Need Input On A Box Mod I Am Thinking About Building

[Portertown]

I need input from the experts on this forum on a box mod I am thinking about building. It will not be regulated, but will not be a mechanical design either. I love mechanical mods and the vape I get from them, but I am getting a little tired of worrying about voltage drop and batteries draining fast when I run low ohm builds.
Below is what I have in my head for a design.
-Two 18650 batteries in series
-Switch will be a 60 amp 12 volt push button
-Switch will be in negative side of current flow
-Positive of second battery in battery string will be contacted by silver coated brass rod that will be 510 positive contact for atomizer(there will be a plastic insert to prevent it from shorting to negative part of 510 connection)
-batteries will set side by side, first battery will be positive down and second battery will be negative down (these batteries posts will be joined by a brass plate they will contact)
-Negative end of each battery will have a spring between it and contact plate
-Wire to switch will connect to brass contact for negative of first battery
-An inline fuse will be in this negative wire between battery and switch
-batteries will set in a delrin holder I will fab
-Negative wire from switch will connect to brass plate on top of mod that will be tapped for the male 510 connection(this brass plate will be isolated from the case of the mod)
-The case of the mod will be aluminum, but all electrical items will be isolated from case.
-Will install a voltage meter and a switch so I can read battery pack voltage while resting to monitor battery charge state and also when the fire button is pressed to monitor battery firing voltage
-Case lid will be held on by magnets making it easy to swap out batteries for charging
-Will fabricate a brass rod that can be used instead of the first battery so mod can be run in single battery mode if I want to

Do you see any issues with using the negative side of the system for the switch and the fuse?
Do you see any other issues with this design.

I have a layout drawing of this, but being the dummy I am, I do not know how to post it.

Thanks for any and all input.

 

[asdaq]

I don't quite get what you want from 2 batteries in series, unregulated. You would start at 8.4v and it would drop the same as a single batt from there. If you did 2 in parallel, you would double the mAh and the current while still having 4.2v from the start. In effect you would double the useful vape time you are used to now. In series, sub ohm would be out of the question and you would need high resistance and the dual voltage option of having a dummy batt wouldn't be useful for a single coil.

Now if you add a regulator the situation would improve.

Sent from my Nexus 4 using Tapatalk

 

[Portertown]

I don't quite get what you want from 2 batteries in series, unregulated. You would start at 8.4v and it would drop the same as a single batt from there. If you did 2 in parallel, you would double the mAh and the current while still having 4.2v from the start. In effect you would double the useful vape time you are used to now. In series, sub ohm would be out of the question and you would need high resistance and the dual voltage option of having a dummy batt wouldn't be useful for a single coil.

Now if you add a regulator the situation would improve.

Sent from my Nexus 4 using Tapatalk

Asdaz,
Thanks for the input. I think you are right about building this mod with the batteries in parallel. It would solve my problems and also let me use the same atomizers on this mod as my other mods. I would not have to have different builds for different mods.
I would not have to deal with a 'matched" pair of batteries as series would require. I am going to build this mod with enough room to move to 26650 batteries later if I so choose.

 

[mamu]

You still should use a matched pair when paralleling batts - type, voltage, and capacity - and you should also match new with new and old with old same as with series.

 

[Portertown]

You still should use a matched pair when paralleling batts - type, voltage, and capacity - and you should also match new with new and old with old same as with series.

Mamu, thanks for the info.
Do you need to check the voltage on each of the batteries before charging and after charging when they are used in parallel? I have read that it is advised when using batteries in series to make sure they are staying equal.

 

[mamu]

For parallel batts I only check the voltage of each batt the first time I charge them to make sure they charged aok and are good batts. If I'm curious, I'll check, but other than that I don't.

 

[Portertown]

For parallel batts I only check the voltage of each batt the first time I charge them to make sure they charged aok and are good batts. If I'm curious, I'll check, but other than that I don't.

Mamu,
Thanks again for the info.
Have you seen these 510 repair kits? I think they would work great for use as a 510 connector when building some mods. They are made of stainless steel and look well made. The only problem may be that they seem to have an adjustable center pin and that may be an issue when the positive wire is soldered on them. In my proposed build I will not use the center pin that comes with this kit. Each kit has three connectors.
Fatdaddyvapes Mechanical Mod Complete 510 Thread Repair Insert Kits | eBay