Friday, November 7, 2014

REx To The Rescue

Those that have followed this blog since before I got my i3 know I toiled a bit over whether to get the range extender option or not. Having lived with pure battery electric vehicles for five years I really didn't like the idea of hauling around an internal combustion engine if I really didn't need to do so, even if it was a very small, efficient one.

Ultimately, the decision was easier than I had hoped. Once it became clear the i3 would have significantly less electric range than the two previous BMW-made electrics that I've been driving (MINI-E and ActiveE) I knew I needed the REx. As much as I love the i3, I'm still disappointed BMW moved backwards with the electric range in every EV they have produced. The MINI-E was good for a reliable 100 miles in moderate temperatures, the ActiveE about 90 miles and the BEV i3 is EPA rated at 81 miles per charge. I drive a lot and 81 miles would just be cutting it too close for me, especially in the winter when the range is negatively effected by the cold weather.

Our Equinox, Tacoma and i3 joined by my old ActiveE before I turned it back in.
So i3 REx it was for me, and fortunately I'm very happy it worked out that way. Without the reassurance of a long range EV like Tesla's offerings, there will indeed be some cases where the limited range of the sub-100 mile EVs require you to alter your plans or make compromises. I accept that because for me the advantages of driving electric far outweigh any small inconveniences that occasionally arise from the limited range or charging times. However the range extender option on the i3 was inciting because I knew I'd be driving on electric for 95% of the time, but still be able to take the car on days that I knew I needed to drive further than the range could accommodate. That has indeed held true because I have a little over 11,000 miles and only about 500 of those miles were with the REx running. However so far the REx was just a convenience, allowing me to take my i3 on days I needed to drive far when I otherwise would have taken one of my gas cars. I hadn't faced a situation where I really needed the extra range, and didn't have any other options, until last weekend.

Plugging the tire
My wife and I have two gas vehicles besides the i3. Meredith drives a Chevy Equinox and I also have a Toyota Tacoma pick up which I use when I need to haul large items like refrigerators for my restaurant, and I also use it to plow my driveway and the parking lot of the shopping plaza that I own and manage. These are our long range cars for trips like when we go to my in-laws in Vermont. So when Meredith needed to go on a company retreat which was 95 miles away in Pennsylvania she naturally planned on taking her Equinox. About a half hour before she was ready to leave, I went out to the garage to give the Equinox a once-over. I always do this when she's going far from home, just to be safe. The first thing I did was a quick visual inspection of the tires and wouldn't you know it, the first tire I looked at had a large screw sticking right into it and in a perfect position for me to see it. OK, there is no time to fix this now so the Equinox is ruled out. No problem, I'll load up her stuff into the Tacoma and she'll use that. It can use a good run anyway since we barely ever drive it. I then remembered that I needed to refill the washer fluid because it was empty the last time I drove it. I popped the hood, filled the fluid and when I closed the hood I heard a loud cracking noise and the hood popped back up. As I lifted the hood I could see the latch that holds it closed was rusted and cracked in half. With no way to secure the hood closed that rules out the Tacoma. There's only one option now, she'll be REx-ing it to the retreat.
The owners of the B&B she stayed were nice enough to let her charge up. They told her their son in law drives a Volt so they weren't totally surprised about a car that needed to plug in.
After a quick REx briefing (I don't think she had ever driven it in REx mode before) she was off. Since the temperature was in the 40's and it was all highway driving, I knew she'd only get about 60-65 miles before the range extender turned on so she'd be driving about 30 miles with it running. I had a full tank of gas so she wouldn't need to stop for gas on the way there, however we didn't know if she could plug in at all once she got there and she may have to drive the whole 95 miles home in charge sustaining mode. I've driven the car enough to know this wouldn't be a problem as long as she kept her speed under 75mph, other than the fact that she'd have to stop for gas twice on the way home. I did a quick check to see if by chance there were any level 2 charging stations near where she was going , but as I expected, there were none. Luckily, the bed and breakfast she stayed at allowed her to plug into an outlet they had on the garage, so she was able to charge at 120v overnight. Since the retreat lasted for four days, she had no problem fully charging even with using the car to run some local errands every day.

