What year allowed more control over regen?

[user 10389]

Hi! I'm looking to purchase a used i3, and I drove a nice 2015 Tera World that I liked except you could not control the amount of regen in the menu (Adaptive/High/Medium/Low) like other BMW EVs. You could only toggle the Comfort/Eco switch.

At what year did they start offering the most amount of regen control? I prefer the absolute least amount of regen.

TIA!

 

[eNate]

There are anecdotal observations that i3 regen was reduced at some point after the launch software version in the 2014 model year.

However others with accelerometers dispute this, and suggest only the tapering off of the last bit of speed to zero was modified for a smoother stop.

My experience only goes back to the 2017 model, which regens identically to the 2021 I now own (I owned and drove both for a few weeks of overlap).

I've never known any way to adjust or select different preset levels of regen.

https://www.mybmwi3.com/threads/has-regen-been-reduced.2389/

 

[user 10389]

There are anecdotal observations that i3 regen was reduced at some point after the launch software version in the 2014 model year.

However others with accelerometers dispute this, and suggest only the tapering off of the last bit of speed to zero was modified for a smoother stop.

My experience only goes back to the 2017 model, which regens identically to the 2021 I now own (I owned and drove both for a few weeks of overlap).

I've never known any way to adjust or select different preset levels of regen.

https://www.mybmwi3.com/threads/has-regen-been-reduced.2389/

In your 2021, is there not a switch or button that has the effect of making the regen less? I once drove a later model i3 (don't know the year), and as I recall when I pressed a button the regen was much less, almost like coasting. The 2015 I drove had WAY too much regen for me.

 

[eNate]

Are you thinking of the Mode button that changes between Comfort, Eco Pro, and Eco Pro+ (and Sport on the i3S)?

I switch between Comfort and Eco Pro frequently and have never detected a difference in regen level.

The only times I note a change in regen is if the battery is close to full (a 100% battery cancels regen and is brakes only), or in my 2017 if I was regenning over a rough patch of pavement, the regen would drop it out to preserve traction.

 

[user 10389]

Are you thinking of the Mode button that changes between Comfort, Eco Pro, and Eco Pro+ (and Sport on the i3S)?

I switch between Comfort and Eco Pro frequently and have never detected a difference in regen level.

The only times I note a change in regen is if the battery is close to full (a 100% battery cancels regen and is brakes only), or in my 2017 if I was regenning over a rough patch of pavement, the regen would drop it out to preserve traction.

I found that by switching from Eco to Comfort on the 2015, the amount of regen was less (but still too aggressive for me). I assumed that more choices meant less regen at the right end? I know that 2015 had more regen than whatever the later model had.

 

[alohart]

I found that by switching from Eco to Comfort on the 2015, the amount of regen was less (but still too aggressive for me). I assumed that more choices meant less regen at the right end? I know that 2015 had more regen than whatever the later model had.

I bought a 2014 U.S. BEV new and a used 2019 U.S. BEV in 2022. By 2022, our 2014 i3's system software had been updated to the version released in November, 2018, which was the date of the system software that was in our 2019 BEV when I bought it. Even though both had the system software released in November, 2018, I did not detect any regen power difference.

The only regen modification that I have detected in almost 10 years of i3 ownership occurred after our dealer installed a stronger attachment bolt for the driver-side motor mount bracket on our 2014 i3. Included in this BMW service action was a system software update that delayed the onset of full regen power for a second or so after ACC disengaged unexpectedly or after the power pedal was suddenly fully released. However, after regen began, it didn't seem to be any less powerful than before this change.

I've also been unable to detect any difference in regen power among the 3 driving modes available in a non-S i3. However, I haven't measured the stopping distance using only regen in each of the driving modes, so maybe there is some difference.

New i3 owners might not be aware that regen power can be controlled continuously between no and maximum regen by adjusting the power pedal position. There's really no need for any regen power settings or paddles to increase regen power. When decelerating or stopping while driving an ICE vehicle, one's foot is typically moved from the power pedal to the brake pedal. Lifting one's foot off the power pedal doesn't result in much deceleration since only engine braking (basically internal friction) is involved. Driving an i3 that way might make one feel that regen power is too strong.

 

[mojo]

Agreed - the modulation of braking (regen) power using the accelerator was the thing that I initially found difficult. My first test drive in an i3 would have been embarrassing were it not for the fact that the dealership simply left me to go out on my own.

The brain adapts fairly quickly, but I still find it hard to drift up to the car in front at traffic lights using only regen and get the distance exactly right - after 8 months, I still tend to end up just a little bit too far back! Better than the opposite, I guess...

 

[ProDigit]

Perhaps unrelated, but smaller batteries may (or may not) have less regen, depending on their charge levels.

 

[alohart]

Perhaps unrelated, but smaller batteries may (or may not) have less regen, depending on their charge levels.

Assuming battery cells that accept the same C-rate of input power, higher capacity battery packs could accept greater regen power, but only if the capacity of the electronic module that converts the 3-phase AC propulsion motor-generator output power to DC battery pack input power is increased. I'm pretty certain that this electronic module has remained essentially unchanged in the i3 despite increases in battery capacity.

Also, the maximum continuous input power of the propulsion motor-generator has remained unchanged regardless of battery pack capacity. I assume that the motor-generator continuous output power has also remained unchanged.

As a result, I believe that the maximum regen power has remained unchanged even as battery pack capacity has doubled.

 

[McDuff]

I see no point in adjusting the regen power; my right foot does the modulating for me and if my shin becomes tired I set the Cruise Control, Adaptive or otherwise.

I was with my son for test drive of a Mercedes GLC a few months ago and found the adjustment superfluous.

 

[ProDigit]

BMW does not change battery cells in packs. They're all the same.

But larger capacity packs have more banks of cells in series, than smaller packs.
The more cell banks, the higher amp flow they can handle.

Should two of three banks have one bad cell in it, the whole bank will be limited to the amp flow of that one cell. If they can handle 50A per bank, for a total of 150A but one cell causes a 25A drop per bank, the overall amps 3 banks now can handle will go from 150A to 100A.
Such an occurrence isn't that uncommon.

At 350V, that's down from 52kW to 35kW of output power.

Of course, i3 battery has more banks than that.

The highest energy flow comes from regen braking. So while you may not notice a decrease in acceleration, the first way to know if some banks have gone bad, is lower regen capabilities.

 

[alohart]

I might be interpreting what you wrote incorrectly.

BMW does not change battery cells in packs. They're all the same.

In i3 battery packs, 60 Ah, 94 Ah, and 120 Ah battery cells are all different in capacity but are the same physical size, so these cells are not the same. All 96 cells are connected in series which results in a nominal 400 V pack.

Battery packs that have cells connected in both series and parallel can increase the number of parallel-connected cells to increase the pack capacity using more of the same cells.

But larger capacity packs have more banks of cells in series, than smaller packs.
The more cell banks, the higher amp flow they can handle.

I assume that a "bank of cells" is comprised of cells connected in series. Connecting more of these banks in parallel increases the pack capacity while keeping the nominal output voltage unchanged. A pack with more cell banks connected in parallel has a higher maximum input and output current.

All i3 battery packs regardless of their capacities contain 96 cells connected in series. Twelve of these cells are installed in each of 8 replaceable modules. In i3 battery packs, no cells are connected in parallel. Different i3 pack capacities are due to using cells of different capacity cells, not increasing the number of cells or connecting more cells in parallel.

Should two of three banks have one bad cell in it, the whole bank will be limited to the amp flow of that one cell. If they can handle 50A per bank, for a total of 150A but one cell causes a 25A drop per bank, the overall amps 3 banks now can handle will go from 150A to 100A.
Such an occurrence isn't that uncommon.

Your statement is correct for series-connected cell strings ("banks") connected in parallel.

Of course, i3 battery has more banks than that.

Your statement doesn't apply to i3 battery packs because they contain only a single "bank" of 96 cells. You might be confusing the i3 battery pack structure of 8 12-cell modules assuming that the modules are connected in parallel when they are actually connected in series. A module is the smallest replaceable battery pack component, but these modules aren't used to construct packs of different capacities by connecting more of them in parallel.

The highest energy flow comes from regen braking. So while you may not notice a decrease in acceleration, the first way to know if some banks have gone bad, is lower regen capabilities.

From BMW's I01 High-Voltage Components Training Manual:

"The maximum power applies for the motor operation – in theory it could also be used in the alternator
operation during brake energy regeneration. However, in practice only a fractional part of this maximum value is used in alternator operation. As a result, the braking torque at the rear axle is restricted so as not to affect the driving stability by the brake energy regeneration."

So for the i3, the greatest power is produced during acceleration, not during regen braking. Therefore, a weak cell would likely be more noticeable during acceleration, not during regen braking.

 

[Allenpien]

Did I buy a boat anchor?? I bought a BMW i3 key fob on Ebay. My dealer says that they cannot program it. Any suggestions?

 

[bmwnomad]

Not heavy enough for a boat anchor, paperweight maybe?

 

[alohart]

Did I buy a boat anchor?? I bought a BMW i3 key fob on Ebay. My dealer says that they cannot program it. Any suggestions?

Please start your own thread and don't make an unrelated post in an existing thread.

Anyone who buys a used i3 fob is giving their money to the seller for little of value in return.