Accessories and Power Use

I grew up in a town where the average temperature in the summer was at least 100 F (38 C).  It was a town where it was assumed that you had an air conditioner or if not at least a swimming pool.  And not having either was cause for living uncomfortably.  I also took a strong interest in car audio in middle and upper school.

The use of air conditioning and audio in automobiles definitely puts a drain on fuel consumption, but it is not as noticeable because the energy density of petroleum is so high.  But how does it affect the driver of an electric vehicle?

Air Conditioning

I was at first wary of using the air conditioner on the Smart ED.  I thought that it, like the heater would cut my range drastically.  It turns out, that in certain driving conditions, my efficiency improves.  Obviously I do not own a perpetual motion machine, but I've noticed that I tend to drive more smoothly with using the A/C.  For whatever reason, my driving manner is different when the A/C is on, than when it is off, regardless of the outside temperature.

The A/C will draw extra power from the pack, but unlike the heater the vehicle does not automatically take a reserve to cover for the cooler.  However, you will notice when you come to a stoplight that an exhaust fan will start up.  This fan is very loud and will make your car sound like an A/C unit on wheels.  This same event occurs on ICE vehicles, but the engine noise usually overpowers it.

Car Audio

Car Audio on the other hand, at least the stock head-unit, is powered by the 12V auxiliary battery.  And in turn the main pack recharges the 12V, just like the alternator in an ICE vehicle.  The stock speakers and stereo are not very good in the Smart ED, but they are better than not having a system.

I tested the audio in the vehicle when I bought it, but I didn't use it for a while either because I was thinking that it would drain the main pack.   In reality, after having used the radio, even at high volume, I have yet to experience a significant difference in the main pack range.

Conclusion

I have no cross-referenced trials to present, but I do have my own experience.  I've driven many times with the A/C on and the radio blasting, and have not noticed a gross difference in the main pack battery.  More often than not it is how I drive that determines the battery performance and longevity.

A serious hypermiler might consider the use of these accessories as detrimental to the extreme mileage possible, but I am no such person.  I already know that by driving electric, I am being much more efficient than any ICE vehicle, but a factor of at worst 2 and at best 20.

I am sure that there are some people who believe that by using the A/C or radio that they are giving up some range.  But if that range is 1 mile, I think I am willing to sacrifice it for the same of comfort and entertainment.