[NH Buzz]

Hello all. On Wednesday I picked up a new i3 with range extender. I live in southern NH. I have been driving a leased electric drive Smart Car for a year and a half - 8,000 miles. I have a Clipper Creek 25 amp level 2 charger in the garage. So I am pretty familiar with living with an electric car.

I do have a few questions about the i3, though. I'm sure I'll have more questions as I get more into it. Any help would be appreciated.

1. It appears, based on my typical usage and the i3's EV range so far, that I could go for months without using the range extender. But, based on my experience with motorcycle engines, I suspect this is a bad idea. In any case I'll probably want to put a little fuel stabilizer in the tank. Of course I can always intentionally run the battery down and force the REX to run for a while. I read in another post that someone has developed a patch to take control of the REX, but I do not feel free to make such a modification to a leased vehicle.

2. The dealership I got it from has a "genius" working there: that's his title. He's supposed to know everything there is to know about this vehicle. He, and the salesman, claim that the BCM (battery control module) only allow use of the top 30% of the battery pack's charge, and that 70% is held in reserve and not usable under any circumstances. They claim that this is to prolong battery life. I absolutely cannot believe this. In the first place, that would be so utterly wasteful of capacity when energy density is the big issue with electric cars. Apart from that, if the design was to limit usable capacity to 30%, it wouldn't be the top 30%: it would be in the middle somewhere. It's not best practice to constantly be "topping off" the charge, nor is it good to discharge all the way very often. So, I'm guessing the usable capacity is 70%, and it's in the middle range somewhere, and the "genius" got it backward. Does anyone have any concrete information directly from BMW on this? Is it in any documentation somewhere?

3. I've seen in several posts here claiming that the car will run (kind of) on the range extender alone, with the battery depleted (or as depleted as the firmware will allow it to get). This seems hard for me to believe, as it's only a 650cc scooter engine (BMW makes scooters, and I am told the REX is based on an adapted BMW scooter engine). Anyway, if this is true it means that the car has, essentially, no range limitation at all. Carry a 10 gallon gas can, and you're good to go. However, this is another claim that I have trouble believing. Has anyone here actually done this, personally? Not interested in what someone has heard. Only direct personal experience.

Those are the questions I have so far. I'm still learning about all the bells and whistles and getting used to one-pedal driving. I love this car! I'm so glad I did this.

Thanks in advance for any help on these questions.

Dave

[Epirali]

Originally Posted by NH Buzz

2. The dealership I got it from has a "genius" working there: that's his title. He's supposed to know everything there is to know about this vehicle. He, and the salesman, claim that the BCM (battery control module) only allow use of the top 30% of the battery pack's charge, and that 70% is held in reserve and not usable under any circumstances. They claim that this is to prolong battery life. I absolutely cannot believe this. In the first place, that would be so utterly wasteful of capacity when energy density is the big issue with electric cars. Apart from that, if the design was to limit usable capacity to 30%, it wouldn't be the top 30%: it would be in the middle somewhere. It's not best practice to constantly be "topping off" the charge, nor is it good to discharge all the way very often. So, I'm guessing the usable capacity is 70%, and it's in the middle range somewhere, and the "genius" got it backward. Does anyone have any concrete information directly from BMW on this? Is it in any documentation somewhere?
Dave

I guarantee you they got it backwards. Almost all EVs in normal use with only go from 15-20 to 80-90% as Lithium Ion batteries are most damaged when fully empty or being fully charged. So the 70% in the middle is more in line. And I would guess (sorry don't have any doc) that its more like 75-80%.

[jadnashuanh]

The i3's battery is 22Kwhr. The usable portion is in the range of 18-19Kw depending on temperature and condition. The computer logic won't let you use either the top or the bottom of the battery capacity.

The REx logic will automatically turn the motor on periodically (something like 6-weeks) for about 10-minutes, even if you don't need it to maintain charging. It won't do that until the battery is discharged a bit so that there is some room to put the additional charge.

Most people get around 4-miles/Kw when driving th evehicle on average...the 34Hp Rex can essentially keep up, but not if you're traveling at higher speeds or climbing a long grade.

If you aren't climbing long grades or driving fast (averaging more than say 56mph on the highway), you can just fill up with gasoline and keep going. IF you are, you'll gradually deplete the battery during those times, and while the car won't 'stop' while it still has fuel, it may reduce your speed and shut off the a/c or heating. The REx takes a bigger hit in the cold than the BEV because to warm the cabin, it's resistance heat verses the more efficient heat pump in the BEV.

[NH Buzz]

Originally Posted by jadnashuanh

The i3's battery is 22Kwhr. The usable portion is in the range of 18-19Kw depending on temperature and condition. The computer logic won't let you use either the top or the bottom of the battery capacity.

The REx logic will automatically turn the motor on periodically (something like 6-weeks) for about 10-minutes, even if you don't need it to maintain charging. It won't do that until the battery is discharged a bit so that there is some room to put the additional charge.

Most people get around 4-miles/Kw when driving th evehicle on average...the 34Hp Rex can essentially keep up, but not if you're traveling at higher speeds or climbing a long grade.

If you aren't climbing long grades or driving fast (averaging more than say 56mph on the highway), you can just fill up with gasoline and keep going. IF you are, you'll gradually deplete the battery during those times, and while the car won't 'stop' while it still has fuel, it may reduce your speed and shut off the a/c or heating. The REx takes a bigger hit in the cold than the BEV because to warm the cabin, it's resistance heat verses the more efficient heat pump in the BEV.

Thank you, jadnashuanh! Very good information. If you don't mind my asking, where can I find the source for this kind of data? I haven't gotten through all of the owners' manual yet, but I'm pretty sure that level of tech knowledge isn't in there.

[jadnashuanh]

A lot of that info is in the user's manual...do a search on the i3 genius training...many of the documents were posted.

[NH Buzz]

Originally Posted by jadnashuanh

A lot of that info is in the user's manual...do a search on the i3 genius training...many of the documents were posted.

Thanks!

[InsanePineapple]

There are a few reasons why gas go bad if it sits too long:

1) Evaporation
2) Water Ingress
3) Oxidation

The fuel tank on the i3 is sealed and pressurized (which is why you have to wait a couple of seconds after hitting the fuel door button, so it can vent). This takes care of all 3 issues, so the fuel can sit in the tank for a year or more without a problem. The REx will also run a maintenance mode every couple of months or so, for about 10-15 minutes.

In my experience, the REx can sustain about a 65mph cruise with the A/C on, if the road is relatively flat.