G Box Mod Atty Melt Down

[PaulyWally]

A new G box mod that I just got decided to auto fire today and burn one of my favorite attys to the ground. Thank God that is all that happened and there was no other damage. I had just brought the box home a few days ago after having it custom built. I had not used it very much until today when I loaded it up with two fresh VTC5s and an atty with a .5 ohm build. It worked flawlessly on both parallel and series firing. I spent about an hour vaping off of the box this afternoon in my home office and everything seemed normal. Batteries did not heat up, button did not stick and volts stayed around 4.19 and went down to no lower than 4.10. I set the the box down on my marble desk top and went to another part of the house for the rest of the day. When I went into my office right before going to bed I noticed it looked like chuff cap on the atty was missing. I soon realized that it had disintegrated along with the coils. There was spray of juice around the mod where I had left it standing up.

Please see pictures in below message.

My question is what happened to make this box auto fire until the coils melted? I followed all necessary safety precautions and was able to retrieve the VTC5s from the mod. I metered them and both still had a 3.2 charge left in them. Good thing they were true 30a continuous high drain batteries.

The mod is a g box with a mini tactical fire button, a volt meter, Two position switch to change from parallel to series and a mosfet. Wiring and build are very clean. All wires are are ran through insulators and all connections are soldered and heat shrinked.

I know for a fact that the mod was not auto firing when I last used it because I remained in the room long enough to have noticed. So a stuck firing switch should be ruled out.

 

[Cullin Kin]

Glad you're safe!! Wow.

I've found the easiest way to post photo's is to just upload them to Imgur, then copy the BBCode into your post. I always have trouble with the sizing, all of my photo's, no matter how much I resize them, are too big.

 

[Thrasher]

Ummmm. At the bottom of this box is a button that says upload file?

 

[PaulyWally]

Thrasher, thanks didn't work last time I tried. Now it does.

 

[PaulyWally]

Glad you're safe!! Wow.

I've found the easiest way to post photo's is to just upload them to Imgur, then copy the BBCode into your post. I always have trouble with the sizing, all of my photo's, no matter how much I resize them, are too big.

Thanks for the well wishes, yes everything was safe and I am really glad I'm one of those that is really careful when it comes to battery safety or it could have been a different story if the batteries had vented. Strange thing is the fire alarm didn't even trigger, although there must have been minimal smoke compared to vapor.LOL

 

[VictorViper]

Glad you're ok! Once you get the serious issue figured out, maybe we can tackle the mystery of how those o-rings survived.

 

[PaulyWally]

Glad you're ok! Once you get the serious issue figured out, maybe we can tackle the mystery of how those o-rings survived.

Thanks VictorViper, funny thing they aren't o-rings, it's the top rim of the POM chuff! Literally melted it down and must have stopped firing and cooled down enough to not melt the top rim.

What is freaking me out is what could of happened to a mod that was just sitting there with no way that the switch could have been pressed and all of a sudden started to fire on its own. At least my batteries survived.

 

[VictorViper]

...funny thing they aren't o-rings, it's the top rim of the POM chuff! Literally melted it down and must have stopped firing and cooled down enough to not melt the top rim.

...yikes.

Have you contacted the builder about what happened? He may be able to use your photos to check if there are any noticeable flaws in the wiring, etc. Whatever the heck happened, thank goodness the mod and batteries could handle the drain!

 

[PaulyWally]

...yikes.

Have you contacted the builder about what happened? He may be able to use your photos to check if there are any noticeable flaws in the wiring, etc. Whatever the heck happened, thank goodness the mod and batteries could handle the drain!

Luckily it's a friend at a local B&M, I will be taking the mod in on Monday to show what happened. I'm thinking the mosfet or resistor failed.

 

[VictorViper]

That was what immediately came to mind, but then I had to wonder what conditions for failure on a chip or diode would need to be met to lead to autofiring. Could even be something as simple as a bad solder joint, I guess.

 

[PaulyWally]

I'm with you on the solder joint as well, depending on how it's wired if the resistor had come lose there could be a scenario where the current could run through the mosfet completely bypassing the fire switch. Either way scary stuff.

 

[Froth]

My bet is on the tactile switch as a fire button causing the issue, though I could be entirely wrong as I'm only basing this off pictures. The back of a domed tactile switch has very little room for connection of wires, they're mostly used in directly mounting to a circuit board and I could see one of those connections causing an issue as it's installed in a very cramped space with a very small area to solder to that switch.

Tactile switch with connection prongs:

The very small prongs are the wire connection points you must use, I would inspect those as best I could and go from there tracing everything backwards. Not the biggest fan of using such a small switch as a fire button.

