ReVolt Technology, a Germany-based developer of rechargeable batteries backed by German energy company RWE’s corporate venturing unit, has extended its series B round by €2m ($2.9m) from undisclosed investors.

The company, which in October moved its headquarters from Switzerland, has also gained €21m in grants, loans, tax credits, subsidized loans and other financing incentives to take its total raised since launch to €26m.

In May last year, ReVolt hired Wade Guindy as chief operating officer and executive vice president of…