Rex seems to be failing to "kick in"

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Chris94

Member
Joined
Nov 27, 2024
Messages
9
Today I went on a drive to check the cold-weather range of my 2017 i3 Rex. When I started, the stated range was 73mi battery/46mi Gas, with a full battery and tank. I recently coded the car to turn on the Rex at 10 percent, as shown by the little triangle in the first picture:

s1.png


After driving 58 highway miles, the battery had dropped to 7.5% and a battery range of 4 miles-- but I hear no Rex and the gas side of the gauges still grey (not "lit up"), so I exit the highway and park. After a few minutes parked I observe that the gas gauge is "lit up," but the rex is NOT running (no sound, no exhaust.) The battery SOC keeps dropping:

s2.png

All I can think to do is to force the Rex to turn on so I can get enough battery capacity to get me to a charge point a few miles away. So I do the "emissions inspection test" and the Rex turns on and runs for 20 minutes. Unfortunately this does little to improve the state of charge. So I set off for the charge point in Eco Pro+ mode. The first charge point fails to connect. On the way to the 2nd charge point I observe that the Rex is running and seems to be keeping the SOC between 5.5 and 7 percent. I charge the car to 15 percent and head home on back roads using the "hold state of charge" function already coded into the car when I bought it. By the time I get home (18 more miles) the SOC is at 12.5 percent. So the "hold SOC" function isn't really doing its job. That 18 miles was at 40-45 mph on level terrain, so the Rex ought to be able to keep up, shouldn't it?

And why isn't the Rex kicking in at the 10% threshold that it has been set to?

Any insights on this are appreciated! I am still a newbie to the i3 (1 month.)

Chris94
 
I recently coded the car to turn on the Rex at 10 percent, as shown by the little triangle in the first picture:
Unfortunately, the change you made affects only the position of the white triangle but does not change the charge level at which the REx engine starts automatically. I don't believe that anyone has discovered how to make that change.
 
Really?! That is surprising. So it just provides a marker to watch, so you know when to engage the "Hold SOC?" I had no idea!

So the Rex will turn on at its default SOC (6 percent?)
 
If you code the Range Extender menu to be on, when you enable the hold state of charge mode the arrow moves to whatever your current charge level is. Otherwise it continues to do 6% default.
 
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