31 January 2010

Another PEU bites the dust

I was getting close to 18,000 miles. My third Power Electronics Unit has hummed while charging since they installed it. At my last regular service I mentioned the humming but they did not change the PEU.

When Mini engineering visited my home to diagnose the cold weather problem with fast charging, they agreed the humming was not good and directed the dealer to replace my PEU as soon as I could bring it in.

Well, a busy month at work meant I put off going in for service until the regular interval. Friday night when I got home with an ambient temperature of 18 degrees F, I had more than the usual trouble getting the car to start charging at 50 amps because of the cold. After about a dozen attempts to get it to start charging, the humming got extremely loud, the lights in the house dimmed (my wife noticed that upstairs) and the car cut off charging after 5 seconds as usual. I stopped trying to get the car to charge.

I dropped it off at the dealer on the weekend with red tape over the charging port and warned them not to try to charge it until the PEU is repaired. The contacts on the plug and the charging port are dark now, as if it got hot.

Maybe too much attention was paid to over voltage cutoff for safety, since an overly aggressive threshold is what has caused a cold weather problem with the fast charger for a few of us. And the AC Propulsion box has its own over voltage safety cutoff also. Maybe a fast electronic cutoff for over current conditions would be in order. The circuit breaker in the electric panel is enough for human safety but may be too slow to protect the connectors on the car. Over current cutoff might be a good feature for Clipper Creek to add to the wall box.

Hey, I'm glad it happened to me. A civilian might have been upset. I do similar stuff at my job so this does not bother me at all. I actually find it to be gratifying when I find a new problem of this magnitude. I bet Mini and AC Propulsion both learn a lot from this. And I bet nobody else ever has this happen to them. Seems like a one in a million failure mode. Good thing to find and fix before they make a million electric cars.

18 January 2010

Some car heaters are dangerous, but this one looks safe

I bought a space heater for the car and posted a link awhile back. The thing was made in China and it is dangerous. The fan stopped, the coils started glowing red and smoke came from the plastic cover. It does not appear to have an overheat shutoff like every hair dryer.

The older heater I got from Napa years ago seems very safe but appears to be discontinued. I hear it cycling off and on as the car gets very warm, so I know the safety sensor is working.  I suspect it was from ZeroStart, which is a Canadian arm of Phillips Tempro.  They still offer a better model with a metal case:

900 watt 120 volt car heater from JC Whitney 

Looks to be around $110 but if it does not set my car on fire, it might be worth it since keeping the batteries warm is giving me Great Range!  Every one else is complaining but I am getting the best range I ever have even in this cold.

The northern Europeans seem to have more choices for car interior preheaters.  They cannot afford to warm their cars up by idling since the fuel prices are higher there.  But the DEFA brand of heaters does not seem to be available in the US.

16 January 2010

Let me count the ways...

In our neighborhood in the winter, many people idle their cars in the morning to warm them up before leaving.  And since most cars run a rich fuel mixture when cold, the neighborhood smells like an oil refinery in Louisiana in the summer.  It Stinks.

This is not the only reason I love the Mini E, which does not contribute to this problem.

We heard today from someone who has an autistic child in the family that living within 3 miles of a major highway is a significant risk factor for having an autistic child.

This is not the only reason I love the Mini E, which does not contribute to this problem.

There was a report recently about the health problems caused by dust from automobile brake linings, which are still severe even though asbestos is no longer used.  I for one usually walk 3 miles a day but I cannot walk near busy roads or my eyes get irritated.

This is not the only reason I love the Mini E, which hardly contributes to this problem because of regenerative brakes which create no dust.

And don't even get me started about OPEC, geopolitical stability, global warming, and on and on and on.

These are not the only reasons I love the Mini E, which does not contribute to these problems.

Back when I did my long commute to work in a gasoline car, I was often exhausted by it.  Now with the vibration free and noise free and fume free Mini E, I am rarely fatigued by the drive.

Should I go on?  I think the point is clear.

There has been a lot of discussion on this blog about the issues with the Mini E.  They are minor minor minor compared to the advantages.

What really bugs the Boss

Now that the charging problem is (soon to be) behind us, I got my wife to drive the Mini E again.  She had been a big fan and always wanted to drive it.  If it is the gas car, she never wants to drive.  But awhile ago she soured on the Mini E and I assumed it was the charging problem, which is now over.

But that was only a small part of it.

So she drove the the store the other evening while I was the passenger.  Short trip, lots of charge, cold night, so what do I do that I never do on my long commute to work?

