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Discussion in 'Model S' started by mrjohnlnguyen, Mar 20, 2014.
Dyno testing doesn't seem very good for predicting real world results. Or is it better than I give it credit for? Also, I suspect that Tesla's battery management system reduces this temperature hit markedly by getting the cells to the proper temp. You just have to make sure and preheat or precool while plugged in for best effect
At -15F, 68mph average speed, heat on at 66, occasional defrost as needed, 2 adults, headlights on, 19" snow tires... made it to our destination 160 miles away with some change left. Once all proposed superchargers are deployed, these trips will become a no-brainer.
I think this points out how useless the EPA EV range figures are. Drivers in very cold climates may find out that they cannot make their commute in the dead of winter, after purchasing their EV based on the EPA figures. And, if you are at the edge of your range, all it may take is a traffic jam in weather that requires heat and defrost while you are standing still to turn your trip into a nightmare.
These results are not good. If they really wanted, would it be possible to solve this decreasing range in cold weather issue?
The batteries generate heat when the car is driven. Assuming starting with full battery and driving at reasonable speed without stop. Wouldn't the heat generated by the battery itself raise the battery temperature enough to avoid decrease in range?
Well, obviously not for the cars tested in this article, but what if the battery pack was put in a thermos (like the sodium battery)?
There is a lot of cooling surface on the underneath of the battery. Also the worst problem occurs when it's cold out and you can't plug in at night.
They could do that, but then they would need a larger cooling system because almost every bit of battery generated heat would have to be removed by the cooling system. In other words, you'd trade cold weather problems for hot weather problems (and additional cost).
The real answer (IMHO) is a battery with more range as the energy density improves. After all, the problem isn't that range decreases in cold conditions--this happens to ICE cars as well--the problem is that you can't get to where you're going. A 400+ marketing mile battery would solve it easily with no additional cost or complexity. (Assumes that in three to five years battery density is improved enough to be a drop-in replacement.)