Loving my Mini-E and having loads of fun with it. However, has anyone else started experiencing Battery Temperature Anxiety with our current heat wave? Or could it be my Mini-E?

First off, to explain - the main reason for this anxiety -- when the battery temp hits 115 degrees Farenheit, the regen no longer is used which changes the driving experience (and potentially distance on remaining battery) considerably. I LIKE the regen and don't want it to go away.

I commute from Pasadena to Covina about 17 miles each way 50/50 highway/city driving. I used to top off the car with a trickle 110V charge at my work, however, since that places the car smack in the sun; I've stopped. There were times I would get in the car and find the outside temp at 102F and the battery temp at 111F already. Just a little merging onto a freeway would usually send it to 115F and that was that for the regen.

Now, when I park at work, I'm always concerned about making sure that I park the car in the shade somewhere. I've played around with keeping windows down, running the A/C, not running the A/C, etc. It seems the main factor in raising the battery temperature is how you drive the car (punching it or not) and the ambient temperature. Now, I find myself gingerly using the pedal simply so I don't suddenly take the temp up into the stratosphere. Would be nice if I could go back to using the Mini-E like before with no care of how hard I pushed it!

Brings me to my question: why is the battery temp limit set to 115F?
Why not 120F or even higher? I mean, how would you use this car in Arizona where the temps regularly get that high? Of course, I'm sure there's a very good reason (lithium battery combustibility perhaps?), but I personally find this one of the real limiting factors in using the car.

Any thoughts?

 

My experiences with battery temperatures have been similar to what you describe. I'm in Victorville (high desert area) and I have to park directly in the sun at work as there is no shade available. I've found that if I can keep one window down about an inch it helps a bit. Last Friday we had some thunderstorms so I kept the windows up, and my battery was at 113 degrees as soon as I turned on the car.

I use a sun shade in the front window and park facing west so it blocks most of the afternoon sun. I also tried a California Pop Top (www.capoptop.com) sunshade on the outside of the car to block all windows, but with our afternoon winds it wouldn't stay in position and it started to scratch the paint.

So far the battery hasn't shut down due to the heat so I've always made it home. The highest battery temp I've had is 117 degrees and even then the regen braking still worked, but my commute is shorter than yours (about 5 miles one way most days). It will be an interesting summer with the car!

 

The temp work-around, no pun intended, is to run to A/C all the time at max.
When you get in the car run the A/C till it is cool. The batts air intake comes form inside the car so the cooler the inside is the cooler the batts will get. You might be freezing but the car will work. You will loose 2 miles an hour range with the A/C on. The A/C in the MINI-E is very efficient. So wear a sweater and kept your batts cool.

 

Jeffu,
Have you actually tried this method?
Unfortunately, every time I've tried this above method, two things happen:
1) It really doesn't get that cold (no sweater required)
2) The battery temp actually goes higher --> I don't know how much the big battery is involved in providing the juice for the compressor and fan, however, it appears to increase the current thereby raising the battery temperature.

I may be incorrect about the last part there, however, I have not seen any noticeable improvement with the A/C. Instead, I find that keeping the windows down, even in high heat and on the freeway, has been an effective way of keeping the battery temp down.

 

wg2345, This was recommended to me by another Plug In America member who I trust. He's an engineer and swears by this. He says windows down uses more batt energy because of increased air drag and the outside air may be too hot and humid for the batts. Using A/C is more energy efficient and can get cooler air to the batt as their air intake comes from behind the seats.

As you may not know I was thrown out of the program for asking too many hard questions. Poor judgment on the part of MINIUSA management as I would promote the Sh#t out of this car if I had one. I have borrowed several MINI-Es from other pioneers and have a good feel for the car. It's a welcome attempt at a plugin car but a program poorly run by not the best choice of "experts".

Knowing the work-arounds will make this car work for you.
The poor battery cooling was the result of rushing this car into the hands of lessees to meet the ZEV mandate deadline. The car needed more test time.
But that design error is not a show stopper for me.

BECAUSE YOU ARE'T BUYING GAS!

 

I'll try using max ac this week and see how that works. I have been avoiding using the ac in the belief that it would raise the battery temps.

The first day I had the car, I stopped at AC Propulsion on the way home to top up the charge. One thing they told me was to try and air out the car a few seconds when it has been sitting in the sun. This will avoid an initial blast of heated interior air flowing through the battery when you first turn on the car.

 

Yes, cool down first.
If I had the car I might try to find a way to run a vent tube from the A/C ducting down the middle of the car to the battery intake vents.
Other BEVs use the A/C directly to cool their batteries.

 

My AC gets very cold in a flash! It seems way oversized for the amount of passenger space that remains in the Mini E. Not that I'm complaining- I like it. That would be an interesting idea to divert some of the AC directly to the battery compartment.

 

Yes, I too have been surprised by how well the A/C works in the Mini E. I remember reading an interview awhile ago where a Mini E exec said that the Mini E A/C wouldn't be as good as in the standard Mini since they needed to conserve battery power. But, it seems to work just fine.

 

Same here - AC works great. I rarely use it as 85 degrees seems tolerable as there is no engine heat to cook you. Though we have had a cool summer in NJ thus far...the AC is impressive.

I do wish they had not chinced on the stereo...not that it is bad but there are no rear speakers, I guess because there was no place to put them with the batt pack...I like my tunes and I like to hear them behind me too Though not a deal killer as the sound of the electric motor and nature (which I can hear clearly now) is sweet.