So even though I've used the REx a dozen or so times already, this was the first time it was absolutely necessary, and further validates my decision to shell out the additional $3,850 for it. It really makes the car so much more versatile, and allows me to not even think about the range. As others have noted, it really does allow you to drive more electric miles because you can use it for trips you otherwise couldn't with the BEV i3. Obviously, the ultimate goal is for longer range electric vehicles to become more affordable, and infrastructure to mature to the point where public charging and DC fast charge is ubiquitous. However until then, the range extender will play an important role in the adoption of electric vehicles, as it allows for utility that is simply unavailable in the vast majority of today's electric vehicles. 
Trip stats: I was very happy to see 3.7 miles per kWh considering it was about 70% highway driving, with the cabin heat on the entire time.

Stats from the trip:

Going to PA: 61 miles on battery, 34 miles on REx
While there: 49 miles all on battery
Coming home: 65 miles on battery, 30 miles on REx.
Total: 239 miles; 175 miles on battery, 64 miles using range extender
Total gas used: 1.7 gallons (.9 gal refill when she was in PA & .8 gal refill when she was 1.5 miles from home). Averaged 37.65mpg while REx was running.


  1. Great post! This is exactly why the range extender is selling at a higher rate than the all electric i3. These things happen from time to time and the range extender removes the limitations of the pure EV

  2. Flap of Freedom, baby! Woo-hoo!

  3. Just curious, how many kWh does it take to fully charge the battery from a 120 V socket ? And what about outdoor temps, is it all the trip in comfort mode ?

    1. It takes about 20kWh to fully charge unless the thermal management is ruining to heat or cool the pack in which case it can be couple kWhs more. The whole trip was in comfort mode. Honestly I don't see much a difference in the different driving modes. It's all how efficiently you drive. Slow acceleration, optimum use of regen, etc will have a bigger impact on your range than any driving mode can. Yes, Eco Pro+ can definitely add a few miles to your range, but nothing like the 20+ miles that BMW claims. If order for you to get that kind of an increase, you'd have to be driving in controlled conditions at a constant low speed (like 20mph). Realistically, I don't expect Eco Pro to add anything to my range and maybe 4 or 5 miles for Eco Pro+, but most of that is because I'm driving slower anyway. Your right foot is the best "Eco driving mode" you have.

  4. Hey Tom, I just bought my REx 10/24. I love it and couldn't agree more with your post. I'm in Southern NJ, with a 20 mile commute into Wilmington. I'm not seeing much difference in the eco modes either. I'm wondering whether part of that is the time of year here and not much need for heat or a/c. I have to admit I'm a bit addicted to trying for getting 5 stars in the eco modes. Anyway, my driving habits are very consistent, just back and forth to work. Anything with the kids or long trips to my family in North Jersey we always take my wife's car. I was convinced I wouldn't need the REx, but bought it anyway and already glad I did. I decided to shoot over to my son's tennis lesson after work and had enough miles on electric to do it, but missed my exit, had to drive up 3 miles to the next exit and back down. That was all it took to kick me into range extender. The peace of mind and comfort knowing you can use the car for anything is well worth it. I've used REx twice since my purchase.

    1. Hi Joe,

      The 80-ish mile range of the i3 will work for some, but not for many others. The REx is a good alternative. It allows yo to drive on pure electric nearly all the time, but on those rare occasions you need more it's there for you. I don't think any of us with i3's like burning gas but without any legitimate alternatives and until the public charging infrastructure improved I believe it is the best option.

      You should take it up to my restaurant in Montclair sometime and recharge while we talk EVs!

    2. I may take you up on that. Thanks Tom. I haven't been by the Montclair area in many years. I went to Montclair State for a year back when it was College, think it's University now. I do have a NJ related question for you. NJ requires front license plate. Dealer just got them and is mailing to me. I just realized the bracket isn't even on the car, but they left me one in the trunk. I don't want to start drilling holes or anything. I can bring it to the dealer to do, wondering if I'm complicating it and easy to install. Thanks, any help welcomed.

    3. It's not too difficult, I did mine myself. There are two pilot dimples on the bumper to align the plate holder. You then just screw the plate holder to the plastic bumper cover. I drove my car for about 3 months before installing it but once I started getting pulled over I decided to put it on before I get a ticket. The car is so distinctive, it attracts attention, and that included police officers.