Help with USB issues
 

Ok here goes. I am alright with tech unless the information is in Spanish, which it is here in Spain. Oh yeah first adventure!
So in preparation I purchased a USB that I wired to the rear of the bike to charge my tablet as I rode along, however this proved to be defective and left me carrying the tablet in my jacket with a wire leading to my handlebar phone charger. Anyway that's not the best solution so I wondered if one of those battery power packs would do the job. However they come in a sealed box and I can't see if they will charge from a USB. Does anyone know?
Also what size will I need to run my Samsung tab for an hour or so a day?
Luckily I packed the OTG cable so I can use a power pack if it will charge from the bike USB.
All as clear as mud I am sure but any help would be gratefully received.
Thanks. Ben (in Spain, did I mention that :D)

Check your wall charger for the charging (output on the charger) requirements. Tabs require large amperage (or at least last time I checked). Your USB output on your bike may not be sufficient. Test the same on the battery block that you're looking at. So long as the picture shows that is has a USB out you're ok. If it doesn't show that you'll need to either ask if you can open it up or use Google Translate.