Thursday, October 16, 2014

BMW Working on a REx Upgrade to Increase Performance

The 650cc twin cylinder engine used in the i3 is borrowed from BMW's Motorrad division and modified for the REx

From the first word that the North American version of the i3 REx would have restrictions not found on its European counterpart, i3 enthusiasts and customers in the US and Canada have wondered how well it would work under strenuous driving conditions.

In fact, it is by far the topic I now get the most correspondence over. I have probably received over 100 emails through this blog from followers that want to know how well the range extender works and how capable it is. People want to know things like what speed the car can maintain in charge sustaining mode and for how many miles can the car maintain highway speeds on a certain percentage upgrade, and so on. I even have had people ask me if I could conduct specific tests with my car to confirm it can do what they need it to. The reason being is the 34hp REx engine can only deliver about 25kWs (although some reports say BMW upped it to 28kWs) of power. That is plenty of power for nearly all normal driving needs, but not enough for continued high speed or long upgrade driving. The problem then arises if you continue to consume more energy than the REx can deliver.
My i3 when the REx turns on. Notice the tiny little bar of electric reserve to the left of the triangle. That indicates the 6.5% SOC position where the REx initiates and tries to maintain. There isn't a lot of buffer there for strenuous driving conditions.

The root of the problem reverts back to BMW's desire to have the i3 REx certified a BEVx vehicle by the California Air Resource Board. This allows BMW to get the most ZEV credits per vehicle, and also allows the i3 REx to qualify for other perks, like sales tax exemption in New Jersey and Washington State. It also allows the owner to get the full $2,500 California CVRP rebate, unlike all other PHEVs which only get $1,500. However this came with a cost, one that everybody with an i3 REx from every state has to endure. BMW had to restrict the REx use to comply with CARB's BEVx classification. The European i3 REx can be manually turned on any time the state of charge is lower than 75%. This is called a Hold Mode and allows the driver to hold a higher state of charge and keep a higher battery buffer which they may need for continued strenuous driving conditions later in the journey. The North American version has no Hold Mode, and the range extender only comes on when the battery is reduced to a critically low 6.5%. For normal driving that is fine, but when really pressed for continued periods, the car cannot maintain full power.
The European i3 REx has a Hold Mode which allows the driver to manually turn on the range extender if they need to. This feature is disabled for North America and is that is the root of the problem.
This creates a problem when the driver needs to drive for an extended period which demands an energy draw of more than 25kWs. The meager 6.5% battery reserve can quickly deplete in these conditions. When this happens, the car goes into a reduced power mode and can only maintain a speed of about 40mph. To make matters even worse, the driver gets no warning and the car just slows down. This is not what you want happening to you when you are on a highway and cars are whizzing by you at 70mph. This is a real issue, and compounded by the problem that most BMW client advisers didn't know how to communicate this to the customers and sold them the cars without informing them how to properly operate the vehicle in REx mode. I've had people contact me that were completely unaware of how the range extender worked and said they were told by their client adviser that "the car can do anything in range extender mode as it can in all electric mode, it just doesn't have quite as much power." That isn't true, and many early i3 REx customers were disappointed when they found out they couldn't drive up that mountain to their summer home, for example. In fact, one the Born Electric guest bloggers here mentioned an instance where he went into reduced power mode with a car full of friends.  
Don Parsons of Denver, Colorado recently took his i3 REx to the summit of Mt Evans which is the highest elevation with paved road in the US. He did experience the REx reduced power mode, but it didn't stop him from completing the14,000 ft ascent to the summit. This, of course is about as taxing on the range extender as it gets!
All that said, I now have over 10,000 miles on my i3 REx and not once have I ever gone into reduced power mode, and I've actually tried to make it happen! The "problem" I'm having is the highways are relatively flat here in New Jersey and the REx can basically handle anything I give it. The times I have tried to make it happen the flow of traffic wasn't fast enough for me to maintain a speed of over 75mph for a long enough period. 75 mph on relatively flat ground seems to be the upper limit the REx can handle for continued driving. There is plenty of energy to go up and down the hills I routinely drive over, and also to have short bursts of power well past 80 mph for passing if needed in REx mode, so for me the car works perfectly and I really don't need a modification. However my friends in California and other areas of the country that have long, steep inclines to negotiate disagree, and want to see some kind of modification to allow the range extender to turn on at a higher state of charge so the vehicle has a larger electric buffer. In fact, there will soon be a two-part post here by an i3 Rex owner in California that has been obsessing a bit over this very topic. (well, I call it obsessing, he calls it studying - I'll let you be the judge when you read his post next week!)
The Chevy Volt has a much more robust range extender engine and can operate under just about any condition without an issue. However it has about half the electric range as the i3 REx, meaning you will need to use it much more, so it has to be more capable. With a 70-80 mile all electric range, most i3 owners will not need to use the REx frequently.

