Is there a way to make a thermal protectiion circuit for LED

[wcricple]

Hi All,
Been making canister dive lights for several years. I've experimented lately with several luminus sst-50 (3) in a lighthead . Too Hot! with taskled driver.
Also 5- Cree MCE with 2- LED dynamic driver. Not too hot so far. But careful not to run out of the water. Any ideas to make a cutoff circuit for when the LEDs are getting too hot? Thats' one problem with water proof divelights , even with heatsinking and transfer to lighthead (Aluminum) the heat needs to be transferred to the water.
Thanks

 

[georges80]

You say a taskled driver, so I presume a H6CC...

The H6CC can be dimmed externally - i.e. you could do some calcs and determine an appropriate thermistor to solder to the POT+/POT- to lower output current as the thermistor heats up. With the H6CC, lower resistance on the POT+/POT- means lower output current.

That would give you thermal protection without a sudden loss of light that a thermal switch would create. Though you could have a thermal switch in series with a resistor that is soldered across POT+/POT- to force a lower current when the thermal switch trips.

Anyhow, lots of ways to skin a cat (or dog ir you're a cat person )

cheers,
george.

 

[Axkiker]

i recently have been researching the exact same thing... several ways not sure whats the best just yet.

 

[Packhorse]

The thermistor is a great trick and I experimented with it while using a voltage regulator based driver.


The other way to do it is to use a thermal switch like what is found inside battery packs. You can order them from battery space. Just make sure they are current rated to match your needs. These may not work as fast as the thermistor set up and will suddenly switch instead of dimming slowly but they are cheap and easy to implement. Depending on how the LEDs are driven you could also put in a by pass resistor/ driver that will supply a reduced amount of current to the LED so you do not lose all light although this should never be a problem with a well designed light in water.

 

[Axkiker]

The thermistor is a great trick and I experimented with it while using a voltage regulator based driver.


The other way to do it is to use a thermal switch like what is found inside battery packs. You can order them from battery space. Just make sure they are current rated to match your needs. These may not work as fast as the thermistor set up and will suddenly switch instead of dimming slowly but they are cheap and easy to implement. Depending on how the LEDs are driven you could also put in a by pass resistor/ driver that will supply a reduced amount of current to the LED so you do not lose all light although this should never be a problem with a well designed light in water.

the thermal switch sounds to be exactly what I need

thanks

 

[Axkiker]

good call on the thermal switch from battery space.... I jumped on their website and it looks to be exactly what I need