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I3 range extender vs. volt

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hello all,

I'm a little confused. Have watched a couple of reviews about the new BMW I3 and i don't know exactly how the range extender works. Some reviewers claim it works much like the volts. When the battery is depleted, the gas engine kicks on and powers the vehicle. In a volt, you can run out of gas, refill, and keep going. Hell, you can use the volt as a basic hybrid and never plug it in if you wanted too.

The I3 i'm not so sure about. Couple reviewers give the impression that it operates like the volt. However, a few reviewers say otherwise and i find their view more accurate. They say that the I3's range extender can only add about 70 miles to the overall range but YOU CAN'T just fill up the gas tank again and keep going.

Makes sense because the I3's engine is only a 600cc motorcycle engine. i don't think it could provide enough power to solely propel the vehicle.

In that case, i compare it to the volt in ERDTT mode. Ex, at -9 Celsius, right before the ERDTT mode kicks on, i can get about 40km's on pure EV power. At -10, ERDTT kicks on and my range can go up to nearly double (80km) in 'pure' EV mode. So i guess the I3 range extender works like that. It can increase range but can't solely power the vehicle.

I3 range extender version is estimated $10,000 more then the volt.

SOOOOO, if i'm correct and the range extender can't power the I3 like the volts system can, then the max range of the I3 is about 120km pure EV, volts is about 70, then with range extender, i3 max range is 230 km and volt is limitless! In that case, you can't drive the i3 (even range extender version) for more then 230km without charging it back up.

If this is true, why are volt owners here considering switching to an i3?????? your paying much more for, i believe, inferior product. Yes the i3 does have its own cool features that the volt doesn't, but so does the volt, and with a volt you have TRUE NO RANGE ANXIETY. an i3 would still give me range anxiety... i could never travel more then 230 km without charge.

I could be wrong, the i3 probably can run solely on gas, like the volt, but if not, why are volt owners even talking about it? Why so much hype around the i3 and so little around the volt?
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My undersrtanding with the I3 is its range extender is about the same as your understanding. The I3 ICE will generate elecricity, but the I3 capable of using more than it generates so the batter is slowly drained. Its my understanding that the I3 could drive with the ICE only, but at very low speads (its a small to mid size motorcycle powering it). So why an interest in and I3? Well its a BMW which will attract attention simply on the brand name. Also, people buy Nissan Leafs which definately have a range limit, so the range limit does not bother some people. Different people have different needs. As for the media comments, the Volt is probably the closest vehicle it can be compared to ... and remember how accurate the media has been reporting on the volt (just kidding).
 

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Discussion Starter · #3 ·
reviewers drive me nuts

haven't heard one of them complain the i3 only seats four but almost all of them complain about that on the volt
haven't heard many of them complain about rear seat room but almost all complain about the volts
haven't heard them complain about the proprietary charge connector

its stupid..... the reviewers make the i3 seem superior to the volt even though it shares many of their same complaints about the volt and then some!
 

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There's still an unfortunate lack of detailed information on the range extender version. Having said that, I'm reasonably confident that you could just fill the gas tank and keep going. Of course, you'd have to do that every 60 miles out so, which would be quite annoying...

The larger battery range would mean never using gas except for road trips, in my case. Rear wheel drive, more electric power, taller sitting position. So yes, I can see some reasons to consider it, even as a Volt owner.

In my case, I do take a number of short and medium road trips, and so the 2.3 gallon gas tank is a non starter - and a ~20 kW ICE with no ability to turn it on early is pretty undesirable. But if it had Hold and Mountain modes or similar and about 10 gallons of gas, I'd be seriously considering it for my next car (which likely won't be for a few more years anyway - and it'll have to compete with a used Model S and Volt 2.0 for my money. Possibly also the next generation Energi twins and Outlander PHEV, depending on what they turn out like.)
 

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Volt - "Electric when you want it, gas when you need it."

i3 answers the WANT more than twice as much, and may be better if you find yourself eeking out your battery's range much of the time.

