Some Cold Weather Battery Testing and Battery Thoughts
I have been following a lot of the discussion on the forums about the Vector X not handling the cold well with the standard cr123a batteries. So, I went out to test it along with the Gen 2 Sig 10k’s and Leica Geovid Pro 32s in 4 degrees Fahrenheit, -15 decrees Celsius. In addition to the factory Varta cr123a battery, I also have a Surefire 18650 rechargeable for the Vector X binos. This is one of the choices on the
Vectornix approved battery list for the Vector X binos. I chose it because it was the least expensive option as it was on sale at Primary Arms for $16 and does not need a separate charging unit as it has a micro USB port on the battery. Surefire advertises that this battery model functions at –20 degrees Celsius. This is not as low as the Nightcore cold weather specific model that advertises –40 degrees Celsius function but, battery and charger considered, it’s less than half the price and –20 is already colder than I intend to be outside shooting in. As for the Leica and Sig models, I had a Panasonic and Varta CR2 and so each set of binos was tested with each battery. In all cases, the binoculars, and batteries were given an hour outside before testing to reach ambient temperature. This was done with the batteries not yet in the binoculars to make sure they were good and cold. None of the batteries used were new and fully charged. All were somewhere in the middle of their lifespan or charge. Battery voltage was also measured cold (4 degress F, -15C, and warm 69 degrees F and 21C) and a few hours later.
Sig Kilo 10k Gen 2, Leica Geovid Pro 32, and Vectronix Vector X with their respective batteries waiting to be tested in –15 degrees Celsius
The results were as follows:
Vectronix Vector X binoculars:
- Varta cr123a cold voltage 3.034V, warm voltage 3.032V. With this battery the Vector X binos would power up and show the pre-ranging screen but immediately died when you attempted to range. The LED hud disappeared and they did not return a range.
- Surefire SF18650B rechargeable cold voltage 3.464V, warm voltage 3.466V. With this battery the binoculars functioned perfectly.
Leica Geovid Pro 32 and Sig 10k G2
Both of these binoculars worked perfectly with both of the test batteries. The test batteries voltages were:
-Panasonic CR2 cold voltage 3.122v, warm voltage 3.047V
-Varta CR2 cold voltage 3.041, warm voltage 3.000V
So, obviously we all know that batteries don’t like the cold and there is some temperate where each one is going to fail you. I can second the report that this temperature is not as low for conventional cr123a’s in the Vector X binos as for CR2 batteries in other laser rangefinders. I am not sure why this is as these batteries typically share the same LiMnO2 chemistry but there seems to be a consensus this is the case. The rechargeable 18650 battery has both a higher voltage and a different chemistry (LiCoO2) so it is not surprising it behaves differently. It might be academically interesting to know at exactly what point each rangefinder quits with each battery but from a pragmatic standpoint it looks like you should just go with a rechargeable 18650 in the Vector X binos if you want it to work in the cold and perhaps the special cold weather Nightcore model if you want it to work in Kamchatka or North Dakota.
On another note, I do have some questions in to the AB folks about rechargeable cr2 and cr123a batteries. This is of interest to me partially in an academic sense and partially because the Leica has eaten a couple of them on me. It’s segmented LED is a bit hungry. For those who are not aware, the chemistry of rechargeable batteries is not the same as non-rechargeable ones. For this reason, they are not actually the same voltage and different types of rechargeables have different chemistries as well. This also results in different voltages. For instance, rechargeable CR2 batteries might be 3.6V like an 18650 with whom they might share chemistry and not 3.0V as non rechargeable versions are. Of course, your Amazon no-names will also often miss-label both the voltage and chemistry of a battery.
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