Saturday, July 25, 2009

ODU's connector for MINI E - is this a robust design?

Boring, technical connector discussion below...

Yes, I worked for 7 years at a connector manufacturer ITT Cannon. I'm dangerous enough to know key details about connector designs...

Take a look at the ODU connector photos below (click on them for larger image).

ODU touts its proprietary hyperbolic contact design to increase the mating cycles of connectors. What they are NOT designed for is "hot-plugging" or mating/unmating the connector under load. These pictures are from connector I had at home, attached to the Clipper Creek's 240V, 32 AMP wall box charger. Here's a direct quote (via email) from ODU:
...Regarding the damaged Springwires inside the contact: The connector was not designed to be hot plugged…we see similar damage on test sets that have been disconnected under load. BMW is aware of this and has indicated this in their manual. This issue will be resolved in the 2nd generation of connectors for EVs...

Fair enough - and it goes to prove the design weakness of the connector. While BMW/MINI was toiling away with ODU for the MINI E connector, SAE has been working on connector standards (J1772) for future EVs or Plug-in Hybrids (e.g. Chevy Volt). So what does that say about BMW/MINI? We know June 30th 2009 was a hard target date mandated by CARB if BMW wanted to maximize its ZEV credit. It appears that SAE's J1772 timeline didn't allow BMW to participate and meet the 30 June 2009 deadline - and who really cares if the MINI E program is strictly a one year "Field Trial Program" and all the cars are going back to the mother ship in 2010, right?

Customers? Day-to-day workability of the connectors? UL Listing BEFORE the charge box/cable/connector is rolled out to hundreds of homes? Details, schemetails - cars will be gone before anyone notices something is amiss. Who cares indeed...

Other connector companies (mainly Amphenol) design multiple safety features where load is interrupted before customer can unplug the connector. They also incorporate a bayonet style feature on connector engagement where you have to rotate the connector clockwise or counter clockwise. This serves several functions, mainly positive feedback to the user that the connector is fully mated. Here is the picture of the Amphenol connector in Tesla Roadster's application (notice also the hefty backshell that protects the connector shell from abuse).

ODU told me that they went ahead with straight plug method to prevent connector or charger damage in case someone drove off with the vehicle while the connector was plugged in. However, MINI E cannot start while the connector is mated - which supports my assertion that there's been poor communication throughout this program and parties which results in poor planning and execution across the board.

Who's running this program again? No, I'm not bitter - just returning the arrows that are stuck on my back :)


  1. This is great, I was wondering what connector the Mini E used. I added the info to Wikipedia's Mini E article under 'Charging' , we'll see if Wikipedians consider your blog an "authoritative source" :-)

    If you want to benefit humanity, you could upload a picture of the Mini E plug and receptacle to Wikipedia. Just visit and follow the instructions. Same idea for a picture of the home charging station, if you've got one. I (spage) can help ( Cheers!

  2. The mini cars are very comfortable for me specially when i need to park in a small place, they can go fast when there are traffic jump that is why I love the mini cars, they are really beautiful Actually i think to approach costa rica investment opportunities and a mini car there would help me a lot.