The link is wrongly done.
I'd be wondrous if people would steer from using the more limited simple post editor, and everything would be editor-unified, but this is another story which involves sb56637; it's not an straightforward task to convert quotes between editors.
Is it this XHP70.2 driver you are speaking of?
So what did you did with it? :-D
This driver is a switching, boost type driver. Technically speaking, these driver types are the ones which actually pull current. Others like this or that don't pull current from the battery, they just regulate or accurately limit the flow of current from the battery to the emitter, as they are regulated variable load devices.
These driver types or switching converters are usually designed with a power output in mind. The XHP70.2 driver claims 4800mA of output at the voltage of a 2S emitter (“6V”, or about twice that of a more standard 1S emitter like the SFT40 in this thread). I am sure it does it. However, bear in mind this already is a lot of power, and this driver will actually pull or try to pull a very high amount of current from the battery for it to be so. Let's do some math:
Pemitter = Vemitter × Iemitter = 6.5V × 4.8A = 31.2W
Pdriver = Pemitter / ηdriver = 31.2W / 0.9 = 34.6̅W ≈= 34.667W
Where P is power, V is voltage, I is current, and η is energy conversion efficiency (values used for voltage at the emitter and efficiency stem from XHP50 emitter tests and buck and boost driver threads).
I can't find any cut-off voltage in the driver's advertisement (bad practice), so I'll presume 3V. This means that, when the battery is discharged, the driver will pull up to Ilowbatt = P / Vcutoff = 34.6̅W / 3V = 11.5̅A = 11.556A for high mode, and with a full or close to full battery it may start from Ihighbatt = P / Vhigh = 34.6̅W / 4V = 8.6̅A = 8.667A.
And why did I use just 4V as voltage from the battery when the battery is full or nearly? Well, because there is resistance in between (battery, springs, a switch, etc.).
So, it is safe to say that such 4800mA “6V” or 2S boost driver requires between 8.5A to close to 12A from the battery to work in high, and depending on battery state of charge and other parameters like actual efficiency and etc.
Advice: take out that driver from the flashlight you stuck it inside Pacolux, undo the ;-) shenanigan you did and restore its original sense resistor, and be done with it.
I say shenanigan because I feel you probably reduced the original sense resistor a lot. This is like taking a stock car to a tuning centre, and expecting its engine to deliver twice or thrice the horsepower just by reprogramming the control box. LMAO!
I do not mean to say that reducing the sense resistor won't work, but you have to understand what are the potential limits. I once built an SK98 with an H1-A boost driver among many major modifications (pill, switch and shaved XHP50 emitter). Emitter was driven at 4.2A maximum or so (I stuck an R050 over the stock R025 sense resistor, if I'm not mistaken), this is because the boost converter is limited to around 10A of input. I still have it by my side.
The H1-A which is sold now uses an 1.5μH inductor, this reduces its efficiency (they cheaped on it). Initial versions like mine employ a 2.2μH inductor.
Many drivers? Not that ;-) many. Drivers which use low value resistors as voltage droppers are the least sophisticated, and usually super-cheap. You may find them in seedy flashlights, and also in some retailers (example: 2600mA 2-Mode LED Flashlight Driver Circuit Board @ FastTech). As a curiosity, I remember a driver I found in an SK68 flashlight, it was a low current output boost type driver which allowed the torch to work with AA cells (alkalines, Ni-MH, etc.), but it also handled li-ion cells. I am fairly sure that the sense resistor was used as a voltage dropper/current limiter in the latter case.
Fri, 08/27/2021 - 17:12