Originally Posted by
Leo L.
Obviously you got a "Nokia 2620 Flip".
Simply using Google, I could not find a replacement battery for exactly this model.
According to the Nokia website, this specific model should be good for "up to 28 days of standby", so if you are using your phone for your pickup contact on the end of your trip, or emergency calls only, you should be fine with just the original battery.
Normally, it is safe to remove the battery and store it separately, and just insert it into the phone in case you need it.
But then, batteries tend to leak a tiny bit and lose some charge even if stored outside the phone, especially if stored in "outdoor conditions" (like, variying temperatures, dust/dirt and damp conditions).
Another bad effect is, that modern phones (running on Android) need a serious amount of battery to just boot.
So usually its more safe to keep the battery inside the phone, and just put the device in flightmode.
Given you are carrying a good quality solar charger, it should work to charge the phone via USB plug.
Again, this provides some issues: Charging the device while hiking (which you're doing normally during the day) would need you to connect the phone and the solar device the whole time, and this may set the fragile devices, cables and plugs at risk of damage. Charging the phone while resting only might not give you enough charging time to keep the device in a good state of charge.
You may get a solar charger that includes a (if small) powerbank, which would save you the hassle of taking care of this fragile stuff while hiking.
My advice is to carry a powerbank of a decent size and charge the phone overnight, if need arises. No solar charger. Powerbanks are designed to keep the charge and work under outdoor conditions.
My Anker 20.000 never failed me so far. You may get about 6-8 charges of you phone out of a 20.000 powerbank.
This works just fine, only drawback is, charging might not work in really severe cold. During winter trips, you might need to put powerbank+phone inside your sleepingbag to get it working.
Have fun with your new phone!