Buying a BMW i3 Range Extender? Read this

If you’re considering buying a BMW i3 you’ll probably know that the carbon fiber hatch is available in two significantly different guises.

The pure electric i3 is straightforward – a lithium-ion battery pack supplies a powerful electric motor and, depending on your driving style and climate, you’ll manage between around 70 and 100 miles of range.

The more popular i3 Range Extender, however, is a little more complex as it blends power from two sources: the aforementioned electric motor and a tiny gasoline motorcycle engine hidden in the rear of the chassis. BMW has released a lot of technical information on the technology, but how does a range extender-equipped i3 perform on a day-to-day basis, and what should you know before buying a i3 Range Extender?

BMW has been sending its dealership staff to ‘Ride and Drive’ events in the run up to the car’s imminent launch in the US, preparing them for nuanced questions from prospective buyers. Manny Antunes, a BMW client advisor from New York City, recently went along to such an event and has spilled the beans on BMW Blog.

Here are the important parts:

  • While most driving will be under the power of electricity alone, longer journeys will trigger the range extender engine to fire up and start generating more power. This happens when the battery reaches five or six percent charge.
  • Unlike plug-in hybrids like the Volvo V60 Plug-in Hybrid, the gasoline generator will not recharge the i3’s lithium-ion battery on the move. The only way to replenish it is to plug the car in.
  • The onboard fuel tank has allegedly been reduced in size from 2.4 gallons on European models to 1.9 gallons in the US. The reason for this is not yet known, but it will affect the i3 Range Extender’s overall range, which currently stands at 180 miles.
  • Surprisingly, the i3’s ‘frunk’ isn’t waterproof. BMW suggests buying an accessory bag to keep the car’s 110-volt charger dry. This seems absurd.
  • The sprint from 0-60mph is nearly a second slower than the pure electric i3, at 7.9 seconds.
  • Level 1 charging (110-volt) takes 20 hours for a full charge. Level 2 charging (c. 230-volt) takes just 3.5 hours. A BMW Level 2 charger costs $1,080 and can be financed along with the car.
  • While a full $7,500 federal tax credit can be applied to the BMW i3 Range Extender, only $4,875 is applied on a lease. This is because the car is registered to BMW rather than the buyer.
  • A sunroof isn’t available on US-spec cars. As the majority of US-bound i3s will be sold in California this is unexpected.
  • The onboard gasoline engine will generate electricity for the motor at speeds of up to 70mph.
  • The BMWi remote app, which can locate charging stations, pre-condition the car’s climate, and display battery charge status, is only available on Android and iOS – not Windows Phone.
  • BMW i3 Range Extender owners will be able to use BMW’s ‘Alternate Mobility’ program, which allows them to swap their car for a conventionally-powered model a few times a year. It means that owning a BMW i3 as your only car and taking long road-trips are not exclusive of one another.

Many electric vehicle buyers are rightly concerned about the longevity of the expensive battery pack and BMW will look to placate them with a eight-year/100-mile warranty. Battery packs in cars sold in CARB states will be protected by a 10-year/150,00-mile warranty. It means that should the battery pack fall below 70 percent efficiency, BMW will replace it.

Nervous buyers will also be encouraged by the fact that individual battery modules can be replaced. This is not only convenient, as they can be held in stock at dealerships, but it’s also far cheaper than replacing the entire pack – either for you or BMW.

You can find a buyer’s guide and model specs for both pure electric and range extender i3 models below.

Posted by Richard Lane

Richard is a London-based automotive journalist specialising in future mobility and sustainable design. Having fallen for cars because of the virtues of a particular German flat-six, it's what we'll all be driving next that now interests Richard most. Dream garage: Alfa Romeo GT 1300 Junior and a Detroit Electric SP:01.

  1. alf rasmussen May 13, 2015 at 7:17 AM

    Hi. Is it possible to iafter market nstall the gas range extender in an I3 that has only a battery configuration.

    Reply

    1. Unfortunately not…

      Cheers,
      TL | ecomento.com

      Reply

  2. Hi regarding the ability of the REX to charge the battery, are you saying that if you take the car to a complete stop while the REX is running that it won’t charge the battery? I know there is a regulatory issue in having the REX on when the state of charge is above 6%, but I’m wondering that in a situation where you tax the battery and REX by going uphill at regular speed so that the SOC of charge falls to say 3%, can you not pull over and have the REX continue to charge back up to the 6% limit?

