Energizer Lithium Batteries in an LED Lenser P7

Hey all.

This is my first post and would like to start with a simple question.

I have gone through a lot of torches over the years and have recently bought an LED Lenser P7 for use at work.

I had planned to outift the torch with Energizer lithim batteries due to their long shelf life and good working temperature range.

However, I have read elsewhere that the Energizer lithium batteries can sometimes blow bulbs in torches!

Is this true? I am hoping somebody can put my mind at rest here.

LL forbids any batteries other than alkaline. The light was designed specifically for them.

what is the real runtime on this light and the p14? The ratings on this light are obviously wrong 172 lumens for 180 hours? Is it just direct drive so that most of those hours are very low output?

As long as you're not gonna run it down continuously until the lithiums are dead, it should be alright to use them. Many P7 / T7 owners have used lithium AAA's with no problem at all, heck, many have done what I said NOT to do with no problems (leave it on till the lithiums are dead) for the sake of runtime charts. There was no reported color shift towards blue during these tests, which is a good sign that the LED isn't being killed. Please note that you will be "technically" voiding your warranty by using anything than alkalines, according to LED Lenser.

:welcome:

sol-leks said:

what is the real runtime on this light and the p14? The ratings on this light are obviously wrong 172 lumens for 180 hours? Is it just direct drive so that most of those hours are very low output?

Click to expand...

Real runtime on the P7 is about 95 minutes on NiMH, alkaline somewhat less.

Actually I don't really believe in Ledlensers alkaline "command".
No other manufacturer comes with such a statement, what I know.
An even output hardly cannot be worse than a higher initial output followed by a lower.
To my LL Quadrat 3xAAA light I use rechargeable NiMh cells. Maybe the initial brightness will be slightly lower than with alkalines, but it runs for a quite long time without a noticable brightness drop.

Regards, Patric

Swedpat said:

Actually I think it's bullshit about Ledlensers alkaline "command".
No other manufacturer comes with such a statement, what I know.
An even output hardly cannot be worse than a higher initial output followed by a lower.

Regards, Patric

Click to expand...

Actually many manufacturers specifically forbid anything other than alkaline. MagLite is one of the larger manufacturers to state this. Hazardous environment lights do also.


LL states it because their lights are almost totally resistor based direct drive, and for the most part with little or no heatsinking. The design takes into account the increased resistance under load of alkaline cells, which gives them a thermal throttling effect.

Marduke,

What does it practically mean increased resistance under load of alkaline cells?

Will not a lower voltage result in a lower brightness?

Regards, Patric

I've used Energizer Lithium batteries since they first came on the market; they usually test around 1.65V, which is higher than AA spec, but I've never had anything damaged by using them, not even sensitive electronics.

It's possible that you could blow out a cheap flashlight that doesn't have voltage regulation, but I don't see anything happening to your LL P7.

P7 runs for about 2 hours to 50% with lithium AAA's and almost constant output!

Marduke said:

Actually many manufacturers specifically forbid anything other than alkaline. MagLite is one of the larger manufacturers to state this. Hazardous environment lights do also.


LL states it because their lights are almost totally resistor based direct drive, and for the most part with little or no heatsinking. The design takes into account the increased resistance under load of alkaline cells, which gives them a thermal throttling effect.

Click to expand...

Oh, I see. So LED Lenser flashlights actually take advantage of the way alkaline batteries' internal resistance increases as they warm up as part of the regulation mechanism. Wow, what a piece of crap.

Threadstarter, return the P7 and get yourself something with a proper voltage regulator. Fenix is a popular brand around here for inexpensive "performance lights".

The question is if the Ledlenser's advice against other batteries than alkalines is something new? Will the new models be like regulated with alkalines?
My 3-4 year old LL 3AAA is not! NiMh works much better with it. Alkalines will drop the brightness after a short while.

Regards, Patric

Swedpat said:

Marduke,

What does it practically mean increased resistance under load of alkaline cells?

Will not a lower voltage result in a lower brightness?

Regards, Patric

Click to expand...

As alkaline cells are run down, their internal resistance goes up. This is what causes the voltage to droop.

This means a direct drive light gets progressively dimmer, and therefore less heat is produced as the output decreases.

LL basically put together the cheapest light they could to squeeze the most profit. Cheap resistors, no boost circuit in most of the line, and less material required for a heatsink because they count on decreasing output of alkaline cells.

It's a fairly common occurrence to have 3xAAA type lights burn out faster using low resistance cells. This is most noticeable with the multiple 5mm lights, where individual LED's progressively burn out.

The problem is when as a selling argument claiming a brightness which isn't intended to be used, because it's practically provided the very first time of the runtime. Therefore I don't like Ledlensers marketing. It isn't fair. :shakehead

Regards, Patric

hello gotta led lenser p 7 myself use it mostly for work used alkalines at first then used lithiums for a while as could get them cheap thru work now using 1000mah nimh cells exclusively no problems .tried on a few occassions to do run times with re chargeables and they last about 2 hours on high till their dead i.e. not enough useable light . Not noticed any degradation in light quality torch does get abit warm to touch after an hour but nothing major .good beam quality though could do with a regulation circuit to make it ideal ,just bought myself a fenix pd 20 as my new edc and cant rate it highly enough for the money similar lumen output to the p 7 but regulated for longer run time on a single cell . To sum it up if you want a light with with a good throw and a flood facility go with the p 7 but use it in small bursts .if you want a light with a good throw and a bit of spill and need to use the light for a longer period and still maintain a good level of light then go with the fenix imho.lol cliff

sol-leks said:

what is the real runtime on this light and the p14? The ratings on this light are obviously wrong 172 lumens for 180 hours? Is it just direct drive so that most of those hours are very low output?

Click to expand...

I got just over 3.5 hours of run time on a set of Duracel batteries on my P14. I was pretty pleased. After that it fell off to a pretty dim state which is suppose to last 180 hours or something. I have used one set of Lithiums through it but as I think Marduke once said, they are designed for Alkaline batteries and Lithiums higher voltages may or may not be too good long term.

Bill

Led Lenser's stated runtimes are for the low mode on the torch. Not the high mode!!!

Guys,

Thanks for all the replies. I think I will stick to alkalines just to be safe.

I am really happy with the P7 so far. I am a police officer and use it a lot on night shift. I am not really concerned about battery life and I use it in short bursts of a few minutes duration tops so it serves my purpose pretty well.

I just got sick of using expensive CR123A cells on my other torches and gaining maybe an hours burn time before having to change them. Also, the heat generated by my old torches (namely a Streamlight Scorpion then an LED Wave one) was pretty off-putting. A couple of times the LED Wave torch activated in my belt holster which was pretty scary.

Even I only get a couple of hours burn time with the 4 AAA's in the P7 I will be happy. When the light starts fading I will bin them for fresh cells. AAA's are so cheap compared to CR123A's I will happily change them out for fresh batteries.

Thanks again.

Yeah, totally. I don't expect to get anywhere near that runtime as I use a mixture of both low and high modes. As I said, even two to three hours of a good light output will keep me happy.