Staying Alive at 35...Percent SOC

It’s a comfortable feeling starting your day with a fully charged EV.  Even though every EV has its range limit, a full tank of electrons gets the day off on the right foot.  But lately, I have picked up the annoying little habit of forgetting to plug in.  So I decided to experiment yesterday when I only had 35% state of charge when I began the day—can I survive my day on 35%?

 

I had a little extra distance to travel because I had meetings in various places.  I was not going to make it without some charging along the way, and some highly efficient driving too (which is not my strong suit).

The first leg of my trip took me from Corona to Riverside, a distance of about 16 miles all on surface streets.  I usually burn up 20% to 25% of my battery making this drive when not trying to be efficient.  Instead, I hunkered down, kept the accelerations slow and steady and stopped well in advance to collect as much regeneration power as possible.  I made it using only 17% of juice—leaving me with 18% of battery in the tank.

The next leg of my trip would take me from Riverside to Ontario, a distance of about 22 miles.  18% wasn’t going to cut it, but I know all the EVSE’s in downtown Riverside so I juiced up during my meeting.  After about an hour and 20 minutes I was back up to 45% state of charge—more than I had hoped for.

I hit the road, mostly freeway travel this time, and paced a few big rigs along the way to increase efficiency—and increase the risk of a rock chip in my windshield.  Upon arrival in Ontario, I had 28% state of charge left—meaning I used 17% of my battery on this leg of the trip also.  Luckily this stretch of freeway is mostly flat and the day had warmed up.  Combined with a little drifting behind big rigs, it really boosted the efficiency.

Time for lunch and another 6% to 7% drain.  I tried charging at my usual lunch spot, but two Chevy Volts ruined that plan.  So I plugged in at Kohl’s across the street.  The problem is that I don’t really like to shop.  So what to do while the car charges?  Wait…and wait…and wait.  After what felt like an hour, but in actuality was only 15 minutes, I had to get back to the office.  My state of charge was back to 28%.

Finally, time to go home, Ontario back to Norco, about 15 miles, all freeway.  Usually I can burn up 25% making this drive when I am carefree.  But a Friday night commute in Southern California saved the day because of the excessive stop and go (charge and go) traffic.  I made it home with 16% state of charge—meaning I used 12% of the battery on the way home, a personal record.

While it’s never enjoyable to start the day with a drained battery, it is possible to survive.   If you know where EVSE’s are located, and you know how to squeeze out the efficiency when needed, you can survive at 35…percent.

The Emotional E: Fun vs. efficiency

The Active E guru (sensei, maestro, etc.) Tom M. set out a list showing how the consumption rate (which is expressed in miles per kilowatt-hour or "mls/kWh") translates into the expected range of the Active E.  The more efficiently you drive, the farther you go on a single charge.  It is based on usable battery power of 27 kWh (the E has a 32 kWh battery pack, but only 28 of those kWh's are available to use and about 1 kWh is apparently held in reserve).  The list went something like this (I say something because now I can't find the list, but this should be the same since its based on 27 kWh):

          2.2 mls/kWh = 59.4 mile range
          2.7 mls/kWh = 72.9 miles
          3.0 mls/kWh = 81 miles
          3.3 mls/kWh = 89.1 miles
          3.8 mls/kWh = 102.6 miles
          4.0 mls/kWh = 108 miles
          4.4 mls/kWh = 118 miles

Knowing your range is important, but how does the Active E make you feel?  There is an emotional connection that everyone feels almost instantly when riding in, and especially when driving, the Active E.  It's quiet, has smooth, instant acceleration, and can beat just about any car off-the-line.  It moves without a drop of gas nor a hint of exhaust.  And it handles like a BMW.

I notice myself struggling between an all out urge to hit the accelerator and have fun (efficiency be damned) or feeling the serene nirvana of achieving the best in efficiency the car has to offer.  So I thought it might be interesting to translate the mls/kWh into the emotional feeling that accompanies it:

         2.2 mls/kWh = whoo hoo, I'm having the time of my life
         2.7 mls/kWh = trying to be serious, but still having fun
         3.0 mls/kWh = moderate restraint, not happy, not sad
         3.3 mls/kWh = repeat with me "must not floor it, must not floor it, must not..."
         3.8 mls/kWh = I am turning into a robot...
         4.0 mls/kWh =  come on! You're killing me!
         4.4 mls/kWh = I am at peace with efficiency.

