Possible smallest range extender engine

It is actually a motorcycle engine, not a scooter.

They need to have a setting to have the engine come on earlier before the battery is as depleted; and that would probably solve most of the long grade climb issues. Remember, a lot of ICE engine cars slow down up long grades, too. This is not a tragedy.

 

The EU versions can enable the REx at 75%. Bimmercode allows me to enable it as well as several other nice to have:

• increased usable fuel in tank, 1.9 to 2.3 gal
• default to more efficient driving mode, smoother accelerator
• disable passenger seat belt warning so groceries and dogs don't have to belted
• add temperature to tire pressure display

Bob Wilson

 

Bob, how hard is it to do those things? I am sure my brother would like to do at least the first 2. If you make the changes, do it mess things up when you go to the dealer for anything? In other words, do they know you have made the changes?

 

Source: http://www.mybmwi3.com/forum/viewtopic.php?f=13&t=4611

When my software was updated, I had to reapply the coding but otherwise they don't care. I keep the OBD device in the glove box. Of course I live in Alabama but it is easy enough to remove the coding before taking the car in if you're paranoid and put it back on a block away.

Bob Wilson

 

I've seen it described as a scooter motor elsewhere. Are you speaking from your own knowledge? If so, then I'll take your word for it. Your comment is the first to object to me describing it that way.

Yeah, a "mountain hold" setting. I think the Volt has that? Maybe some other PHEVs, too?

Slowing down to 55 MPH isn't a tragedy. Slowing down to 25 MPH is quite dangerous on a twisting mountain road with limited sight, where another vehicle might approach you from behind at highway speed.

See this report:

I picked up my BMW i3 REX yesterday. I live in the SF Bay Area (North-east corner). I frequently travel to the beach near Santa Cruz, CA via Highway 17 (for those who may be familiar with the area). I feared that this could be a challenge for the i3 as the base of the hill over to the beach is about 60 miles away from home (meaning battery could run out before climbing the hill).

Let me start by saying I knew that REX mode has some power limitations, and I don't expect to use the REX in daily commuting. But this is a trip I make every couple of weeks. I saw no definitive info from BMW on the nature of the REX limitations, but had read online that you could cruise at 75MPH on flat ground and that it would maintain 45-50MPH on grades. The speed limit on Highway 17 is 50 MPH, so I felt like even the worst case would be tolerable. I was wrong.

After the ICE kicked on, the car maintained speed for maybe 5 minutes, then began to feel very weak. On the next uphill section, my speed fell quickly from 50MPH down to 25MPH and was falling (this while at WOT). Cars backed up behind me and I needed to put on the hazard blinkers and crawl to the next turn out.

I waited on side of road while the engine continued to run (but seemingly not at full load). I did not know how long to wait. After 3-5 minutes, I attempted to merge back into traffic (I was still on an uphill section). The car initially had good power, accelerated to ~40MPH, then crapped out and fell back to 25MPH. I crawled to next turnout and waited 10 mins. That was enough to get me over the next hill and get me on my way.

This wasn't just annoying. It was dangerous.​

Perhaps it's not fair to judge the i3 REx by this one anecdote. Perhaps that's just an "edge case". But this indicates to me that the i3 REx' scooter/motorcycle motor simply is not powerful enough to support safe driving on steep mountain roads.

​

 

My drive home from Charlotte NC to Knoxville TN:

I had no problem following trucks up the climbing lane as I had coded the car for REx enable at 75% SOC operation. The topology grid maps from Knoxville TN on the left to Charlotte NC on the right.

BTW, don't get lost in semantics of motorcycle or scooter. Just cite Wiki:

W20K06U0 25 kW 647 cc, two-cylinder generator (optional) with a fuel tank capacity of
9 L (2.4 US gal) in Europe[3]
7.2 L (1.9 US gal) in the U.S.[4]
a 647, two-cylinder, four stroke, gasoline engine.​

Bob Wilson