When I need to completely float my Rigol DHO924S (not very often) - I use the "Essager 65W 15000mAh" power bank, bought during 11.11 sale on AliEx. I did not use it for long sessions, so cannot speak to how long it will run DHO924S on full charge, but as it powers DHO924S (the most hungry model in the series) without issues, it will likely power DHO802 as well. I suspect any 65W USB-C PD power bank will do fine.