Breaking Ohms Law?

[medman1234]

,I have been using a lr(1.5ohm)atty with a pass-through(AC adapter,not computer) @ 5v 2.1a.I have read several places that you cant use a lr with a pt , but it is fantastic.But ohms law says it can't be.
http://thelocust.net/ohm/

FAQ: What are these HV and LR attys? Do I need them? Are they safe to use? | Vaping Guides


5V @ 1.5ohm=16.6 watts....YIKES!but needs 3.33amps.
5v@2.1a=10.5watts,2.38ohms.
The usb adapter has 2 outputs,1a and 2.1 a.
I can't tell the difference in them so I would assume that the atty is not drawing more than 1 a.
Am I missing something here?
you need 3.3 amps for an atty @5volts and 1.5ohms.What happens when you don't have the amps to power it?
Since I can't possibly have the amps,what is going on?

 

[AC0J]

It depends, but it is likley that the voltage starts to drop as the power supply maxs out, this would drive the current up but at less voltage, its 6 of one and a half dozen of the other.

 

[medman1234]

bump for answer

 

[BradSmith]

Does your PT have a batter or just a wire?

 

[AC0J]

Sorry I thought I answered this for you. If you don't have enough power supply, you CANT AND WONT get maximum performance. If you are limited to 2.1 amps, you will not get the wattage that will be there at 3 amps or more. It will level off at the maximum power output you get from your supply. Thats why you cant tell a difference. Both scenarios are producing similar wattage. Watts is what makes the performance difference. To get more watts, you need more Amps. The LR atty may be a little better, but its not performing like it would at higher amps.

 

[Switched]

In this particular case you are not stressing the battery but the atomizer which will lead to pre-mature failure of the atomizer.

....an LR atty mimicks 5V vaping at 3.7V. LRs were intended for 3.7V. IMO folks get too hung up on Watts.

 

[AttyPops]

Lol. Not breaking ohm's law.... just stressing hardware. The Ohm's law calculation in this case is for an ideal condition with unlimited amps available, perfect voltage level, and zero resistance (other than the atty itself). Obviously, that's not the case.

AC0J is correct about your rig being amp-limited. Although I'm surprised you like 10-ish watts... a little hot IMO. Would do better cleaning the atty if it isn't new. Is it a new atty??????

Like switched said: An LR may still go "pop" fairly quickly at 2 amps..........
Like BradS said, you are using a direct-PT and not a battery PT, correct?

 

[Nuck]

Given a static load (resistance) and in this case a regulated current limit, the voltage will fluctuate to ensure ohm's law is met.

At 2.1 amps you will be vaping at 3.15v under load with a 1.5 ohm atty. The power generated will be 6.6w. You aren't stressing the atty at all and are actually on the low side.

I have to disagree with Switched on the importance of watts. Power is the only real measure of the energy consumed by the atomizer.

 

[AttyPops]

Yeah, but..... I have a PT that is 5v, on an AC adpater rated for 2.0 amps. IDK what it actually draws, but it could well be over the 2 amps. I definately don't use an LR atty on it, when I put one on by accident it was WAY too hot.

Note that his port is RATED for 2.1 amps. IDK what it allows. He would have to measure actual current draw in use. That's why the ohm's law calc is more theoretical/ideal rather than actual (he would have to give us actual measurements to know for sure). For example, if the AC adapter allowed 2.5 amps to get through, he'd be at 9.4 watts. OTOH he might just fry the ac adapter by over stressing it (not having enough resistance and over-loading it).

 

[Nuck]

Yeah, but..... I have a PT that is 5v, on an AC adpater rated for 2.0 amps. IDK what it actually draws, but it could well be over the 2 amps. I definately don't use an LR atty on it, when I put one on by accident it was WAY too hot.

Note that his port is RATED for 2.1 amps. IDK what it allows. He would have to measure actual current draw in use. That's why the ohm's law calc is more theoretical/ideal rather than actual (he would have to give us actual measurements to know for sure). For example, if the AC adapter allowed 2.5 amps to get through, he'd be at 9.4 watts. OTOH he might just fry the ac adapter by over stressing it (not having enough resistance and over-loading it).

That would be true if the adapter had no current limiting or fuse/breaker. Most of todays adaptors have protection built in so in the absence of a link we have to assume his does. If would be a brave retailer that sold an unprotected adapter in North America.

