LED Light Switch

[cvriv]

This is a very basic problem that has me a bit confused. I got my hands on a few of these LED light switch things:

https://www.amazon.com/COB-Wireless-Night-Light-Switch/dp/B016VCC7JM

I was using them in my closet. I decided to gut them and rewire then to run off a 12 converter brick using one of the switches to turn them all on and off.

When I opened up the switches I found two SMD strips (12 SMD's each), and a single 0.5w resistor. I measured the resistance of this resistor and measured 0.5ohms???

Anyways, i wired three of them up in series and brought 8.5v across them and found they were drawing 150mA. They were very slightly warm to touch and just about as bright as they were when they were in their original state with freah batteries. Anyways.... I calculated that i need a 24ohm resistor to run the three in series across a 12v supply. The thing is that 0.5w will be dissipating during operation. I have a 24ohm 0.5w resistor but im not ok using it because that resistor gets hot as hell.

Now my question is, and i should of ran them first with their guts hanging out, how were they running before I gutted them? They used four AAA batteries so thats 6v, 3v each, pulling at least 150mA. Thats almost a whole watt of power! You think these thing were cooking inside the whole time? Am i missing something here?

Also does anyone know what type of LED strips those are? I tried google to find them but failed.

[TheUnnamedNewbie]

It's not unheard of for cheap LED lighting things to absolutly boil the living bits out of the resistors.

Something that can easily be done if you don't have the right power resistor or don't feel great about the temperature it will be running, is just use 2 of half the resistance in series, or two of twice in parallel. This will double your power rating.

If you only have 24ohm resistors, you can use 4: make two strings of 48 ohms and put those in parallel.

Depending on how the LED's are wired up, you could also just look at getting a constant-current driver instead of a constant voltage one. They are quite cheap.

[cvriv]

Thanks for the reply. Yea I already knew about the wiring of the resistors as such. I was just wondering if there was something I was missing when calculating power because like I said,... there was only one 0.5ohm 0.5w resistor inside each one. That's just craziness. Wouldnt last very long at all. Thanks.