Can I use a longer cable to power the Joolca Pump? Updated October 11, 2022 01:31 Yes. Get a 5.5*2.1mm DC to 5.5*2.1mm DC cable. Where 5.5mm is the outer diameter, and 2.1mm is the inner diameter. Was this article helpful? 1 out of 3 found this helpful Yes No Still need help? Contact Us