Your described problem, I am very familiar with, of brief access to mains power and wanting to ingest at maximum possible speed.
Buy one of these kits, based on your needs.
Tiny version: Good for low power needs, like ad-hoc phone.
- Powercore Fusion 5000. One single product recharges your phone and itself. Limitation is its not high wattage, but it is compact.
Small version: Good for a few days between having an overnight recharge option.
- Powerport2. Recharge the Powercore 1000 below and something else at the same time.
- Powercore 10000. Advantage is dense energy for small to carry, but it only 2A input so ingests at half the speed of the Medium and Large below.
Medium version: Good for a few days where you need to make best use of a few hours, or where you need to go many days and then an overnight recharge.
- Powerport 2. Outputs two 2.4A.
- Powercore II 20000. Input two 2A. So this takes 4A input from the above.
- Two Powercore 10000, combined is two 2A input, advantage is its two separate Powercore to allow for Powercore failure.
Large version: Good for even longer off-grid or where you need maximum ingest in a few hours.
- Powerport 4. Outputs 8A across 4 ports, a max per port of 2.4A
Powercore 26800. Input two 2A. So this takes 4A of the above 8A with two ports left over to also recharge your other devices at the same time.
Three Powercore 10000, taking 6A total from the 8A available, one port left over.