30 miles isn't enough for me in Winter, and I'd take a couple more gas stops on long trips rather than getting caught up managing range in my 45 mile days.
 

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The i3 with range extender option does operate similar to the Volt, except:

1) the engine is not powerful enough to climb long grades at speed
2) the gas tank is less than 3 US gallons, so you have to stop and fill up every 60-70 miles. Not good for road trips, and a major disadvantage compared to the Volt in my opinion.

GSP
 

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I'm not certain on my answer but this is what my understanding is.

The i3 range extender is a pure series connection like the Fisker Karma. I believe the gas engine acts as a generator to maintain the average power demands of the vehicle while trying to maintain a certain battery buffer. While just like the Volt the i3's EV powertrain can use more power than the generator can provide the battery buffer should make up for this under most circumstances. Keep in mind it's very rare for a car to need anywhere neer it's maximum power for an extended period of time. However during steep inclines or periods of long acceleration and sharp deceleration (like racing) would likely induce a reduced power output.

Not too much different from the Volt however the Volt has the added parallel function for more efficiency under certain circumstances.
 

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I view the i3s big compromise is a new type of range anxiety, once I run out of juice can I make it to the next gas station? It amazes me that the volt still remains ahead in EV range and fuel flexibility combined. The Cmax EV range is too low and the i3s fuel range is just silly. I kind of expected someone to provide some serious competition to extend EV range and have a fuel option, and the i3 could have done it by just adding a bigger fuel tank, but now there are doubts. Well have to see what happens when real people buy and use the i3 and give their real world impressions.
 

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I've read over on a BMW i3 Forum that the 600cc extender can in fact maintain the the batteries needed SOC of around 5% and allow you continue driving until needing fuel then you can continue refueling and driving like the Volt albeit much sooner due to the smaller gas tank.

So it appears the i3 REX can be operated like a Volt.
 

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Discussion Starter · #11 ·
range extender

so Iconfirmed, the range extender is simply an emergency back-up to provide some power to extend the range. The i3 can't be continuously powered by the ICE. Makes sense seeing as it only provides 20KW of power. I've seen the volt draw almost half of that just to heat the cabin and battery on really cold days. Also, BMW wouldn't offer free car loaners if the i3 could keep going on just the ICE.

that being said, 90% of my driving is in EV mode. I wouldn't have gotten a volt if it wasn't. a dodge dart would be more economical. of the remaining 10%, half the time, yea, an extra 20km of battery would've got me home. The other half, its a longer road trip.

Would you still get an i3 over a volt? considering the $10,000 premium?
 

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I think BMW has primarily promoted it as a city car.

With the range extender it's a city car with range extension to allow you to push the range without anxiety.
 

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Discussion Starter · #13 ·
True its a city car primarily but at that price point, with the drawbacks it has, I don't find it reasonable to swap a volt for it.

I was researching the i3 because frankly, I was considering a swap. The only benefit is a slightly extended EV range at a cost of not being able to continuously run on fuel. Doesn't seem worth it, even worse because of the premium added cost.

If BMW made the i3 about a foot longer and wider, the rear seat could comfortably seat 3 adults and if they swapped that 600cc motor for a 1.2 litre diesel that could run the car continuously... I would happily pay an extra 15,000 for it. In the end, it just doesn't hit enough points that the volt is lacking. It only hits one, a little extra EV range but at a hugeeeeeee cost of not being able to run continuously on fuel.
 

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reviewers drive me nuts

haven't heard them complain about the proprietary charge connector
Mikeyvolt,
North American version of i3 has the same DC fast charge option as the Spark EV with DC fast charge option. It's called the SAE Combo DC fast charger: http://media.gm.com/media/us/en/gm/...ges/news/us/en/2013/Jun/0611-fast-charge.html

It's the new SAE standard for fast charging, rolling out in North America as we speak. It is backwards compatible with our L1 & L2 J1772 interconnects deployed "all over" North America, allowing the driver to charge at most public charging stations.

