Advise needed on a Tesla 26650

[iTiger]

So I have a Tesla Invader 26650 box mod and let someone else barrow it for an hour and they managed to fry the "MOSFET chip" (supposed to be 4 MOSFETs on the chip) and I'm wanting to buy some 3034 MOSFETs and a resistor and wire it back up but not sure the best way to pull it off so here I am asking.
I'd still like it for fire down to 0.1Ω as I normally build 0.2Ω and like to have that safty if it dips down.
The guy that fried the chip put a 0.05Ω build on it and fried it.

For anybody looking at this the box is parallel 26650 or 18650 with adapter.

I'm sure I'm going to need to stack a couple MOSFETs in parallel to get it where I want it but not sure how many.

Thanks for any help.

 

[Mooch]

Each IRLB3034 can handle about 25A without overheating. More if not chain vaping or near a hot battery.

 

[iTiger]

Thanks that makes sence why most single MOSFET boxes say 0.2Ω is the safe limit because ohm law says 4.2V @ 25A = 0.17Ω

So what I'm getting is two MOSFETs in parallel would be ~50A; so 4.2V @ 50A = 0.08Ω

So I should be good with 2 MOSFETs thank you.

 

[Mooch]

Current sharing between mosfets isn't perfect so I would assume 40A-45A for two of them until you get it built and can see how hot they actually get.

 

[iTiger]

Thanks I'm hoping for 42A @ 4.2V = 0.1Ω

So what would 3 MOSFETs get for amps?

 

[Mooch]

Start with 60A and see how hot they get.

 

[iTiger]

I'm just trying to decide before placing an order.

My 26650s are 40A cdr /60A pulse so was thinking 3 MOSFETs while not really needed would probably let me take full advantage of the batteries but think 2 MOSFETs is plenty.
The big thing that made me think 3_(if they would fit) is heat

I'll get a pic of the area the MOSFETs will need to fit into when I get home but you can see from this pic not a tone of room under the panle at the top.

 

[Mooch]

Yea, that's a tight fit.

What batteries are you using?

 

[iTiger]

My bad just checked my AWT 26650s are 35Acontinuous discharge and a 75A pulse

 

[Mooch]

Umm...is it this battery?



If so, it didn't test out to anywhere its ratings:
https://www.e-cigarette-forum.com/f...bench-test-results-only-a-10a-battery.703276/

 

[iTiger]

Yeah good thing they were a freebee to me (they were new never used) havnt even used them yet myself (and now plan to never use them).

What would you suggest?
I want to have 42A combined cdr with 2 26650s.

Edit: I followed a couple links and there were only test results of a few 26650s and of those the MNKE Orange 30A 3500mAh 26650 were the best.

 

[Mooch]

I've only tested three 26650's so far but the MNKE was by far the best.

 

[iTiger]

Ok they will go on my list especially seeing as they are amongst the cheapest 26650s right now (around $6-$7 each).

And at 25+ A each they and the MOSFETs will be a good combo.

 

[iTiger]

Ok so I'm getting my order ready and it was easy to find the MOSFET because the part number is common knowledge so I've got 2 of these in my cart http://www.mouser.com/Search/m_Prod...BFvirtualkey57370000virtualkey942-IRLB3034PBF

But I'm having fun finding the resistor as there site doesn't play well with with my phone when it comes to manually finding parts.

Edit: my google ing resulted people linking they use this 15K ohm resistor so I'll toss 2 in the cart at 10¢ each http://www.mouser.com/Search/m_Prod...irtualkey57620000virtualkey603-MFR-25FRF5215K

 

[iTiger]

Ok parts ordered.

The fun will come when the parts show up and I try to fit them inside this little area.

 

[iTiger]

Got the MOSFETs and resistor today and soldered it up.
Added a kill switch while I was at it.

Here's how it is for now (testing)

Seems to be working great. Think I'll run it as is for a couple days till my volt display shows up and then glue the kill switch to the housing and fix the horrible factory wiring to the fire button.