Turn on the heater!

And what does the heater do that is very reminiscent of a Microsoft product or device?

It crashes!  It was very warm for several minutes and then ice cold.  And nothing I did with the knobs made any difference once it went cold.

And my wife's tone made it very clear that this is why she has soured on the car.  I recall once several weeks ago she eagerly took the Mini E to choir practice, about 25 miles away.  The heater crashed on her, and she froze.  Never since has she wanted to take the Mini E.

I suspect the PTC design (positive temperature coefficient) is simply unstable and if the fan is too low for the heat setting, it cuts off.  But I will have to take some data.  I think Robert pointed this out first, and I recall Tom agreeing the heater was not dependable.

I don't know if this problem is in just a few cars or all of them.  Or something wacky like the charging problem that arguably had to do with outside variables.  (Any Mini E would have had that charging problem at my house probably.)  I suppose I have to head over to the Facebook discussion group and see who else has observed this issue.

I do know that if there is any hope of extending the lease on my Mini E, it will only be possible if Mini can make that heater dependable.  Because my boss likes to be toasty warm and does not like to have to think about a fussy heater when she is driving.  And that is the way it should be.

Diagnosis - high voltage

So the team from BMW came by last week to verify their plan of adding a buck transformer to lower my line voltage.  Yes, of course it worked to fix the problem with the fast charger not starting.  The electrician will be coming back in a week or so to install the smallish transformer permanently.

I assume the six of us with this problem all had positive results from this test.  This is really a work-around and not a root cause solution, but it is good enough for a prototype program.  The bigger question in my mind is whether the analysis they have done explains what Mike and myself and others have observed:

1) Waiting will allow the car to start charging even if the line voltage is still higher than nominal.

2) The problem is worse in the cold regardless of line voltage.

3) When the voltage is really high and the temperature really low, there are three stages of symptoms:  No response at all, then after waiting awhile the car will blink once and wall box will shut off with the red light, then wait longer and the car will blink several times before stopping while the wall box stays on.  Eventually if you wait long enough the car will charge normally.

Of course this might only be if the garage is warm enough and the only real variables are voltage and temperature.

But hey, the problem solution is complete.  All I care about is soon I won't have to turn on the 8000 watt sauna heater in the basement to pull down the line voltage far enough to get my car to start charging.

But the good folks at BMW might want to dig a little deeper.  Cold weather performance is what separates the Men from the Boys, as they say.

11 January 2010

Happiness is a warm battery

Everything is fine now, the batteries thawed out nicely and stayed warm enough with the portable heater on the floor to charge all night.  I left for home with 85% charge today.

And now I have an analysis target for that annoying monster of data that I have in my trip logs.

I am going to troll through that data and see if the temperature of the batteries on departure is related to the range.  Most people are complaining about a big drop in range in the cold, but not me.  And as far as I can tell no one but me is preheating the car from shore power and thereby keeping the batteries really warm.

Of course, I just had the one glaring exception of last Saturday when the batteries got so cold that they stopped charging from the slow charger.  (I suspect the fast charger would cause enough self heating of the batteries that they would not have stopped charging at 10 degrees F ambient temperature.)

I expect that the data will show the range hardly affected by the cold weather as long as the batteries are warm.

10 January 2010

Dogged the cold "bullet"

Drove to work last Saturday, the first time I have driven very aggressively in the Mini E. On arrival I had 15% charge left, batteries up at 90 degrees F, and the forecast saying ten degrees expected that night.

Plugged in the car on the slow charger, but with only a few hours at work and much lower charge than usual, it was clear I was leaving the Mini E over night and driving my gas car home for the 65+ mile drive.

I left my 900 watt 120 volt accessory cabin heater on the timer to run 30 minutes on and 30 minutes off all night. But I did not have a good feeling with the low temperature forecast. So I went back on Sunday and sure enough, it had stopped charging at 40% and did not want to start charging again.

Driving around the parking lot, I had the symbol with the thermometer in a gear on the dash. The book says that means the battery is too hot (there was no regenerative braking) but I think it also comes on when the battery is too cold. The dash display said 56 degrees F but someone says that is the warmest battery pack, I suspect some packs were too cold to charge.

When trying to restart the charging, the car would blink several times and then the safety box would cut off with a slow blinking red light. I think it was labeled "charging fault" but I did not pay much attention.

I turned on the built in heater AND plugged in the 120 volt accessory heater full time, and for a while I aimed the accessory heater straight down the vents to the battery packs, switching back and forth between the two vents.

