building a quadruple 18650 mod

[Jtterrible]

Any advice?.. i'm finding it difficult to find tutorials using 4 batteries.. I'm debating on using 4 in parallel or 2 series ran parallel. I found some diagrams to show how to wire it in series or parallel with a mosfet. I am wondering if i can run it with 2 parallel series and place a resistor to drop it to 5v or 6v. unless using all parallel would yield more power.



Also wondering what would be best. I want to build a high watt mod but the chips are out of budget for the time being, other than the okl-t20 but the wiring diagram i found in the guide is hard to read for me. I need a simple tutorial because i'm new to building.

 

[Jtterrible]

also considering using a step up transformer.. then i could run the batteries in parallel and have the higher Amp rating.. or i could use a resister or step down transformer to lower the voltage from the series..

 

[Zanderist]

If you use a resistor to drop the voltage you will need to factor in the power they need to dissipate. This will add to space used in the mod. I also don't know of any 5 volt regulator chips that can handle high amperage in excess of 5 amps.

You need to use AC if you want to use a transformer, or very rapidly press the button.

I think the safest is 4 in parallel (evenly disturbed current draw, will make a 10 amp draw battery seem like a 40 amp draw battery)
I think the mildly safe is two in series two in parallel
I think its unsafe to go with 4 in series.

Just for fun if you choose the series option.
4 fully charged batteries at 4.2 will yeild 16.8 volts.

If say you planned on using a .1 ohm build ( the mosfet doesn't matter because it's such a small resistance on the circuit), it will draw a current of 168 amps(V/R=I) (omfg).

You will yield a power output of...oh god...2822.4 watts. (P=VI)

I don't know what happens to PTC fuses when they super exceed the current limit, my guess is they might pop.

Besides that you've shown you only have 30 Amp draw batteries, depending on the chemistry they will rapidly sag in voltage or pop like a fire cracker.



Someone correct if needed,
A series parallel build of 30 amp gives you a voltage of 8.4 volts and max current draw of 60 amps. The lowest you can build to determined by your fuses (60 amps total) is .14 ohms (V/I=R) the power used at that build 504 watts( V^2/R=P). However you need to be highly skilled at coil building and factor in the change of resistance due to heating to be at your max. I'd say build to 45% of your maximum wattage capacity (the 45% thing isn't a standard by the way) so that would be around 227 watts, giving you a current draw of 27 amps and your allowable coil build to be around .3. It would probably be even better to build to an even low capacity. Anything 50% will be really hard builds. Something like 2 wrap micro coil 28 gauge kanthal A-1

 

[Jtterrible]

i think i'm going to use the full parallel set up.

I have a couple questions about that.. with the fuses do i have to wire in a .... load of 15amp resettable fuses or do they make higher amp ones?.. having the 4 in parallel yields a 120A max draw which translates to a range of 444w to 504w at max load. Also what type of switch, mosfet, and resistor will i need to handle that kind of power? cuz from the plans i've read on the dual battery mods they recommend a 15k resistor. Do i need to put a volt meter on it or not?.. my schematic just had one so i drew it in the circuit. If i did want one in the circuit to tell me when the batteries begin to sag, what volt meter would handle it?..

 

[Jtterrible]

anyone willing to help me to get a parts list goin?

 

[Zanderist]

Make sure you buy more than one of everything.

You can use a 10k-15k resistor all the resistor does is takes away any charge on the gate of the mosfet.

No one can really give you a full parts list because it's up to you what you want to see done.

I can however say that this is the mosfet I use to much success

PSMN2R7-30PL,127 NXP Semiconductors | Mouser

What's key is that it is logic level, meaning a low voltage signal from a small micro processor can turn it on.

What you want to look for in mosfets for these builds is three things:
Logic Level
High Amp draw
Low 'on' resistance

What comes down to again is what your building you coil resistance to be.

As for fuses I've learned the hard way that getting a single fuse to handle everything is not the way to go, because they take up a lot of space. You would be better off getting a bunch of smaller fuses and putting them in parallel. The fuses you pick should be to protect the batteries.
There is a problem though, while the fuses protect the batteries they may fail to protect the mosfet which and break and remain on.

Voltmeter is for awe value. It's only needed if you want to keep an key on your battery level.

Best part about this type of build is you can use any type of switch. The switch needs to only be able to handle around 5 volts or more. You are sending a voltage signal to the gate of the mosfet and the mosfet is what is acting like the switch.

I think you should reconsider your power levels because this is an unregulated build.

 

[Jtterrible]

the coil size is mostly around .07 to .1 ohm.. i will be using dual coils or tri coils.. mebe even quad in the future.. the advantage of the build is it would full power sub ohm multiple coil builds.

I guess since i'm new to this i just need some examples of each of the components to pick because mouser and digikey have so many options.. i just don't want it to fail because i picked the wrong component and with how many details listed it is kind of overwhelming knowing which specs are desireable

http://www.mouser.com/ProductDetail...GAEpiMZZMshyDBzk1/Wi7r8jvGh7mrdQq%2bkQXdVgqE=

http://www.mouser.com/ProductDetail...GAEpiMZZMsxR%2bBXi4wRUNXkmM90UIcXqMBhMvjkkew=

http://www.mouser.com/ProductDetail...=sGAEpiMZZMsgGjVA3toVBAK0o4DxfcqijSchET4px6U=

http://www.mouser.com/ProductDetail...=sGAEpiMZZMtlubZbdhIBIOunD5kldQozXSFXBP1ApbU=

will these work?

 

[Jtterrible]

I really need some help picking my components so that they will allow the most out of the batteries..

I also found this mosfet
AUIRFB8409 International Rectifier | Mouser

but i am unsure on the specs being enough.. can anyone help me please?

 

[Zanderist]

The fuse will take 20 seconds to trip at 75amps.

I think you may need two mosfets in parallel to be safe. What you've shown looks okay based on the gate threshold vaule.

The High amp rating you see listed would only be possible with proper heat sinking, otherwise you run the risk of frying the mosfet.

By the way here's the thread your looking for,

http://www.e-cigarette-forum.com/fo...y-box-unregulated-box-mod-450w-build-log.html

 

[Jtterrible]

any guides on wiring mosfets in parallel?.. also which 2 would I use? I can fit a heatsink in my box as well. I'm just worried that I won't be able to safely vape to full capacity without frying out my mosfet.

Should I find a different fuse then?

 

[Visus]

Here ya go Jt
I forget who made this but it is a good drawing...