P7 D bin

[beetleguise]

I recently built 5 P7 D bins for friends, and I noticed my C bin is a little brighter. I checked the amps at direct drive using 3 alkalines and 3 NiMh and found I never went over 1.9 amps. My C bin is regulated at 2.8 amps and is slightly brighter. I am wondering if 4 cells would be better for the newer D bins since forward voltage is slightly higher, or would I kill the led.
I ran the D bin without a heat sink and found that the amps were significantly higher ( around 2.9) , but I was forced to abort the test because of the heat build up. The amps were climbing, but so was the heat of course.
So, has anyone tried the D bins with 4 cells direct?
Thanks!

 

[f22shift]

what Vf?

 

[beetleguise]

C bins are 3.7 V I believe, and direct drive I get 3.2 amps with a fully charged NiMh. My D bins I think are 3.9 V and are only drawing 1.8 A .:shrug: