Posts: 1
Joined: Sun Nov 14, 2021 8:24 pm

New REX owner

Sun Nov 14, 2021 8:32 pm

I've owned my 2019 i3 REX for 4 days, really love it. But now a question that some or many of you can probably answer. Yes, I read how to hack the gas generator to turn on sooner, but I have decided not to do that until the warranty is up and I bought a certified one so my warranty is up in 4 years. But, my question. I did test the car and I see that the REX turns on at 6.5% charge. So, actually 2 questions.

1). I noticed that the REX generator stays on for sometime after shutting down the car. I did not stay by the car to see if it was for 1 min to 5 mins but I think I came back after 2 mins and it was still running and I came back in over 5 mins and it had stopped. Is the REX generator motor supposed to keep running after a shut down?

2). I own an old classic 1976 455 manual Black and Gold Trans Am, now you know why I now also own an EV as my mpg on the Trans Am is like 9-11mpg. But I do make sure that I use enough gas in the Trans Am so the gas doesn't;t go stale. Does the REX cycle the car into generator mode periodically so I can actually use up the gas and refill before it goes stale?

That's all I've got. Thanks for any replied.

Posts: 197
Joined: Fri Nov 25, 2016 11:23 pm
Location: USA West Coast

Re: New REX owner

Sun Nov 14, 2021 11:28 pm

I'm not a REx owner so I don't know the specifics of its maintenance cycles.

Your profile doesn't mention where you're located, but in the USA, the Sta-Bil line of products has a lot of options for engines that don't run often. I've been using their pink "Fuel Stabilizer" for years and have been very happy with it.

Posts: 35
Joined: Fri May 01, 2015 12:17 pm

Re: New REX owner

Mon Nov 15, 2021 5:17 am

1) the REX will run till it hits the level where it was started at. So if it came on at 6.5%, it won't stop till it regain that 6.5% level- I coded it so long ago that I don't remember if it will run after you stop the car. I think that would be a liability for BMW if you pulled it into a garage and the REX would not shut off. What you may be hearing is the cooling fan running. From what I understand nobody has had a problem with the warranty coding the REX to turn on earlier. I would highly suggest that you code it to the car. It makes the car much more "usable" allowing you to use it for longer distances, allows for less stress about electric range, prevents turtle mode when the battery is low and the REX cannot keep up, and from what I understand taking the battery down to that 6.5% level on a regular basis is not good for the battery long term.

2) The REX will run a maintenance cycle if you don't use it, if I remember correctly about once a month. This is not to keep the gas "fresh". What keeps the gas from going stale is that the tank is pressurized to keep the fumes from escaping. I've never had a problem with gas not being good, and I only rarely use the REX.

Posts: 89
Joined: Sat Mar 07, 2020 6:15 pm

Re: New REX owner

Mon Nov 15, 2021 8:05 am

The REX should not only stop when you park the car, it should stop as soon as the car comes to a stop at, for example, a stop sign or traffic light. I think you might be hearing the cooling fan.

You can run an "emissions test cycle" if you want to make sure the REX is in good operating condition before a long trip:

Get into the car and close the door.
Press the trunk/hatch release button.
Press the Start/Stop button (BRAKE NOT PRESSED)
Press and hold the accelerator pedal.
Press and release the brake pedal.
Press and release the brake pedal again.
Press and hold the brake pedal.
Release the accelerator pedal.
Press the Start/Stop button.

The REx should start and run at a low idle.

If you press the accelerator pedal the REx switches to a high idle.

The REx will stop in 20 minutes or when you press the Start/Stop button.

Be sure to close the trunk/hatch when you are done.

Posts: 1
Joined: Mon Nov 15, 2021 1:07 pm

Re: New REX owner

Mon Nov 15, 2021 1:27 pm

Hi, I'm a first time BMW owner and I chose a late 2016 94Ah REX less than a year ago. The maintenance cycle for the REX has only run a couple of times as prompted by the car when I have been electric only for several weeks at a time. However, my car allows me to go via the menu and prompt the car to 'Maintain state of charge', but only when below 75% battery. By googling info I found I could use that function more easily by adding it to one of the 8 user programmable buttons, which I did on button 8. When driving below 75% SOC, one press of button 8 and the REX turns on, and that's without any coding (don't know if that's as easy in the USA). This has been useful a couple of times on extended trips of 150-160 miles. As another user mentioned when running the REX, it stops when I get to junctions and have to stop myself. Then when parked up and stopped I have noticed the cooling fan running on for a few minutes.
Other than that I've found with careful driving I average around 4.8miles/kwhr, for a summer range of 130-140 miles BEV only, and another 80-100 on the REX. I thoroughly love the car, and am sure you won't be disappointed.

Posts: 18
Joined: Mon Nov 22, 2021 3:30 am

Re: i3 Very loud REX

Mon Nov 22, 2021 3:47 am

Hi ,
I want a REX because it makes sense especially at this early stage of EVs
with range, and charging practicality issues.

I was viewing a 2018 i3 Rex at a dealer's Yesterday,
the 94Ah had low charge and the REX was running immediate up powering up.
It sounded so loud like I was literally standing next to Road Works

I was thinkomg Is this how the REX works, or there is a fault in this particlay i3?
Sure , it is the 21st century, someone can come up with a much quiter small
petrol engine. even a miniatre 4-stroke if need be. just to drive an alternator.

I occasionally have to go out to work at before 6am or sometime return home
around that time.
I can see me reversing into my drive and the REX comes on
My neighbours miles around are going to love me

Has anyone come up with a noise damping/insulation solution?
I am still considering getting one, IF, that rattling sound problem can be resolved
Thanks in advance

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