 

[CapeCAD]

Yeah, but..... I have a PT that is 5v, on an AC adpater rated for 2.0 amps. IDK what it actually draws, but it could well be over the 2 amps. I definately don't use an LR atty on it, when I put one on by accident it was WAY too hot.

Note that his port is RATED for 2.1 amps. IDK what it allows. He would have to measure actual current draw in use. That's why the ohm's law calc is more theoretical/ideal rather than actual (he would have to give us actual measurements to know for sure). For example, if the AC adapter allowed 2.5 amps to get through, he'd be at 9.4 watts. OTOH he might just fry the ac adapter by over stressing it (not having enough resistance and over-loading it).

It's quite simple to measure the voltage under load and the resistance of the atty, then you use Ohms law to calculate the current (Amps) supplied (I=V*R) and power (Watts) supplied (P=V*I).

If current is 2.1 Amps, then the Voltage will measure approx 3.15V and power is about 6.6Watts. If current is higher, then voltage and power will also be higher because resistance is fixed.

 

[Java_Az]

I was about to call the cops! But no laws have been broken here

 

[AttyPops]

If current is higher, then voltage and power will also be higher because resistance is fixed.

Yeah, that was my point.......

The other point was that HE has to measure it, 'cuz we can't.

I was about to call the cops! But no laws have been broken here

lol. Ohm's law is still intact. <wipes brow> funny

That would be true if the adapter had no current limiting or fuse/breaker. Most of todays adaptors have protection built in so in the absence of a link we have to assume his does. If would be a brave retailer that sold an unprotected adapter in North America.

funnier. Bet it pulls more than 2.1 amps....... (ID even K what adapter it is) betcha a virtual nickel......... Let's get him to measure it........


Plus.... do the calc with a 2.5 ohm atty...... 5v, 2 amps = 10 watts @ 2.5 ohms..... he's got even more stated amps available at 5 volts (2.1 or so) with lower resistance (1.5 ohms vs 2.5 ohms) which is why (I assume) he asked the question. But he's amps limited. So it will max out at a given power. We just don't know what that power really is unless he provides measurements.

So, I say... take real world measurements and you will know what it is doing. That is if you can rig up a connector to measure amps and also don't have a PWM type device, or have a meter/scope that can handle the PWM measurements.

 

[medman1234]

here is the adapter.
4-in-1 iPad Travel Charger - Emerge

 

[Switched]

*SNIP

I have to disagree with Switched on the importance of watts. Power is the only real measure of the energy consumed by the atomizer.

True enough Nuck but I believe you have taken my intent out of context. Some folks think bigger is always better, where you and I know that the sweet spot is nowhere near the upper reaches. Hence, my post too many folks get hung up on watts. Buddy is running an LR 1.5 at 5V yuck... 2.2 - 2.5 a better vape IMO and only slightly cooler.

 

[AttyPops]

Yeah, switched. That's what I thought you were getting to.... people get hung up on HIGH WATTS.... I like about 7-8 watts myself. Since the OP is using 5v, and has a rated 2.1 amps available, he needs a 3.1 ohm atty and only 1.6 amps for 8 watts.

But I think his question is along the lines of "why don't I get a difference"? I wish he'd comment on all this........The adapter doesn't help me much......

Hey medman1234.... how does a regular atty work for you?????

 

[medman1234]

Yes a reg atty works,The lr @5volts(lower since to few amps?)works much better IMO.It's not to hot and produces more vapor with shorter drags.I guess since the amps are not there the volts must be lower=lower watts.I was just trying to figure it out because I did not think I wasn't vapeing at 16watts.And when I used ohms law it said I was,I wanted to know what was going on.I'm just trying to understand.If I don't understand something it just bugs me to death.
I have also noticed that the vapor from the lr hangs in the air longer than from a reg atty.Smaller droplets?anyway,thanks for the comments

 

[Papa Lazarou]

The AC/USB adapter I have (rated 2A @ 5v) shuts down straight away if a low resistance atty is used. I've got another one, lower rated (1A @ 5v) which fires up the LR atty, but only just. It doesn't run even close to how it's supposed to.

 

[medman1234]

I looked around and made sure it was rated at 2.1(for the IPAD).