this is not so easy to answer. ima try ramble it together.I am wondering about something and i thought i better ask... Does anyone have any idea how does Cold coil resistance of an atomizer effects batterylife and performance.
I know coil resistance varies from tubo to tubo and it is tuned for each unit,but what exactly is the difference if any.
Lets say there are two TUBOs A and B.
A TCR = 190
B TCR = 220
Would TUBO B be more wasteful on batterylife or more powerful than TUBO A ?
for unregulated coils/heaters this resistance controls how much current can flow at a given voltage. this current at that voltage defines the power that the coil will dissipate. less resistance => more current => more power.
but we are using a box mode that is mainly controling said power by changing the voltage at the coil. it basically takes the battery voltage and raises it (boost) or lowers it (buck) to reach a targeted power output.
my research has lead me to believe buck converters are slightly more efficient than boost converters, fogot the numbers was not by much if i recall correctly.
i chose the coil resistance in this range because if the coil resistance is low, battery voltage does not need to be boosted only bucked.
at low battery voltage tho it needs to be boosted in the range we are.
so the difference between TUBO A and TUBO B would be in the point in time/battery voltage where the switch is from buck to boost.
battery life would be most affected by the difference and maybe board temperature.
@KeroZen or @rz or anyone feel free to correct me.
something else that plays into this is:
since i use the same material for all tubo heaters, 316L stainless steel 28awg twisted. the difference in resistance also means difference in length of the coils, as the length is what defines the resistance of a metal strand.
so TUBO A has shorter coils than TUBO B.
shorter also means less metal mass and less surface area. surface area is where the exchange of heat is taking place mostly.
on the other hand less metal mass can be heated up faster, it reacts faster to changes. the box mod will react to all these changes.
so maybe to conclude: TUBO A has less contact area to transfer heat but is faster to control the heat of the coils, board temperature might be slightly cooler and battery life at low voltage minimally better.
TUBO B has more surface area for better heat exchange, but reacts slower, at low battery voltage it might need to push harder and get warmer.
as @KeroZen said another time. too low resistance is bad for the resolution for analog digital converter. on the other hand too high resistance (increased heat transfer) the coil is slow and the chip runs hotter.
i tested both extremes. one with very short coils 0.1ohm , super fast on temp, not very stable temp reading, not so good heating of the air. and the other, double the coil length of normal tubo heater 0.5ohm, great resolution, slow to get to temp, overheating of the chip.
i lowered the average resistance from the early units of around 0.270 to around 0.200, later i upped it again to 0.230.
i really dont think there is noticeable difference in all of them.
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