2017 Chevrolet Bolt EV Long-Term Update 1: On Charging and Charges – Motor Trend

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It won’t always be the first question someone asks about an EV, but it’ll be in the first five: charging. How long does it take? How much does it cost? How hard is it to find a charger? If there’s anything everyone instinctively knows about batteries of any kind, it’s that they take a while to charge, and that’s a problem when you’re in a hurry.

To answer your burning questions about charging, we’ve been keeping a detailed log. It includes date, location, pre- and post-charging battery state of charge, pre- and post-charging estimated range (both ideal and predicted), kW-hrs consumed in the charging process (when that information is available), and the amount of time the car predicts it will need to reach a full charge.

From this data, I’ve extrapolated some averages and absolutes from the car’s first two months with us. The longest trip made on a single charge is 205 miles, but on average, we charge the car every 80 miles or so. Although we’ve drained the battery to as low as 10 percent, we typically plug in around 55 percent. You might assume we leave it plugged in until it’s full, but with the Bolt’s 238-mile EPA-estimated range, having a full battery is less of a concern than with shorter-range EVs. On average, we pull the plug around 87 percent. When we plug in, the ideal range averages 132 miles, but the predicted (and more realistic, I find) range averages 122 miles. Afterward, the ideal range averages 239 miles, and the predicted range averages 195 miles. Average predicted charge time: 5 hours and 15 minutes.

Because we’re generally plugging in when the battery is half full, each charge is only consuming 24.3 kilowatt-hours (kW-hrs) of electricity on average, less than half the Bolt’s 60-kW-hr capacity. Don’t take that last figure as gospel, though. Even though Motor Trend has an expensive meter wired upstream of our charger, I didn’t spring for one at my home. (If I owned the car and charged at home more regularly and would for the next several years, it might have been worth the investment.) Public charging stations vary wildly, with some, such as ChargePoint, reporting the electricity dispensed down to the thousandth of a kilowatt hour and others not providing any information at all. Eight of our 29 recorded charges thus far have no kW-hr consumption information. However, based on all our metered charging at MT HQ to date, I’ve calculated the Bolt consumes 6.86 kW-hrs of electricity per 10 percent of indicated battery charge. That is, to go from an indicated 45 percent battery level to 55 percent, it consumes 6.86 kW-hrs. Knowing the pre- and post-charging state of charge, I can estimate the electricity consumed, although without a meter, it will never be more than an estimate. To make matters less exact, the Bolt’s battery meter doesn’t report its exact state of charge but rather displays a graph of 20 bars, each representing 5 percent. Thus, what shows as 65 percent on the graph could mean anything from 61 percent to 69 percent, depending on how Chevrolet has programmed it to display.

From this information, I can extrapolate my costs. For public charging, it’s easy because they tell you. We scored one free charge and paid for eight. In total, we’ve spent $57.44 on public chargers so far at an average cost of $6.38 per charge.

Like many EV adopters, for me part of the car’s appeal is the availability of a free charger at my office. As an added perk, ours is located in our tech center (you’ll recognize it from most episodes of Hot Rod Garage on our YouTube channel), so I rarely have to fight anyone for access. Even though it’s free to me, it’s costing my employer money, so I got a copy of our monthly power bill and did the math against the meter on our charger. TEN: The Enthusiast Network, Motor Trend’s parent company, pays between $0.04 and $0.07 per kW-hr for electricity at our office depending on the time of day (noon to 6 p.m. being more expensive “peak” hours). We haven’t been recording the times of day we’ve been charging the Bolt, so I’m going to present a cost range based on both rates. The actual cost will be somewhere in the middle because we generally plug it in in the morning during “mid-peak” hours and unplug it in the afternoon during “peak” hours. After 15 charges, TEN has spent between $16.01 and $28.02 charging my Bolt, an average of $1.06 to $1.86 per charge, all depending on time of day. Given we generally plug in when the battery is around 55 percent and usually when we get to the office in the morning, most of the charging is likely done during “mid-peak” hours. As such, I’ve averaged the costs at the two different rates and come to an average cost of $1.47 per charge and $22.02 spent to date.

At home, the math is even fuzzier. Because I don’t have a meter on my charger, I have to use that 6.86 kW-hrs per 10 percent figure and the Bolt’s battery meter to estimate my cost, and there are myriad charges and fees on my power bill that obfuscate the actual cost of the electricity. Southern California Edison charges me an average standard rate of $0.16 per kW-hr up to 291 kW-hrs per month. For the past four months, I’ve averaged 6.4 kW-hrs per day. If I exceed my baseline allocation of 291 kW-hrs per month, my rate jumps. From 101 percent of my baseline to 400 percent, I’m charged $0.25 per kW-hr. That works out to a maximum of 1,164 kW-hrs per month. If I exceed 400 percent of my baseline—more than 1,165 kW-hrs per month—I’m hit with a High Use charge of $0.31 per kW-hr.

Assuming I limp the Bolt home empty and fully charge it, my bill would look something like this: 6.4-kW-hr average daily usage at $0.16/kW-hr plus 68.6 kW-hrs of Bolt charging at $0.16 per kW-hr (yes, that’s greater than the Bolt’s published battery capacity, and I’ll get to why shortly). Add that all up, and a full charge would cost me $12.00 each day I charge it ($11.00 just for the Bolt).

