Can a B80 expansion battery be used to charge the new AC70 in power bank mode?
Yes, but you’ll need this:
How about the B230 expansion battery? A p090-d to XT90 and then a XT90 - XT60 adapter?
I only have the B80 so I cannot answer your question regarding adapter compatibility. It’s best to email support, service@bluettipower.com, for the official answer (24 hr. reply) but others here might know. Also, I was unable to find the cable I needed above through a normal search until Bluetti provided a direct link. Their accessories website lags behind new product releases.