Idaho National Lab Compares Volt, Leaf and PEV Charging Realities

Recently, the largest plug-in electrified vehicle infrastructure demonstration in the world uncovered many findings, including that the Chevy Volt traveled only 6-percent fewer all-electric miles per year than the Nissan Leaf despite having less than half the EV range.

Before we get to that, we’ll brief a few highlights to give a greater grasp of the context of the study, and another central takeaway was charging stations need not be as ubiquitous as gas stations.

Is this common sense? Maybe if you are already attuned to living with a plug-in electrified car like the 8,700 vehicles studied for a period of three years consisting of Leafs, Volts and Smart EDs.

Initiated in 2009 by the U.S. Department of Energy, run by the Idaho National Lab, and with full findings announced Sept 30, 2015, this latest info is not to be confused with previous INL studies, and is called Plugged In: How Americans Charge Their Electric Vehicles.

A counterpoint key finding about a new kind of automotive paradigm was the most important places to charge are home, workplace, and public “hot spots” that serve multiple venues.

Anyone who thinks public “charging stations” must be equal in number and placement to public gas stations is not on board with the actual needs of the new way of things, says the federal study.

Charge Point America project, Chrysler Ram PEV Demonstration, General Motors Volt Demonstration, South Coast Air Quality Management District/Via Motors PHEV Demonstration, and The EV Project – installed roughly 17,000 charging stations and deployed approximately 8,700 PEVs across the U.S.

Charge Point America project, Chrysler Ram PEV Demonstration, General Motors Volt Demonstration, South Coast Air Quality Management District/Via Motors PHEV Demonstration, and The EV Project – installed roughly 17,000 charging stations and deployed approximately 8,700 PEVs across the U.S.

Serving EVs the most like gas stations do for an internal combustion engine (ICE) car, DC level-3 quick charging used with the Leafs was also advantageous, and these findings answered early questions about how to transition to electrified cars.

“A commonly cited barrier to adoption is the lack of public places for PEV drivers to plug in their vehicles,” says the Sept. 30 document highlighting the study. “To reduce this barrier, critical questions must first be answered: How many and what kind of charging stations are needed? Where and how often do PEV drivers charge? How many electric vehicle miles are traveled and what level of petroleum reduction can be achieved?

Data was collected by INL from a variety of sources in five separate projects. Its research partners agreed to participate in what was described as a real-life laboratory. These were the Blink Network, ChargePoint, General Motors, OnStar, Nissan North America and Car2Go.

In all, 130 million driving miles were evaluated and six million charge events were evaluated.

Home charging could be AC level 1 (ordinary wall current), or level 2 (240-volt, like a dryer would use). The study accounted for 17,000 AC level 2 and DC level 3 charge points.

About half of all project participants who’d volunteered to let their charge events be monitored charged from home. Leaf and Volt drivers, the study found did 85.5 percent of their charging at home.

Source: ChargePoint.

Source: ChargePoint.

Among those who charged away from home, the vast majority favored three or fewer away-from-home charging locations.

This state of affairs contrasts widely from gas stations on every corner, and an obvious reason is implicit for why this is: charging takes a lot longer. Even level 3 charging at 480 volts can take up to half an hour or so, and level 1 or 2 charging take several to many hours.

So to put a charger where the car will not be parked for other reasons – such as to go shopping or to work – would make less sense than a gas station where a 3-minute fill-up is possible. PEV owners simply are not prepared to stand around that long and wait. (See what we meant by common sense – but maybe this is not always intuitively obvious).

As for those times when a public charger might have been accessible, the study found behaviors compared to ICE drivers shifted here too.

“PEV drivers adjust their charging habits based on conditions, such as fees and rules for use,” said a study fact sheet. “Drivers were less likely to plug in at work if they had to pay to charge or if they were required to move their vehicle after charging.”

On the other hand, more often than not people were polite and got along when they did need to use public chargers installed at their place of work.

“PEV drivers charging at work were generally courteous and worked together,” said the study. “They used social media to communicate, moved their vehicles to allow others to charge, and even plugged in neighboring cars after they finished charging.”

And, when strategically placed public level 2 charging was accessible – such as near shopping venues, or the like – these “saw very high usage,” or about 7-11 charges per day.
Nonetheless, the cars that took advantage of this were the minority.

“Overall, 20 percent of vehicles studied were responsible for 75 percent of the away-from-home charging,” said the findings.

Volt vs. Leaf

Among extended-range electric Volt and all-electric Leaf drivers, the study found the Volts traveled only 6-percent fewer electric miles than Leaf drivers despite having significantly less electric range per charge.

Volt e-range varies from 35-0 miles; Leaf range varies from 73-84, by EPA reckoning.

Volt e-range varies from 35-0 miles; Leaf range varies from 73-84, by EPA reckoning. Source of this and following images: INL.