So now that we understand the problem, what is the solution. Should BMW simply give up the value of the BEVx designation and allow the driver to initiate Hold Mode as the European i3 REx owners can? That isn't happening as far as I can tell. What I do believe is going to happen? Well for starters there will be software updates that include better indicators that the car may be headed to reduced power mode if you don't take action to alleviate it. Perhaps by slowing down 5-10 mph you can completely avoid having a problem at all. I also expect there will be a better state of charge display so the driver has more accurate display of how much power they have left. I would also love if BMW could add a display that would show the actual power draw you are using, so the driver can see if they are drawing more energy than the REx is producing. That would be an awesome tool for the driver to use in these situations and I do hope the BMW engineers consider adding it.. However I'm saving the best for last. It is my belief that BMW is working on an update that will indeed allow the range extender to turn on much earlier than the 6.5% threshold if the car determines you will need the extra power. This will work with the navigation system which accounts for topography. Once a destination is entered, the car will determine how early the REx will need to be turned on so it avoids reduced power while climbing an upgrade at the end of the journey. 
The i3's range extender sits next to the electric motor above the rear axle
While this isn't quite as good as having the ability to manually turn on the range extender, it's pretty close. The bottom line is people just want to be able to get to their destination without worry of a reduced power "slowdown" while driving on the highway. If the modifications that BMW are working on do indeed work, I don't think anyone will complain. In fact, I've privately asked this very question to quite a few current i3 REx owners and every one said as long as it works, and they can use the car to drive up long, sustained inclines at highway speeds, then they'll be very happy. From what I understand the update could be available as early as the first quarter of 2015 and will indeed be available as a software update to existing i3 REx owners.Of course it would have been better if this was available right from the launch, but at least BMW is working quickly (the i3 has only been available for about five months in North America) to correct the problem.

23 comments:

  1. Given the 15-30% reduction in power output of the REx engine here in Colorado due to the normal reduced power output of an ICE engine at altitude, I hope the BMW engineers take altitude into account as well as % Grade and road speed limit when setting the turn on point for the REx engine

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    1. After 2,300plus miles on my REx, the great "slow down" happened to me once (yes, with a full car load of friends, an embarrassment that we turned into a good laugh) but only once. Tom, I am really happy to hear about the improvements coming to the REx as they will go a long way towards alleviating anxiety. What I learned from my great "slow down' was that a little planning will go a long way. I drive my i3 across Southern California freeways two and sometimes three days a week at speeds between 68 and 80 miles per hour. My trips run anywhere from 85 to 120 miles roundtrip. Until the day we get a battery with greater range, the ever dependable REx is absolutely necessary to my needs. But let me underscore this point--just a little bit of planning will prevent the REx from going into slow down mode. Nevertheless, the improvements from BMW are certainly welcome. Tom, thanks for the good discussion.

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    2. Hi Dr B. Yes, I agree. Most people that understand how it works can usually avoid any issue. As I wrote in the post, it's never happened to me but I do admit I don't have very long steep inclines to negotiate. I do know people that do have to drive in those conditions and are able to avoid any problems by carefully monitoring the SOC and driving accordingly. However many people either aren't capable of doing so, or just don't understand why it's happening so having a solution for this is indeed the right way to go.

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  2. Tom, two things I think you left out of your article. First you mentioned 3 states that are effected by credits or tax issues, that leaves 47 states that are not. Or 47 that are being punished by 3. BMW could have easily created it so that the REx hold could be enabled in those 47 states (remember when cars used to have totally separate CA and 49 state versions?) If I can enable it in 2 minutes, then the BMW dealers in the 47 states could AND SHOULD turn it on for their customers. I am sure they are not allowed to by BMW. Shame on them. Second you should mention to people reading your article here (who are not in the i3 Facebook group) that you can enable it in the US if you want to. For those who don't, fine, but hiding information is not cool, and the consumer should at least be aware that it is fairly easy to fully enable the REx hold feature on American cars (as the 'fix' for enabling based on possible rout in GPS is a joke). - JC

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    1. I understand what you are saying and on the surface it makes sense (only restricting the REx in states that have some benefit) but I'm not sure it is that easy. I don't know if CARB will allow that and still certify the car as BEVx. Also there are about ten other states besides California that have adopted CARB standards so I'm not sure how the car could be sold in those states either.

