Gasoline range extenders like those in the BMW i3 mean more EV miles travelled

Great story, John. It's one of the more underreported aspects of the EV industry, and I agree with your take on the subject. It certainly appears as though plug-in hybrid choices will proliferate much faster than BEV choices in the foreseeable future.

I'm the proud owner of an i3 REx (since the start of March). I've been averaging 2000 miles per month in it, and although many of my journeys involve an element of REx running (I'm logging what proportion), the REx allows me to use the car as my only vehicle, whereas if it was a pure BEV I wouldn't have bothered.
My longest trip has so far been 335 miles in one day, with no opportunity to recharge at any stage - used around 25 litres of gasoline (5.5 UK gallons) and a full charge, so around 50mpg when running on the REx, even at motorway speed.
So, the long and short is that I agree with the article 100%, and I'm COMPLETELY convinced that REx electric is the sensible, pragmatic solution.

You've hit the nail on the head here. We have an i3 REx with about 1,850 miles on it, of which 1,450 are electric. Around town, it runs 100% on electricity. But every couple weeks, we take it on a 195-mile one-day round trip. No charging stations along the way. Without the REx, we'd be using our ICE car for that trip instead. We get the first 72 miles of freeway driving on the battery, the rest on the REx. (For that situation, I do wish we had the flexibility of the European model to decide when to use the REx and when to use the battery as well as the larger 9-liter European gas tank. And we're in a non-CARB state, so the modifications BMW made to qualify the car as BEVx in the CARB states (7-liter tank instead of 9 liters and no control over when to use the REx) do us no good. Hear that BMW?)

But there's another possible benefit of the REx--longer total battery life. I understand that the best way to store a lithium ion battery is at less than a full charge; the common recommendation is around 50%. That has some benefit for total battery life, though probably not a huge benefit. So when we don't need a lot of range the following day, we'll let it sit overnight at about a half-charge. If plans unexpectedly change the next day and we need more range, we've got the REx. Without the REx, we'd be charging it to 100% every time we pull into the garage.

Excellent observations and I agree with the conclusions. I do find it interesting that the article suggests that this a novel finding among PHEV owners. While it's certainly true for the i3-REx owners (which I'm soon to be myself), the Volt community has been enjoying this advantage for some time. I'm proud that in the last 3+ years I was able to rack up over 25K of pure EV miles with 29K total, over 86%. Having the extended range offered more opportunities to drive longer distances, maximize my EV range, yet find opportunities to charge.

Driving a BEV (been doing that for a long time as well) has always been somewhat of an adventure for longer distance travel. The key point is about the predictability of charging when you go beyond the "point of no return" (below 50% SOC). With the increasing popularity of plug-in vehicles, particularly in Southern California--the public charging infrastructure has become increasingly oversubscribed, reducing predictability. That serves as a deterrent for those who have trepidation about mapping out new locations with uncertain charging reliability.

One finding not mentioned in the article is the type of drivers we now encounter who drive PHEVs. These individuals are "regular" drivers who didn't have a lot of knowledge about how EVs work. They just were looking for transportation that held advantages (e.g., fueling costs, solo HOV lane usage) over traditional ICE vehicles. That is certainly a good thing for the EV Movement, adding new converts to our ranks.

David

Regarding the battery buffer and degradation: while this is headed in the right direction, some of the information is not quite correct. Take the Nissan LEAF, for example. There is a 4-5% buffer on the top. Meaning that when the customer charges the traction battery to full, the total stored capacity and voltage are below the physical maximum. Likewise, when discharging the cells, the cutoff voltage for turtle mode is quite high, and very safe. There is little energy left in the pack, about 2-3% of its maximum stored energy. It's critical to disconnect the traction battery from the rest of the vehicle at that stage, because if it continued to discharge through parasitic losses, for example, the voltage would quickly drop, and the battery could suffer irrecoverable damage.

From a consumer perspective, it really does not matter if you charge the battery to full or how often you have driven the car to turtle mode. Both end points have very safe limits and other safeguards in place. In terms of longevity, unless you were turtling the vehicle every day, and left it in that state until early morning, you most likely won't see any measurable impact on the battery at all.

Please keep in mind that we have been conditioned to different type of battery chemistries over our lifetime. Lead-acid batteries like to be stored fully charged, and hate deep discharges. NiCd batteries want to by cycled fully, and should not be recharged unless they were nearly empty, because they will lose more capacity due to their memory effect. Lithium-ion batteries, like what's in modern EVs, like to sit half-charged, especially in storage. They also prefer shallow cycles, but won't mind occasional deep cycles at all. While the cycle type will affect the life of the battery, it's not the most critical factor.

I would simply use these traction packs in the most practical way possible, and not worry much about them. When going on vacation, I would ensure that the pack was at most half-charged, the vehicle was parked in a cool place, and the battery was conditioned (cooled) if possible.

Pure electric cars are not lab experiments... they tell us the truth about the true nature of sustainability, as solar and wind can only provide a fraction of what our fossil fueled lifestyle can provide.

Hybrids are a lame attempt at lying about that... as in packaging a hard pill with sweets. And the proud owners are stuck with neither option being as good as each separately (as a pure BEV doesn't carry the added weight of the ICE engine, and a pure ICE lets you still party while the oil is flowing, without the expenses of a battery pack)

In practice most plugin hybrids I know rarely charge from the grid at all... because they just can. I wouldn't be surprised if the number is around 90%+

I own a BMW i3 BEV and I am one of those criticizing the gasoline option... and I live happily with it as my sole ride.

I do a 100 miles per day commute each way and I always have 20 miles of reserve and most charging stations are reliable. Just THINK and PLAN. Simple.