Decreased battery capacity?

[AySz88]

You'll have to point out where I supposedly said that.
WOT

I don't know where he's getting the thing about the odometer.... But I think the bit about kWh is confusion about "battery pack capacity learn procedure". What exactly is learned about the battery pack that, if wrong, might cause the "displayed kW*hr used" to be wrong?

I've been presuming that the kWh used display is calculated the way a Kill-a-watt meter would do it, i.e. it comes from a voltmeter and ammeter at (or near) the battery, and then calculated using integral(V*I dt) ~= sum(V_n * I_n * deltat_n for each sample n). But that doesn't sound like what's happening?

[edit] Clarify... And oops, current's symbol is I, not A.

[focher]

There is at least one very clear example when the KWh Used reading is not really accurate, at least for the purpose of knowing how much capacity is available for driving. If a recharge doesn't reach "full", then the in-car display doesn't reset. Additional driving or battery usage simply adds onto the reading. It's quite easy to get the KWh Used reading to display well beyond 10+ KWh with this method.

I see the confusion is that we assume "KWh Used" is something that helps us understand KWh remaining when, in fact, it's not.

[Koz]

I would be interested in knowing under what circumstances the odometer display would be inaccurate.

Non-spec tire diameter perhaps.

[Cord]

"I would be interested in knowing under what circumstances the odometer display would be inaccurate."

driving your car on a safety check station dynamometer to charge the battery.

[focher]

I dropped the car off today and was reminded of what not to do ...

The service manager called over the Volt technician about the battery capacity. I explained to the technician about the problem, then made the mistake of mentioning that someone on a forum gave me a TID that should be followed. I then suffered through a monologue about forums and the reliability of the information on them. I tried to change the focus from "this is where I got the information" back to "this is the problem and can you please solve it". It took a few minutes for him to let it go, but he finally did.

Anyway, the car is in and let's see. I suspect from the technician's speech that he's still relying heavily on direct contact with GM's support when he faces any Volt service requirements.

[WopOnTour]

I dropped the car off today and was reminded of what not to do ...

The service manager called over the Volt technician about the battery capacity. I explained to the technician about the problem, then made the mistake of mentioning that someone on a forum gave me a TID that should be followed. I then suffered through a monologue about forums and the reliability of the information on them. I tried to change the focus from "this is where I got the information" back to "this is the problem and can you please solve it". It took a few minutes for him to let it go, but he finally did.

Anyway, the car is in and let's see. I suspect from the technician's speech that he's still relying heavily on direct contact with GM's support when he faces any Volt service requirements.

Yea, unfortunately that would pretty much be the response anywhere.

But it all boils down to 1 question. Did he or did he not perform the last 2 steps of the battery replacement procedure? (reset>relearn)

WOT

[tboult]

Yea, unfortunately that would pretty much be the response anywhere.

But it all boils down to 1 question. Did he or did he not perform the last 2 steps of the battery replacement procedure? (reset>relearn)

WOT

Even if he did not.. the other question wil be would they admit it. They may keep it and end up reporting something else just to save face. Anyone that instinctively gets their hair in a tizzy about data from a forum is going to not want to admit that data on the forum explained what they did wrong. I'd expect a different "reason" even if the actual corrective action was reset-relearn.

[WopOnTour]

Even if he did not.. the other question wil be would they admit it. They may keep it and end up reporting something else just to save face. Anyone that instinctively gets their hair in a tizzy about data from a forum is going to not want to admit that data on the forum explained what they did wrong. I'd expect a different "reason" even if the actual corrective action was reset-relearn.

True, but perhaps not for the reasons you suspect. Sure, they want to save face, but more importantly they:
1) want to get paid for any further time they spend on the car
2) want to fix the problem and get this forum-lovin' PITA out of their hair

Hopefully they get their wish
WOT

[focher]

Just wanted to share the end of my story - hopefully. I got my car back about 9 days ago. Funny part is the only thing the service department did in regards to my range complaint was to leave a TID on my car seat explaining the possible reasons for range fluctuations (as they delivered the car so I never actually spoke to them). Since getting it back, I have been driving it as I normally would, which is about a 16 mile round trip to work and then errands. We drive the Volt exclusively on the weekend. While I hadn't been running to anywhere near the upper battery capacity, I was consistently driving with over 4 miles per KWh according to the gauge. What was slightly irritating is that the Estimated Range started at 38 and then even dropped to 37 as the week progressed.

This weekend, I decided to drive until the whole capacity was used. I was happy to see the car stay in EV mode until the gauge read 10 KWh used before the ICE came on. I got about 42 miles on battery. So far so good.

I plugged it in and went out in the evening after a full charge. The Range Estimate said 36 miles. It got shorter. Needless to say I was irritated. But I have a .25 mile downhill from my house to the main road, and on the way down suddenly the range went to 49. Woo hoo! All was good, until I turned onto the main road and the estimate went up to 50.

I'm back, baby!

[DonC]

I plugged it in and went out in the evening after a full charge. The Range Estimate said 36 miles. It got shorter. Needless to say I was irritated. But I have a .25 mile downhill from my house to the main road, and on the way down suddenly the range went to 49. Woo hoo! All was good, until I turned onto the main road and the estimate went up to 50.

I'm back, baby!

I'm glad you're happy but I don't understand what is good about this. You're getting roughly 42 miles of EV range and the estimate is either 36 or 50 miles? My Leaf bounces around like this and it renders the estimate worthless. One of the advantages of the Volt is that it's pretty consistent and accurate.

AFAIK we haven't had another report of anything like this. The issues of range after the battery reinforcement work are usually that the car resets the default to 38 miles, but nothing like the wild swings you're experiencing.