Musk said the announcement would be pushed back to make room for news that Tesla may repay its loan from the Department of Energy (DOE) Wednesday.

The early repayment would be a big deal for Tesla and the Department of Energy, but the Supercharger announcement could be more important to the electric car maker's long-term health.

The biggest problem for electric vehicles is the lack of cheap, powerful battery technology, keeping ranges limited, charge times long, and prices high.