Batteries/Wattage

[stols001]

Um, kinda all of it. What I thought I understood, I am now completely confused about.... But yeah, mainly about regulated devices, I thought I understood that of course the resistance of the coil changes the amps drawn, or doesn't it? I have no explanation at all about why my batteries will be used up quicker with lower resistance coils than higher ones at the exact same wattage. I thought that was WHY the mod even read the resistance, but goodness at this point? I'm almost thinking of going to radioshack and getting some rechargeable regular batteries.

Anna

 

[NicotineRush]

Confused because 'nicotinerush' seems to be taking credit for what 'the wind' posted?
2 user names same person?

Hardly.
@the wind mentioned the calculator I built and put up on my site, k4kmg.com. I simply explained why I built it in the first place.

 

[Caterpiller]

I'm not going to single anyone out, but I think it's a real shame that this thread has now digressed into semantics and pointless discussions regarding irrelevant aspects of physics that don't pertain to the OP's question.

The simple and relevant fact is that when using a regulated mod you don't have to consider Ohms. The mods electronic trickery handles everything except potentially too high amp draw.

What the OP needed to know was:

Power (watts) / 3.2 (min battery voltage) / number of batteries = amps

And that this number needs to be lower than the 20 amps most of us have available with 20 amp 18650 CDR batteries.

Or put simply stay under 60 wattd per battery.

I'm not claiming to have a special understanding of the physics - quite frankly everything I know I learnt on this forun, but I don't understand why anyone would want to cloud these basic facts from new members wanting to understand the operating limits of their equipment.

 

[zoiDman]

IMO that is not correct.it has to put volts to the coil witch has a set resistance.how does this mod change ohms law?

Ohm Law isn't being Changed. You are just Applying it at the Wrong Place.

If you want to Calculate the Amp Draw at the Atomizer, you are good to go. But if you want to Calculate the Amp Draw at the Battery, then you need to use Watts Law and you should Account for the Regulated Board's Efficiency.

Because the Battery in a Regulate Mod isn't Directly connected to the Atomizer like in a Mech Mod. It is directly connect to a Board that is doing Work.

This Confusion about Amp Draw at the Atomizer vs at the Battery in a Regulated Mod has gone on as Long as I can Remember there being Regulated Mods.

 

[the wind]

Ohm Law isn't being Changed. You are just Applying it at the Wrong Place.

If you want to Calculate the Amp Draw at the Atomizer, you are good to go. But if you want to Calculate the Amp Draw at the Battery, then you need to use Watts Law and you should Account for the Regulated Board's Efficiency.

Because the Battery in a Regulate Mod isn't Directly connected to the Atomizer like in a Mech Mod. It is directly connect to a Board that is doing Work.

This Confusion about Amp Draw at the Atomizer vs at the Battery in a Regulated Mod has gone on as Long as I can Remember there being Regulated Mods.

now we are getting some where.so to be save with your battery's you can use ohm's law to over calculate the amp draw to be sure you are with in the battery's limits on regulated mod.do you agree?

 

[Topwater Elvis]

No, not really, as the battery voltage in a regulated power device drops, amp demand increases because watt output remains consistent.
At the power devices low voltage cutoff amp demand will be highest.

60w / 4.2v = 14.2a
60w / 3.2v = 18.75a
The above not including any power device inefficiency which slightly increases battery amp demand.

Mooch explains it in simple easy to understand terms if you read the link provided.

 

[zoiDman]

now we are getting some where.so to be save [safe] with your battery's you can use ohm's law to over calculate the amp draw to be sure you are with in the battery's limits on regulated mod.do you agree?

Sorry. But No... I Don't Agree.

Because the Ohms of your Atomizer plays No Role in the Amp Draw on the Battery(ies) in a Regulated Mod. It's the Watts the Mod is Set at. And it is How Low the Voltage State of the Battery(ies) that determines Amp Draw at the Battery.

Set a Regulated Mod to some Wattage. Now put Any Build you like on it. The Amp Draw on the Battery is the Same for a 0.05 Ohm Build as it is for a 3.0 Ohms Build.

Ohms Law doesn't work here because a Change in Ohms doesn't Effect a Change in either Volts or Amps. You need to use Watts Law. And you should take into account for the Board's Efficiency.

Maybe this will help...

Regulated mod amp draw (watt mode)

 

[the wind]

I'm done with this.there is a lot of truth and untruth. My main goal was everyone to be safe with their battery's. I'll go back to building coils now.

 

[zoiDman]

now we are getting some where.so to be save with your battery's you can use ohm's law to over calculate the amp draw to be sure you are with in the battery's limits on regulated mod.do you agree?

