Why can't a Fenix tk45 use Energizer l91 lithium primaries?

Hey all! First post here, but I've lurked on and off for about a month or so.



In selfbuilt's awesome review of the tk45, it's mentioned that it draws ~1A on turbo mode. That being the case, it seems like a perfect candidate to run on AA lithium primaries.



But, in Scuderia's first impressions thread (post #40), it's mentioned that the extra voltage would fry the emitter. Wait, what? What extra voltage? Don't l91's run at 1.5v, just like alkalines? According to Energizer's datasheet here, they should. Am I missing something?



I get that L91's would get expensive quickly if the light is getting used regularly. I'm just wondering if it's possible. Like, say, if I wanted to keep an emergency-use tk45 in my car, L91s would be a great option.



I figure if anybody knows for sure one way or the other, it'll be somebody here. Do you guys have any input?

I am also very interested in the answer to this question. Google directed me here. Is there still nobody that knows the answer to this question?

best bet, ask fenix

All the Energizer Ultimate Lithiums I've used come out of the package reading 1.8-1.83 volts even though the package clearly states 1.5 v. Any alkaline I've measured are 1.57-1.6 volts. If this light is running 8 AA batteries in series the extra voltage of the lithiums may present a problem.
Search "Selfbuilt's TK45 review" or "HKJ's TK45 review". They only tested with alkaline & nimh.

I just noticed those reviews are two years old!! Holy s#*t, time flies! I'm sure someone will have tried this by now.

from what i remember reading, it's perfectly fine to use lithium AAs in them; it's just that if you insert a lithium battery the wrong way, it can overheat and explode. the companies don't want to be responsible for that, so they just tell people not to use lithiums at all. again, i'm not sure if this is correct, but it's what my memory is telling me.

I've read that this also true of the LD20 and maybe a few other Fenix multi-cell AA lights for the reasons that Up All Night mentions - Lithiums put out too much voltage out of the box. With the LD20, the owners have said the light goes into direct drive and that they lose some of the lower modes until the L91 wears down to a lower voltage.

I understand that Fenix drivers have tight voltage tolerances to maximize efficiency around a given battery. In theory, wider voltage tolerances allow you use a multitude of battery chemistries, but won't be able to offer quite as much runtime for a given lumen level.