4.2V vs 8.4V. in the same tube.

4 posts / 0 new
Last post
elbakan1
Offline
Last seen: 28 min 50 sec ago
Joined: 12/05/2013 - 06:48
Posts: 255
Location: Miami Fl
4.2V vs 8.4V. in the same tube.

Some of my lamps say 4.2V to 8.4V. Some even 3V to 18V.
Is there any advantage in using 2-18350 vs 1-18650 in power output?
Or 4-18350 instead of 2-18650?.
I know there will be a loss in capacity. But more light?.

Thank you for your replies.

Cheers.

Lighting up the world one flashlight at a time.

sarge12
Offline
Last seen: 4 hours 36 min ago
Joined: 05/31/2020 - 08:13
Posts: 93

It largely depends on the driver. I have some lights that can take 3 stacked protected 26650, but it does not get any brighter with the tube extension and extra battery installed, it just runs longer. The driver just limits the current used. Some lights have drivers and emitters that can accept the higher voltage, and some are current limited to operate at the same wattage off of the 8 volts as the 12 volts. Others will not allow over a certain voltage to be supplied. Actually they all have limits, but with some adding a third battery would ruin the emitter or pcb. I do not think there is a standard adhered to. The light might also not run as hot with added batteries due to reduced amps being used by the supply of the higher voltage. If the driver allows 48 watts to the emitter, and 8 volts is supplied by the battery, it would draw about 6 amps if 2 batteries are installed. It would draw about 4 amps if 12 volts is supplied. The wattage used and lumen output would remain the same.

elbakan1
Offline
Last seen: 28 min 50 sec ago
Joined: 12/05/2013 - 06:48
Posts: 255
Location: Miami Fl

Thank you for your input.Took me a while to digest. Well explained.

In my specific case I’m referring to P60 lamps.
I know the xenon part. More volts more power.
LEDs. well, I’ve burnt a few. If I only would leave
the lights the way they came.
Thanks again.

Cheers.

Lighting up the world one flashlight at a time.

Lightbringer
Lightbringer's picture
Offline
Last seen: 5 hours 42 min ago
Joined: 08/30/2016 - 14:12
Posts: 11786
Location: nyc

Æons ago when the XP-L was more or less new and I saw a drop-in that had one in NW, I jumped on it. Claimed 3-18V or something, figured it had a regulated buck/boost driver, or at least a buck driver, and got one. Worked beautifully. Wanted to try a pair of 18350s, and the LED immediately went blue and dim. Wtf?!?

Yeah, only had ballast resistors inside, NO WAY would it handle even a pair of ’123s, let alone a pair of Li-ions.

You need a driver that’s meant to handle higher voltages. And often, you won’t gain anything except maybe more consistent output. Eg, the EC4GT takes a pair of (protected) 18650s, and it’ll hold a consistent output right up to the point one of the cells drops dead and cuts off.

Any other normal 18650 light will start to drop output as cell voltage drops to just a smidge higher than the voltage-drop of the LED. How big a smidge depends on the driver. With 7135s, it’ll be 0.1V, so if the LED drops 3.3V, the light will hold consistent output ‘til the cell’s at 3.4V, then gradually start dropping.

09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0