Unregulated mod with 20g wire

[Noah Pan]

Hey guys,
So I bought a unregulated mod off eBay with a mosfet and I was thinking that replacing the stock 20g wire with 14g wire would decrease the voltage drop. Is this true? I've been vaping it and the mosfet and the whole wiring gets hot after awhile. I'm sure it's not short circuiting but can someone tell me if this is safe?

 

[suprtrkr]

Hi and welcome. If you are good with electronics and have good soldering technique, then yes, replacing the wires will result in less voltage drop. However, voltage drop may not be the problem, or not the whole problem. You say nothing about the mod, or the load you're putting on it. One or two batteries? What's your build? What kind of batteries? What MOSFET is in it? If your build is loading the batteries beyond their capacity, it's gonna get hot regardless. Same if the loading is beyond the capacity of the MOSFET. Same if it has a cheap 510 connector that won't carry the load.

 

[Noah Pan]

Ok so the batteries are wired in parallel and the mosfet is a b30100g and its a 30A max. I feel both the mosfet and switch heating up should i replace both? Also how do i know if the 510 cannot carry the load?

 

[suprtrkr]

Ok so the batteries are wired in parallel and the mosfet is a b30100g and its a 30A max. I feel both the mosfet and switch heating up should i replace both? Also how do i know if the 510 cannot carry the load?

Ok, we're getting there now. What is the resistance of the atomizer you're putting on it, and what kind of batteries are you using? It seems unlikely the switch is going to be a problem as it should be carrying any load to speak of. That's what the MOSFET is for. The switch is just a signal to tell the MOSFET to turn on. If it's heating, it's likely conductive or convective heat carried from some other part of the machine. If the MOSFET itself is heating, you may have loaded it beyond it's capacity. It might need to be replaced with a more powerful unit, but we don't know that yet either.

 

[Noah Pan]

Ok so this is the skimatic i drew. I think I have to replace the mosfet because it has a max 30 a right

 

[Noah Pan]

I have a .1 build on it, so

 

[suprtrkr]

Yeah, that's the problem, all right. A .1 build at full charge voltage of 4.2 draws 42 amps. So, if you insist on going that low, you'll need a 50 or 60 amp MOSFET, minimum, and 2 LG HB6 batteries, minimum, to prevent overheating. I think I'd go up to 14, or even 12, gauge wire, too. Or you could raise your build into the .2 range, which would put everything back into the 30 amp arena, and you can use that MOSFET, and get by with 2 x 20A batteries.

 

[Noah Pan]

Ok so my samsung 35A batties would work then. With a 50A amp mosfet, to prevent overheating. Ill stick with my 14 gauge wire. So if my build is drawing 42A, that means its equivalent to 176 watts?

 

[suprtrkr]

176 watts is correct, 176.4 to be exact. However, I do not think you have any 35 Amp Samsung batteries, no matter what the label may say, because Samsung does not make 35 Amp batteries. Nobody does, actually, except a few, small volume cell manufacturers and they are hundreds of dollars a cell. The only honest 30 amp batteries I know of are LG HB6s, and the Sony VTC4s are 20 Amp batteries that can be run to 30 Amps without dangerous overheating, although this damages them. AFAIK, no Samsung cells exceed 20 Amps, and thus a pair of them would be overloaded at 42 Amps. Have a look at @Mooch 's battery selection chart for more info. Mooch is one of our resident battery gurus, and he does actual bench tests on cells.

 

[Noah Pan]

Damn, a pair of lg HB6 are expensive... i Dont know what to do then, id have to up my build to a .2ohm

 

[Mooch]

The B30100G is a dual diode, not a MOSFET. Your setup is passing all the current through the switch, not a MOSFET. According to your schematic, the diode is doing nothing more than just getting hot and lowering the voltage to your 510 by half a volt or so.

You were ripped off.

You need a pair of IRLB3034 mosfets wired in parallel with a gate resistor. Check the web for circuit examples or go to the Box Modders FB group files section...lots of diagrams there.

 

[suprtrkr]

I think I'd do that anyway, if it were me. That would bring you in at 21 amps and 88 watts, and you shouldn't have to do anything at all to your mod. I am assuming when you say "Samsung batteries" you mean the 25Rs. They're the most popular, easily available and fairly cheap, so most everybody uses them. Those are really good batteries, too, they're just not good for more than 20 amps. Ask me, I don't like to load a 20 amp battery more than half way anyway, I think they last longer. If you really have to have a .1 build, go get a Hammond box and mod you up a triple-parallel box which, with Sammy 25Rs, would let you carry 60 amps with some chance of survival I wouldn't look for a 60 amp MOSFET, necessarily, you could get 3 30 amp ones and parallel them.

 

[suprtrkr]

The B30100G is a dual diode, not a MOSFET. Your setup is passing all the current through the switch, not a MOSFET. According to your schematic, the diode is doing nothing more than just getting hot and lowering the voltage to your 510 by half a volt or so.

You were ripped off.

You need a pair of IRLB3034 mosfets wired in parallel with a gate resistor. Check the web for circuit examples or go to the Box Modders FB group files section...lots of diagrams there.

Ah, Mooch, thank God you're here

 

[Noah Pan]

Ok so ill buy this, International Rectifier IRLB3034PBF MOSFET 40V 343A 1 7MOHM Ideal for Box Mods | eBay
I'm Following this diagram now, IRLB3034 Mosfet Builds
Mooch, why did you say that it needs to be parallel?
Thanks i thought something was wrong with the schematic.
Ill also order some LG HB6s

 

[Mooch]

I highly recommend not buying the MOSFETs from ebay...way too many counterfeit IRLB3034's out there. Order from Mouser or Digikey or a reliable box mod parts vendor.

Each IRLB3034 can handle about 28A max so you'll need two of them in parallel.

 

[Noah Pan]

Ok so I'll have two mosfets in parrallel with one 15k resistor. I'll see if that heats up