New Aimpoint photos leaked

[JAD]

If I didn't have a really good reason to use an alkaline battery in a serious piece of gear, I would not do so. There just isn't enough incentive for cell makers to maintain high quality in that format. I would worry a lot about being able to consistently source good alkalines.

[ETA: I do of course grok the CONOPS of the subject sight. It just doesn't make any sense for an active member of a free market economy.]

NiMH is a low grade consumer secondary chemistry. Eneloops are a consumer product. Fujitsu eneloops are made in Japan and are second gen. Panasonic eneloops are fourth or fifth gen and are Chinese. Eneloop Pros are Japanese for now.

[BillSWPA]

If I didn't have a really good reason to use an alkaline battery in a serious piece of gear, I would not do so. There just isn't enough incentive for cell makers to maintain high quality in that format. I would worry a lot about being able to consistently source good alkalines.

NiMH is a low grade consumer secondary chemistry. Eneloops are a consumer product. Fujitsu eneloops are made in Japan and are second gen. Panasonic eneloops are fourth or fifth gen and are Chinese. Eneloop Pros are Japanese for now.

You can always use lithium 1.5 v. AAA cells.

All of the Panasonic Eneloops I have say made in Japan.

I have been phasing out alkaleaks for awhile now, and would not use them if another option was available. However, given the stated purpose of this optic, it makes sense to accept a battery type that can be found anywhere in the civilized world, even if it means using one from the TV remote in the hotel.


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[farscott]

What kind of AA are people using in the COMP M4? I am partial to Israeli Tadiran TL-5903 batteries, which use a primary lithium-thionyl chloride chemistry. The appeal for me is the ten-year shelf life, the capacity (2400mAH), the ability to source current from -55C (colder than I ever hope to be) to +85C (hotter than I ever hope to be), the strong construction, and the very flat voltage versus time discharge curve.

http://www.farnell.com/datasheets/17...719.1496445620

The functional negative is the nominal output voltage is 3.6V. I know the COMP M4 has an internal regulator, but I assume it is a linear. So the extra voltage becomes heat. (If the regulator is indeed a boost or a buck-boost, my admiration for Aimpoint reaches a new level.) The other negative is that these batteries are specialty batteries, so online shopping only.

[JAD]

Li primaries are OK, great density for a jelly roll, and awesome quiescence. Bummer is that Tadiran sold to Alcaltel who sold to Saft, who makes some of those cells in Germany and some in Zuhai. Caveat emptor.

ETA: yes, that's too much of a voltage mismatch.

[farscott]

Li primaries are OK, great density for a jelly roll, and awesome quiescence. Bummer is that Tadiran sold to Alcaltel who sold to Saft, who makes some of those cells in Germany and some in Zuhai. Caveat emptor.

ETA: yes, that's too much of a voltage mismatch.

I am not sure it is too much of a voltage mismatch as the real issue is power dissipated in the regulator and the junction temperature of the pass transistor in the regulator. Let's assume the battery is at 3.6V and the regulator output is at 0.8V. So that is 2.8V dropped across the regulator, and I am unaware of any regulator that cannot handle that. So the next step is power dissipation. 80,000 hours (from the Aimpoint literature) and a 2400mAh battery implies a steady-state current of 300uA worst-case. So we are looking at a power dissipation of 840uW. If we assume the thermal impedance of the package is 166C/W (which is pretty high for a SMT regulator), the temperature rise in the regulator is still insignificant.

[JAD]

I like your math just fine. Shows what I know; I'm just being over cautious, which with 600v batteries is kind of an occupational hazard.

[farscott]

I like your math just fine. Shows what I know; I'm just being over cautious, which with 600v batteries is kind of an occupational hazard.

Yeah, 600V is a whole 'nother ball of wax. I have designed three-phase motor drives with 340V DC link bus voltages and an induction cooktop that ran up to 1500V. Losing control there is a neat way to create a loud bang and a crater.

[KeeFus]

I picked up a Comp M5 from Larue yesterday (man, they send a kot of swag...paint mixer...?). Its going on my patrol rifle so it will get a fair amount of use over the next few months. Im kind of interested to see how it withstands the extreme temperature differences it will be exposed too in my patrol car. So far I like that its so compact compared to my PRO.

To be continued...

[M2CattleCo]

Ha! Yeah Larue does send a lot of junk but their hats are great. I've wear out two or three a year and have been for about ten years.

[Mike C]

I picked up a Comp M5 from Larue yesterday (man, they send a kot of swag...paint mixer...?). Its going on my patrol rifle so it will get a fair amount of use over the next few months. Im kind of interested to see how it withstands the extreme temperature differences it will be exposed too in my patrol car. So far I like that its so compact compared to my PRO.

To be continued...

Please let us know how you like the Comp M5.