powerbank recommendations

GT60

Another vote for Anker products.
They have a two year warranty
I had the 20100 powerbank but found it to heavy for me
So now have the Anker PowerCore Slim 10000, Ultra Slim Portable Charger, Ultra-Compact 10000mAh
It's only a 100 grams lighter but I can feel the difference due to a spinal cord injuryand it is the same size as a Samsung S7 phone so both my powerbank and OnePlus 7 phone now fit in my coat pocket.

If your phone battery is say 4000mah you need a power bank that's at least 10000mah so is can charge the phone 2.5 times.
Check out Anker.com
Hope this helps

almillar

They're all lithium Ion pretty much, so you choose a size and capacity you're happy with. If you're going to store it for a while, leave it half charged, not empty, not full. Plenty of recommendations in the thread if you have a look through.

MothballsWallet

I got myself one of these a few years ago: I've got a Motorola Moto G 2nd Gen and a full charge of this power bank gives me 9 or 10 full charges of my phone.