It will compete with CHAdeMO which has been the DC fast charge standard in Japan. This is the fast charge option in Nissan LEAF, Misubishi i-MiEV and KIA Soul EV.

And the main reason for i3's gimpy ICE range extender can trace to CARB (California Air Resources Board) regulation on what kind of motivation qualifies an EV as a zero emissions vehicle (ZEV). Many plugins currently qualifies as AT PZEV, advanced technology partial ZEV. AT PZEVs qualify for coveted green HOV stickers in California which are limited to first 40,000 registrations. CA will hit the 40,000 cap in few months: http://www.arb.ca.gov/msprog/carpool/carpool.htm

BMW NA worked with CARB to create a category where a AT PZEV with very limited ICE capability (ICE range shorter than EV's AER) to still qualify as a ZEV, earning the white HOV sticker which has no cap on number of registrations. For reasons not explained to the public, CARB decided i3 no longer qualifies for the white ZEV sticker.
 

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BMW has allowed very controlled test reviews up to this point with the i3, often with a BMW employee along for the ride. I'm waiting for Motor Trend or Car & Driver to take the keys, ditch the BMW brass and do some canyon carving - take it to its limits.

I also think all the drive reviews up to this point have been in battery-only i3s without the range extender. Kind of makes one wonder what's up -
 

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The I3s range extender is a "limp home or to the nearest charging station" solution. The engine is too small (650cc) to provide normal propulsion and the gas tank is too small (2.4 gallons) to extend the range significantly, once the batter is depleted. However, it does solve the problem of getting stranded if the battery runs out. The intention of the generator is to take you to the nearest charging station. In other words, you can not take an I3 on an extended road trip on gasoline alone, like you can do with a Volt. Also, I3s gasoline backup is optional.
 

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That's not true. As long as you drive 75MPH or less on fairly level terrain, the range and is unlimited and performance is the same as running on the battery. You can fill up the tank repeatedly with no problems. For my use, I think the i3 REx is great - double the Volt EV miles and allows me to go on 150-300 miles trips comfortably (0 to 2 refills). Those articles are early reports, The referenced UK one being very biased (think of the negative Volt articles).
 

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The I3 range extender is sort of like having an ordinary generator you can buy at Home Depot integrated into a BEV. It basically runs at one speed and it's power output is less than the average power usage demanded by the vehicle. So when you know you will be traveling further than the battery will support, you turn on the range extender and it charges the battery. Since the generator produces less than the average power required, the battery will eventually run out of power. It sound as if the amount of power is sufficient for city driving but insufficient to maintain highway speeds or to maintain speed on hills, sort of like the Volt in Depleated Power mode except the amount of available power is way less.

The I3 specs show that it gets great range. One reason is the use of very advanced carbon fiber for much of its body making it very light. I suspect another reason for the high AER is it allows the battery SOC to drop to pretty low levels. Battery SOC is very critical with range extended vehicles because a relatively high SOC is required for dynamic conditions like starting from a stop or climbing steep hills. This is why the Volt maintains a relatively high SOC in Normal Mode and increases even higher in Mountain Mode. Pamela Fletcher, the Volt's chief power train engineer likes to describe the power flow as leading with the battery and following with ICE. This, and the fact that its ICE and generator is sized large enough to provide sufficient power to maintain the desired SOC over time allows the Volt to operate throughout its entire performance envelop in either electric only or in CS mode. Since the Volt operates the ICE/generator to maintain a target SOC, most of the power generated goes directly to the traction motor and not used to charge the battery which is inefficient. In contrast it sound as if the I3 range extender generates at full capacity whenever it is turned on. Since its output is less than the average power requirements of the car, sometimes this power goes to the traction motor and supplemented by the batter, and when idling or at light loads the power is used to recharge the battery. As such, the Volt's range extension capabilities appear to be more complex and refined than the I3's.
 
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