From June 2009 to June 2010 I had the privilege of Driving an All Electric MIMI E for a year, it was a great experience, and got me hooked on electric cars. I've since moved on to other electric cars which I will blog about.

Monday, February 9, 2009


The Lithium Ion Batteries used by the MINI E work best if used at a temperature around 74F. It is very important that they not get too hot because high temperatures can permanently reduce their performance, and there is the risk of them catching fire (mostly if it was damaged or there was a defect in manufacturing them). Batteries at low temperatures can have their performance and ability to hold a charge severely reduced, but this is temporary and has no long term effect on the batteries.

BMW is aware of this and they have mentioned that the housing the batteries are in is designed to keep them cool. I dont know the details of the system but I can make some speculations and what I'd like to see.

The Tesla Roadster goes to great lengths to keep the batteries at an optimal temperature, it has a liquid cooling system that runs all the time, and I've read numerous criticisms of it as being a big energy waster, the MINI E uses air cooling with temperature load and speed sensitive fans also it is mounted inside the cabin so it must take advantage of the heating/cooling used for the driver. I have wondered if this is a passive or active system, if the batteries start to get too hot will the car automatically turn on the AC? When the car is left out in a parking lot on a hot day this could end up using a lot of power, but would also mean you'd have a comfortable cabin when you got inside. The EV-1 had a feature where you could tell it to pre cool the cabin but only while it was plugged in.

Being in New Jersey I dont expect problems with over heating to be that much of an issue, but I do worry about poor performance in low temperatures. I'm hopeful there will be someway I could tell the car to warm up the cabin on a cold day maybe an hour before I plan to leave, so the batteries will be able to hold a full charge, and I wont have to blast the heat as soon as I get going. Also I wonder how much of a range hit I'll get on those days when I need to use the heater or AC all during my driving.

Its all just speculation at this point but this will be something Ill talk about in more detail once I have some real experiences to back things up.


  1. Robert, I live in the Mojave Desert where summer temps over 110 degrees are common, and of course much higher inside a parked closed car out in the sun. As you said, it will be interesting to see how the Mini E handles this, and I suppose this is what the field trial is all about. I don't have to worry about winter cold as it rarely gets much below freezing here and then only at night when the car will stay warm in the garage.
    I noticed the next generation Prius will have an option solar panel roof to power interior fans that keep the car cooler when parked. I may just have to keep the windows cracked a bit.

  2. I read that future cars will have more insulation so less energy has to be spent adjusting the temperature. I assume you'll be using the AC a lot, I'd be interested in your observations in how that effects your range.

    I think cold will have a bigger effect on range then anything else, luckly I'll have at least 6 months to get use to driving the MINI E before I'll have to worry about the cold.

  3. "Being in New Jersey..."

    You're the first local MINI-E I've found - please join us at NEMINI.ORG - we've got lots of local MINI events in NJ...

  4. Thanks Paul I'll stop by.
    BTW can you tell me how you found my site? I've been trying to get my site listed on search engines but haven't seen it with my search unless I use the full site address.

  5. Robert - I saw the link while reading the MINI-E thread on NAM. Thanks for signing in at NEMINI - there's alot of interested MINI owners there!