LI-ion battery for Jet Beam 1-MK
- Thread starter pennzy
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This is kind of long but you might find it informative.
My theory is this:
Single AA lights that are designed to run both alkaline/NiMh voltages along with the higher lithium ion voltages need to have a driver that can accommodate voltages from 0.9v on up to 4.20v. Since the LED's forward voltage drop is around 3.0v, this necessitates a boost driver circuit for the alkaline/NiMh chemistries. But when utilizing something above 3.0v (ie: 14500), you need to have some type of buck circuit. So it presents an issue for designers as to which is the best and most cost effective way to accomplish both. I have seen the Nitecore MT10A and the Jetbeam Jet I-Mk utilize some type of pwm for the 14500 power yet have a rock solid efficient current controlled drivers with the alkaline/NiMh.
The other issue I have with AA/14500 lights is that I have seen a couple of them not be as efficient with a 14500 as similar lights that were CR123A/16340........even though the 14500 typically has about 100 more mAh's. If wanting a little pocket rocket, I tend to favor the 16340 lights and when wanting something that utilizes the availability of an AA, I tend to just use Eneloops because of the pwm issue. Now all manufacturers may not be like this but I do know that the Jet I-MK is. However the Jet II-MK is not and is very well regulated. It also puts out a little more on its top end. A little bit of that may be due to the XP-L in it vs the XP-G2 on the Jet-I MK.
So, typically I prefer the Eneloop in the AA/14500 combo lights, but I do like the 14500 in a Fenix LD11 because they did a good job with their driver between AA and 14500. Fenix's new LD12, NW did not do as great of job in my opinion with balancing the mode levels, and the efficiency with an Eneloop at the highest level is terrible..........but I'm getting side tracked.
The Jetbeam Jet-I MK is one of my favorite single AA lights because of its efficiency, regulation and price.......but that is mainly utilizing the Eneloop.
Probably my favorite 14500 is the Fenix 800mAh. But I've only owned like 3 different brands. Keeppower makes a nice 14500 and the one I have is a little fatter than the Fenix. Both are based off of the Sanyo / Panasonic cell. My Keeppower 14500 won't fit in the new Fenix LD12 but works fine in the Fenix LD11. But I think Fenix made the tube kind of narrow in the LD12.........so the LD12 is the issue more than the battery. I'd test it for you but its in the truck that has a cover on it and its stinkn' cold outside. Maybe tomorrow I'll dig it out. My guess is that the Jet I-MK won't have an issue like the Fenix LD12 with any 14500 battery.
On this particular light my vote is for the Eneloop. This is a very well regulated light and efficient with an AA Eneloop. Also the spacing is good with an Eneloop. With the 14500 there is some type of pwm or frequency varying control to the light. You don't see it with your eyes, but a data logging light meter picks it up as would an oscilloscope on the LED. As an EE and purist with the driver circuits, this sort of bugs me and so I focus on an Eneloop with that particular light.
My theory is this:
Single AA lights that are designed to run both alkaline/NiMh voltages along with the higher lithium ion voltages need to have a driver that can accommodate voltages from 0.9v on up to 4.20v. Since the LED's forward voltage drop is around 3.0v, this necessitates a boost driver circuit for the alkaline/NiMh chemistries. But when utilizing something above 3.0v (ie: 14500), you need to have some type of buck circuit. So it presents an issue for designers as to which is the best and most cost effective way to accomplish both. I have seen the Nitecore MT10A and the Jetbeam Jet I-Mk utilize some type of pwm for the 14500 power yet have a rock solid efficient current controlled drivers with the alkaline/NiMh.
The other issue I have with AA/14500 lights is that I have seen a couple of them not be as efficient with a 14500 as similar lights that were CR123A/16340........even though the 14500 typically has about 100 more mAh's. If wanting a little pocket rocket, I tend to favor the 16340 lights and when wanting something that utilizes the availability of an AA, I tend to just use Eneloops because of the pwm issue. Now all manufacturers may not be like this but I do know that the Jet I-MK is. However the Jet II-MK is not and is very well regulated. It also puts out a little more on its top end. A little bit of that may be due to the XP-L in it vs the XP-G2 on the Jet-I MK.
So, typically I prefer the Eneloop in the AA/14500 combo lights, but I do like the 14500 in a Fenix LD11 because they did a good job with their driver between AA and 14500. Fenix's new LD12, NW did not do as great of job in my opinion with balancing the mode levels, and the efficiency with an Eneloop at the highest level is terrible..........but I'm getting side tracked.
The Jetbeam Jet-I MK is one of my favorite single AA lights because of its efficiency, regulation and price.......but that is mainly utilizing the Eneloop.
What is your take on the Sofirn SP10 A (or B) . They also are a 14500 /aa light .
I haven't done enough testing with the Jet 1-MK on a 14500 but I have with an Eneloop. Typically what I have found on a couple of other brands is that run times are comparable at the med and low levels between 14500 and Eneloop. The big difference is at the max level. When lights try to max the current capability of an AA / NiMh battery, the capacity drops off. On a run time test if you compared the area under the curve which is efficiency and is output x time.......it tends to be higher for the 14500 than the Eneloop at the turbo or max level. At the medium and low levels they are similar.
An 800mAh 14500 will have 2.88 Watt-hours of energy according to the label. A 2000mAh Eneloop will have 1.30v nominal voltage x 2000mAh = 2.60 Watt-hours.........so they are close with the 14500 slightly edging out. The result boils down to how efficient and what type of driver is used. Current controlled switching type of regulators are a little more efficient than PWM types...(at least that is what I believe).
Because as previously mentioned, two different driver types have to be employed depending on what type of battery is used, run time efficiency at the lower levels boils down to the driver since both batteries have about the same amount of energy.
I noticed that Jetbeam specs the outputs as the same for 14500 and Eneloop except the turbo level of course. I can't measure the output very accurately with a 14500 because of the time varying signal (ie: some type of PWM). However I have a couple of Jet 1-MK's and I put a 14500 in one and an Enelop in the other and to my eyes, the 14500 was slightly brighter on low and medium..........and of course way brighter on max. There is no problem with mode spacing since the max level is a lot brighter so it looks very proportional spacing.
Good thing you got the Fenix 14500. I just checked my 800mAh Keeppower and it will not fit the Jet 1-MK. It's the width that is the problem. I measure the Fenix at 14.35mm x 52.07mm. The Keeppower is 14.61mm x 50.8mm. Fenix embeds the label documentation as part of the battery wrap. The Keeppower uses a separate label and its the label that is mostly the problem as it wants to tear off as you put it into the flashlight. But the diameter w/o label is also a bit tight.
Sorry, I am not familiar with those lights.
Thank you for all your input . Although I haven't kept up with it , I got a AAS degree in ET back in the 70s . Some of it is coming back to me reading your posts . Getting back to my original post , manufacturers should standardize their specs listings to make it easier to buy the correct batteries . It's a crap shoot .
Overclocker
Flashlight Enthusiast
get the Klarus 14500UR75. built-in USB charging. 776mah actual capacity. slightly shorter than an Eneloop so no length issues
