The EN-EL15a is not new, it was released with several cameras already. It's also 'Li-ion20' in Nikon-speak, as you can see from an image on this thread. Scroll down to see it. Nikon is committed to safety and to providing to its customers only the highest quality products. We regret any inconvenience this matter may cause you and appreciate your continued support of Nikon and its products. We have received reports indicating that when a fully charged, earlier generation of the Rechargeable Li-ion Battery EN-EL15 is used with the Nikon D500 digital SLR camera, the maximum number of shots possible is low (battery life is short). It was also reported that the amount of charge remaining, displayed by the D500's Battery info option, is significantly less than that displayed by the Battery info function of other model cameras using the EN-EL15 battery. I find that the en-el15 (rev01) has a much poorer life than either the en-el15 (rev20) or en-el 15a on my D850.

The older EN-EL15, 15a, and 15b batteries can also work on the Z6ii. You can always try one of those if you cannot find any EN-EL15c, but the C variation can hold more charge and therefore can last longer. More third-party APS-C autofocus lenses for Nikon Z-mount coming soon: TTArtisan 35mm f/1.8, Meike 55mm f/1.4 and Sirui Sniper 23mm+33mm+56mm f/1.2

Nikon already offered to swap out Li-ion01 batteries for Li-ion20 batteries for D500 users (for free), this amounts to a tacit recall, I'm guessing they don't want that situation cropping up again so they probably made sure EN-EL15 batteries work just fine with the D850. The unit is also able to charge AA & AAA NiMH rechargeable batteries and USB enabled devices via the 5V 1A USB port. https://www.nikonimgsupport.com/eu/BV_article?articleNo=000038557&configured=1&lang=en_GB&setRedirect=true Used together with your Nikon D-SLR, the camera's fuel gauge accurately displays the remaining charge and number of shots since the last charging. It used Nikon MH-25 Charger The Genuine Nikon EN-EL15 Lithium-Ion Battery is a rechargeable battery for the Nikon Z6, Z7, 1 V1, D600, D610, D750, D800, D800E, D810, D810A, D850, D7000, D7100, D7200, D7500 digital SLR cameras. Lithium-ion batteries will not suffer from the adverse memory effects that are normally associated with other battery types. It providing 7.0v and 1900 mAh power.

If the 9th character of the lot number is any other letter, your battery is not affected by this recall. Nikon’s digital SLR D800, D800E, D810A , D810 , D610 , D600 , D7200, D7100, D7000, D500 cameras and the Nikon 1 V1 advanced camera with interchangeable lens as well as any other Nikon cameras are also not subject to this recall. https://www.bhphotovideo.com/c/product/1578220-REG/nikon_en_el15c_rechargeable_lithium_ion_battery.html I have had a Z6 for three years and a Z6ii for six months. My experience is that their battery consumption is not bad. Sometimes I capture 4K video continuously for an hour or two; in such case I may need to change battery after an hour. For still capture, there is typically no issue.I've been using the same batteries in my D800 with no issues, I was quite spoiled, I would charge that battery maybe once a month or so. It never died on me. With the Z6II however, even with the EN-EL15C's, it barely makes it through an afternoon, and I don't chimp much at all. You are in a much colder climate. That may affect battery life, outdoors. But after you cycle a new battery a few times, battery life should improve. Your description doesn't sound normal.