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November 29, 2020
Paul Gipe

2020 Chevy Bolt EV Battery Capacity Anecdotal Observation


After two months of driving a 2020 Chevy Bolt for some 2,000 miles we've found that the traction battery of our car has a capacity of 64 kWh, not the 66 kWh advertised. More interestingly, the 2020 battery pack of our car has only 2.5 kWh more than that of our previous 2017 Bolt. This anecdotal observation may not reflect the rest of the 2020 Bolt fleet.

I've kept a log of our miles driven, kWh used, and other accessible parameters for all the EVs I've driven. For example, I tracked the 2017 Bolt's traction battery capacity with an OBD reader and Torque Pro for much of the time we drove the car. I report on our experience driving electric to encourage others to do so and have written about the 2017 Bolt.

We purchased our 2020 Chevy Bolt in early October 2020 to replace our leased 2017 Bolt. I began a log on the 2020 Bolt immediately upon purchase.

2020 Bolt Blocks Capacity Signal

For some unknown reason the 2020 Bolt blocks the signal for battery capacity to the OBD reader. I'd used this signal with Torque Pro to track the slight battery capacity degradation of our 2017 Bolt over 2.5 years.

However, we can infer battery capacity by knowing how much percentage of the battery was used for so many kWh consumed between full charges. For example, on a recent trip, beginning with a full charge, we consumed 54.3 kWh and arrived home with 14.1% State-of-Charge. Thus 54.3 kWh/(1-0.141) = 63.2 kWh.


Disclaimer: I worked for GM's Delco-Remy Division 1968-1970 as a cooperative engineering student. I was a member of UAW Local 1981 until the National Writers Union left the UAW in May 2020. The Chevy Bolt is assembled by UAW Local 5960.


Battery capacity varies from charge to charge whether using the car's OBD signal or the inference method above. In the case of the Bolt, the capacity can vary 1-3 kWh per charge cycle.

Bolt's Advertised Capacity

The nominal capacity of the 2017-2019 Bolt was advertised as 60 kWh and that for the 2020 as 66 kWh. However, the actual capacity is somewhat different from the nominal capacity.

Korea's Ministry of the Environment publishes the measured traction battery capacity of EVs as reported by the manufacturer. They report that the 2017-2019 Bolt has 60.9 kWh of capacity and the 2020 has 65.94 kWh. That's a difference of 5 kWh and not the 6 kWh as suggested by the difference in nominal capacity.

Are we splitting hairs here? Yes. The reason is that there appears to be only a few kWh difference between the two battery packs based on my observation of our two vehicles.

Anecdotal Observations

We've driven our new Bolt about 2,000 miles so I'll compare the measurements I've made on the two vehicles during the first 2,000 miles. First, the 2017 Bolt.

 

The average estimated capacity during the first 2,000 miles is 61.3 kWh. The capacity varied from 59.6 kWh to 63.8 kWh. Next, the 2020 Bolt.

The average estimated capacity during the first 2,000 miles for the 2020 Bolt is 63.8 kWh. The capacity varied from 62.1 kWh to 65.3 kWh.

The difference between the two averages is about 2.5 kWh. At an efficiency of 4 miles/kWh, our 2020 Bolt has 10 miles more range than our 2017 Bolt did. This isn't a significant difference.

Now, let's take a look at the range estimator on the DIC (Driver Information Center), otherwise known as the GOM (for Guess-O-Meter).

The range estimates for the 2017 model averages from 215 miles to 311 miles on a full charge at an average efficiency of 4.3 miles/kWh.

The range estimates for the 2020 model averages from 219 to 315 miles on a full charge at an average efficiency of 4.3 miles kWh.

The difference between the range estimates for the two cars is 4 to 7 miles or the equivalent of 1 to 1.5 kWh at 4.0 miles/kWh. The difference in range is essentially insignificant.

Are the 2017 & 2020 Batteries Different?

The battery packs in both models are made by the Korean conglomerate LG Chem. The battery packs for the 2017-2019 models were made by LG Chem's Korean plant. However, the battery packs for the 2020 Bolts are made by LG Chem's plant in Holland, Michigan.

Are the two packs different? If they are, the difference is subtle and could be partly attributed to the different plants using slightly different components.

Hyundai's Kona EV also uses LG Chem's Korean packs and rates their nominal capacity at 64 kWh.

GM announced this week that it was recalling 2017-2019 Bolts for a problem with their battery packs. Hyundai did as well for their Kona EV. The 2020 Bolt battery packs made in Michigan are not part of the recall.

The Bolt is not a Leaf

To put these numbers in perspective let's compare the 2020 Bolt to our 2015 Nissan Leaf. Nissan advertised the Leaf with a 24 kWh battery. However, only 21 kWh were actually usable. That's a difference of 12.5%. The 2 kWh difference from the 66 kWh advertised by Chevy is only 3% or one-fourth that of Nissan's Leaf actual versus advertised capacity.

Temperature as a Factor

I am discounting any temperature effects. I began the logs on both cars when we began driving them in the fall. Bakersfield, California is not Michigan. Fall here is mild. Though it does get down to freezing at night on occasion, it warms up during the day.

It's not the absolute number of kWh that's important in this comparison; it's the difference between the two vehicles. One vehicle, the 2017 model, reported as much as 3 kWh more than its nominal capacity. The other vehicle, the 2020 model, reported 1 to 3 kWh less than its nominal capacity.

What to Make of This

I am not sure what to make of these observations. I don't see much difference in capacity or range between the two model years.

Am I upset? No, not really. Though we do own the 2020 Bolt as opposed to leasing it. In other words, it's our car, not GM's. We would have bought it anyway if GM had advertised a nominal 60 kWh battery rather than 66 kWh.

Would I prefer 66 kWh over 61 kWh? Yes indeed. However, the difference between what Chevy advertises and what we experience is probably within the normal range of variability of complex manufactured products.

The car delivers what we want. We drive it where we want, when we want. The small difference in capacity doesn't affect how we use the car--not in the least.

I am more disturbed or frustrated with the fact that Chevy has blocked the signal to the OBD for battery capacity. Why did they do that? The implication is that they have something to hide from their customers. In an age of rampant conspiracy theories, why ask for suspicion? Just report the data as you would to any technician servicing the car. Only nerds are going to go to the trouble of plugging in an OBD reader and setting up Torque Pro to read the messages. We're a decided minority of EV owners. And mostly we just chatter to each other. It's not like it's a great scandal that needs to be hidden away from the prying eyes of the public or pesky journalists.

Summary

Based on my observation of the battery capacity of the 2017 Bolt and the 2020 Bolt, there's only a modest increase in capacity for the new model, about 2.5 kWh, and not the 6 kWh that GM advertised.

See also.

 

 

 


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