I'm in the process of making a box mod. I'm trying to hand pick the components but having trouble figuring out what exactly the MOSFET does and how to choose one. I know it's a safety type feature but that's about it. Any help would be great.
Can someone explain MOSFETs and how I would choose the right one.
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its a switch... it takes a small amount of electricity to turn on a larger flow ... kinda like a relay 
Here. This is what I used on my non regulated boxes... they take the amp load off the fire switch so your switch contacts dont melt and fuse shut causing a continuous firing mod.
Guess i should attach the link huh.....
http://www.amazon.com/gp/product/B0...rd_t=36701&pf_rd_p=2090149782&pf_rd_i=desktop
http://www.amazon.com/gp/product/B0...rd_t=36701&pf_rd_p=2090149782&pf_rd_i=desktop
when MOSFETs fail they usually fail "closed" in other words, they stay on..
get one that is rated for 50A if possible and 250W heat capacity...
get one that is rated for 50A if possible and 250W heat capacity...
Just stick with the tried and true IRLB3034. If your running really high current you can parallel two of them.
MOSFETs don't add any protection to the mod. They just allow you to use a small button/switch to control large amounts of current.
A "TO-220" case MOSFET can dissipate about 2.3W of heat (without a heat sink) before reaching its maximum operating temperature. Call it 2W because it's covered by heat shrink. This is about 25A for the popular IRLB3034 MOSFET, the one I recommend for your box mod. Two of them in parallel can handle about 45A unless chain vaping like crazy.
The diagram you put has fuses in it. Never seen that one before. So the two fuses are restricting amperage making it 30 amps to the 510 correct? I know I'm asking a lot and I appreciate everyone who's helping. This is how I learn by asking every little detail.
The fuses won't directly restrict current to 15A. The fuses are rated at 15A each and act as resettable circuit breakers. At above this 15A rating the fuses will eventually blow. Otherwise they have almost no effect on the amount of current flowing. How fast they blow depends on how much above 15A the current is. At 20A it could take an hour. At 100A they blow almost instantly.
Installed as in the diagram the fuses protect the batteries from short circuits in the atomizer or wiring. They also prevent the batteries from directly short-circuiting together if you put one in reversed.
http://www.mouser.com/ProductDetail...TqFbpUcg4SopNyIqIYHZs0LSfhNjcIvFspgovy6/gFw== I use these fuses in most of my boxes. Mooch is dead on about the fuses. Technically they say 30amp trip but its more involved than that. Its a cheap bit of safety anyway. You can just solder one to each battery clip or you can make a small copper clad board to hold them.
Unfortunately, it depends on how long each pulse is and how long you wait between pulses.
You're heating up the fuse when you draw current through it. At a certain temperature, it trips.
I don't know the answer to your question. You can check the datasheet for the fuse to see how long it will take to trip at 60A. Or post a separate question about using two of those fuses with a coil build that draws 60A. You can also try the /OpenPV sub-reddit and the Box Modders FB group. Both groups have lots of box modders who might be able to answer your question.
I must be confused here. The batteries amp rating is irrelevant. As long as you don't run that fuse on a circuit designed to for a lot less. The real question would be how hard your going to drive the circuit. Just say you built a .1ohm coil, that's about 40amps which is around 170w. One of those fuses on each battery shouldn't trip unless your chain vaping it. The real problem is that you want a fuse that protects the circuit but has enough room not to trip everytime you use it. To small and it will trip to often, to large and it will become useless because by the time it trips the damage is done.
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