Taifun power source
Operation manual
What is the problem?
1.) Low supply voltage
One problem is, that the power of up to 24 watts must be provided by a single Li-battery with a voltage range of
only
2.8 - 4.2 volts.
If you set the output power to, for example, 24 watts (P-mode) this is the minimum power taken from the battery
(please consider the loss caused by the efficiency factor).Therefore the battery has to provide a current of at
least 8.6 amps!
8.6A = 24W / 2.8V (I = P / U)
This high current causes a voltage drop at the various contact points and materials. The system "loses" power
that can not be converted into heat at the evaporator (see drawing). The input current is increased more to com-
pensate the loss to maintain the same power at the output (and the degree of efficiency gets worse).
Suppose, you have a total parasitical resistance of only 0.1 ohms on the battery side, you'll get a voltage drop of
0.86 volt at this resistance.
0.86V = 8.6A * 0.1Ω (U = I * R)
This means, there is only 1.9 volt left for the control (Ubattery – Uparasitic), but the control needs at least 2.8
volts to work properly!
Even with parasitical resistance of 0.01 ohms you'll get a voltage drop of 0.086 volt, which still leads to a shut-off
of the power supply. A commercially available multimeter's cable already usually has a resistance of 0.1 ohms!
If we wanted to compensate the power (from the 0.86 volt voltage loss), we would need to load the battery with a
current of 12.4 amps. This, however, would cause an even greater voltage drop and so on. This "escalation"
would destroy the battery or at least shorten its life drastically.
This is the reason for the minimum cut-off threshold of 2.8 volt!
This example shows very clearly, how necessary it is to reduce parasitic resistances, which inevitably exist by
contacts or materials. The battery charge will last longer and the battery is less stressed!
The same problem, as described above, appears at the power supply's output (see drawing).
To limit all voltage drops caused by parasitical resistances and the current that flows through it, is a task which
should not be underestimated.
You as a customer and user can help to keep the parasitical resistances low, by keeping the battery and evapor-
ator contacts clean. Also you can tighten all screws of the evaporator, the evaporator itself and the battery's
screw cap (but don't overdo it!)!
The battery's quality is important here, too. Its internal resistance is relatively high and it also varies depending
on the manufacturer, type, age and state of charge.
Only if all contacts are clean and all screws are tightened (parasitical resistances) and the battery can provide
the necessary current (internal resistance) the power can be supplied to the evaporator.
Otherwise you heat up
anything else, but the liquid!
2.) Low load resistor
The second problem is the relatively low coil resistor (evaporator). With such a low resistance (R coil) of 0.7 - 6.0
ohms, the parasitic resistances on the evaporator side have a greater effect.
If the parasitic resistances (R pos. contact, R screw 1. R screw 2 and R neg. contact) as described in point 1 are
together 0.1 ohms and the evaporator coil, for example, is only 0.7 ohms, then only 87.5% of the power "arrives"
© 2013 SmokerStore GmbH
Page
: 12 of 16
Содержание the eye
Страница 1: ......
