# A simple 2 led battery voltage monitor.



## blujeenz (5/11/15)

Im busy in the design stages with a little boxfet hybrid (mechanical/electrical and semiconductor) and wanted an on/off switch in addition to the fire button.
After some thinking, I figured if it was recessed in the bottom it would be protected from accidental switching and yet still allow the mod to be placed on a flat surface.
I also wanted some form of simple voltage monitoring and came across a rather simple red/green led voltage monitor over at Talking Electronics. Its under the Battery monitor mk1 and is the single li-ion cell version.


A user on Youtube, wtam69, covers the build at .

Some thinking and prototyping later and I had the on/off slide switch soldered to the veroboard for an integrated solution.
I used a strip board with 6 rows of 5 holes and soldered the switch on the edge.



The component side, no jumpers used, make sure no leads touch each other.



Another component side view.



Showing the normal voltage state with a 3mm green led.
Bear in mind this led will be on continously while vaping, so it also serves as an on reminder, but could get annoying if you're trying a stealthy *vaping selfie* at night. 



The low voltage state, as you can see the green is still glowing faintly, so a high power flashing red and blue light might not be a good idea. I had thought that the on/off transition would have been sharper, but still...not a complete train smash.






So, heres a quick sketch of how its getting hooked up. I started drawing the wires and then just included the 2x1mm dia twisted bare copper that I'll be using for the high current busbars.
The battery is an 18350 with a max of 10A, the twisted 2x1mm can handle 26A in enclosed enviroment, so more than capable.
The mosfet is the IRF1404 (R18 @ Mantech) good for 202A continous and 808A pulsed, no worries there. 
The Lp30-500 is an auto-resettable fuse, 5A continous 10A trip.
The fire switch is a 1A lever type micro switch, will do the trick via a 1k ohm resistor to the mosfet gate.
Im using the 1k resistor to pull the mosfet gate down harder because it isnt a logic level high sensitivity type like the vastly more expensive IRLB3034.
Finally, with switch mounted from the inside with a cutout and countersunk holes, will yield a neat, safe and functional device.

The green and red leds will be placed behind a perspex insert to somewhat mimic the switches of the protected mods that we use,eg EVOD style lit buttons.



Although this switch hasnt been field tested yet, I dont foresee any problems and thought I'd post it for the benefit of other uses who may want to upgrade/ customize their Reo's or home brewed mods.

Reactions: Like 1 | Winner 2


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## Yusuf Cape Vaper (5/11/15)

http://www.ecigssa.co.za/index.php?threads/DIY-Mod-build-Q&A..11996/
Check out this thread 


Sent from my iPhone using Tapatalk

Reactions: Thanks 1


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## blujeenz (5/11/15)

Yusuf Cape Vaper said:


> http://www.ecigssa.co.za/index.php?threads/DIY-Mod-build-Q&A..11996/
> Check out this thread
> Sent from my iPhone using Tapatalk



Thanks, thats what sparked my whole mosfet thingy.


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