Little changes make a big difference in range. A few weeks ago I posted a blog entry about my range anxiety over a recent trip back from my fiancee's house, during which my charge droped down to 3% and I froze myself the most of the way, afraid to use the heater. After last week's MINI E meet up I had a chance to talk to other MINI E drivers about their range extending strategies and overcoming the MINI E's poor range in the cold. Well this weekend I put what I'd learned to the test.
When I first got the MINI E, I took a tip from HyperMilers and filled the tires to pressure well above the recommended amount. Over the last five months I'd forgotten to keep this up and when I tested my tires they were down to 30 psi, so I brought them all up to 46.5 psi. We've known for some time that driving fast kills your range, so I looked at google maps, and found they have an option to avoid highways while planning a route. I used this to plan a new route to my fiancee's house, and came up with one that uses 30miles less highway driving and is 5 miles shorter.
On my trip there I started off with a full battery, and a warm one too at 70 degrees as I'd been using it all day. The weather was a little cold 55 degrees but I was able to make the trip without using the heater, I was very tempted too though and wouldnt want to do this on a ragular basis. The MINI E is always trying to bring fresh air in to cool the batteries, unfortunately no matter where I set the air select switch it always seems to be coming in on my legs, and the recirculate button will automatically deactivate after 5 minutes, I spent most of the trip hitting the recirculate button every 5 minutes and rubbing my legs to keep them warm.
I was very careful to keep my speed down rarely going above 55, my new route had a large section of 25mph roads and stop lights at which my batteries could rest and the range increase. I completed the trip driving 71.4 miles with 41% left on the battery.
Over the weekend I let the car charge on the 110v charger, I'd planned to run the heater on Sunday to increase the battery temperature and drain the batteries a little so it would be charging overnight (while charging, the batteries generate heat) but it was fairly warm an I didnt feel like going out after dinner so I'll save that test for anouther day. I hope BMW's next electric car has a way of pre-heating the car and the battery either from a remote or on a timer.
On Monday morning the batteries were at 61 degrees, which is a little low but not bad. I drove my new route home, again trying to keep my speed under 55mph, the outside temperature was 49 degrees so I turned the heater up to full from the start, After the cabin warmed up I backed the heater off slowly to about half way, I the ride was comfurtable and I found keeping the heat blowing on my legs seemed to work best anywhere else and my legs would quickly get cold. I did not use the recyrculate button at all on this trip, I know my milage would have been better if I had, but its a pain so I'll save myself the trouble until its really cold. I arrived home after 71.4 miles with 25% charge left. Not as good as without heat but still much better then I had been doing and with my room for extra heat on those really cold days just arround the corner.