 

[PaulyWally]

Yeah that switch had me a little worried at first but mainly because I thought it would not hold up to the wear and tear of constant use.

@Froth, so if I understand you correctly you feel that the switch connection points were too close and my have arced causing the auto fire condition? I have looked closely at the switch and its wiring points and it does show signs of discoloration around one of the prongs.

 

[Froth]

Yes essentially that is what I think may have happened, the wires have to be pretty close already since there's so little room to work with. When I scrolled through your pictures it's what my eyes were drawn to immediately, to me it's uncommon to see a tactile switch mounted where it is, especially being so close to the right-hand battery positive connection.

 

[PaulyWally]

This sounds like the most likely thing that happened. I feel better knowing that it was a builders flaw as opposed to a mysterious spontaneous one off equipment failure.

Assuming that this is what happened in order to salvage this box it looks like each switch connection point needs to be check to make sure there is no possibility of arcing and then being insulated with some cement. Next a non conductive barrier between the switch and the positive post of the battery sled.

 

[PaulyWally]

Well, I dropped the mod off on Monday. The builder can't find anything wrong with it. Says that he has been using it for the last couple of days without incident. The guy is a friend and I have no reason to believe that he would be anything but honest with me. Offered to give the mod back to me or a refund. He did ask if it was possible that I had the batteries in backwards or if maybe I screwed the atty in to far and caused a short.

Batteries could have not been in backwards, I was using the unit for an hour without incident and I was checking to make sure that the batteries weren't getting hot (not even warm), everything was functioning correctly. Lately with all the different mods regulated and not that have their positive and negative poles in different positions, I have been extra careful not to insert batteries backwards.

I really don't think that I screwed the atty in to far but due to the fact that I am 199% positive that I would have detected a firing mod the minute that I shorted the positive pin of the atty to the positive of the battery sled. As I said I was in the room with the mod after using it for about 15 minutes and it was not more than three feet from me.

Pretty scary stuff. I really like that mod but I want more and better answers than it's working fine now and we haven't had any problems.

My angle is that this mod is a pretty simple electrical device. Just like a tube mod, it is either making contact or it is not. Of course when you add the additional wiring for the parallel or series switch, tactical fire button and volt meter, you introduce more areas that could cause failure to not fire.

 

[duc916]

Did you try another atty after the incident or did you leave it alone until the builder got to it?
Sometimes pride in one's workmanship, or the preservation of one's reputation, supercedes some levels of "friendship".

I'd be more inclined to look at the series/parallel selector switch, which carries high current, as opposed to the firing switch, which only carries enough current to fire the mosfet (not enough to generate enough heat to arc or melt solder). I'd also be more suspicious of the mosfet itself than the firing switch.

 

[VictorViper]

No disrespect intended here, but how skilled is your friend, at the end of the day? Unless I was less than 100% certain it wasn't user error, if a builder came back to me and told me there was nothing they could find that was wrong, I'd be taking them up on the refund option.

I'm only asking because anyone can put together a mod, but not all should. I have no doubt he's otherwise being truthful about not finding anything wrong, BTW, but what are his methods/tools for diagnostics?

 

[PaulyWally]

@duc916 I did not try another atty after the incident so I don't know if it worked or not. I think I know what you are getting at, maybe the builder found an obvious problem with his build and fixed it. To save face he is just telling me everything is working. I'd be okay with this but not too cool of a friend.

@VictorViper by what I've seen and heard from others in our vaping community the guy is pretty skilled. Unfortunately I feel the testing and diagnostic methods have not been more than a visual check of connection points and just using the mod to see if anything goes wrong. Keep in mind this is just speculation on my part.

Before I make a decision to either keep or return the mod I would like to speak to him in person and go over the mod with him. I am going to need a very compelling explanation of what I could have possibly done to contribute to this situation. I will also need assure backed with facts that it will not happen again.

 

[PaulyWally]

Did you try another atty after the incident or did you leave it alone until the builder got to it?
Sometimes pride in one's workmanship, or the preservation of one's reputation, supercedes some levels of "friendship".

I'd be more inclined to look at the series/parallel selector switch, which carries high current, as opposed to the firing switch, which only carries enough current to fire the mosfet (not enough to generate enough heat to arc or melt solder). I'd also be more suspicious of the mosfet itself than the firing switch.

@duc916 noticed your screen name, do you ride? Also noticed you are in NorCal, I moved to Texas from Sac. Texas is cool but I really miss home and the riding community up there.