah will stay the same. 

*what does this have to do with my battery drain?*

_if you had a 0.5ohm coil and your pushing 50w on a single 20A battery (Samsung 25R) >_
you would be using 11.9A with your battery limit being 20A

_the same build on a dual 18650 parallel mod >_
you would be using 11.9A of current with a battery limit of 40A

_the same build on a dual 18650 series mod (double the battery voltage value) >_
you would be using 5.95A of current with a battery limit of 20A

*since the amp draw is less the battery life will be much better than a single 18650 even though the mah is the same 

*How exactly does it work ?*

There are two main types of mods: Regulated, and unregulated (mechanical). As far as battery drain is concerned, these are two completely different animals.

In an unregulated mod, a lower resistance atomizer means more current drawn from the battery, and less battery life. In a regulated mod, things get more complicated, and the rules are different.

*Unregulated mods – a battery with a coil on it*

Unregulated (mech) mods are very simple devices. They have one circuit. This circuit can be easily modelled using Ohm's law. In other words, if you have a basic understanding of Ohm's law, that is all it takes.

The battery drain is determined by two factors:


The resistance of the atomizer, which is more or less constant after you have built your coil(s).
The voltage of the battery, which decreases as the battery drains.
There is not much more to mech mods. They are about as simple as an electrical circuit can get:

The voltage hitting the atomizer is the voltage from the battery (minus the tiny voltage drop in the switch and conductors).
The current flowing through the battery is the current flowing through the atomizer.
A multimeter and some straightforward use of Ohm's law you will give you all the numbers you need.

*Regulated mods – fixed or variable voltage or power*

Regulated mods are more difficult to model. But even though they are much more complex than mechs, with some selective simplification we can safely ignore most of the complexity. So we break these mods down into two circuits and a black box. This makes our regulated mod model little more than twice as complex as our mech mod model.

The two main circuits of a regulated mod are:

The atomizer (output) side.
The battery (input) side.
And never the twain shall meet. The regulator circuit takes care of that. It can have a bunch of more or less advanced circuits in itself, and it uses a little bit of power, but for the most part we can envision it as a black box separating the battery circuit from the atty circuit.

source : Steam-Engine.org

http://www.steam-engine.org/batt.asp

Reactions: Like 4 | Winner 2 | Informative 5 | Useful 2


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## shaunnadan (2/2/16)

@Andre - i would love for you to add anything i may have missed in this article

Reactions: Winner 1


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## Christos (2/2/16)

Best rule of thumb. 
If in doubt don't do it


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## Stosta (3/2/16)

Hey @shaunnadan !

Awesome piece! I've really been trying to get into understanding this battery thing but certain things allude me! When you say double the voltage value in a dual 18650 mod in series, do you mean I can literally change the "Battery Voltage" section on the calculator from 4.2v to 8.4v?

Reactions: Like 1


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## shaunnadan (3/2/16)

Stosta said:


> Hey @shaunnadan !
> 
> Awesome piece! I've really been trying to get into understanding this battery thing but certain things allude me! When you say double the voltage value in a dual 18650 mod in series, do you mean I can literally change the "Battery Voltage" section on the calculator from 4.2v to 8.4v?



Correct !

Reactions: Thanks 1


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## Stosta (3/2/16)

shaunnadan said:


> Correct !


There was no "love" rating, so I could only thank you! This is great news! I was having a discussion about battery safety on my new KBox 200w. Established that with my 0.28ohm setup I shouldn't go above 70w with LG HG2s. We didn't take into account the effect of two batteries being in series!


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## WARMACHINE (3/2/16)

Stosta said:


> Hey @shaunnadan !
> 
> Awesome piece! I've really been trying to get into understanding this battery thing but certain things allude me! When you say double the voltage value in a dual 18650 mod in series, do you mean I can literally change the "Battery Voltage" section on the calculator from 4.2v to 8.4v?



i always refer back to this link when I am unsure: https://en.wikipedia.org/wiki/Series_and_parallel_circuits 

Parallel and Series circuits are great to manipulate voltage, current or resistance

Reactions: Thanks 1


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## shaunnadan (3/2/16)

Stosta said:


> There was no "love" rating, so I could only thank you! This is great news! I was having a discussion about battery safety on my new KBox 200w. Established that with my 0.28ohm setup I shouldn't go above 70w with LG HG2s. We didn't take into account the effect of two batteries being in series!



so the max you should be pushing on those batteries with 0% headroom is 151W
20% headroom would be safer at 121W

Reactions: Thanks 1


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## Stosta (3/2/16)

shaunnadan said:


> so the max you should be pushing on those batteries with 0% headroom is 151W
> 20% headroom would be safer at 121W


Same numbers I got! Thanks for the comfirmation! Come to Durban, let me buy you a Bells!


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## Andre (3/2/16)

shaunnadan said:


> @Andre - i would love for you to add anything i may have missed in this article


Perfect, nothing to add, thank you.

Reactions: Thanks 1


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## Cave Johnson (3/2/16)

Someone, give Shaun a Bells.


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## Greyz (3/2/16)

Well put together thread with simple explanations. Thanks @shaunnadan for sharing with us.


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