Mech batteries

[thatguy]

At 0.5 ohms you'll draw about 8.4A from a cell.

This is all good on a 10A rated cell under good conitions. Then you factor in the accuracy of the ohm testing gear most people use (sadly, mosty use a mod like a vamo,mvp,sigeli or other box mod which have a resolution of 0.1 ohms so a build could be anywhere from +-0.1 ohms{ accuracy and resolution erros combined]). On top of this add increasing internal resistance to the equation and the variation between individual cells.....

I'd be happier seeing builds from 0.6 ohms up to give comforatble headroom. 0.5 gives 16%, 0.6 gives 30% a small change but much safer.

As a rule of thumb, always allow 15-20% headroomas an absolute minimum on cells. If you must go for builds below 0.2 ohms, look at 26650s and not 18mm cells.

[tim]

Jun 14, 2015 23:48:57 GMT thatguy said:

At 0.5 ohms you'll draw about 8.4A from a cell.

This is all good on a 10A rated cell under good conitions. Then you factor in the accuracy of the ohm testing gear most people use (sadly, mosty use a mod like a vamo,mvp,sigeli or other box mod which have a resolution of 0.1 ohms so a build could be anywhere from +-0.1 ohms{ accuracy and resolution erros combined]). On top of this add increasing internal resistance to the equation and the variation between individual cells.....

I'd be happier seeing builds from 0.6 ohms up to give comforatble headroom. 0.5 gives 16%, 0.6 gives 30% a small change but much safer.

As a rule of thumb, always allow 15-20% headroomas an absolute minimum on cells. If you must go for builds below 0.2 ohms, look at 26650s and not 18mm cells.

Only occasionally do I go as low as 0.5. Like on my Lemo or C'thulhu. I will probably not use those on the Gizmo. Will prob use a subtank mini (or three) at about 1 ohm. Thanks for the 15%-20% tolerance advice

[Ripshod]

Good advice from everyone there. One point that was raised was a potential 4.25Volts on a freshly charged cell. To make things a little more positive here I'll state that as soon as any current is drawn from a cell it's voltage will drop significantly. The higher the current the lower the cell's voltage.

Adding to that the volt drop across the mod (including the switch) will come more into play the higher the current.

I think a 4 Ohm coil would be fine on a 10Amp cell.

Jun 14, 2015 23:08:46 GMT VapingBad said:

AWT 18500 IMR 1200mAh 18A (states 15 A continuous which sounds like an overestimate to me, probably more like 10 A)

I concur.

Like I stated though I have no experience of actually using 18500s with regards to fit, all I can do is work the maths and datasheets and suggest suitable ranges.

Again, 10 Amps will be fine.

Maybe stick with the 18650s when subbing.