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Discussion Starter #1
I have a 2012 Volt, VIN 07960, bought in May of last year. I have had a gradual loss of the reported total kWh on the battery before the generator kicks in over that time. It was over 10kWh for most of last year. It has crept down and the last few times it reported 9.7 kWh before the generator kicked in. Something weird happened the other day and that number has dropped rather rapidly to 9.2 kWh.

I knew I was going to have several errands during the day. I started with a full battery. I had unplugged it the night before because of storms. I plugged it back in after turning the car back on for a second, and it charged for another 15 minutes on top of the full battery. I did one of my errands and used up all but about 4 miles of the range. I plugged it in for about 5-10 minutes outside the garage on my level 2 Blink charger. Then I unplugged it to move it into the garage. It showed the little grayed out battery instead of the green battery on the display, but I didn't think anything of it. Then I plugged it in again for about 20-30 minutes. Did an errand of about 8 miles that usually takes about 2kWh. During this drive, the kWh meter did not budge. I started at 9.6 kWh used, and that is what it read after I arrived back home. I charged for another 20- 30 minutes or so, and then did another errand, and had to use the generator. The usage screen said 59.9 miles for 10.3 kWh used. Would be amazing if true.

After this, the time to complete charge estimator has become inaccurate. It used to be very accurate. Now it overestimates the time to complete charge by about 30 minutes. (The car completes charging about 30 minutes before it originally thought it would upon plugging in. Even during the charge, the Onstar app is about 30 minutes off.) I became worried that the car has lost track of the battery SOC, and maybe some usable part of the SOC has become "lost."

I drove the car today to use up the whole battery. It delivered 9.2 kWh for 41.3 miles. The kWh is the lowest I have ever seen on the car. The miles delivered is not horrible, but I believe is too low. In this weather right now here in Fort Worth, in the 80's-90's, I am used to getting 45 miles or more out of the battery for the kind of driving I was doing.

I remember the Tale of 2 Volts thread. I presume there is some sort of calibration issue. If I remember, the way it was addressed was to repeatedly drain the battery all the way and charge all the way up multiple times. Any other ideas out there?
 

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I've been told to use the charge up until the ICE comes on and then recharge and do some extended driving. I recall this will reset the algorithm used to calculate the batteries range.

Good luck and let us know this helps.
 

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It sounds like multiple small charges per day and the range estimate is getting off. I'd try driving to the lower SOC for a few days with no intermediate charging.

If that doesn't work, maybe disconnect/reconnect the 12v battery. This should reset the computers.
 

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Measuring the actually kWh in the battery is sort of a game really. It is just an estimate really do many times the number mid trip is really sort of off. I think WOP did a nice post on it here someplace.
 

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Discussion Starter #5
I understand the displayed kWh used is subject to a lot of variability and is not necessarily directly correlated with miles driven. That is why I have the miles driven, too. It is really hard to control for all the variables. I subjectively feel that I am getting a little less than I used to. I got more than 50 miles per charge a few times last summer. I can't even come close this year so far, even with optimal temps and not using AC. It sure feels like the loss of reported usable kWh corresponds to loss of a bit of range. This is also not a one time event. It has been a slow consistent decrease over time with this latest punctuation of a more dramatic loss. Even if the kWh has nothing to do with the miles (which I don't believe) why would that be dropping over time? There is some software issue here that I don't think has been explained.
 

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Check out this front page post (and the related threads in the forums).
http://gm-volt.com/2013/02/26/a-tale-of-two-volts-the-summary/


One the SOC reading is far out of wack the car will not fully use the battery range it might and hence it may loose actual range.

It may take a few full discharges to get it there.. Note you might do this in your garage, just leaving the car on will drain the battery.. Maybe listen to some tunes or read a book while usingthe car's AC to avoid the heat! When you get to 0 miles, then let it sit for awhile, try again (to make sure its really0), then let it sit again for a few hours and then charge. A few cyclesmay restore your SOC estimation .
 

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Discussion Starter #7
Thanks tboult. I'll give that a go. I haven't let it sit around very long at the low end of the SOC before charging. Hopefully this will help. Loved your posts at priuschat.
 

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If you really want to do a test that is the same each time and drop most of the unknown parts ( speed -temp -regen -ect ) put the car in a A/C area and just use the heater to drain the battery.

Yes , and end the test when the ICE starts.
 

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Thanks tboult. I'll give that a go. I haven't let it sit around very long at the low end of the SOC before charging. Hopefully this will help. Loved your posts at priuschat.
Thanks.. lets us know how it goes..

Hmm I don't think you see a tboult over at priuschat.. sometimes names are changed to protect the innocent because some people cannot handle the truth ;-)
 

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Hmm, my charging estimate has been about a half hour too conservative ever since I got the car.

I guess I would be concerned except that it lets me get to 10.5-10.6 kWh before kicking in.
 

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Discussion Starter #11
Battery came alive yesterday.

F/U on my previous post.

I have been trying to deplete my battery recently in the hope that this exercise would return what I perceived to be some loss of my usable SOC. I had been having reported kWh usage on full battery discharge in the range of 9.2-9.6 recently. My Blink charger would usually report about 11.6 kWh or so total power used for a full charge.

It took 3 days of not charging to deplete the battery from Sunday through Tuesday (short daily commutes.) The last part of that drive was a little weird in that I was on track for 48 miles and I pulled into my garage Tuesday afternoon with 4 miles reported range left. I checked it about 30 minutes later and it lost 3 of those miles and reported 1 mile of range left. I took it out and drove around the neighborhood and got it to zero miles and plugged it back in for a delayed charge in the AM. It reported 45.3 miles on 9.3 kWh used at the end of that. The next morning, the Blink charger reported 11.8 kWh to charge to full which seemed like a slight improvement over the 11.6 kWh I had been seeing.

Yesterday I had a lot of driving to do. Work in North Richland hills in the AM (18 miles), then drive back to Ft Worth for the afternoon (about 10 miles), then a meeting in Arlington (17 miles) and a drive back home (23 miles); highway driving for a good part of it. I expected to need the range extender at the end. I had a chance to plug in in the afternoon for 5 hrs on 120V 8amps. Before the afternoon charge, it reported 18 miles of remaining range. It reported 32 miles of range after the charge. It acted a bit weird after that in that I drove probably a good 10 miles towards Arlington and my expected range didn't budge from 32 miles. I got there and it showed an estimated 22 miles of charge left. I drove home and I saw it was going to be close, and I got off the highway and nursed it home and made it on EV. It reported 67.4 miles on 12.7 kWh with one mile remaining at the end of the day. (5.3 miles/kWh) I think the stars were aligned somewhat with warm but not too hot temps in the low 90's and some sections of heavy traffic and I have been using more D instead of L even off the highway for coasting, which I think helped.)

Anyway, after a full charge overnight the Blink charger reported 12.4 kWh delivered. That's more like it!

Don't know if I will have any higher reported kWh usage on a full charge after this, or if there is any moral to the story, but I feel optimistic.
 

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Thanks for the follow-up, joshill!
 

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I've never seen my car report more than 9.6 KWH used and it's usually 9.2 - 9.4. My understanding is that this really isn't that meaningful of a number. I understand that the important number is how many KWH's are put into the battery during charging. And, at the end of the day, the real number to me is how much or little fuel I use and how many EV miles I can travel.
 
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