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[Matt Heaton]

Hi, quick question. Would a short on the negative post cause the mod to auto fire? is that possible I just built a dual 18650 mosfet mod and it was hitting like a champ with the lid off( its in a hammond g box ) as soon as i screwed the lid down it started auto firing like I've never seen an atty go. any ideas my solder job on my battery clips are pretty bad.

 

[drmarble]

If you are using an N-channel mosfet then shorting the negative would be a problem. N-fets work by switching the negative circuit. The case is floating rather than negative when you aren't firing. If the lid touches the negative wire at the battery you are bypassing the fet and it will auto fire. Put some electrical tape on it, or better, solder it well and keep the exposed ends isolated.

 

[Visus]

Mos definitely, you are mosfetting, restricting ground to the 510, the positive is already there at the 510 waiting for the mosfet to feed ground when you press the button.
If any thing of the case touches negative/ground copper metal the mod will auto fire.

easy fix stop the case from touching erryting mon''...

Put a piece of tape over your exposed wires put the lid back on, it shouldn't fire but you will need to rewire it because tape will wear out..
Just check it, make sure its the battery sled and not from you maybe stuffing the excessive wires in there to close the lid, if that is so..

 

[Visus]

doc hit post b4 I

yeah good stuff doc lol

 

[Rickajho]

Pictures you help a lot on this one.

 

[Matt Heaton]

Cant really post a picture I tore it down to resolder some things and make everything fit better. But I have another question Before I go soldering. (sorry if this is a dumb question) will it matter if I wire like this.


or do the wires leaving the battery have to be on the same side?

 

[drmarble]

As long as you have connected the +s and -s together the wire doesn't care which side it comes from. The wire connecting them makes them essentially the same point electrically.
In you picture, you are missing the resistor across the mosfet. I hope that is just artistic license. You need a 15k across gate and source (the two end ones). It can be a little 1/8 watt resistor. I think it is needed to bias the mosfet. Without it you could wind up firing randomly.

I hope this picture helps.

 

[Matt Heaton]

As long as you have connected the +s and -s together the wire doesn't care which side it comes from. The wire connecting them makes them essentially the same point electrically.
In you picture, you are missing the resistor across the mosfet. I hope that is just artistic license. You need a 15k across gate and source (the two end ones). It can be a little 1/8 watt resistor. I think it is needed to bias the mosfet. Without it you could wind up firing randomly.

.

Yea I have a resistor, just didn't draw it in. Ok so it will work thanks a lot man I had it put together already but was just so sloppy I decided to redo it all.

I will pos a pic once its all said and done
Thanks to all that helped in this thread.

EDIT: Little off topic but I have a basic question. Ok so my understanding is if im running two batteries in parallel do they share the amp load. For example my atty is pushing 20 amps do the two batteries split it like 10 amp each battery.

 

[Visus]

If they are solidly soldered and all things perfect yes, new batts married measured batts..

Use proper gauge wire and they will in perfect of theory share the load they act as one cell so yes and no.
Any resistance from soldering or improper gauge they will fight slightly the stronger batt or less resistance from soldering will push a few more..
Two 30 amp batteries become one big 60 amp battery... But when u let go of the button they equalize but if you take them out one may be at a slightly higher charge than the other...

welded links make this happen @ much better chance but without knowing the batteries internal resistances* exactly its closer but still not perfect without knowing their IR..


.

 

[Matt Heaton]

If they are solidly soldered and all things perfect yes, new batts married measured batts..

Use proper gauge wire and they will in perfect of theory share the load they act as one cell so yes and no.
Any resistance from soldering or improper gauge they will fight slightly the stronger batt or less resistance from soldering will push a few more..
Two 30 amp batteries become one big 60 amp battery... But when u let go of the button they equalize but if you take them out one may be at a slightly higher charge than the other...

welded links make this happen @ much better chance but without knowing the batteries internal resistances* exactly its closer but still not perfect without knowing their IR..


.

After I built this mod I went out and got two new batts. I charged them full and tested the volts with a multimeter I used it for awhile took the batts out and tested and they both kinda matched up well they both jumped form 4.01 to 4.02

This is the size wire I used

Is there anyway I can test voltage drop and the resistance of the mod with my multimeter?

 

[Visus]

Yes put your leads on the 510 inside your mod one on negative or anywhere close to the five ten on the metal case with the other leade on pos pin with cover off insidepu o ton atomizer your using hit the fire button. Being careful to not touch the case with the pos lead. You can put piece of plastic under so if you slip off the pos lead, really simple..

Typin on my phone and sleepy

You also can just put it on the battery± but that wont give ya all the loss u have in the wiring connections/mosfet @ the 510. You generally wanna measure as close to draw as ya can..