Do I need a soft start switch?

[JCD]

Do I need a soft start switch in order to run a SF P91 lamp assembly in a SF 6P with 2x IMR16340?

Also, can the Lexan window of the 6P (old style round body) handle the heat produced by the P91 or do I need to pick up a hex head with a glass window?

 

[Bullzeyebill]

Yes, soft start is a good idea. P91 is on edge, and high resistance/sagging of CR123's keeps it in check, from instaflashing. Two IMR's will probably ruin bulb.

Yes, by all means get a SF head with glass window, or, for example, a Solarforce L2 head. I partly melted the lexan in my round headed SF head using the P90 and two RCR123's.

Bill

 

[gswitter]

A soft-start wouldn't hurt, but it's not necessary for 2x IMR16340's. Some have even run the P91 on bigger IMR cells - even IMR18650's - but there have been lots of failures among the success stories.

And the P91 will drain a pair of IMR16340 cells in about the time it will take you to make a sandwich.

 

[JCD]

A soft-start wouldn't hurt, but it's not necessary for 2x IMR16340's. Some have even run the P91 on bigger IMR cells - even IMR18650's - but there have been lots of failures among the success stories.

And the P91 will drain a pair of IMR16340 cells in about the time it will take you to make a sandwich.

Cool. Thanks.

I've unexpectedly acquired a P91 just today, and I'm wanting to play with it to see what it will do, but I'm not quite curious enough to burn through three primaries right before hurricane season is upon us here in Florida. I already have some IMR cells ordered for my E2D, and I have a couple 6P hosts (I can borrow a glass windowed hex head from one of my C3 lights). I'm to use them to try out the P91, maybe compare it to my MC-E equipped 6P.

I don't have a permanent host available for the P91, but I'd like to see for myself what it's capable of nonetheless. I just want to make sure the chance of instaflashing the LA is minimal without the soft start switch. Runtime isn't of any concern for this experiment.

 

[gswitter]

I haven't used the P91/2xIMR163240 combo daily, but after a year+ of occasional use, I'm still on the original bulb. I've run it in two different hosts (G2Z and Leupold 121), and haven't had a single problem with it.