What power banks are compatible with Precision 7530?

I'm having a hard time finding out what portable power banks are compatible with the Precision 7530.  Supposedly it supports PD charging via the Thunderbolt connections but the Anker PowerCore I purchased (also supposedly PD compatible) will not charge the laptop.  Dell sells a couple PD power banks but the specs are confusing and it's not clear which laptops are supported.

Has anyone successfully charged the 7530 with a portable power bank?  If so, what power bank did you use?

Thanks,

rgames