Thursday, October 24, 2013

The Sound(s) of Silence

Silence. That’s got to be one of the most appealing virtues of an EV for many of us early adopters. I didn’t really experience it during the test drive; I was too busy yapping away with the guy in the passenger seat wearing a tie. I’m a has-been amateur racer, he moonlights as a stunt car driver. We had a lot to talk about. So I didn’t really notice just how quiet an EV can be until after the papers were signed and I was well on the way home.

Tire rumble. Wind noise. That’s it. That’s all I really noticed. At first it felt surreal; like being in a dream, because in dreams, there always seems to be something a little bit wrong. Something missing or out of place. Did I really buy a Focus Electric? Let's see... I wasn’t naked, nor was I driving over a cliff. And I still hadn’t heard an alarm clock in the distance, progressively getting louder and louder until it sounded like it was on a nightstand next to my side of the bed. Must be the real thing.

Just for kicks, I turned off the climate control system fan. I then noticed the soft, high-pitched whir of the motor/drivetrain. Hard to hear at a constant speed, much more pronounced when accelerating or off the pedal. Autocar described it best in a first-drive review of the euro-built Focus Electric:

“At some speeds there’s also a faint but pleasing whistle from the engine bay that, in quality if not volume, is akin to a Cold War jet fighter taxiing.”

I love reading articles and reviews from across the pond. They really know how to write over there.

Close to home, I rolled my window down and started noticing other sounds, while driving at about 20mph, that I don’t ever recall hearing while driving my ICE cars through the neighborhood.  Kids playing off in the distance. Leaves rustling in a gentle breeze. A couple talking while on their daily stroll. The soft squeak of tire tread blocks rubbing against the wide, smooth, white paint stripe as I slowly pull away from a stop sign. A crinkling sound as I drive over gravel – just several small stones, not a large patch – that gathered on the pavement at the corner of my street. I was simply amazed.

After 12000 miles, the Focus Electric is still as silent as it was eight months ago, but the novelty has worn off for the most part, except under heavy acceleration. I’m still not used to the utter silence while rocketing from 30mph to 70+mph; I’m so used to hearing hundreds of confined explosions per second increasing in volume and frequency that the lack of that corresponding noise makes it seem like I'm accelerating even harder than I really am. It’s the exact opposite effect of those hollowed-out coffee can mufflers and tailpipes that kids put on old automatic-transmissioned Civics and Integras; those things sound like they should be at warp speed when taking off from a stop light, yet I pass them as if they are standing still.

Unlike many early adopters, I do occasionally miss the romantic sound of a properly tuned internal combustion engine. Sometimes I drive the truck on short errands, just to hear the rumble and roar of a modern Dodge Hemi. And I do enjoy driving my Focus Electric's ICE backup... Mercedes did a great job giving their supercharged 4-cylinder C230 Kompressor Sport Sedan a noticeable lope at idle and beautiful song at full throttle. Or at any throttle, for that matter.

Nostalgia aside, for the day-in and day-out routine, the most gratifying sound for me is now that of a pure electric vehicle.  My own personal Cold War jet fighter.

Saturday, October 12, 2013

Prolonging Life

From what I’ve seen, much of the angst of those contemplating EV ownership is centered around the battery. Range anxiety seems to be the most prevalent worry bead.

Another source of angst is battery life. And why not? For those not driving an EV yet, their only experience with batteries in cars is with lead-acid units that last five to seven years before crapping out. Even worse, their only experience with Li-ion batteries is probably with cell phone and laptop power sources that suffer noticeably degraded performance after a couple of years of continuous use. Not to mention the fact that there are stories of LEAF owners out there that lost 20% or more of their range after two or three years. Why should we believe that the batteries in EVs will fare any better than cell phone and laptop batteries?

Fortunately, my Focus Electric came with an 8-year/100K mile warranty on its thermally-managed Li-ion battery, so initially I didn’t worry too much about battery life, figuring that I can just ditch the car after three years if the battery turns into a relatively useless brick. But in short order I fell in love with the car, and since it might be a keeper, I started surfing the net for battery info and started paying attention to articles offering tips on prolonging Li-ion battery life in a plug-in EV.

There’s lots of stuff out there, but this is one that I like to refer folks to, from

Understanding Battery Capacity Loss From A Four Year BMW Electric Trial Veteran

In short, five tips offered in this article are (in case you don’t want to read through the whole thing):
  1. Avoid deep discharge.
  2. Don’t leave a fully charged EV sitting unused for long periods of time.
  3. Avoid excessive fast charging.
  4. Don’t leave the car parked in a hot parking lot in direct sunlight if possible.
  5. If you don’t need all the range the car can offer on a daily basis, then don’t fully charge it every night.
There are other similar articles out there on prolonging EV battery life, they pretty much say the same thing, but it’s nice to have a second source to help draw your own conclusions and plan of action. So here’s my second favorite, from

Eight Tips to Extend Battery Life of Your Electric Car

This article has more tips than the previous one, but they center around the same three mantras as the first article: (1) avoid deep discharge/full charge, (2) avoid excessive fast charging, and (3) keep the battery cool.

