Infinity Ultra w/Lithium, vs. Alkaline ?

I recently started putting Lithium Energizers in my Ultra-G instead of the Energizer alkalines. I am somewhat startled by the very large difference in brightness between the two, (Lithiums brighter). I have observed that a difference of 20-30% in lumen increase very often goes unnoticed, but this difference is quite perplexing.

Has Quickbeam, or any of the other "testers" quantified this difference ?

This is a different Ultra with Lithiums..... Wow !!

The difference is because the lithiums have slightly higher voltage (about 1.7 volts). The lithiums also have flatter discharge curve and slightly more mAH. Total runtime will be slightly longer with the lithiums, not enough to make a fuss about at normal temperatures. More interestingly the lithiums will keep the light running at basically the same brightness the whole time, while the alkaline will get dimmer and dimmer.

I don't know much about batteries but will a rechargable with mah 2300 make a difference?

Rechargeables have a slightly lower voltage and the Ultra will be a little bit dimmer than with alkalines, but they still work fine.

Really, if you're concerned about making your Ultra run as bright as it possibly can, you're using the wrong flashlight and you should get a Luxeon light or an incandescent. The Ultra is supposed to be "just bright enough", not "bright as can be", so it gives you good short-range illumination and long runtime.

Hells bells Paulr, I know that, I was just astonished at the brightness increase of a magnitude I didn't expect !

I like it.....

JohnK,
I understand your thoughts on lithiums...I received a 4-pack of lithium AA batteries for Christmas and threw one into my Arc AA. It IS brighter and much, much lighter than using it with alkalines. I calculate 20% longer life with lithiums VS alkalines so I will get 17 hours or more of intermitten use with the lithiums.
From what I understand, the Infinity Ultras have a better regulation curve than the Arc AA so they benefit less from lithiums. Checked my Arc AA/lithium on a lanyard, it is more "wearable" with a lighter feel so that is what the Arc's diet with consist of.
I wish the price of them would drop down to about a buck per cell...

Personally, I don't notice a difference when I replaced my Infinity Ultra's alkaline with a lithium. I suppose if I did a side-by-side comparison then I would have.

To me, the main reasons for going to a lithium AA was the lighter weight and cold resistance.