How did the Volts do this? For one, because they have gas back-up, the drivers had no fear of running right up to the end of the electric range, unlike Leaf owners which must stay within a comfort zone lest they run out completely far from a charger. The Volt drivers also recharged more intraday – a trick that can serve any plug-in hybrid to increase effective daily range.

Specifically, INL found Volt drivers charged on average 1.5 times per day and Leafs charged 1.1 times per day. Leafs also tended to recharge earlier as they had no gas backup like the Volts.

“Volt drivers averaged slightly more miles traveled annually than the 2013 national average, while Leafs studied were driven noticeable less,” said the study adding a bit that could not have been said if it had been written by Chevrolet: “Volt drivers tended to fully deplete their batteries, whereas Leaf drivers favored recharging with significant charge left in their batteries. This is an expected difference between pure electric vehicles like the Leaf and range-extended electric vehicles like the Volt.”

“Volt drivers averaged slightly more miles traveled annually than the 2013 national average, while Leafs studied were driven noticeable less,” said the study adding a bit that could not have been said if it had been written by Chevrolet: “Volt drivers tended to fully deplete their batteries, whereas Leaf drivers favored recharging with significant charge left in their batteries. This is an expected difference between pure electric vehicles like the Leaf and range-extended electric vehicles like the Volt.”

This validation for the “extended-range electric vehicle” concept Volt fans love to bandy about sounds like it could have been written by GM’s marketing department, but it was not. This was the finding of researchers working for a federally funded project.

The number of Volts in the study were however fewer – about 1,800 versus 4,000 Leafs, but the Volt drivers proved more diligent in maximizing eVMT (electric vehicle miles traveled).

Average monthly vehicle miles  traveled varied seasonally  but was otherwise consistent over time.

Average monthly vehicle miles traveled varied seasonally but was otherwise consistent over time.

That was for generation one – and now the just-being launched 2016 Volt has 53-miles range instead of 35-40 for gen one. True also, Nissan will have 107 miles for 2016 and maybe nearly double that for gen-two when launched either 2018 or maybe 2017.

Leaf and Volt drivers performed most  of their charging at home.

Leaf and Volt drivers performed most
of their charging at home.

As described in the opening section, the main charge point for Volt and Leaf drivers was at home overnight. The INL researchers noted PEVs have an advantage over internal combustion cars in that – while the ICE can fast fill – it does not have the benefit of fueling at home.

About half of Volt drivers tended to use level 1 charging for its smaller 16-kwh battery, and the other half used level 2 at home.

Leaf drivers, while level 1 compatible and equipped with a level 1 cord included with the car like the Volt gets as well, tended to charge their 24-kwh cars with level 2. All Leafs in the program were set up with level 3 compatibility via CHAdeMO connectors. All had level 2 at their homes. Away from home, 8-percent of charge events used level 3, and the rest was a mix of level 1 or level 2.

92% of Volt drivers and 77% of Leaf drivers did most (at least 80%) of their away-from-home charging at three or fewer locations.

92 percent of Volt drivers and 77 percent of Leaf drivers did most (at least 80 percent) of their away-from-home charging at three or fewer locations.

The study, linked here, goes on to show numerous comparisons between home, workplace and other public charging patterns.

The bottom line is the plug-in lifestyle is possible with some adaptations over ICE ownership, and need not be a hardship. While true, Nissan did recently divulge it loses 25 percent of its Leaf buyers who are not prepared to accept range, charge time, and lack of accessible infrastructure in their daily orbit.

If we were to counterpoint this for the Volt, objections for it include its limited back-seat space. GM has not said it loses a lot of Volt drivers though, and they remain overwhelmingly loyal, though no doubt some have other criticisms beside.

This is not to ultimately compare the two in any comprehensive manner, as that would be its own lengthy article.

What the study found was people do learn to live within limits, even with first-generation PEVs.

And now the second-generation cars are either coming or due in the next year or two with greater capabilities.

The first 200-mile range electric car priced in the mid $30,000 range before subsidies is to be the 2017 Chevy Bolt. It’s expected to be followed by the second-generation Nissan Leaf, Tesla Model 3, and whatever other surprise we learn of next.

How usage patterns will shift for “mainstream-priced” EVs with far more range than a 73-84-mile gen-one Leaf remains to be seen.

Source: INL.

Source: INL.

The existing advantages for the Volt with gas backup appear poised to carry forward with greater effect due to longer e-range. For its part, GM said OnStar data prove 80 percent of gen-one cars drove gas free on a daily basis, and now 90-percent might do that with the longer range Volt just released.

This may be so, but plug-in watchers are also wondering if EVs, including the long-range sibling Bolt may in themselves help with range anxiety the Volt for now answers with gas-engine backup.

It and others still will have limits too, however, and “200” miles would mean less in actual use – as discovered by first Leaf drivers – because no one can run them to zero, and less-than-tame driving will also sap range from ideal window sticker values.

Undoubtedly more discoveries are in store.

Brief fact sheet.