what is the advantage of parallel unregulated box mod ?

[Edd Harbin]

Looking into box mods and was wondering what the advantage was of a dual 18650 parallel box mod over a tube mech ?

 

[Rossum]

• Ability to deliver twice the current without taxing the batteries
• Twice the battery life at reasonable currents
• It doesn't look like a piece of plumbing

 

[Cjax]

It's just twice the battery life, not the current. Twice the current requires the batts to be in series (like stacking batts in a tube mod), parallel gives you twice the run time.

 

[cracoucax]

Not really:

AFAIK parallels batts will give you twice the max amperage and mah.
Serial batteries give you twice the voltage.

Current is ambigious in this case: parallels will support twice the current, but serials will ouput twice the current of a single battery, simply because there is more voltage.

Also it seems that parallels batteries carries almost the same dangers as serials : chain reactions in case of failure. So it's probably a very good idea to have a (very high amps) fuse in a parallels mech mod.

 

[Edd Harbin]

So its less battery sag and longer vape time .

 

[Rossum]

It's just twice the battery life, not the current.

Into the same load, parallels will deliver the same current -- assuming we disregard battery sag. But what I wrote was: "ABILITY to deliver twice the current without taxing the batteries." (emphasis added)

In order to get twice the current at the same voltage you obviously have reduce the resistance of the load. For people with deep sub-ohm coils, parallel batteries are a big plus. Parallel batteries basically act like a single battery of twice the size. They have the ABILITY to deliver twice the current, or twice the run-time (but not at the same time).

Twice the current requires the batts to be in series (like stacking batts in a tube mod), parallel gives you twice the run time.

Stacking batteries produces twice the voltage and would indeed put twice the current (and hence four times the power) into the same load as a single battery.

 

[UncleChuck]

One thing to add to Rossum's excellent post (really more of a clarification so nobody gets the wrong idea) stacking batteries will up the current going through the circuit assuming the same resistance, but they will not up the current handling ability of the cell. In other words, if a single cell has a 10 amp limit, stacking them will not increase the "safe" current draw to 20 amps, you still have a 10amp limit on the battery (being two cells)

 

[Rossum]

Right!

Forgetting about the resistance of the load for a moment,

• Stacking batteries gives you higher voltage -- but not the ability to handle higher currents.
• Paralleling batteries gives you higher current-handling ability -- but not more voltage.

In either case, stacked or parallel, the cells should be a "matched pair" and always be kept, used, and charged together. If they ever show signs of becoming unmatched (different voltages on removal, or significantly different charge times) I'd be using a new pair.

 

[supertrunker]

Here's the bit i'm not quite getting. i run 30A batteries. if i run 2 in ll then they turn into one 60A battery and i can therefore run coils at stupid low resistances?

the voltage remains at 4.2 say, but the rating of a single 30A battery means i cannot go lower than 0.15Ω and i never thrash them like that. I'm failing to see the benefit of paralelling or stacking them.

T

 

[VapingTurtle]

The benefit comes in greater capacity. You'll get a longer run time.

 

[Rossum]

Even if you don't run stupid low resistances, what's the sag in one of those 30A batteries at whatever resistance you do run? Yes, it's difficult to measure that vs. drop in the mod itself. But in any case, two cells will be a "stiffer" voltage source than one.

 

[supertrunker]

Thank you both.

T