Summary

27 July: 58.3miles using 12.9kWh (includes 2.2kWh top-up charge)
Propulsion power reduced immediately the battery was exhausted and again 25 miles later after we had been parked for an hour. :-(

28th July: 41.9 miles on battery using 8.7kWh from full charge then 0 miles remaining, 9 miles estimated range disappear while parked for 10 minutes (15 miles dropped to 6 miles) :-(

29th July: 39.3 miles from 9.3kWh, 6 miles estimated range remaining.

30th July: 29 miles covered, 21 miles estimated range remaining.

31st July: 44.2 miles from 10.2kWh (including 45 minutes charging at 10amps), 0 miles remaining. 9 miles estimated range disappear while car parked for 10 minutes (11 miles dropped to 2 miles) :-(

1st August: 39.8 miles from 8.8kWh, 0 miles remaining. 10 miles estimated range disappeared while parked (13 miles down to 3 miles). :-(

2nd August: 0 miles covered

3rd August: 39.5 miles from (apparently) 11.4kWh (just one charge, no top-up charging). Range remaining dropped from 15 miles down to 7 miles over 2 or 3 miles distance while power used went up rapidly. :-(

4th August: 51.8 miles from 10.7kWh, 0 miles remaining. :-)

Sunday 4th August - I love my Volt when it behaves

Today by some miracle my Volt decided to behave the way a Volt should behave.
Starting range was down to 46 miles, presumably as a result of yesterday getting under 40 miles for a putative 11.4kWh, but that's alright, it's just an estimate.

19 miles later and the estimate has gone down by 22 miles. However this picture was taken just after driving up a very steep hill (Uffington Castle), so that's to be expected and the view was good too.

Going back down the hill put several miles back on the range estimate so 28 miles from home and I still have 26 miles remaining when we reach Ian Fleming's grave (one of our more obscure local tourist attractions).

The journey home. Absolutely nothing remarkable happened to the range (except that it didn't disappear) and the switch to the engine was similarly uneventful.

Home, and it looks like I get to join the 50 mile club: 51.8 miles on a single charge using 10.7kWh battery, then 1.5 miles on internal combustion engine. Even more impressive given the drive up White Horse Hill in the middle.

Saturday 3rd - Just when I thought I understood it

Just when I thought I had it figured, I get new and even stranger behaviour from my Volt. Back when it worked properly I used to get somewhere between 10.1 and 10.8kWh power used from a full charge. This varies a bit because it's only an estimate, but I've never heard of anyone getting over 10.8kWh without some top-up charging during the day. Then on Saturday I apparently got 11.4kWh, except I don't believe it was anything close to that.
On Friday, BTW, the Volt stayed in the garage, so it isn't that I've missed a day, just that there's nothing to report.

Saturday started with a 49 mile range estimate, 11141 miles on the clock. We drove to Oxford (10 miles, 37 miles estimate remaining).

 The plan in Oxford had been to recharge, but a single car had managed to ICE both charging spaces, so when we left the numbers hadn't changed:

We came home along the A34 so 13 miles and several of them at 70mph which reduced the estimated range remaining down to 20 miles. Normally at this point I would have plugged in to recharge, but as I hadn't managed to charge earlier, and interesting things happen when the charge gets low, I didn't plug the car in.

Despite not being plugged in the range has jumped up quite a bit when we leave an hour and a half later to go shopping:

 4 miles to the shops, 4 miles off the estimate:

Range pretty much unchanged while at the shops:

 Home again. 4 miles driven, 8 miles off the estimate. My wife was driving and commented that we nearly got home with 17 miles remaining, but 2 miles disappeared in the last couple of hundred metres.

I left the car as it was for an hour thinking that might trigger the 10 mile drop I've seen several times now, but in fact the range stayed steady at 15 miles. Also at this point we've apparently used about 7.9kWh for 30.7 miles (average 0.26kWh per mile). Time for another shopping trip.

I pulled over less than a mile from home because seriously strange things were happening: the range estimate was steadily counting down every few yards, and the kWh estimate was shooting up, at this point nearly 1kWh in under a mile. During that mile my speed never exceeded 30mph (in fact it probably never got much over 20), and it was dead flat as well.

