I didn't see anything forbidding DRM. Even if DRM itself wasn't permitted, there's nothing stopping the manufacturers patenting some aspect of the battery syst

I didn't see anything forbidding DRM. Even if DRM itself wasn't permitted, there's nothing stopping the manufacturers patenting some aspect of the battery system. At a guess, the connector would be the cheapest and easiest place to come up with some patentable novelty that doesn't actually matter. It could be physical OR an electronic interface of some kind. Then it's a case of "Well, yes, you can license the connector design... for $xxx per unit"