Possible to use resistors to get 5v??

[basementcat]

So I am wondering if it's possible to use a resistor or maybe 2 or more in series to get down to 5v from the standard 7.4ish that two lit ion cells put out? I've made 5v and variable volt mods using regulators but can this be done with something smaller like a resistor? And if so what rating of resistor would be needed? I've been searching all over online for an answer myself and keep coming up stumped. I'm guessing I could figure this out using ohms law but alas it just confuses the he'll out of me and make my head hurt lol. So if anyone can tell me if this is possible and what ohm rating the resistor or resistors would need to be it would be appreciated. I'm pretty sure that's how the glv2 5v works so I'm thinking it can be done. Thanx.

 

[SlimXero]

regulators aren't that large, why not just use a 5v regulator? I'm sure it'd less hassle.

 

[basementcat]

I've done that before. Kinda hard to get a regulator and pcb into a small cylinder. Wanna try something new.

 

[asdaq]

A 3-pin reg is quite small, and you can avoid using pcb. You could try 3A barrel diodes in series, but they are quite big and take off .8v each. One problem though is they reduce voltage at a steady rate, but the batts will drop in voltage and so will the end voltage. The reg keeps you at 5v the whole time, spot on, and a more stable vape.

 

[WillyB]

This will get you close enough.

1.0 ohm 10W 10% Wirewound Resistor (2-Pack) - RadioShack.com

If you can find one a 5W should be smaller and still do the job.

Till just very recently all the 5V mods used a resistor.

 

[basementcat]

Thank you willy. Always a wealth of knowledge. Hats off to you sir.

 

[basementcat]

What are the disadvantages of using a resistor besides uneven voltage due to battery drain? Also would 5watt be the absolute lowest I would want to use or could I get away with 3 or 1? Thanx again everyone for your input.

 

[WillyB]

Well if you figure for a 3Ω atty, + 1Ω resistor (4Ω):

7.4V = 13.7W, 25% of those watts will be dissipated by the resistor = 3.43W. With a Joye atty over 4W.

 

[Rocketman]

maybe a lower duty cycle would allow you to use a 2 watt.

You know, come up for air every once in a while.

 

[basementcat]

maybe a lower duty cycle would allow you to use a 2 watt.

You know, come up for air every once in a while.

Come up for air? Huh?

 

[Rocketman]

Sure,

vape for 10 sec, let resistor cool for 10 sec, average power dissipated is half instantaneous or 50% duty cycle.

Try not to just vape continuously.

Resistor still wastes battery power like willy said. But winter is coming and a warm mod could be your friend.

 

[basementcat]

Sure,

vape for 10 sec, let resistor cool for 10 sec, average power dissipated is half instantaneous or 50% duty cycle.

Try not to just vape continuously.

Resistor still wastes battery power like willy said. But winter is coming and a warm mod could be your friend.

Aww ok I get what your saying now. Makes since. I already knew excess energy was burned off as heat. It has to go somewhere. It won't just disappear. Anyone know how large a 1ohm 5watt resistor is? I can't seem to find a scale size picture anywhere online.

 

[Rocketman]

1 ohm 5 watt is bigger than a regulator, 1 ohm 2watt about the same size but round instead of flat.
Unless you get the flat one.

5 watt resistors (except for high voltage, high megaohm ones) are about half the size of ten watt ones, but still bigger than a regulator. They can cram a bunch of ohms in the same package (they're actually kind of small ). It's the watts that take up the most room.

 

[Rocketman]

Just kidding Smork,
Here's a little chart (remember the 5 watt is about 1/2 as long as the 10/11 watt one )