The counters settled down a bit after, so here I'm 4 miles from home with an estimated 6 miles remaining, but apparently those 4 miles took over 2kWh. In fact it was worse than that because most of the 2kWh went in the first couple of miles but I didn't have anywhere to pull over sooner for a photo.

Shopping done, can I get home (about 5 miles), on 5 mile estimated range?

Stopped at traffic lights, nearly home, I might just do it before the petrol engine takes over:

I got home with no green bars showing, but still on battery. The kWh used estimate is an unheard of 11.4kWh, but given that I got under 40 miles from the charge I think it is way, way off the mark.

39.5 miles covered, but I don't believe the 11.4kWh, let's see if I can guess what I think it should have been.
The morning estimated range was 49 miles, if the battery gave me 10.8kWh that would be 0.22kWh per mile. The 8.8kWh used I've seen several times at 0.22kWh per mile would have given me 40 miles, so those numbers all seem to fit close enough. I think that despite the crazy 11.4kWh figure on the display I probably got under 9kWh from the battery again.

Thursday 1st August - a pattern is emerging

I'd like to thank Bellinger for suggesting I keep this diary. So far I've found it very useful and it has actually changed my view of what is wrong with my car.
Before recording my range I thought I had an intermittent problem that meant about once a week I either had the Propulsion Power Reduced message or lost 10 miles of range whenever I stopped with less than about 15 miles remaining. Now that I've been recording it I realise that it isn't intermittent at all, it seems completely repeatable.

Here's what I think is a summary of the behaviour:

• If I park anywhere with more than ~15 miles range remaining the range estimate remains pretty much steady give or take a mile or two.
• If I park anywhere with less than ~15 miles range remaining I lose 9-10 miles from the range estimate and only get about 8.8kWh total from the battery.
• If I park anywhere with less than 9 miles remaining I lose all remaining range and get Propulsion Power Reduced when I start the car (which isn't surprising if I suddenly have -5 miles of range)
• If I keep driving over that last 15 miles I get up to 10.8kWh from a full charge, but also drop into Propulsion Power Reduced when the ICE starts because the battery has drained too far.

Here's today's log:
Same as yesterday, the initial range estimate is 49 miles:

 13 miles drive to work and I'm doing slightly better than the estimate:

Lunchtime and the range has dropped slightly over the morning. I go out for lunch driving a total of 12 miles though the range estimate isn't going down as fast as expected:

 

Time to leave work, and the range estimate has crawled back up another 5 miles, in fact at this point 25 miles covered plus 32 miles estimated would be 57 miles total range.

 We need to get some shopping on our way home, so we leave the Volt showing 13 miles range remaining, 8.2kWh used. If I could actually achieve that range I would get about 51 miles from a single charge. That would be nice.

 ... but not going to happen as I return to find only 3 miles remaining.

Total battery capacity used 8.8kWh which is in line with all the other times that I've seen this without any part charges to confuse the issue. I am consistently getting 8.7-8.9kWh out of a full battery charge.

I think I have a duff battery.

Wednesday 31st July - there goes my range again

Tuesday doesn't merit a separate post. Total distance covered was only 29 miles, range estimate started at 48 miles and dropped to 21 which doesn't seem to be low enough to trigger the mysterious battery drop:

Wednesday on the other hand again shows the mysterious loss of range. The days starts well with 49 miles estimated range (it would be so nice to get something neat the start of day estimate; last year that was no problem but no such luck this year).

 Drive 13 miles to work, range drops 13 miles

 and drops another 2 miles during the day. That's alright, a few miles variation is fine:

13 miles home again and we're pretty much on course for the morning 49 mile range estimate, but we're going out again for the evening, so time for a part charge:

I think that 48 minutes of charging, 10A at 240V is probably about 1.5kWh extra battery capacity, anyway it gives us another 6 miles of range:

A brief stop, 40 miles covered today, 11 miles remaining (including the extra from the 48 minute charge).

and 10 minutes later, the car hasn't moved but 10 miles of range have disappeared:

Remember that the 9.7kWh includes three quarters of an hour charging, without a part recharge I actually get less than 9kWh out of a full battery charge:

 I actually managed to double the 2 miles back up to 4 miles before running out of charge, but still leaves at least 8 miles unaccounted for. Subtracting the estimated 1.5kWh top-up would indicate about 8.7kWh for the full capacity of the battery: