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[Zelidar]

Last weekend I went on a little hike from the parking lot located near the top of a mountain. My bike (SR/F Premium with 27'000 km, FW19, configured with 100% regen braking) was at about 70% SoC and so I plugged it into the locally available station to recharge to 100% before leaving. It began flawlessly charging with 5.8 kW telling it needed about 28 minutes to finish. All looked fine, and so up I went.

I returned to the parking lot about 1 hour later. The bike was fully charged and quite normally had turned itself off automatically. I got ready to ride down, about 500 m height difference. Immediately I noticed something peculiar which I will try to explain the following way: Regenerative engine braking = 100%, no engine braking = 0%.

0, 0, 0, 0, 0, 0, 0, 100, 100, 0, 0, 0, 0, 0, 0, 0, 100, 100, 100, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 100, 0, 0, 0, 0, 100, 100, 100, .... etc. continuously for about 30 minutes.

Going downhill it was nearly impossible to keep a constant speed, on the contrary it felt as if the bike would accelerate although I was not twisting the right handle. For most of the way down I ended up using the rain mode which has the least engine braking. The next day it behaved as usual again, I suppose a shutdown and booting back up could have solve this issue right on the spot. I did not so this dangerous and very unpleasant behavior continued until I had reached my destination with a 95% SoC, including when driving on flat roads. That wasn't the first time I drove down starting with a 100% SoC battery but usually it will gradually provide regenerative engine braking as the SoC gets below 100%.

First time I make such a scary experience with this bike, anyone else? Could it be linked with battery "aging"?

[DerKrawallkeks]

This sounds very normal to me.
When the battery is full, the bike can not put energy into the battery.
This is not done using the SOC in %, but using the battery voltage I think. The voltage of the battery at the moment of regen is allowed to be slightly higher than 100% SOC if i'm not mistaken.

You going down the hill will regen brake, which pulls the voltage up, then you hit the limit and it'll stop regen completely. Since the battery wasn't really charged/soaked to the voltage limit, but it was just pulled up temporarily by the large charge current, it'll sag back down. And then the same happens again.

My theory;) maybe someone with an SR/F knows more.

[Zelidar]

This sounds very normal to me.

Normal is what usually happens, or even in that same day but in the morning, when I was in a similar situation but I stopped the charging at 98%. Driving down, the regenerative braking began by being non-existent and there was no intermittency, at all, it was continuous, predictable and smooth: -->  , 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, and then it slowly started braking, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25 then 50, 50, 50, 50, 50, 50, 50, 50, 50, 50, etc. until back to normal with 100% regenerative braking.

[Richard230]

I have owned three legacy Zeros and all three would do the same thing when fully charged to 100% (116V) and riding down the hill from my home. But after about 1/2 mile of riding using the throttle, the on-off regen symptom would go away. Perhaps there is a bug in your BMS or MMB programming? It has been known to happen with the SR/F and S models.    Maybe Zero will get all of the bugs worked out of the Cyber III system in a few more years. 

[Crissa]

This is normal.  You slip below the limit, it allows regen again, it fills up and stops regen again... It's kinda annoying.

Especially since the cells can actually take more than the '100%' estimation.

I think it's an edge case where it turns on and off.  I have had rides where it turned off and then stayed off the whole ride annoyingly.

-Crissa

[Zelidar]

I think it's an edge case where it turns on and off.  I have had rides where it turned off and then stayed off the whole ride annoyingly.

Thank you for sharing your own experience about this. I've been riding this bike for over 27'000 km and, for me, this only happened once, last weekend. I suppose that, before, I didn't have all the "conditions" aligned.

[Crissa]

I live up a hill, so I think I'm giving it fits.

-Crissa

[alby62]

È ovvio che non ha freno motore ovvero rigenerazione,  come può ricaricare la batteria, se parti col 100% , di batteria e poi  ti percorri una discesa,  succede anche a me  appena parto dopo una ricarica al100%, nei primi 500 mt,  il Regeni non funziona

[Zelidar]

... il Regeni non funziona

I already know that and this was not the point of my post.

I have driven this bike for 26'000 km, charging almost always to 100% but it was only last month (July 2021), shortly after going over 26'000 km, that I began getting the problem with the intermittent engine braking. Of course I have driven downhill with 100% battery before reaching 26'000 km. Back then there was simply no engine braking, as you describe, and nothing was going "intermittent".

I suspect a problem with either the latest firmware (V19) or the hardware, BMS or battery or whatever else. Right now my range and SoC estimates are going a little crazy, I suspect this is probably linked.

[Zelidar]

That is strange! This weekend I could again charge at 100% (SoC as shown in the display) at 1600 m, I then drove down to 1000 m with a passenger. My SR/F behaved just like it did all along until about 26'000 km, logically no engine braking but, most important, nothing was intermittent and it was all enjoyably predictable. Overall, from the estimated ranges I am now getting, it appears that I have lost about 30% of my original battery capacity so I am beginning to think that the two situations are somehow related.

[NervEasy]

I mentioned the following problems to my dealer:

- Really bad range
- SoC jumps (up and down) of more than 10%
- Not always charging to 100%
- Charge times are off the chart and wildly different (extremely short and sometimes extremely long)

This was mentioned over a period of several weeks and my bike was at the dealer for a week for diagnosing. but afterwards they could not find a problem.
Ultimately after my latest complained, Zero said they would swap my pack (waiting for it to be delivered now). Zero told my dealer they know some bikes have issues but they don't know what the cause is. That's what my dealer told me.

I think there is an issue with inter cell connections.

[Zelidar]

(1) - Really bad range
(2) - SoC jumps (up and down) of more than 10%
(3) - Not always charging to 100%
(4) - Charge times are off the chart and wildly different (extremely short and sometimes extremely long)

Thank you for sharing your experience with me Jan, that is much appreciated. Your points are indeed interestingly very similar to mine:

(1) I typically saw between 120 and 140 km of range at full charge. After a long downhill ride barely reaching 240 km, whereas last year I reached a funny 400 km in the same condition.
(2) Same here, after powering back up and a pause > 30 minutes.
(3) It did show 100% but going on with charging at 5.8 kW for a solid 20 minutes at times.
(4) Regarding the charging time, over the weekend where I drove +- 600 km, it would generally charge at 5.8 kW (Premium), but also a few times I had the charging power following a lazy sine curve reaching below 1 kW.

[NervEasy]

Yeah the long charges are sometime +3h longer than what it should be for me...

[Zelidar]

I think there is an issue with inter cell connections.

Yes, that was the case for me as well. Yesterday I went to my dealer to have them download the full log. That operation took over 2 hours. The same day in the evening he uploaded it to Zero headquarter (NL) and this morning he wrote me that a new battery pack was on order.

I wish I didn't have that problem, going through all the consequent inconveniences I mentioned in this post, but kudos to Zero Motorcycles for a very speedy handling and acknowledgement of the battery problem I had.

[NervEasy]

Hmm, indeed. Did you get a clear explanation what the problem was/is?