BMW Range Extender Explained

What is a range extender? Is the BMW i3 a hybrid? In this video we try to explain one of the least understood cars on sale in America. What is the range extender, why does it exist and what's it like to live with one.

[evingmadeez]

If you have this BMW i3 with Rex you can get the computer to reset to Europe mode.
that way you can put the EV on hold use the gas to charge it at any time.

[krrk]

You just explained the best point of i3 better than BMW!

[AnonymousFreakYT]

The 6.5% SOC limit is the most obnoxious. Especially when combined with the range limit. It means when you get low on gasoline in REx mode, you have to stop for gas *IMMEDIATELY*. You have only a couple miles of range left. It also means that if you are going to be going on a road trip where you know you'll go a while between gasoline refills, you may be hosed. 160 mile drive, where the last gas station before your destination at the 80 mile mark? Tough luck, you won't have used any gasoline yet, and you'll just barely be squeaking in to your destination.

Got a used i3 REx a couple weeks ago, and took it on a trip to the coast. ~90 miles to the coast, over large hills (or what East Coast USers would call "mountains.") with no gas stations for the second half until you were right at the coast. Made it on just EV power, got there, only to discover that the only level 3 charging station is the wrong connector. Oh well, REx it from there. Drove up the coast, arriving at the next level 3 station with about 3 miles of REx range left. Couldn't have filled with gas at the first town, it hasn't even used any gas left. No gas stations in between.

Had I been allowed to use "Range Hold" mode, I would have done that for the initial trip, and arrived in the first city with gas tank empty, and plenty of electric range; filled up with gas, and not had to worry about charger problems.

The day after I got home, my bluetooth ODB-II adapter arrived, and I unlocked both Range Hold mode and the full tank size. Took another "range stretching" trip yesterday with no problem. "There and back" was pretty much exactly the maximum range of battery+REx, with about half of it on freeway. So I used battery to get to the freeway, then switched to REx for the freeway drive one way, switched back to battery in the city on the other end, back to REx for the freeway drive home, ran out of gas pretty much right when I got off the freeway, with enough electric range left to stop at the gas station and get home with 10 miles to spare. Got home with a full gas tank, and battery to spare, rather than having an "empty" gas tank (really 1/3 full, but with the artificial US limit) and empty battery barely limping in to the gas station.

[mitchellbarnow]

I'm really happy that you explained how this system works. I'll stay with my PHEV, with it's 500 miles of gas in the tank for road trips and enough battery range for daily short commutes.

[gopimanne]

The best and clear explanation I have heard on REX so far. I always have trouble explaining the REX to others.

In 2014-2016 models, the battery is only 22kwhr and they software limit the gas tank to 1.9 gallons to avoid the california law. But its easy to code the BMW to enable to the hold mode and enable full gas tank in older models.

[glennmartin]

Ah! Thankyou. You've given me the information I needed. Every description I've come across said the extender is only meant to help the I3 make it to the next charging spot. So there's no limitation on refilling the tank. I wonder if you can buy a rig to hold a jerry can on the back.

[Trendsetic]

Very good explanation. True explained better than almost any video out there.

[jybe]

Extremely clear. Subtile compromise between securising autonomy without becoming a sort of diesel-electric car.

[Phrancis]

A decade before Tesla there was a small EV sport coupe called the "Tzero" It had an optional towed trailer with a gas generator to extend range in an essentially "series-hybrid" set up. The Volt is probably more affordable and pragmatic. A cheap pure EV for city commuting and renting a regular car for occasional road trips is another way.

[ebernier]

It seems like Florida is a perfect state for the I3 REx. Very flat terrain.

[texmex]

I have the i3 REX 2017. 120miles on the battery 100 on the extender. Have taken a 1000 mile road trip with about 1/2 begin on the extender. Never got into limp mode, and never had a problem other than knowing I had to fill the tank often when on the REx.

[donswier]

"Perfect is the enemy of good" is how to describe the EV situation. The BEV absolutists are harming their own cause.

After living with a REx for 2 years, it has been both an ideal commuter and road trip car.
25 gallons of gas last year for 24, 000 miles of driving (plus $500 of Northwest hydro power) is green enough for us.

Having more range extended vehicles would cut weight of cars (vs BEV), reduce need for both huge batteries and Rare Earth mining. It would allow seamless road trips that don't require half-hour to 6 hour charging stops.
It would nearly eliminate need for a multi-billion $$$ public charging network. It would work for rural folks, high-rise and apartment dwellers.

The cost of running the REx generator for us is about 4x compared to a charge from home, so that's plenty incentive to plug in for pure EV driving.

[theevermind]

It's a true series hybrid.

And memes aside, a detachable trailer with generator is a fantastic idea for EVs. Leave the weight off when you don't need it (regular driving around town), and then just hook up the generator like a bike rack when you want to go further.

I also think that a simple & obvious hack for the i3 is to fit it with a larger gas tank. Change it to a 6 gal tank, and BAM! another 200 mi range. The ultra-poor man hack would be to simply haul around a couple 2 gal cans which you fill up at the same time as the car's tank, so you just pull over, dump one into the car, & continue driving.

[robertp.wainman]

Why haven't 'range extenders' become popular? For me it eliminates the range anxiety of all electric.

[supraphonic]

I avoided this by getting the i3 BEV and planning my trips well in the first place. No need for a backup.

[Bodzio]

What is the max kWh this generator can do? I noticed that generator works at different power as well. The faster you drive the harder it works. I’m curious if could hack it just to use as the backup charger than to keep up level of the charge.

[rickybobby]

Were there changes to the range extender’s output in different years or models? I had a 2017 i3 that would loose battery if driven over 57 mph while on range extender. My newer 2019 seems to do pretty well at 65mph on range extender.

[thomasblaesi]

Alex, I own a 2014 i3 REX. You can easily get it in "turtle mode" going over Hwy 17. It happened to me once. Now I have the car coded and can switch on the REX manually.

[theamazoner]

Alex does the Rex use the 12v battery to start the engine or does it use the generator like most hybrid cars out there.

[mglmouser]

it's hard to convince all the gas sippers out there that a 2.4g 100 miles tank wont give them range anguish. In that respect, the Gen2 Volt makes so much more sense with it's 600km tank.

Funny thing is that after 18 months of driving a Gen2 Volt, it's when I drive my legacy gas car that I'm nervous about the gas tank.