      As for the other thing you are referring to, that is something that is just beginning to happen now and really isn't an option for the vast majority of people because they don't have the knowledge or equipment to do so. That being said I do plan to do a dedicated blog post for it in the coming weeks. Not hiding anything here

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    2. Judging the number of people who are trying to enable the hold mode, risking potential warranty hassles, means that significant number of people are NOT ok with BMW's proposed fix. I As the OP said, the mod only takes a few minutes. Therefore it should be easy for BMW to support two software that is only slightly different.

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    3. Edmond, nobody even knew about the proposed software changes until this week, much less how robust it will be. I've talked with dozens of i3 REx owners and everybody basically said they would be fine with it as long as it works correctly and allows them to get to where they are going without any safety concerns or slow-downs. That won't satisfy everybody, and the i3 REx won't satisfy everybody. The best way to communicate this to BMW is not to buy the car if you don't like how it operates instead of getting one and then wishing it was something it wasn't. That or coding it yourself as some are doing :)

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    4. We did not get what we paid for. Those of us in the non CARB states got ripped off by BMW. I got the news after I placed my $1000 non refundable deposit.

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    5. "The best way to communicate this to BMW is not to buy the car if you don't like how it operates instead of getting one and then wishing it was something it wasn't."

      I bet a lot of us were truly shocked by the last minute changes to the REx by BMW, including the missing REx hold mode and reduced fuel tank capacity. Purchasing the car doesn't mean I need to be happy with everything about it, especially when there is no other crossover electric car I can buy. There is no perfect car for everyone, that is why there is a long wish list in the file section in our group. Some of us are very passionate about this feature than the others because it is more than just a convenience feature. BMW really crippled the car when it could be much more.

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    6. The reduction from a 2.4 gallon tank to 1.9 gallons was indeed last minute and was actually a surprise to BMW also. The range extender hold mode was not last minute though. BMW announced that last November, months before they ever took any orders in the US. The problem I see is many of the dealers didn't fully understand how it works and couldn't really explain it to the customers so there were definitely people that bought the car but had no idea how it actually worked. That is indeed unfortunate and likely grounds for a buyback if the issue was properly pursued. I totally understand why you or someone else would be more passionate about it. As I said above the REx has always performed perfectly for me so how can I complain. That being said, I still wish it were available here with the same functionality as the Euro spec car is, just as you do. If for no other reason than there would be no ongoing controversy as there has been.

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    7. Sorry, but I've just got to pile on here. Washington state is not a ZEV state, and despite what you said above our sales tax exemption isn't dependent on meeting CARB BEVx requirements. (Ironically, if one version of my bill on the subject had passed, it might have been, but we dodged that bullet.) As someone who lives in the foothills of the Cascade mountain range, I'm regularly hitting this "reduced power mode" and it's completely embarrassing and demoralizing to be passed by fully-loaded tractor trailers when crossing Snoqualmie Pass. This isn't the BMW experience that we were sold when we test drove the EU version of the BMW i3 REx with Range Hold, Traffic Jam Assist, 26% larger fuel tank, and a sunroof. I'm a lifelong BMW fan, but I'm very bitter about this particular issue and have been encouraging folks expressing interest to hold off until the car is no longer crippled for the US market.

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    8. Hi Chad,
      Thanks for chiming in on this here. That's interesting because I believe most people think that the BEVx designation was the reason (or at least one of the main reasons) that the Washington legislators gave the REx the same tax exemption that you give ZEVs.

      If that isn't the case, and I'm definitely not doubting you, then can you explain how the car did become tax exempt? Other PHEVs like the Volt are not tax exempt there, and the i3 REx is the only PHEV that is. Is there a set of characteristics or requirements that make an extended range EV qualify for tax exempt status and if so can you post them here, or do you just look at it case by case which wouldn't sound very fair for the other automakers?

      Thanks again for commenting here again.

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    9. "This isn't the BMW experience that we were sold when we test drove the EU version of the BMW i3 REx with Range Hold, Traffic Jam Assist, 26% larger fuel tank, and a sunroof."

