Why?

[Zutankhamun]

Hey guys. Probably been answered many times but I just thought i'd ask; How comes in my vw, when I increase the resistance of my coil I increase the volts produced at 50 watts? I know you have to decrease resistance in mech mods because of the constant but why is the voltage result negative in my vw. Thanks

 

[bwh79]

Watts = Volts^2 / Ohms is why. It's a fundamental law of nature and can't be circumvented. When you increase the resistance (ohms), the voltage must also increase to achieve the same power (watts) level. Since your device is adjusted in watts, it sets the voltage automatically to the required amount to produce the wattage you have set, based on the attached resistance.

If your device adjusted in volts instead, and again you increased the resistance but left the settings alone, you would notice a decrease in wattage output since the volts then would have to stay the same, and the equation has to balance one way or another.

 

[Zutankhamun]

Thanks a lot bwh79. I get it. But... Then the only reason you would choose a mech mod nowdays is because there is no circuitry to fail, because vw devices can dwarf mechs in terms of vapour production and what not. Unless you can enlighten me. Thanks again

 

[MoDmAnDaN]

But... Then the only reason you would choose a mech mod nowdays is because there is no circuitry to fail, because vw devices can dwarf mechs in terms of vapour production and what not. Unless you can enlighten me. Thanks again

There are 2 basic reasons, as I see it, To use VW devices instead of a mech

1. You can adjust the voltage/wattage to your liking.
2. You can produce more voltage (in most VW devices) than a mech is capable of. Especially if the VW device takes 2 or more batteries and still get more battery life than in a mech.

A mech can still fail or have too much of a voltage drop to work properly.

 

[DaveSignal]

A mech can put out infinite wattage. You need to make sure what you are doing is safe for your batteries, as there is no protection circuitry.

 

[Zutankhamun]

kay, cheers guys. How would you work out your wattage or voltage on a mech mod if your out and about. Do you have to use a piece of equipment to check it? I use a real basic dovpo 1 battery 50 watt device and with a 1.1 coil i'm getting 7.4 volts. If I keep increasing the resistance, my voltage just goes up. is there a certain limit I can go to? What kind of volts and watts can you get from a top of the range mech that's running a .01 resistance. Cheers

 

[Thrasher]

Thanks a lot bwh79. I get it. But... Then the only reason you would choose a mech mod nowdays is because there is no circuitry to fail, because vw devices can dwarf mechs in terms of vapour production and what not. Unless you can enlighten me. Thanks again

Uhhhhh,

Come again?




Real cloud chasers don't need flashy screens and shiny buttons

 

[roxynoodle]

Do not try to run 0.01ohm resistance on anything On a mech, that's a dead short. And no regulated mod will do that.

You use the Power Law to determine your watts on a mech. P = v^2 ÷R. Your voltage is determined by the charge of the battery.

 

[speedy_r6]

kay, cheers guys. How would you work out your wattage or voltage on a mech mod if your out and about. Do you have to use a piece of equipment to check it? I use a real basic dovpo 1 battery 50 watt device and with a 1.1 coil i'm getting 7.4 volts. If I keep increasing the resistance, my voltage just goes up. is there a certain limit I can go to? What kind of volts and watts can you get from a top of the range mech that's running a .01 resistance. Cheers

4.2*4.2 at a full charge(assuming no voltage drop at all) is 17.64, now divide that by the resistance(0.01), and you get 1764 watts, or 420 amps. If you did this, you would probably have your battery vent instantly. If you are at 3.7 volts(nominal amount), you are looking at 1361 watts, or 370 amps. Again, this will instantly make the battery vent.

 

[Thrasher]

4.2*4.2 at a full charge(assuming no voltage drop at all) is 17.64, now divide that by the resistance(0.01), and you get 1764 watts, or 420 amps. If you did this, you would probably have your battery vent instantly. If you are at 3.7 volts(nominal amount), you are looking at 1361 watts, or 370 amps. Again, this will instantly make the battery vent.

Actually under that kind of load the battery would drop to 3.4v or lower, heat up instantly and put out an anemic looking cloud. Continue and the battery will reach thermal failure


Edit- wrong quote meant to grab roxy

 

[petrotech]

I use mechs because they're sexy.

just sayin'.

 

[Zutankhamun]

That's it thrasher?? I get more out of my breath on a cold day. No just kidding. Ok I see. They are good looking, I like flashy screens and shiny buttons though. So do mech mods always win in these comps I hear about? Ok so you can go as far as your battery will allow. Cool, thanks a lot guys

 

[Rabbit Slayer]

T So do mech mods always win in these comps I hear about?

The ones I've seen online they have rules stating only mech mods are allowed, so yes, they win every contest

 

[Zutankhamun]

lol. just found out how to get those faces.

 

[Susan~S]

The highest amp battery in existance is 30A CDR (continuous discharge rating). Most batteries that are labeled 35A, 38A, 40A, ect. are labeled with the "pulse" rate not the continuous. In most of these cases these batteries are 20A CDR.

Purple Efest Batteries not as Advertised

When using a mech mod I try to never exceed 50% of the CDR (continuous discharge rating) of a fully charged battery (4.2v). So with a 30A battery, that would be 15A. This Ohm's Law Calculator tells me that a 0.28 ohm build is as low as I would want to use.

The reason that I place a 50% limit is because as a battery ages the mAh of the battery degrades. As the mAh degrades so does the batteries c rating (amp limit). So down the road, a 30A battery may only be a 15A battery.

 

[WonderDude32]

If anyone is reading this that had a hard time understanding the above posts, read ohms law for dummies and you will understand. I have an excellent grasp and still learned something reading this thread. I dare anyone to find another forum with as many experts. Just awesome.

 

[petrotech]

If anyone is reading this that had a hard time understanding the above posts, read ohms law for dummies and you will understand. I have an excellent grasp and still learned something reading this thread. I dare anyone to find another forum with as many experts. Just awesome.

I learn something new every time I come to the forums. it's when you think you know it all that something bad happens.

 

[Bunnykiller]

you have a garden hose running in the yard, very little restriction going on and it is flowing at 5 gallons a minute... you kink the hose and the resistance of water flow has occured... how do we keep the same flow of 5 gallons a minute now? we increase the pressure ( voltage)