turning Rex on after coding, 71% SOC, no engine start

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Jki3

Member
Joined
Jun 27, 2018
Messages
11
Coded my 2018 i3, USA, 250mi from brand new, for "hold state of charge", among other things, seemingly successfully.

Driving car around today w/approx 71% SOC, and checked box for "hold state of charge" in display. I could not hear the engine start up. Tried a few times from stop, driving, etc, and just didn't seem to hear it fire up.

Is there something I'm missing?
 
Did the gas range bar turn from grey to white? Give it a while, it doesn't run much until charge drops a few percent below set point. Turn to the energy flow screen to see if engine is running. It is very difficult to hear in some circumstances (windows up on highway).

The time I notice it is when it is 4 or 5% below set point and running full throttle to keep it charged. At low speeds you will feel it, and definitely hear it with windows down. At highway speeds it feels more like a steady mild vibration or droning, still not loud though.
 
Gas bar definitely changed colors. Last time I drove a Rex was a 2014 when I purposely ran battery down below 6% to see what would happen. I clearly heard the engine switch on and felt the vibration.

This time, no add'l sound at all. I wondered if the muffler had become much more effective but I coldn't imagine that's the case-who knows. I'll give it a bit more time for SOC to reduce and see what happens.

Thanks
 
The SOC when you turn the hold on becomes the desired hold point. SO, before the REx will turn on, the SOC will have to drop some. Then, if it hasn't run for awhile, it will need to run for long enough to fully warm up, and that might also mean the SOC might have to drop some more. Once the REx is warmed up, it will turn on and off as needed to maintain or regain that original set point.
 
My expectation was that the instant I checked the hold box, Rex would turn on. Your explanation clarifies the process and what needs to happen. I'll give it a try and see what happens.
Thanks
 
I would only add that when the car stops, the REx may continue to run for less than a minute. Don't panic if the REx stops when the car stops (or less than ~6 mph.)

Bob Wilson
 
Did you use bimmercode ?
I noticed that bimmercode shows my Rex start is at 12% , when it is at around 7% , the original settings.
Something is clearly wrong as, 7 and 12 % are different and bimmercode is reading some other value or perhaps even worse...
 
The Rex did indeed fire up after a few minutes and reduction in battery % as mentioned. Rpm was definitely slow at first but it did increase after a few minutes of running.

Regarding 6% or 12%, I read somewhere that the only option to change automatic Rex startup to was 12% using bimmercode. I seem to recall that other %'s were not available and that they weren't sure if it was a bimmercode issue or not.
 
The controller waits after initially firing up the REx to maximum in order to let it warm up before high outputs are allowed. Once that initial warm up, it tends to turn on/off and run at whatever speed it needs to for the current conditions.
 
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