The next item to consider is a portable USB battery, frequently referred to as a USB power bank. These range in size from a little credit card-sized 2500mAh up to massive power bricks with over 60,000mAh. Note that USB power banks that provide QC or PD charging levels have recently started hitting the market, and they tend to be somewhat more expensive than the older ones that only provide 5V/2A outputs.
I ended up using one that I picked up a while back, which is the Miisso 5000mAh model. It provides two USB A output ports, is capable of providing up to 2A per port and weighs 3.5oz. It can provide a little over one full charge for my phone, or multiple smaller charges across different devices. I’ve found that it’s more than enough for a 3-4 day backpacking trip when I start off with all of my devices fully charged (I keep my all of phone’s wireless communications turned off when I’m backpacking and only use it for navigation).
If you want a battery that can provide a lot more power and supports faster charging, I recommend the Nitecore NB10000 Gen 2, which has 2 QC charging ports and provides 10,000mAh of power storage. It weighs 5.3oz, so for 50% more weight/size you get twice the rated power. It also supports QC for charging input, so you can recharge the battery a lot faster if you have access to a QC power source.