After this heating, the charging would start and kept going for over an hour. The battery temperature on the dash display came up to 59 degrees. So I went home, leaving the accessory heater running full time all night in the Mini E. I'll see if the car is still charging in the morning.

I knew when Mini said you have to have a garage for this car, they meant it. A prototype with an air cooled battery is not up for New York Metro area winters outside. I was afraid I was headed down the path that some others have reported with a hard failure and weeks with no word from service. Maybe I still am, tomorrow will tell. But next time I leave it outside on a cold winter night, the accessory heater is staying on full time. Part time is good enough for in the garage only.

But I am completely confident that the production electric cars with liquid based temperature regulation for the battery will not have this problem even parked outside.

05 January 2010

Heated seats and blankets

When we visited Ken last week to charge at his place on our trip, he mentioned that a heated seat would be nice in the Mini E and probably use less power, thereby not reducing the driving range as much as the cabin heater.

Now, I like to brag that I don't use the heat on my 120 mile commute but I admit it is getting a little old.  And it turns out there are many 12 volt electric blankets and heated seat cushions on the Internet for sale.  The hard part is finding one that specifies the amount of power it draws.  The Mini E has only one 12 volt outlet that I can find, which is limited to 200 watts.

Here are some that do specify power drain:

60 watt heated blanket

45 watt heated seat cushion

80 watt 12 volt blanket

I think I am going shopping.  I might have to retire my hot water bottle if one of these work.  But then I won't be able to call myself a Manly Man anymore, using a sissy heater...

Does wearing wool underwear qualify one as a Manly Man?

Buck Boost transformers

A few posts ago, I speculated about a way to lower the AC power line voltage for those half dozen of us that are having trouble with the fast charging in cold weather. It is clear that the problem is related to a supply voltage that is slightly above nominal. The car should accept this voltage and indeed it does but only in warm weather. So OK, great, we found a small problem that AC Propulsion and Mini can fix before the production car comes out. But the problem remains for six of us in the frozen north.

The cost of a transformer that can sustain 12,000 watts for my 50 amp charger is prohibitive, as is the size. It occurred to me that all that is needed is a small transformer with a 12 volt 60 amp output, wired to oppose the 240 volts from the power company feed. This is only a 720 watt transformer, much cheaper and smaller than 12,000 watts.

Well, none of my engineering colleagues had heard of this but everyone thought it should work, at least theoretically. (None of us specialize in power transmission, so what do we know? Nada.) When drawing up my idea shown above, I looked around the net and behold, there is an entire class of such devices called Buck Boost transformers. Technically they should be called "autoformers" since the primary and secondary windings are connected.


I got the call today, Mini is coming by next week to either fix my charging problem or at least test a fix. I suspect they already figured out the Buck Boost Autoformer option. We'll see.

And yes, the National Electrical Code has a whole section on how to wire the things. So it is all kosher. Well, maybe not the switch I show in my fantasy schematic. That would let you easily go back to the higher voltage in summer and charge a few minutes faster. But I have not read the code in detail to see if it is allowed. I bet not. But theoretically it should work without burning down the house.

Public power for electric car charging

I have heard there is public access to power for slow chargers (so called "level one" charging) in Washington DC but we did not look them up on our trip. However I have seen them at the Lehigh Valley mall in Allentown PA and I hear the Saucon Valley mall and King of Prussia mall also has them. The security people have the electric Gem cars for patrolling, and a few spots are reserved next to their parking spots with 20 amp 120 volt GFI outlets by each one.

The photo was taken on Christmas Eve at Lehigh Valley mall, so it is not too surprising that someone parked in the spots reserved for charging electric cars. I will contact security at the mall to make sure a charging spot is available before driving the Mini E there and charging. These spots are just to the left of the Apple computer store, which is to the right of the photo frame.

It would be fun to get two or three Mini Es to go together and all charge at once.

04 January 2010

The first LONG trip

We got the roof rack and cargo carrier on Mini E #458 and headed off for the New Year's holiday. We stopped and used other fast charger's along the way and then the slow charger when we were far from New Jersey. Thanks to Ken and Amy, Joyce and Tom, Stephen and Phyllis and others for letting us charge on the way. I guess 200 miles in one day is not that much but without public infrastructure for fast charging, it was an adventure.

Not much impact on range from the roof top cargo carrier when driving reasonably slowly. Still getting 100+ plus mile range by also taking it easy on the heater. A lap blanket does wonders in addition to tricks mentioned in earlier posts.