Using a LED flashlight with the car battery

[AGZ]

Greetings all
I have a no-name IR LED flashlight that runs on 2X 16850 batteries, i.e. about 7.4V (?)
I need to connect it to the roofrack and run it from the car battery (12V). I couldn't find a 12V IR spotlight, at least not for a reasonable price, only the array types which have a limited range.
Does anyone know if the 12V would destroy it?
Cheers
A

 

[hamhanded]

Yes it would. You either need to open it up and swap out its current limiting resistor for a different value so you can run the light at 12v, or use an external buck circuit/voltage regulator to use the existing current limiting resistor at the correct voltage.

You can use this to calculate the correct resistor value, but you would need to know the LED's current forward voltage: https://www.digikey.com/en/resource...ors/conversion-calculator-led-series-resistor

Or try something like this regulator, which regulates to 6v, slightly underdriving it: https://www.digikey.com/en/products...52/10451178?s=N4IgTCBcDaIAoHsA2yCuACA7CAugXyA

 

[Lynx_Arc]

It would be more than 12v by a lot if you had the engine running could be 14v even and the batteries could be connected in series or parallel make sure of that too and if the light has a charger for it or uses USB etc.

 

[AGZ]

I found a 12v to 7.5v 10A 75W DC-DC converter, so I guess I'll use it to solve the problem. Thx all

 

[Lynx_Arc]

I would test the inverter before I hooked up something to it as voltage could vary depending on load and input voltage.