As an Enginerd, I yearned for technical information that these tips are based on, as well as some specific data and values that can provide better guidance (i.e. how cool is cool?). Fortunately, is a great reference for such information:

How to Prolong Lithium-based Batteries

Interesting stuff in this article includes a comparison of cycle life as a function of depth of discharge, which illuminates why we should avoid full charging and deep discharging. It also illustrates the effects of elevated charge voltages on cycle life, which backs up the the tip to avoid excessive DC fast charging. It talks about capacity loss as a function of temperature and state of charge:

“Lithium-ion suffers from stress when exposed to heat, so does keeping a cell at a high charge voltage. A battery dwelling above 30°C (86°F) is considered elevated temperature and for most Li-ion, a voltage above 4.10V/cell is deemed as high voltage. Exposing the battery to high temperature and dwelling in a full state-of-charge for an extended time can be more stressful than cycling.”

With 86F being a considered an elevated temperature, it’s no wonder that a thermal management system should be considered a necessity for an EV. It also explains why I’m constantly frying laptop and cell phone batteries, which have no thermal management system.

Although not published anywhere, owners of Focus Electrics have figured out that only about 85% of the battery’s advertised capacity is used, leaving a 15% reserve. One owner on did a pretty good analysis (in my opinion), and surmised that 10% of that reserve, about 2kWh, is used to avoid full discharge, and 5% (about 1kWh) is used as a buffer to avoid full charge. I would think other EVs also implement similar reserves and buffers to prolong battery life.

What about when we need to leave our EV unplugged at some parking facility, like at an airport, for a long period of time? Well, here is another article that might help:

How to Store Batteries

This article addresses how to store several types of batteries, including Li-ion. In essence it says to avoid storing at elevated temperatures, and that leaving it at a partial state-of-charge, ideally 40%, is recommended.

Oh, there’s one more article on this subject of prolonging life that I like. It's from DesignNews, one of my favorite trade rags:

Can EV Batteries Last 20 Years?

This article states, “Lithium-ion battery packs need to stay as close as possible to a 50 percent charge”… “usually going no higher than 80 percent and no lower than 20 percent.” It’s a good read, explains why we should expect thermally managed Li-ion batteries to last 20 years before losing 20% of its capacity… as long as we treat them right.

Sunday, October 6, 2013

Charge Depleted

It's inevitable. If you own an all-electric vehicle, you will be asked.

“Have you ever run out of charge?”

A perfectly reasonable and appropriate question from someone contemplating EV ownership, thanks to the current state of battery technology. It’s also an engaging topic for EV owners to discuss, sharing stories of how they ran an experiment to test the range limit of their vehicle, or how they have come so perilously close to the end of the line that their EV resorted to some kind “limp mode” to extract as many miles (or yards) out of that last fraction of a usable kWh remaining in the battery.

For me, answering that question is somewhat cleansing (i.e. forgive me Father, for I have sinned), because unfortunately my answer is yes. I have run out of charge. Once. So far. Never again. And out of the many BEV owners online and in person I’ve talked to, only one other person has confessed. Luckily for him, he was maybe a hundred feet or two from a receptacle, so he was able to push his beloved Focus Electric to salvation. As for me? Well, if you haven’t seen the story in one of the Focus Electric forums, please read on…

February 4, 2013… it happened on my FFE’s maiden voyage, a 78 mile round-trip commute to work, with a 1200ft elevation loss/gain, and stop-and-go freeway traffic for about 30% of the trip. Did not intend to go round-trip on a single charge, but I thought my chargepoint account was set up for the charging station at work, and it wasn’t. Fortunately I elected to freeze my extremities on the way down to work (kept the heater and bun warmers off), so I had well over 60% of charge left, which the FFE translated to 62 miles, to get me back home.

Well, that wasn’t enough for a 38 mile, 1200ft elevation gain. But, damn-the-torpedoes idiot that I am, I opted out of every opportunity to stop for a quick jolt at a free charger or Blink station along the way. Heck, I even thought I was going to make it when FFE was telling me I had a mile of charge left with 7 miles to go. Stupid, in hindsight.

Then it happened. “Charge depleted, pull over safely”. I felt a chill down my spine, and it wasn’t because all life support systems were shut down for the entire trip. I was still 4 miles from home, going uphill before a final descent into the valley.

I slowed down from 50-55 to 35-40mph, with semis blowing by me as I crawled up the truck bypass. Went about a mile more until the charge was really depleted. The crest of the hill was within sight, but my speed was gradually falling… 25.. 20… 10… 5… I thought we were on the downhill side by now, but it must have been an optical illusion… we were moving, at a leisurely walking pace, but the speedo needle was on zero.

I got religious for a moment.

Speed finally started picking up after we really crested the hill, got to about 15mph when I lightly braked, maintaining 15-20mph all the way down in hopes that we’d generate enough energy to drive home. No such luck – still had zero range at the bottom of the hill, so I pulled into a park and ride area and shut down, making sure the FFE was positioned for a quick tow hookup.

So now I know – charge depleted means, well, that the charge is depleted. Got maybe a mile or three to go. No “reserve” like in most ICE cars – which I’ve taken 20-30 miles on fumes a number of times.

Also – Ford Roadside assistance works well. Free of charge, very courteous, and perhaps even expecting the call…

“Ford or Lincoln?” she asked.
“Ford, a Focus Electric.”
“Aww, did you run out of charge?”
“Don’t worry honey, that’s why we’re here.”

That's right, she called me "honey". In a sweet southern drawl, no less. Suddenly I felt better about this sorry situation I’ve inflicted on myself. In fact, if I wasn’t happily married, I’d have asked her out for a cup of coffee or something.