      Curious to where you drove the EU REX. All of the EU cars used in the US for test drives were BEV.

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    10. That is correct anonymous. BMW didn't begin to allow i3 REx test drives to the public here in the US until after the car actually launched in May. All of the cars brought over previously for the test drive events like CES and the LA Auto show were loaded BEVs with sunroofs.

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  3. As a new bmw owner, where is bmw in all this? I have called bmw and sent emails that have yet to get a response. It is bad customer service.

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    1. Have you called your BMW i Concierge? That should be where you start.

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  4. Just curious, what (gasoline) fuel economy do you usually get in Rex mode only ?

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    1. It really depends on how spirited I'm driving, bu tI've seen anywhere between 33mpg and 40mpg

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  5. Can someone please post the link to the facebook discussion on how to enable the hold state of charge mode? I probably wouldn't do it but would love to see what the process is. Thanks.

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    1. If you do some smile google searches for BMW i3 coding, you'll find the forums that are discussing it. On Facebook there is the BMW i3 group the I started a few years ago and there has been discussions there also.

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  6. I own a I3-REX since 1 month now, 60 miles commute everyday. I do not need the REX but just peace of mind and I can drive the speed I want including Clim or heater, radio, all in comfort mode without worrying about the range. I spent 12 hours total reading about coding I3 (including downloading +5GB files) , bought $20 cable. He took me 30 min first time to code the REX as it was intended to work. I did some experiments after that, above 75 the battery is still discharging with REX on, below 70 the battery is charging! I added other features yesterday adding AM radio and removing annoying disclaimer screens in less that 10min. I love this car for commute, it is so relaxing to drive.

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  7. A fix that requires input of your destination into the navigation system is really no fix at all, in my opinion. Because of the integration with my mail and calendar, I much prefer using Google Maps on my smartphone for navigation, and so I've never actually used the built-in iDrive system for driving directions. Also, this approach again ignores John Higham's point about the need to enable spontaneity. If you haven't planned ahead and managed your trip carefully, you'll quite possible be power limited on the range extender after it's too late to do anything about it. Honestly, all I want here is a manual override for the 6% setpoint, something I can set even after the SOC has dropped below that level. The range extender at that point will just make every effort possible to maintain or restore that SOC, taking advantage of the flat or downhill topography when its available.

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  8. 2015 I3 Rex
    Hi All,
    Love our i3 - but the great slowdown is dangerous. We also live in NJ and have been traveling up thru bear mountain of ny lately (85-100mile round trip) after the 60miles of battery power is deepleted we hit the long steep high speed incline on 9W - the car slowed down to a 40mph without warning - not fun - also dangerous.

    This was when we first starting doing trips with the i3 - so I was still learning and yes driving style can be adjusted - but that will not help on a steep long incline - 6% is just not enough batt power and the rex strains / races to give enough killowatts - thats a losing battle.

    Here's what was what put me over, on the way back to the city we decided to take the ny thruway - we only had rex power - hindsite is 20/20 yes.
    On the nystate thruway gas stations are 30-40 miles apart and even though we were full - the rex stopped as we tried to make it to the next stop (10miles more to go!) in the middle of the night - fun:) She fired right up after dino juice was added - even though shaniqua at bmw roadside insisted we get towed because "once the furl is depleted the gas engind will not turn on - the car must get fully charged) Not true - the rex started right up and we were back on our way (after an hour waiting)

    Then I find out the eurorex has 2.4 gallons - not 1.9 and that it is only software holding us back.
    So contrary to bmw roadside and the car - it actaully wasnt out of gas :0

    Looking for that mod if anyone knows where it is?

    Also I mod'd and unlocked the hold state of charge yesterday before our trip upstate again.

    Amazing difference - Im able to hold the batterys charge during highway driving - zoomed up that same hill that I had my hazzards on the week before, and truly feel safer in the car. Driving along with 75% battery and using the rex when you need it alleviates range anxiety
    - using all your battery then driving at 6% with the rex engine humming away to make power but not enough - generates anxiety.

    We did almost 200miles (country cruising as well in our i3 this saturday, yes 2 fillups and a full charge - But no issues at all powerwise - nor issues making it to the next gas stations - hint it is MUCH better to risk running low on gas with electric power left - then the other way around!

    Most of our daily driving is under 40miles so its always in elec mode. We love our i3 even more now that it is unlocked


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