cree solder points / ceramic base temp

[aljsk8]

could someone tell me the max temp for the ceramic area or the top solder points on a cree xre

i have a chanel of aluminium with 3 warm white (q3 5a) cree xre's on it
direct driven (resistored) from a 12v sla the voltage of each led is around
3.5v when the sun has been charging the battery up to max (2w solar panel charges the battery and keeps it topped up)

after about 10mins the ceramic and solder points are at 75C and then stay there and drop as the battery runs out hours later

i know max junction temp is 150C but for obvious reasons i cant measure that

also what lumen loss am i getting at this temp

any help would be great

Alex

 

[aljsk8]

nobody? really could do with some help on this one

thanks

Alex

 

[aljsk8]

nobody

could really do with some help here

thanks

Alex

 

[R33E8]

Nobody probably knows because nobody knows what the thermal resistance from that part to the die is.. A heatsink temperature next to the emitter would be give approximate results (Cree has thermal specs on their datasheet) but is still slightly dependent on how you applied thermal compound(and if you applied any) and the specs of it.. One way to measure the temperature is the measure the voltage drop.. I think there is a thread on finding it somewhere around here...