Mechanical mod and ohms

[MrBogdi]

I have a sony vtc5 with 20Amps, what is the smallest amount of ohms i can put in there to not blow up?

[Walt]

I'm going to do you a huge favor and not answer that.  You have to understand what you are doing with a mech mod.  

Learn how to use this site:  http://www.steam-engine.org/wirewiz.html

Study this:  https://www.e-cigarette-forum.com/blog-entry/14-ohms-law-explained-for-vapers.6293/

Use this to find accurate amp ratings for batteries:  https://www.e-cigarette-forum.com/blog-entry/list-of-battery-tests.7436/

Use google and read up on "mechanical mod safety"  

[Rixter]

We'll need to know a little more about your setup to give you an accurate answer, but In a mech mod, the lowest resistance load you can safely go with on a fully charged battery (4.2v) and stay under your battery's 20 amp limit is .21Ω, which will yield 84 watts.

Voltage / Resistance = Current (amps)..........Voltage² / Resistance = Power (watts)

Remember, your resistance can/will change do to a variety of reasons, so it's imperative that you keep a close eye on your coil's resistance fluctuations, especially if you are setting it up to run at your battery's safety threshold.

Edited January 7, 2018 by Rixter

[MrBogdi]

I'm going to do you a huge favor and not answer that.  You have to understand what you are doing with a mech mod.  
Learn how to use this site:  http://www.steam-engine.org/wirewiz.html
Study this:  https://www.e-cigarette-forum.com/blog-entry/14-ohms-law-explained-for-vapers.6293/
Use this to find accurate amp ratings for batteries:  https://www.e-cigarette-forum.com/blog-entry/list-of-battery-tests.7436/
Use google and read up on "mechanical mod safety"  

By the way this is a good answer and i am glad that you answered like this, thank you)

[MrBogdi]

We'll need to know a little more about your setup to give you an accurate answer, but In a mech mod, the lowest resistance load you can safely go with on a fully charged battery (4.2v) and stay under your battery's 20 amp limit is .21Ω, which will yield 84 watts.
Voltage / Resistance = Current (amps)..........Voltage² / Resistance = Power (watts)
Remember, your resistance can/will change do to a variety of reasons, so it's imperative that you keep a close eye on your coil's resistance fluctuations, especially if you are setting it up to run at your battery's safety threshold.

Why fully charged battery has 4.2V if theres only 3.6V on vtc5, i do not understand that? :/

[Walt]

Just now, MrBogdi said:

19 minutes ago, Walt said:

I'm going to do you a huge favor and not answer that.  You have to understand what you are doing with a mech mod.  
Learn how to use this site:  http://www.steam-engine.org/wirewiz.html
Study this:  https://www.e-cigarette-forum.com/blog-entry/14-ohms-law-explained-for-vapers.6293/
Use this to find accurate amp ratings for batteries:  https://www.e-cigarette-forum.com/blog-entry/list-of-battery-tests.7436/
Use google and read up on "mechanical mod safety"  

By the way this is a good answer and i am glad that you answered like this, thank you)

You are very welcome!  Mechanical mods can be very enjoyable and produce wonderful vapes.  That is what I wish for you to have. Understanding the physics that make that happen is the best way to get there.  

[Rixter]

9 minutes ago, MrBogdi said:

Why fully charged battery has 4.2V if theres only 3.6V on vtc5, i do not understand that? :/

Fully charged LI-ION batteries are 4.2 volts. Nominal voltage is usually listed on various batteries at 3.6-3.7v, but when it comes off the charger, it's 4.2v. It drops with use, and you should stop using it before it drains below it's safe-discharge limit. Each battery has it's own set of specs, so you can google how low your particular battery can go before charging. I usually recharge mine when they get to about 3.2v. You'll experience a cooler vape as the voltage drops, so with some experience, you'll learn when to change out batteries based on the vape you're getting. Until then, change out early.

Edited January 7, 2018 by Rixter

[Walt]

1 minute ago, MrBogdi said:

21 minutes ago, Rixter said:

We'll need to know a little more about your setup to give you an accurate answer, but In a mech mod, the lowest resistance load you can safely go with on a fully charged battery (4.2v) and stay under your battery's 20 amp limit is .21Ω, which will yield 84 watts.
Voltage / Resistance = Current (amps)..........Voltage² / Resistance = Power (watts)
Remember, your resistance can/will change do to a variety of reasons, so it's imperative that you keep a close eye on your coil's resistance fluctuations, especially if you are setting it up to run at your battery's safety threshold.

Why fully charged battery has 4.2V if theres only 3.6V on vtc5, i do not understand that? :/

18650 Batteries can charge up to 4.2V and produce that when first put into a mod.  They will spend most of their life around 3.6V as that is the "nominal" voltage.  Obviously 4.2V will pull more current.  It's all about safety with a mech mod.  There are no electronics protecting the mod.  

[Rixter]

Walt, did we go to the same mech mod class? lol

[MrBogdi]

18650 Batteries can charge up to 4.2V and produce that when first put into a mod.  They will spend most of their life around 3.6V as that is the "nominal" voltage.  Obviously 4.2V will pull more current.  It's all about safety with a mech mod.  There are no electronics protecting the mod.  

Thank you for your answer!

Fully charged LI-ION batteries are 4.2 volts. Nominal voltage is usually listed on various batteries at 3.6-3.7v, but when it comes off the charger, it's 4.2v. It drops with use, and you should stop using it before it drains below it's safe-discharge limit. Each battery has it's own set of specs, so you can google how low your particular battery can go before charging. I usually recharge mine when they get to about 3.2v. You'll experience a cooler vape as the voltage drops, so with some experience, you'll learn when to change out batteries based on the vape you're getting. Until then, change out early.

Thank you! I understand now

[Walt]

1 minute ago, Rixter said:

Walt, did we go to the same mech mod class? lol

Lol, entirely possible.  The only place I see our approaches differing is that I am very reluctant to do the math and give specific answers.  There is so damn much involved with these batteries regarding safety.  We've got re-wraps out there, completely bogus specs out there.  There's battery sag, and of course that 100°C line where thermal runaway can occur.  I would much rather the person went to school the way we did and get a rounded education.  

[Rixter]

4 minutes ago, Walt said:

Lol, entirely possible.  The only place I see our approaches differing is that I am very reluctant to do the math and give specific answers.  There is so damn much involved with these batteries regarding safety.  We've got re-wraps out there, completely bogus specs out there.  There's battery sag, and of course that 100°C line where thermal runaway can occur.  I would much rather the person went to school the way we did and get a rounded education.  

Absolutely. There's a ton of battery bogus-ness (re-wraps, outright lies on specs, etc.) going on these days in the name of the almighty dollar. It's a lot to stay on top of.

[Walt]

18 minutes ago, Rixter said:

Absolutely. There's a ton of battery bogus-ness (re-wraps, outright lies on specs, etc.) going on these days in the name of the almighty dollar. It's a lot to stay on top of.

Amen!  And the progression is ludicrous.  One mistake and someone burns half their face off.  The talking head on MSLSD sells more cokes by screaming "Vaping is Bad".  Ten thousand more sheeples plod around droning "Vape bad, bad vape".  I get to deal with some impromptu lecture from church lady during a leisurely  stroll around the block.   Senator Numbnuts seizes the opportunity to tax vape gear at 75%.  Just peachy.  

Edited January 7, 2018 by Walt