Mosfet help

[NikZak]

Well, I've had a look at some local (Australian) electronics retailers websites as well as gone into one of their stores here nearby but none of them stock anything capable of anything higher than 100W capability.

None of them could even help me with sourcing such a thing, I was mostly wondering if anyone had a link to something I could get from overseas as it seems a bit light on here... every time I search for mosfets over 300w all I get is audio amplifiers which clearly isn't what I need

 

[Rossum]

any suggestions for a mosfet capable of handling that kind of power? I can find 100W mosfets but having trouble with something around the 3-400W mark

Why do you want a MOSFET capable of dissipating 300W? Let's say you choose one with an RDSon of 5 milli-ohms. If you push 100 amps though it, it's only dissipating 50 watts. Unless you're planning to use the MOSFET itself as the heating element in your atty, you don't need a MOSFET rated to dissipate that much power.

 

[NikZak]

so what would you suggest for something that will be pushing 1,500 watts then? Basically I want something that will protect my switch from both getting hot and subsequently burning out

 

[Rossum]

1,500 watts? How much current? At what voltage?

 

[NikZak]

4.2v, 65c battery, 0.012 ohm build = 1500watts

It will be capable of a 0.006 ohm build according to the pulse of 130c rating of the battery giving 2940 watts

I'm building the first SAFE 1.5kW device

 

[Rossum]

Can you say, "Not Advisable" ???

 

[WKS01]

4.2v, 65c battery, 0.012 ohm build = 1500watts

It will be capable of a 0.006 ohm build according to the pulse of 130c rating of the battery giving 2940 watts

I'm building the first SAFE 1.5kW device

There is nothing "safe" about attempting a build like that. 4.2V with a 0.012 ohm load is 350A. There is no reason anything like that should be built for vaping. That is nearly double the current most homes have for service. Where do you plan on dissipating 1.5kW of heat exactly?

 

[NikZak]

Well, the battery is rated as perfectly safe for that, nobody actually HAS to build a coil to that low of a resistance, I'm building it for myself and if nobody broke the boundaries of what we all thought was possible we'd still be fish living under water

 

[Rossum]

If I were going to make a crude 1500 watt battery-powered portable fog machine (and that's what it would be, a fog machine, not something that any human should vape), I wouldn't try to do it with a single-celled battery. I'd use a protected stack of batteries such as those commonly found in power tools. That would get you more voltage and proportionately less current, meaning much lower losses in the device itself -- including the switch. Remember, losses are proportional to the square of the current.

 

[WKS01]

Well, the battery is rated as perfectly safe for that, nobody actually HAS to build a coil to that low of a resistance, I'm building it for myself and if nobody broke the boundaries of what we all thought was possible we'd still be fish living under water

Just because the battery is rated for it does not mean the overall idea is safe. The battery may handle the current, but what about the heat? Can the other components handle the conditions, wiring, enclosure, 510 connector? Whatever MOSFET you might use you would then need to make sure it also can handle the conditions as the ratings will certainly change with the current loads and temperatures. What you want to design is not a simple task and requires knowledge of these components most DIYers simply do not have.

 

[NikZak]

If I were going to make a crude 1500 watt battery-powered portable fog machine (and that's what it would be, a fog machine, not something that any human should vape), I wouldn't try to do it with a single-celled battery. I'd use a protected stack of batteries such as those commonly found in power tools. That would get you more voltage and proportionately less current, meaning much lower losses in the device itself -- including the switch. Remember, losses are proportional to the square of the current.

Yep, this is an RC battery, rated for 65c/130c which is very similar to the 'stack' of batteries you get in 12v, 13.8v, 14.4v and so on power tools. I never said it would be a single battery cell. It is a competition-spec racing car battery at 3.7v

I know the calculations are only rudimentary and don't take into account losses through components so I'd be playing it safe (and surely wouldn't build as low as 0.012 ohm) but it would be nice to know that it would be engineered to handle that and be safe all the way down to that. (I'd rather it be over engineered than under engineered)

 

[Rossum]

I'm bowing out here. Good luck. Please make sure you have good fire extinguishing equipment and keep spectators at least 10 meters away.

 

[NikZak]

I don't see how it could cause a fire but I'll show it off when it's built and working... should be in a couple of weeks, still have to build the OKR chip mod first

 

[fire8spitter]

I think this is the pic that was mentioned earlier.
Sorry about the crappy quality. It looks better on my phone. Uploading pix here sucks.

 

[NikZak]

Yeah, I have about 3 different versions of those diagrams, will be building my OKR-T10 chip box mod as soon as the damned OKR chip arrives, should be here in the next couple of days, that one will be using an RC battery also, I feel like their stats (as well as the fact I have a long history of working with RC cars, including full custom wiring jobs etc) as well as the fact that I'm comfortable working with them precludes me to use them for this purpose.

My only issue is their size mostly but at the end of the day, safety is more important to me than portability and I have big hands and am not upset by using large mods. I feel more comfortable holding a large 26650 mod and atomizer than an 18650, they just fit my hands better

 

[Trickydick666]

Yeah, I have about 3 different versions of those diagrams, will be building my OKR-T10 chip box mod as soon as the damned OKR chip arrives, should be here in the next couple of days, that one will be using an RC battery also, I feel like their stats (as well as the fact I have a long history of working with RC cars, including full custom wiring jobs etc) as well as the fact that I'm comfortable working with them precludes me to use them for this purpose.

My only issue is their size mostly but at the end of the day, safety is more important to me than portability and I have big hands and am not upset by using large mods. I feel more comfortable holding a large 26650 mod and atomizer than an 18650, they just fit my hands better

Not gonna lie, what your talking about building is beyond the "holy ......." level in my opinion..but your set on it so I agree about the fire extinguisher and such and please record test fires I would like to see whether it works or you lose some limbs...again not meant sarcastically but be carefull dude

 

[NikZak]

no worries, I still have a little more things to research about it first, have to make a couple of prototypes and test rigs first (to test for cooling and heating cycles and weld/solder holding at those temperatures and currents etc) but I'll definitely report back when I have something worthy...

Will probably be building an OKR-T10 box this weekend though with an RC battery also to test how good they last in a box mod