unusual hard judders and jerks under regen on motorway

hi,

unusual situation yesterday, not had it before. Have now done just under 10,000 miles (16,000Km). Here's the story - After 40 miles (64km) battery empty (30%) going on motorway at 70mph (112km/h) when I went down a modest descent with traffic started to build a bit up ahead so I used B3 and the regen jerked and juddered horribly. Nothing behind me so no immediate drama. But then kept doing that for the rest of the journey (about another 20 miles) in all regen settings (B1/ D / B3 / B4 / B5), Also when braking gently. Very violent as if regen on / off / on / off / on / off. Flow diagram showed constant regen wheel to battery but level jumped wildly. (the power dial jumped from almost full regen to some regen then back). Tried speeds from 50mph to a "large" 70mph, all affected

Anyone experienced before?

Anyone any ideas what it is and what to do if happens again?

It was not pleasant at all. Car charged fine overnight. No dramas today but not flattened battery yet, was only 20 mile journey. Thanks in advance,
HJB

I've never seen this, but my style of usage is rather different, so you can't read too much into that. I do think that the car's behaviour is not particularly deterministic - I guess that the designers used fuzzy logic techniques and an innocuous difference in operating conditions can have a big impact on behaviour. In an effort to avoid a high revving engine, I normally keep my battery quite highly charged - this works most of the time but every so often the car seems to get into a state where it revs the engine high in response to a demand for power even though there is plenty of charge in the battery. This can continue until I stop the car, power it down and back on again. Our old Prius would behave rather similarly - there's a moderate hill that I have to climb most days when I leave our house - with a fully charged battery, the Prius would usually do it with ease but every now and then, it would scream its guts out on the way up!

My first PHEV, exhibited pulling to the right with EV, REGEN, ABS and more warnings come up on the dash. Was not related to battery remaining capacity. Was able to drive in B0 with ASC turned OFF. Turned out to be a wheel speed sensor failure. Diagnostics revealed what was wrong. Error codes were cleared when PHEV powered OFF. Had to be driven again for error codes to be back and able to be read. My PHEV was not driveable with the fault until REGEN and ASC was turned OFF.

Hopefully the problem in your PHEV will represent again and diagnostics will find the problem. Really important to not turn the car off and if possible drive to a service dealer with the fault still evident. It was not until my dealer experienced the fault in my PHEV first hand, that any attempt was made to fix it.

thanks gwatpe. I didn't have any warning lights at all, and OBD2 displayed no warning codes, it was as if car thought everything was fine.

It had my FCM apply suddenly on an open road. My dealer could not find anything in the logs, but connected the car online to Japan, where they found a few errors in the software. They reinstalled the software and the problem has not reoccurred. In other words, have your dealer do an in- depth check.

jaapv said:

It had my FCM apply suddenly on an open road. My dealer could not find anything in the logs, but connected the car online to Japan, where they found a few errors in the software. They reinstalled the software and the problem has not reoccurred. In other words, have your dealer do an in- depth check.

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Dam... really hate to visit any dealer especially if you buy a new car!!!

thanks jaapv. Tempted to wait to see if it happens again as I'm quite a distance from dealer but if it does, makes a lot of sense for it to be a software issue, I hadnt made that connection
HJB

Does FCM actually do more than flash a BRAKE message on the dash?? Maybe this was the fix. To only now flash up the warning and not effect the car physically.

gwatpe said:

Does FCM actually do more than flash a BRAKE message on the dash?? Maybe this was the fix. To only now flash up the warning and not effect the car physically.

Click to expand...

I don't have FCM. I liked the idea of a software glitch but it's not FCM that caused this. In some ways I'm quite relieved not to hear this happen to anyone else as I can now chase harder with my dealer knowing it's a fault.
HJB