    Thanks,. Chris

    Reply

    1. Hi Chris,

      In my experience the range extender generally cuts out when the car comes to complete stop – even when SOC is so low that the engine has automatically kicked in. It’s likely calibrated this way because if it’s running and you’re not moving the noise is horrible.

      That said, there have been a couple of occasions (when we’ve been driving, at least) where the engine has continued to whir away even after the car has come to a stop, charging the battery rather than merely generating immediate power for the wheels.

      Concerning the hill you mention, it’s likely that power would be reduced. I can’t say for sure whether the car would recharge if parked up and left turned on, but I suspect it might.

      Thanks,

      Richard

      Reply

  3. If I’ve a REx version and I’m on the highway, can I just refill the tank from the fuel station and continue driving? Or it has to be charged first using plug?

    Reply

    1. Hi Him,

      Although BMW will tell you that the range extender is designed to be a ‘get me home’ feature, you could theoretically charge the car up once with electricity and solely refuel at gas stations from there on. So, yes, refueling on a long highway route isn’t a problem.

      The i3 is much nicer to drive in pure electric mode, though, as we found out when we reviewed it.

      Thanks,

      Richard

      Reply

  4. I rode in a BMW i3 at a event at a dealership in Oregon that has a sunroof.

    Speed is not limited to 70MPH when the generator is on, though it probably can’t keep up at speeds much higher than this.

    Reducing the gas tank to 1.9 gallons is to satisfy California BEVx rating or something like that. The engine check light problem may be because the evaporative emissions sensor thing is calibrated for the 2.4 gallon tank and didn’t calibrate it for the smaller tank.

    Reply

  5. With all the tech. we should have the car being charged when the wheels move.

    Reply

  6. Is of possible to have two batteries and interchange them so to extend the mobility from 100 miles to 200 miles with electric power and then charge both batteries separetely?

    Reply

    1. Hi Alex,

      Yes it’s possible, but the car has to designed from a very early stage in its development with battery swapping in mind. The Tesla Model S, for example, is designed to do this, but there are a number of problems that have to be overcome.

      We spoke to a group of VW suits at the launch of the e-Golf who steadfastly believed that the technology isn’t a option right now for a number of very good reasons.

      That said, Tesla has already executed a successful battery swap in public, and in less time than it took to refuel an Audi A8. It was impressive.

      BMW has kept quiet on the subject so far, but judging from the i3’s ‘surfboard’ style battery pack it seems possible in theory. Don’t hold your breath though.

      Thanks,

      Richard

      Reply

  7. You say the range extender will not recharge the battery while on the move. I understand that the i3 has regenerative braking, which does recharge the battery when going downhill. While the range extender may not be very powerful, surely it can be used at lower speeds to drive the car so that the regenerative braking will recharge the battery?

    Reply

    1. Hi Rhys,

      Good question. The range extender engine develops 34hp so you’re right, it could modestly power the i3 if BMW desired.

      In order to turn the wheels with power directly from the engine, however, BMW’s engineers would have to fit heavy hardware, such as a new drive shaft and transmission. As the result, the price of the i3 Range Extender would increase and efficiency would suffer, so there’s nothing to be gained at all from offering the option.

      Nothing is lost by not offering it, either. As I understand it the i3 Range Extender can still recuperate energy into its lithium-ion battery through the brakes even when it’s operating in extended range mode, but the engine itself won’t recharge the battery. The generator that’s driven by the two-cylinder engine merely maintains the battery’s state-of-charge at a constant 5 percent.

      Thanks,

      Richard

      Reply

      1. The gas engine does recharge the battery, but only to maintain a SOC of 6%. So, if you are in range extender mode and driving aggressively, you may be able to reduce the SOC below 6%. If that happens, the gas engine will continue to try and return the SOC to 6%, as long as there is gas in the tank. So if you stop the car and the SOC is 6%, then the gas engine will auto-stop. If you stop the car and the SOC is less than 6%, the gas engine will continue to run until the SOC is 6%.

        Reply

  8. Are you staying electric only I3s don’t get to use the Alternate Mobility Program?

    Reply

    1. Hi Darren,

      Not at all. Owners of both the zero emissions BMW i3 and the Range Extender model will be able to make use of the program.

      As the i3 REx is essentially able to travel unlimited distances like a conventional car, it wasn’t initially clear whether BMW would extend the offer to owners. As it happens, they will.

      Out of interest, has that made up your mind to get the pure electric i3?

      Thanks,

      Richard

      Reply

Leave a Reply

Your email address will not be published. Required fields are marked *