BTW - Here is a Simplistic Comparison that might help you Understand what is going on.

Consider the Brakes on a Bicycle compared to the Brakes on your Car.

On a Bike (usually) the Brakes are a Direct System where the Amount of Force that is Applied to the Brake Level is transferred Directly to the Brake Force at the Wheel via a Cable.

So you can relatively Easily compute the Force at the Wheel by using F = MA. The Amount of Force applied with you hand (via the Lever of the Brake Handle) is what you get at the Wheel.

But can the same be said for the Brakes in your Car? And if not, Why?

Because in your car, there is "something" in between your Foot and the Wheel that is doing "Work".

That doesn't me that F = MA is wrong or invalid. F = MA is a Fundamental Principle of how the Universe works. It just can't Directly be Applied from your Foot to the Wheel of your Car because of that "something" that is in between that is doing Work.

Same with a Regulated Mod. That something is the Circuit Board. So the Battery Doesn't See the Atomizer. Just like you Foot Doesn't See the Wheel in your car.

All the Battery Sees in a Regulated Mod is the Circuit Board. So if you want to Calculate Amps Draw at the Battery, use Watts law.

If you want to Calculate the Amps at the Atomizer, Use Ohms Law.

 

[Hawise]

Um, kinda all of it. What I thought I understood, I am now completely confused about.... But yeah, mainly about regulated devices, I thought I understood that of course the resistance of the coil changes the amps drawn, or doesn't it?

No, it doesn't. People will usually use higher wattages with lower resistances and that changes the amps, but at the same wattage different resistances would still use the same amps - on a regulated mod.

I have no explanation at all about why my batteries will be used up quicker with lower resistance coils than higher ones at the exact same wattage.

They shouldn't. At the same wattage, you should get the same battery life.

I thought that was WHY the mod even read the resistance, but goodness at this point? I'm almost thinking of going to radioshack and getting some rechargeable regular batteries.

Anna

No, the mod needs to know the resistance so the board can do its job and provide the correct voltage to the coil. The battery doesn't see the coil and couldn't care less what its resistance is (on a regulated mod).

I'm going to have a go at explaining things another way. If I screw this up, someone please correct me.

Watts = volts x amps


Battery <---> Board <----> Coil

The board takes electricity from the batteries. You pick the wattage of this electricity. The voltage is determined by the state of the batteries' charge and the number of batteries, and it drops as the batteries discharge. To keep the wattage the same (i.e. where you set it), the board pulls more amps as the batteries discharge and the voltage drops. Only the batteries' voltage and your wattage settings matter in determining the amps drawn from the batteries.

The board now has a given wattage of electricity - what it got from the batteries. Unfortunately, it's at the wrong voltage for the coil. So it changes the voltage - that's its reason for being, to adjust the electricity into a form that works for the coil. (This is where Ohm's law comes in - the board uses the coil resistance to decide what voltage it needs, but it does all the calculations so you don't need to.) Remember that watts = volts x amps. The wattage has to stay the same, because you've only got the wattage you pulled from the battery. So, when the board changes the volts it changes the amps too to keep the wattage the same. That's why the volts and the amps you might see on your screen are irrelevant to the battery - they're what the board changed things to, not what it got from the battery.

Short version: Your battery doesn't care what your resistance is. Your board does.

 

[Topwater Elvis]

I'm done with this.there is a lot of truth and untruth. My main goal was everyone to be safe with their battery's. I'll go back to building coils now.

Indeed...
Truth is, when using a regulated power device the resistance of the coil(s) used in the delivery device has no bearing on battery amp draw/drain.

Battery safety when using a regulated power device is very simple.
When in doubt check mooch's charts of tested cells.
Only buy name brand cells from reputable dealers.

If you don't know your specific power devices low voltage cutoff don't exceed;
60w per 20a CDR cell
75w per 25a CDR cell
90w per 30a CDR cell

There are a few exceptions that will drain a cell to 2.78v - 2.84v & few that drain only to 3.5v

 

[Mooch]

I'm done with this.there is a lot of truth and untruth. My main goal was everyone to be safe with their battery's. I'll go back to building coils now.

Perhaps it would help us understand you better if you pointed out these untruths instead of just making accusations and leaving.

By definition though, the battery current can't change if the power setting remains the same and the coil resistance changes. Otherwise the device wouldn't be holding the power steady.

 

[the wind]

Perhaps it would help us understand you better if you pointed out these untruths instead of just making accusations and leaving.

By definition though, the battery current can't change if the power setting remains the same and the coil resistance changes. Otherwise the device wouldn't be holding the power steady.

sorry I should have not posted that.i have no desire to help on this subject, please except my apology.