Choose your level of fun vs. efficiency and drive accordingly.

Eco Pro vs. Eco Amateur: Do I have what it takes to beat the ActiveE at its own game?

Driving efficiently is the name of the game in trying to squeeze every last mile of range out of an EV like the Active E.  On most days, I don't need that much range, so no need to be efficient.  Besides the E has a nice feature called "Eco Pro" where it manages the amount of electricity being used by the electric motor and all the other electric components of the car (including things like the air-conditioning, heater, and heated seats).  Eco Pro helps boost the efficiency of the E without you having to worry your pretty little head over it.

And yet, I wonder...can I be as efficient without the help of a professional?  I had to find out.  Eco Pro (the car) vs. Eco Amateur (me) in a head-to-head competition to see if I had what it takes to beat the E Professional.

First, for some factual assumptions.

In order to make this contest a little more even, I chose to measure the E's driving efficiency (which is measured in miles per Kilowatt Hour (or mls/kWh)) over the course of two days.  On day one, I drove without the Eco Pro engaged from home to work, a trip of 16 miles.  I used only side-streets--no freeway driving--because the flow of the freeway is unpredictable over the course of two days (especially here in Southern California).  More stop-and-go traffic means more efficiency for the E, and I wanted the amount of stop and go to be about the same both days.  By taking city-streets to work I had a more consistent trip between the two days.

I also did NOT use the air-conditioning.  Since the Eco Pro setting manages the amount of power being used by the air conditioner, something I cannot do myself, I choose to measure the efficiency without using air at all.  On both mornings the outside temperature was about the same (64 degrees on day one and 60 degrees on day two).  Finally, I took the exact same route and stopped measuring in the exact same location both days.

The Results.

Eco Amateur: Here are my results on day one, where I (the Eco Amateur) tried to manage efficiency all by myself:

I averaged a respectable 3.7 mls/kWh.  Not bad for an amateur.  My average speed was 29.7 m.p.h. and the trip took 37 minutes to complete.  At 3.7 mls/kWh, you can expect to reach an overall range of around 100 miles--assuming you could maintain that same efficiency for the day.  That is not likely because as the day gets warmer, a/c is a must--and that would take more power.  With Eco Pro that power could be managed, but during this "amateur hour" of driving I can't manage the a/c other than turning it off (or setting the climate control at 80 degrees--no thanks).

Eco Pro: Here are my results on day two using Eco Pro:



I averaged 3.9 mls/kWh, with an average speed of 31 m.p.h.  And the trip was a bit shorter at 35 minutes (a result of my higher average speed).  At this level of efficiency you could expect around 105 miles of range, assuming you could maintain the same level of efficiency for the entire trip.  Again, it may be hard to maintain 3.9 mls/kWh for an entire trip, but with Eco Pro engaged the electronic systems--including a/c--would use less power.

And the winner is:  Eco Pro!  But not by much, which is surprising.  I have done the same trip using Eco Pro before and obtained an efficiency of 4.0 mls/kWh (my highest efficiency rating ever).  Slow, steady starts is the friend of efficiency--such as this:




The more you can keep the needle from moving past that first hash-mark to the right of "Ready", the better.

But the car's ability to zoom off the line (leaving every other driver looking surprised when seen through the E's rearview mirror) is the enemy of efficiency.  And yet, I it never gets old.  So if you are going to drive efficiently, don't do this:





Notes and Conclusions:

A couple of observations.  First, was I driving more conservatively on day one when trying to measure my efficiency without Eco Pro (how dare you accuse me of that!)?  Yes, I was.  Not intentionally, but overall I clearly was driving more conservatively on day one, which is why I had a lower average speed on day one than I did on day two.  I am not sure if it is even possible to drive exactly the same over two days, but taking this into account means that Eco Pro is probably better than these numbers show.

Further, Eco Pro would definitely be more efficient when using the air-conditioning or the heater.

Is there any reason to drive without Eco Pro when trying to be efficient?  Not really.  There are times when I will start without Eco Pro so as to cool the car faster in summer, and I know others who drive without Eco Pro to heat the car faster in Winter.  The E also has the ability to precondition before unplugging from a 240V power source--which means that the car will cool or heat itself and its battery to optimal temperature before departure.  This is a real power saver.

Overall, however, there is no reason to drive without Eco Pro when trying to be efficient--unless you want to see if you can best the Eco Professional.  Even then you may learn, as I did, it's hard to beat a Pro.