Regulated Mods - Batteries, Resistance Explained

[levis]

nice, thanks

 

[less500]

I'm using 4 imerin 3500 mah battery so I get 1400 mah in duo series the box says will work 20 there was a press release saying we were wronk it must be used with to I recommend 3500 mah battery's imerins pacifically if your vape shop carry's them or Sony vct6 battery's

 

[Big E Joose]

so what if I have an Lg 3000 mAh 3.7v 20a battery. I've got a .2 ohm build in my deck the math adds up to 18.5 amps, and if I use 4.2 volt adds up to 21.0 amps. Is that safe at all or should I use a higher ohm?

 

[KingPin!]

so what if I have an Lg 3000 mAh 3.7v 20a battery. I've got a .2 ohm build in my deck the math adds up to 18.5 amps, and if I use 4.2 volt adds up to 21.0 amps. Is that safe at all or should I use a higher ohm?

Single or dual battery regulated mod (what mod are you using)?

 

[placemace]

In my first post I talked about 2 circuits, focussing on what's happening between the battery and the mod (the input circuit). In this one I'll refer to the 2nd circuit between the mod and the atty (coil), or as its called the "output circuit"

"Since we are looking at two separate circuits, you can never mix numbers from both sides of the regulator in your calculations. For instance: You cannot determine the current drained from the battery by measuring the resistance of the coil and the voltage of the battery. Using the resistance from one circuit, and the voltage from a different circuit, will result in a nonsensical answer. Nor can you determine the current going through the coil by determining the current from the battery".
Source - http://www.steam-engine.org/batt.html

With this in mind we need only know that the mod has the voltage and current available from the 1st circuit to do what it needs to do...when it can no longer perform it will display the low battery message in most cases
For this second circuit we are interest in either the wattage or voltage as an output, also resistence in this second circuit does play a role, as to why though we need to come back to ohms law (but two variations depending on the type of mod you are using)

1) for variable wattage mods (VW)

We use V= [square root] of P x R

Voltage (V)
Wattage (P)
Resistence (R)

1) You know the wattage it's showing on the device in wattage mode
2) You know the resistence of your coil

Those wanting to venture down to super low ohm builds the good news is you can although there are a few things to take into consideration:

A) you are limited by your chips settings, take my HPriv example again - let's go for max wattage just for the hell of it 220w. My mod will allow a coil resistence down to 0.1ohm (anything lower my mod will display a warning message to me and won't fire)

B) other mods have setting like maximum wattage output or maximum amps output which limits how far the mod can be pushed so look your mods specs up to know what values you can use.

C) if using more than one battery how is the Mod wired Series or Parallel?

Mods Connecting in Series
When connecting your batteries in Series you are doubling the voltage while maintaining the same capacity rating (amp hours) and CDR value of one battery. Example below


so two 18650 batteries will have a combined total of 8.4v when fully charged and 6.4 (5.6v with sag when it's time to change them) which is handy for this second post and is why most regulated mods are series wired ....let stay focussed on the depleted number 5.6v

Mods Connecting in Parallel
When connecting in Parallel you are in theory doubling the capacity (amp hours) and CDR while maintaining the voltage of one of the individual batteries. Now since not everything is exactly equal for safety purposes take 50% CDR away from one of the batteries to err on the side of caution (For example you have two batteries, each have a CDR of 20... minus 50% from one gives you a CDR of 30)



so two 18650 batteries have 4.2v when fully charged and 3.2v (2.8v with sag) when it's time to change them. (but these have 1.5 times the CDR which handy for the first post ....let's stay focussed on the depleted number 2.8v

Important notes: Don't use two different chemistries when connecting batteries.

Always use married batteries I.e bought together always charged and used together, otherwise voltages will be different, but more importantly the charge rates will be different and the capacities may be different, thus resulting in a shortened life span.

Match capacities. When connecting batteries in a pack you should try to match the capacities as much as possible to avoid discharging one battery quicker than another. A pack operates at a combined voltage so your one cell that discharges quicker will likely discharge deeper than it may be able to recover.

I won't get into what's better ...suffice to say they achieve the same things in different ways

Why do these things matter? Well if you want to understand how to optimise the life of your battery before changing them and avoiding that low battery message earlier than we should we can now find out how

Ok HPriv example @220w, Resistance of 0.1

Square root of 220 X 0.1 = 4.69volts
- this is ok right jobs a gooden my mod is wired in series so has 6.4v to cover this when nearly empty (or 5.6v with 12% sag) except don't forget my first post on current draw!

Lets now go for something most people advise 0.3 ohm resistence but trying to maintain our 220w

Square root of 220 x 0.3 = 8.12v
- dammit more than my mod can handle it simply cannot work at that wattage for long ...I'll take like 6 puffs and I'll get that damn message low battery even though my batteries still look charged

Ever wondered why on the Smok beast tank the TF-T8 coil is resistence of 0.16ohms?

Square root of 220 x 0.16 = 5.93volts
This is right on the the threshold of low voltage cut off my 2 batteries in series can deliver at 220w (with sag) at near empty! Awesome right

Well there you have it knowing this voltage output will allow you to target a desired coil resistence build between the upper and lower wattage setting you want to vape at, which will allow the full range of the battery before the low voltage cut off build into most regulated mods kicks in (do check if you mod has this feature first)

So going back to my 110w I don't tend to go past and knowing my lowest resistence allowed in 0.1ohm

Lowest threshold
Square root of 110 x 0.1= 3.32volts

Highest threshold
Square root of 110 x 0.3 = 5.74 volts

I now know to build my coils for a max wattage setting of 110w between 0.1 and 0.3! This will allow me to vape from fully charged all the way through to empty

2) for variable voltage mods (VV)

These devices need a different equation from ohms law as you have a diffent input

P = V x V / R

Wattage (P)
Voltage (V)
Resistence (R)

This time you know only the voltage and resistence

So unlike VW mods you can only see the voltage and turn it up or down as you go, but its a little more difficult to dial in for that perfect setting but you can get close!

Let's take my VW example into consideration I want to vape at 110w how do I do that?

A number of ways

6v output with a 0.33 resistence

6 x 6 / 0.33 = 109.09watts

4.7v output with a 0.2 resistence

4.7 x 4.7 / 0.2 = 110.45watts

3.3v output with a 0.1 resistence

3.3 x 3.3 / 0.1 = 108.9watts

Now I know at these settings it will be at 110 watts turn it down to go lower or up for more

As you can see both of these mod types achieve the same thing but in different ways ...and now you're equipped to select the right coil build and correct battery

Please follow this link for Moochs recommended batteries (select the right one with the information you've ascertained above)

https://www.e-cigarette-forum.com/forum/blog-entry/moochs-recommended-batteries.7593/

If anyone wants Devices added to post 1 by all means call them out

Thanks for help!

 

[placemace]

Thanks a lot!