[Duncan]

You'll all remember from an earlier thread here that back in February Cambridge Chevrolet replaced my battery. After that all was well until the start of June when I got the PPR message again several times.

The problem seems to be slight different, there aren't any logged error codes, and Chevrolet UK are trying to say that PPR is a normal situation, pointing to the page in the manual which says it can occur when driving in mountainous terrain (Oxfordshire?). The garage suggested I keep a diary to get some solid numbers, so as of this weekend I'm blogging all my mileage and ranges.

Any comments and feedback will be most welcome.

 

[hopbackguy]

Sounds a pathetic excuse by the garage. Mountainous terrain means The Rockies or the Alps, where this car works fine, not the Lake District and certainly not Oxfordshire! Kinda sounds like they may have needlessly replaced the battery if its happening again doesn't it.

 

[Duncan]

Just to be completely clear, it isn't exactly what happened before.

Previously the range dropped from about 20 miles to 0 and then after cycling the power slowly recovered back to where it should be; there was an engine warning light and error codes. Cambridge Chevrolet replaced the battery and I believe cured that problem.

Now, I have no engine warning light and no error codes (I believe Chevrolet UK think there can't be a problem without an error code, Bellingers, the Volt dealer in Oxfordshire admit they have seen a problem but can't find the cause and can't go further without Chevrolet UK agreeing to look at it). Sometimes I'm losing a chunk of range, but power cycling the car doesn't get it back. Sometimes I'm not losing the range but the car is acting as though the battery has been over drained. This looks to me as though the actual battery capacity is reduced but the system that monitors remaining capacity isn't detecting that reliably.

There could be some overlap between these two issues (perhaps the fault is with the controller), but the more I think about it the more I think it is simply that one duff battery has been replaced by another differently duff battery.

 

[Parax]

Eek they must be taking the piss.. Yes PPR is normal IF you have a flat battery AND are using MORE than 74bhp AVERAGE!
That's pretty hard to do on normal roads, it would take severe hills or severe driving (drifting?) I take it you are not out on track?

It does sound dodgy that it turns off and on sporadically, I suspect that it'll be a dodgy battery controller/Sensor misreading occasionally. Good luck getting them to acknowledge the problem!!!

(I believe there are multiple battery controller units each monitoring multiple cells, these may not have been changed with the battery cells)

 

[Duncan]

I've come to the conclusion that I was wrong in one important respect: I thought the problem was intermittent but in fact now that I've had a few days recording what happens it seems to be completely repeatable and the only thing that varies are the symptoms exhibited which depend on the driving pattern.

That gives me hope that I'll be able to persuade them there is actually a problem: if I drive until there is about 12 miles of range remaining (not sure the exact upper limit) and then park for a few minutes, then I lose range and the battery will be fully discharged after 8.8kWh (+/- about 0.1). Forget the PPR, that is an easy to demonstrate number that I don't think they can argue with.

If I keep driving so the car doesn't recalculate the remaining battery then I can get beyond 8.8kWh but when the ICE does kick in that's when PPR triggers.

 

[Duncan]

Quick update for anyone interested:

The garage wants my Volt in for a couple of days next week so they can apply some software updates. After that I'll monitor the charging and range again as I did before. If the updates don't fix the problem then the car goes off to Luton for Chevrolet to look at it directly.