Going on a cross country trip solo to several NP's & NM's want something for safety on the trails. Would like the best bang for the buck. Thanks
@GramaNana I would definitely test it before taking it into the backcountry but mine has always had a charge left on it when I get home and doesn't seem to deplete at all while it's being stored for the next trip. The one downside to the Nitecore batteries is that they only have a 3 light "battery meter" so it's hard to get a good read on how much is left when I get home. Just looking at what you're taking with you (2 phones, 2 watches, 1 to 2 PLB and possibly a GoPro), I believe that 2 of the 10,000 mAH ones should last but you check the specs on your devices to see what their draw is and compare that to the battery capacity and get a decent idea of how long they will last .
I've used a 25,000mamp battery on my last several 7-10 day hikes. Turning off the phone when not in use, imo, is best.
I need to charge (periodically) my sony batteries (for night sky shots), and the phone, it gets down to about 70% after about 3 days (iphone 7plus)
I also charge up my gopro 7black batteries.
My last trip, 8 days, with the gopro running almost all day, and the iphone in constant use for waterway navigation (in airplane mode, remembering to turn the screen off immediately when not in use) - almost, but not quite, used up the entire battery pack.
I do not directly have experience with long treks and large power banks, so I can’t offer specific advice on what you will need. But I hadn’t seen anyone mention that in cold temperatures, most batteries tend to lose their charge faster. So keeping your power banks and devices protected from the cold (in pockets near your body heat/ inside sleeping bags at night). There are a lot of factors that go into how far these batteries can take you (environment, frequency of device use, age of device batteries, battery capacity of each device, charging efficiency). I have to echo the advice the only way to “know” is to test on your own devices yourself. Try to replicate the use you will experience on your trip - carry these devices for 10 days (powered on, with intermittent use) and only charge using a power bank to see how many you need. Then be sure to give yourself a reasonable margin of error when packing for your trip.