z3i3rich
Posts: 8
Joined: Thu Apr 23, 2020 7:56 am

Odd coding problem

Tue May 12, 2020 8:58 am

Hello all,
I just filled up my 2017 Rex and I ran the basic fuel tank remove limitation on bimmercode and got some unexpected results below:

gas GOM went from 65m to 99m....it crept down to 80 by the end of the day, and this morning was 66m. I have read other posts that describe that I should not go by the GOM, but by how much you can put in the tank at fill up. Doesn't make a great deal of sense, but it was not the surprising part. That was....

The electric GOM went from 80m at about 80% to 120m....This should not have been effected at all by changing the gas limit. Over night it corrected a bit while doing a short charge. It is now at 93m at 86%.

From all this I am left with the following questions:

what range SHOULD I get on the Rex? I have read 80m in multiple places but there is a lot of contradiction out there (ie 80m, but less in USA or 80m in USA but more in Europe)

Why did this coding mess with my electric GOM? My worst fear is that I have removed a limit cap that prevents battery degradation by not charging over 80%. I did the basic coding so that SHOULD NOT be the case, but I am still worried.

symonray
Posts: 50
Joined: Thu Mar 07, 2019 8:52 am

Re: Odd coding problem

Tue May 12, 2020 10:07 am

The fuel tank limitation was eliminated in the 2017 model year as the car received a larger battery with extended EV range.
Timothy Simonds
2017 BMW i3 Rex

Timjohn
Posts: 34
Joined: Mon Nov 11, 2019 9:37 am

Re: Odd coding problem

Tue May 12, 2020 10:27 am

These numbers of range seem to bounce around and I figured its the i3's computer estimating your last few miles of driving. So I find the range indicated by the display changes and it confuses me as well. Its not a static number and I think what happens is depending how you were driving the i3, it will adjust it's estimation. So maybe this is why when you think coding the i3 for a larger volume gives you a different range (electric and gas) can be confusing.

alohart
Posts: 2023
Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: Odd coding problem

Tue May 12, 2020 11:35 am

z3i3rich wrote:
Tue May 12, 2020 8:58 am
Why did this coding mess with my electric GOM?
Saving changed parameter values (a.k.a., coding) can reset the values of other parameters used by the same module. This might explain the GOM change.

As has been pointed out, the gasoline tank capacity in North American i3 REx's wasn't software limited in 2017 and later models. So it would probably be best if you restored the parameter values back to their original values by saving the values in the backup the BimmerCode automatically creates.
z3i3rich wrote:
Tue May 12, 2020 8:58 am
My worst fear is that I have removed a limit cap that prevents battery degradation by not charging over 80%.
The unusable battery pack capacity cannot be changed by coding. The battery management system (BMS) can be reset using one of BMW's maintenance programs, but even that doesn't change the initial unusable battery pack capacity. FYI, the BMS allows the battery pack to be charged to ~95% of a true full charge, not 80%. It also prevents the battery pack from being discharged below an actual ~9%.
Aloha,
Art

2014 BMW i3 Arravani Grey, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, JuiceBox EVSE

jadnashuanh
Posts: 4916
Joined: Thu May 22, 2014 2:07 pm
Location: Nashua, NH USA

Re: Odd coding problem

Tue May 12, 2020 1:20 pm

The battery range can change overnight as the temperatures vary. The nominal value displayed is based on about the last 18-miles you drove it, so if that had been all highway at a good clip, then your next driving was out in the country at slower speeds, I've seen mine essentially stay the same while doing that for in the order of 10+ miles, i.e., not going down as I was driving.

Just like on an ICE, how you drive influences the estimate of miles to empty.

FWIW, if you put a destination into the computer, it can then make a better estimate since it knows the speed limits and terrain of your intended trip. Otherwise, it is only going on recent history, expecting you to continue doing what you had been, which often, may not be correct.
Jim DeBruycker
2011 535i x-drive GT, 2014 i3 BEV

z3i3rich
Posts: 8
Joined: Thu Apr 23, 2020 7:56 am

Re: Odd coding problem

Tue May 12, 2020 2:35 pm

Thanks for the input. As a follow up question...with the exception of the coding session in question, my estimated gas range has been super consistent at 64-66 miles regardless of how I drive. Should it not be 80 as the tank is not limited as noted above?

jadnashuanh
Posts: 4916
Joined: Thu May 22, 2014 2:07 pm
Location: Nashua, NH USA

Re: Odd coding problem

Tue May 12, 2020 4:37 pm

The REx will adjust its speed to account for the current loading...so, if you're treating the vehicle gently, the REx won't need to run that much or that fast to maintain your battery capacity. But, on the other hand, if you're running the REx barreling down the highway and up a long slope...the REx will be running as hard as it can...so, just like any vehicle, it depends on how you're using it...the range will vary. Most people seem to get around 34-38 mpg, and with that small tank, while you may be slightly on the low side, it doesn't seem abnormal to me given its size. If you were puttering around town using the REx to maintain, I'd expect you'd see a lot higher number as when it did turn on, it wouldn't need to run very hard.
Jim DeBruycker
2011 535i x-drive GT, 2014 i3 BEV

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