09 December 2009

I get #008 as a loaner? Not #007 ? But my name IS James!

So my #458 went in for 13,000 mile routine maintenance today, and Jimmy G at Princeton Mini managed to get me another electric Mini as a loaner. Wow. Very nice. But maybe there was a practical reason in addition to Jimmy being such a great guy...

You see, I have been having charging trouble with #458 as a few others in New Jersey have. It has gotten quite consistent lately. Most days I get home and the Clipper Creek wall box trips the Ground Fault Protection when I plug in to charge, and the red indicator lights up on the wall box. At the very least, the wall box stays on but the Mini E's yellow charging light stops blinking after only 6 seconds, 8 seconds at the most.

Tonight I got home with loaner #008, pull into the garage and guess what? Six yellow blinks and the car stops charging. It did it twice. Third time and it goes on to complete charging. That is a fairly normal scenario when my #458 has trouble, unplug and try again a few times and it is OK. Sounds like the problem is in more than one car, and maybe something about my place makes it act up? But what could it be? The line voltage does not drop much when the car starts charging, I have measured it. And the 120 volt slow charger always works.

There was one funny thing today though: When I got home from work and plugged in before going to the dealer to drop off my #458, I parked OUTSIDE my garage and did NOT have trouble charging from 240 volts for the first time in WEEKS. But the loaner did have trouble when in the garage.

This is getting interesting. I rained very hard last night and today, but the sun came out on my way home. However, it usually takes days of warmer dry weather for the charging problem to go away. (My theory is moisture in the wiring or in the battery modules is causing a Ground Fault Interrupter to trip.)

So could there be a difference parking outside on the blacktop driveway that was in the sun versus inside on the damp concrete? Maybe damp concrete is a better conductor than sunny bitumen and with damp tires, any leaking electricity could get to ground and trip the safety protection and stop the charging? I don't usually get home when the sun is still up but I left early today so I could get the loaner on time.

OK, I'm not going to do anything for a couple days so I can see if things with loaner #008 are exactly the same as my #458 or not. (Hmm, maybe this is WHY they loaned me another electric Mini? To see if it has the same problem with my charging box?) Over the Christmas break I should have time to make some measurements in the Clipper Creek wall box with an oscilloscope, current probe and high voltage differential probes. But it is too busy right now, and I hear that Mini has started sending engineers to the garages of some Mini E drivers that are having charging problems. So maybe they will get to it before I do. I hope so. I am an electrical engineer, and I have a healthy fear of high voltages. I would rather they figure it out, but I am getting excited about fixing this and I might not be able to wait...

I can't stop wondering what would happen if I dry out the inside of the Clipper Creek box with a hair dryer. I had to do that months ago with the little yellow portable charging box, and it worked perfectly. (For the post about that episode click here.) But even if something like that works, it does not give specific enough information on the root cause of the problem.

Or maybe I will park on pieces of wood to see if that insulates the car and stops the Ground Fault trip. At least that would not destroy evidence like the dryer might.

Ah, I know! Next time it trips and the red indicator lights up on the Clipper Creek wall box, I will measure from a metal tire rim of the Mini to ground and see if there is any voltage that could trip the GFI. Charging always works after letting it sit for ten or twenty minutes, maybe that is long enough for the tires to dry off? If this finds leakage, I bet the leakage it is out of phase with the hot line from the 120 volt charging cord. That would explain why it only has trouble with 240 volt charging, the only wire that is leaking is the one that is grounded on the 120 volt box.

This sure is getting interesting. The solution is so close I can almost smell it. Being an engineer is fun. The future is almost here!

Anyway, they probably didn't make a # 007 Mini E... Or a # 013...


  1. What a fascinating problem you have there! But it sounds like your thinking could be close to the truth :)

  2. Let me tell you my trick for getting it to charge. STOP. I have had insconsistent success. But if I wait for the car to "cool down" (ie sit in the off position) for anwhere from 10 min to 60 minutes the car ALWAYS charges after that. And NEVER if I dont.

    My new routine is to do any chores involving the garage (garbage, etc) and las thing I do is to plug in the car. If I get distracted along the way, taking more time, even better.

    Try this. Rather than plug in immediately. Go inside for 30 minutes and tell someone to remind you to go back out. My trick is to leave the garage door open so I know I will ned to go close it. Forgetting to go down and plug in is the worst part about this approach.

    But your second car failure is fascinating.

  3. Maybe MINI should offer a timer, that starts charging half an hour after you connect it!

  4. Mike

    Yes waiting works. My theory is that it drys while waiting.

    If Mini cannot reproduce the problem, I think grounding a wheel rim should cause the problem. Then they can find the root and fix it right.

    Sometimes I cannot wait.

    Do you park inside?

    Jim McL

  5. it is always inside other than A-B driving. It parks overnight and charges in my garage at home and is parked in a heated garage all day.