Considering my average bill for the last four months has been $35.16, an extra $11 per charge is a big increase. My commute is 17.6 miles round trip, so at a minimum, I would need to charge the Bolt twice month, resulting in a bill increase of $22.00 if I only charge at home. That means a total of $57.16 per month, or a 62 percent increase over what I’m paying now. That’s assuming, of course, I only commute to the office and back all month and don’t need to run a lot of errands or go out of town.

Now consider this: I’ve been using 191 kW-hrs per month on average the last four months, 221 in the winter months and 145 in the spring months. Based on those averages, I could get in two full charges per month in the spring without breaking into the higher pricing tier, but in the winter when my home consumes more electricity, I could only get in one full charge before I’d jump into the higher pricing tier. At $0.25 per kW-hr, the price to fully charge the Bolt climbs to $17.15 for just the car and $18.75 including my average daily home power usage. At $0.25 per kW-hr now, my average monthly bill climbs to $38.32, and two full Bolt charges bump it to $72.62—nearly double and well up from the $57.16 noted above. The good news is once I’ve broken into the higher pricing tier, I could fully charge the Bolt 14 times a month without getting hit with the High Usage price. Of course, all of this depends on how much driving I do, how many times I charge the Bolt at home each month, how low I let the battery get before I charge, and how much power my home uses each month.

On the other hand, show me another five-passenger vehicle that can fill its tank for $11 and go 238 miles. Assuming I only charge at home, my Bolt costs me $0.05 per mile. Of course, if I owned this car, I’d be on the phone with Edison right now switching to a time-of-use account rather than a flat rate because in Southern California, a person on time-of-use billing who only charges overnight pays as little as $0.13 per kW-hr, dropping the cost per mile to just $0.04. For comparison, at Toyota Prius costs $0.06 per mile at Southern California’s $3.08 per gallon average gas price right now. Even against the benchmark for fuel efficiency, I’m saving money. If I really wanted to save money long-term, though, someone would be on my roof installing solar panels right now. (Without the Bolt charging regularly, I don’t qualify for any of the lease deals, and I don’t have the cash to buy solar panels outright.)

Here’s what I’ve actually paid for two home charges to date, after all the charging math: $7.68. That works out to an average (with an admittedly small sample size) of $3.84 per charge.

Total, it’s cost us about $87 to go nearly 3,200 miles on 29 charges. That’s a pretty good price. To go the same distance in a Prius at 56 mpg combined, it would take 57 gallons of gas costing around $175 at $3.08 per gallon average. That’s with a Prius Two Eco. A fully loaded Prius Four Touring, which is more comparable in equipment, gets 52 mpg combined and would need 61 fill-ups costing about $190. Because the standard Prius (not including the Prius Prime) doesn’t qualify for federal or state tax credits in California and the Bolt does, I’ll only have to drive about 23,700 miles to make up the $763 price difference between my loaded Bolt and a loaded Prius Four Touring.

There are some important caveats to these calculations, though. As mentioned above, the Bolt’s battery meter displays in 5 percent increments, and 45 percent could mean anything from 41 percent to 49 percent depending on how it’s programed to display. Therefore, my 6.86 kW-hrs per 10 percent of battery charge metric is an estimate. As I mentioned earlier, that figure works out to a total charge of 68.6 kW-hr, but the Bolt advertises a 60-kW-hr battery. Several things are going on here. First, according to a Bolt engineer I spoke with, 60 kW-hrs is the usable battery capacity. The battery is actually slightly larger, but some of that additional charge is buffer to protect the battery and electronics. He wouldn’t say exactly how large it actually is. Second, during charging, some energy is lost converting the AC electricity coming out of the wall into DC electricity the battery needs, and some is also lost to heat. Third, the Bolt’s battery has a conditioning system designed to manage its temperature for longevity and safety (feel how hot your phone gets when it’s charging), and this requires energy to run. Finally, a battery’s capacity isn’t fixed like a gas tank. Depending on the outside temperature, the battery can store more (when it’s hot) or less (when it’s cold) energy. That last point has been moot lately because the local temperature has been very moderate the last few months. I should also mention the car underwent both Real MPG range testing (244 miles, better by 6 miles than the EPA estimate) and our standard instrumented testing early on, so some of the usage and charging in this first segment has been abnormal.

Then there are the related questions about finding and using public EV chargers, managing range anxiety, and planning road trips. I’ll cover all of these in future updates as I get more experience in all those areas. For now, though, I do have one final update on the upfront cost of the Bolt. In the Arrival story, I broke down our costs acquiring the Bolt and a home charger. The car itself was $43,905 out the door, and the home 240-volt Level 2 charger was $1,398 with installation from Aerovironment. To that I can now add a city permit fee of $255, bringing the grand total to $45,558 before tax credits. With the $7,500 federal tax credit and $2,500 California state tax credits applied, the total cost to acquire a top-trim Bolt and get a home charger was $35,558 (slightly higher than the U.S. new vehicle average transaction price of $34,000).

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