Is BMW struggling to source affordable electric car batteries?

Only a few months ago BMW was waxing lyrical about a challenge to Tesla in the world of electric cars. Unfortunately over the last few weeks we have seen a significant descaling of these hopes leaving many electric car experts scratching their heads. So, why has BMW seemingly taken a step backwards when everything seemed to be in place?

There are rumours that while the BMW battery system has significant benefits over the likes of Tesla it is significantly more expensive. BMW needs to partner up with a battery specialist which will allow the technology to be rolled out across different sectors thereby reducing unit costs. Is this the next big move for BMW?

Surely BMW would not have made such a simple mistake? Announcing plans before the plans were costed and put in place seems terrible management.