G4 Halogen Bulb Wattage versus Runtime

RobertMM · Dec 12, 2019

Hi all.

I just got a NOS Solarforce L600 and noticed it has the 6 Volt 20 Watt G4 bulb in it.

I enjoy it immensely and am thinking of getting 15 or even 10 Watt bulbs for it.

Does anybody have any data on runtimes on these bulbs with two 18650 cell?

I personally use 3500mAh and 3000 mAh cells.

fivemega · Dec 12, 2019

6 Volt 20 Watt
Watt:Volt=Amp
20:6=3.3 Amps
Since you are overdriving a 6 volt bulb at 7.4 battery volt, then we can assume this 6 volt bulb will consume 3.5 Amps current draw.
If your batteries are 3500mAh or 3.5Ah then run time will be theoricaly one hour. (Ah:A=hour)
In real world, part of battery energy wasted as heat. The higher current draw, the more heat and more waste.
I would accept 45~50 minutes of run time. Assuming batteries are good brand, new, (fully healthy) and fully recharged.
That specific flashlight uses unprotected cells. If anyone decided to use protected cells, make sure PCB won't kick in.
Also when choosing a 6 volt bulb to power with 7.4 volts, make sure bulb life is rated at 100~150 hours.

RobertMM · Dec 13, 2019

Thanks very much Fivemega.

I will use your sample computation to determine rough runtimes for the other wattage bulbs.

Much appreciated.

G4 Halogen Bulb Wattage versus Runtime

RobertMM

Flashlight Enthusiast

fivemega

Flashlight Enthusiast

RobertMM

Flashlight Enthusiast

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