Range Extender

Just got an i3 with range extender and my battery ran out while on the highway. The car slowed down to under 30miles/hour and I was forced to wait for the battery to charge back up to above 2% (ish) to get going again.
Is there a way to start the engine in order to generate electricity prior to running out of juice completely?
Let's say that you're about to start a drive that would take 30 miles, but you have 15 mile electricity left. Can you sit in the car, or have the car use the engine to build more electricity prior to your drive?
My point is: What's the point of generating 1% battery per mile, if you're consuming 2% battery per mile? (the data is not real, just an example) It would help if you could generate this power prior to you reaching below a certain mark.
I feel like the backup is useless unless you're driving very slowly on a normal road, without AC, sound, or anything else.

Unless you are driving > 65 MPH on the highway, mostly uphill, with the A/C &/or heat fully on on a 100 or -32 degree day, the REx should be able to produce more capacity than you are using. Assuming your car is not coded, you still have 6% buffer to start with which you have to burn through before you get "throttled."

If your performance is different, I'd get the car checked out by BMW. In the interim, plan ahead as if your vehicle is a BEV.

ArdyBay said:

Is there a way to start the engine in order to generate electricity prior to running out of juice completely?

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i3 REx's sold everywhere but in North America allow the driver to start the REx engine anytime the battery pack's charge level is below 75%. This allows the driver to start the REx engine prior to driving in a manner that consumes more electricity that the REx generator can produce which will deplete the battery pack's charge as you discovered. But BMW disabled this feature on North American REx's so that the REx could be categorized as a range-extended electric vehicle by the California Air Resources Board. This gives BMW valuable credits that allow them to sell their gas-guzzling vehicles.

The default behavior can be restored by a procedure described as "coding". Many REx owners have done this which can also enable/disable and modify other behaviors. If you have a laptop that can run Windows, you could install the coding software and, via a purchased cable, connect to your i3 to allow you to make the changes that you desire and possibly others. There are coding resources in various places on the Internet, or there are individuals who will code your car remotely for a fee.

ArdyBay said:

I feel like the backup is useless unless you're driving very slowly on a normal road, without AC, sound, or anything else.

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Other REx owners have reported that they are able to drive at up to 70 mph on a flat road with no headwind without exceeding the REx generator's output and thus depleting their battery pack's charge. So just slowing down a bit would likely prevent the power loss that you experienced.

Thanks for the info!

Yes, my commute does include hills, so it's def not a cruising drive at 60mph.

I am in North America, and my i3 is on a lease, so I'm not certain if I can code the car to operate in that way.
I'll look into it.

ArdyBay said:

Thanks for the info!

Yes, my commute does include hills, so it's def not a cruising drive at 60mph.

I am in North America, and my i3 is on a lease, so I'm not certain if I can code the car to operate in that way.
I'll look into it.

Click to expand...

You can, but you may want to save settings and restore before retuning the lease. I strongly recommend doing it, there are also a couple of other great little things you can enable that are very useful. But I always you the SOC hold with Rex around 15-20% if I know I need the REX just to have battery buffer for climbs, etc.

When your battery SOC is getting low, you really need to watch that level and adjust your driving style to let it recover or at least maintain. When your battery is nearly dead, the 34Hp engine cannot power the 170Hp electric one and all of the accessories...while things get converted, power is still power! Once you reach that critical point, all you have is that 34Hp, about what an original VW bug had, and that definitely had trouble climbing hills and certainly didn't have a/c and lots of other creature comforts dragging it down. FWIW, it doesn't matter if you have it coded, if you let your SOC get low, the same thing will happen. 34Hp can keep you going if you aren't stressing things, the battery needs to fill in the (momentary) gaps, but cannot without damaging the battery if the SOC gets too low.

My first drive, ever, in a BMW i3-REx was the drive home from Charlotte NC to Huntsville AL via I-40 and a 2,800 ft. pass. After getting the purchase contract and VIN, I contacted http://www.dvdinmotion.com/ and for $150, got a file to load on a thumb drive. A block down the road, I applied the patch and saw the option. Twenty minutes later, the SOC was low enough I could enable the REx and continued home:

• 463 miles
• 11 hours
• one short charge at Biltmore Park
• 6 fuel stops, ~1.5 each, and I'm home

The 'code' is binary. Odd numbered applications turn it on; Even numbered applications turn it off. ... Do the math.

In my case, I bought a used, 2014 BMW i3-REx with 6,440 miles on the odometer. How does this great little car go two years with so little use? Perhaps it was a dealer demo. Perhaps it was someone who had a bad experience with REx in the mountains near Charlottesville, VA. Regardless, I'm already over 8,400 miles and climbing and that was with almost two weeks of 'shop time.'

Bob Wilson