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Discussion Starter #1
So, my 2013 Volt, bought new in October 2012 and now with about 41K miles, ~95% electric, has always given me 10.4 - 10.5 kWhr before going to generator. A little over a month ago, I noticed that it went to generator at 9.9 kWHr. At first I thought I thought it might just be a fluke that would correct itself, but now it has done the same thing about 4 more times (note that most days I don't run to full depletion so I don't know what the changeover point would be). To be clear, EVERY time I have run it to full depletion since I first noticed the problem, it has gone to ICE at between 9.9 and 10.1 kWhr.

Do I have degradation? a bad battery module? Currently I am getting only about 40 - 41 miles range. Where I live in the Pacific Northwest my range is very seasonal dependent, but at this time of year I should be getting about 44 - 45 miles range based on my past experience, so this is a a real loss.

Also, About 2 months ago I had it in for an oil change and they did the software update for "unintended engine running". Now, as I said most days I don't run to full depletion so I don't know what the ICE changeover point would be. I believe that the first time I saw the 9.9 kWhr changeover was the first time I ran to full depletion after the software update. Could this have caused the problem?
 

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Well, I understand the estimated range is a guess based on driving history, but the kWhr used should be a direct measurement of energy flowing out of the battery. I have never seen it vary much in the past, just 0.1 - 0.2 kWhr perhaps. Moreover, I'm sure my range is less than it has typically been for the weather conditions and my driving style.
 

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Also, About 2 months ago I had it in for an oil change and they did the software update for "unintended engine running".
Any reprogramming of the HPCM2 module can reset the learned battery capacity. I've experienced the same thing: mine always switches over at 10.3 but after a reprogramming it switched at 9.8 kWh. Took a number of full/empty cycles for the computer to recalculate the capacity back to 10.3
 

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"Estimated fuel savings vs. my truck: $15750" interesting stat. :cool:
That's about the price of a clean pre-owned Volt.
 

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Estimating the remaining SOC is a lot of science but the voltage is flat across the discharge cycle so it's an estimate until the voltage drops and you switch to gas. The software update may have changed the estimate. Also as mentioned if you don't routinely deplete the battery the estimate can get a little wonky.

I think I may have lost a few miles of range but it's difficult to say. Plus like you I'm still getting more range than promised so it's hardly something you can complain about. All batteries degrade. The Volt has really exceeded expectations but ultimately there will be some degradation. It's just the technology. What I've found is the amount of gas I use is more dependent on the trips I take than on the miles per charge.
 

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the kWhr used should be a direct measurement of energy flowing out of the battery
But it's not. Read the FAQ.
 

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Discussion Starter #8
Thanks everyone for the input. I've read the FAQ and see it is somewhat more complicated question than I imagined. Still, it seems odd to me that before the update the energy information estimate regularly told me I was getting 10.5 kWhr out and I got 44 - 45 miles range. Then, after the software update in one fell swoop It's telling me I'm using 9.9kWhr from the battery AND I'm getting 40 - 41 miles range. For me this is a bad outcome and it doesn't seem like a software update should have this result.

So perhaps I can expect the system to recalibrate over time and get my range back?
 

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Do a series of full battery discharges and recharges. That may do the trick. Can't hurt. See The Tale of Two Volts as an example.
 

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Take about 5-10 minutes (if you on L1) to start your car while its plugged in, shut off all climate controls and turn off the headlights.

Let the car sit plugged in idling for about minutes, the green flashing light should go from flashing to green and once it turns back to flashing, unplug and go on your way.

Be sure to do this activity when you plan on depleteing the pack.

Report back on the result.

Cheers
Ryan
 

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Thanks everyone for the input. I've read the FAQ and see it is somewhat more complicated question than I imagined. Still, it seems odd to me that before the update the energy information estimate regularly told me I was getting 10.5 kWhr out and I got 44 - 45 miles range. Then, after the software update in one fell swoop It's telling me I'm using 9.9kWhr from the battery AND I'm getting 40 - 41 miles range. For me this is a bad outcome and it doesn't seem like a software update should have this result.

So perhaps I can expect the system to recalibrate over time and get my range back?
The flaw in the kWh Used vs Battery Degradation FAQ is the failure to note that a decline from, say, 10.4 to 9.7-9.8 kWh Used on a newer Volt is more likely to be a result of corruption creeping into the computer’s algorithm for determining the battery state of charge than of battery deterioration.

As for the kWh Used number, is there any reason to think it is any less accurate a gauge of fuel consumption than the Gas Used number, even if it was "estimated" and not "measured?" A computer that adjusts an soc estimate when the car is stopped could just as easily adjust the kWh Used estimate calculations once underway again to compensate for any soc adjustments made while parked. Would the car even feature Full Charge and On the Fly ev range estimates without having a method of accurately calculating the rate of electric consumption?

Your Volt display screens don’t provide you with full charge and full discharge soc % readings that would allow readings showing the current size of the useable soc window to be compared to readings made prior to the software update. I suspect you are still getting your usual electric mileage (i.e., miles/kWh), even if it seems the AER is lower. Because the Volt battery is never completely recharged, the system never really has a chance to recalibrate any "100 % charge" data point readings. The recent software update may have introduced discrepancies into the soc estimation algorithm data point readings. If the car is rarely driven to full depletion, errors in soc estimates that are minor when only a portion of the battery is used can have a much more pronounced effect when trying to estimate when the minimum soc point has been reached.

A degraded algorithm could "switch" the Volt to ICE when the "on the fly" soc estimate said the minimum soc level has been reached. If the true soc was still above minimum level when the ICE was started, the final portion of the true soc window of useable power would not be available, truncating the potential AER and kWh Used. The Tale of Two Volts seems to offer such a scenario, where the one Volt’s algorithm was recalibrated via the use of a few cycles of full charge/full discharge, restoring a previous AER and kWh Used range.

As Steverino suggests, try a few cycles of full charges/ full discharges, and as rmay635703 suggests, start your car while it’s still plugged in and let it stay "on" while plugged in for ~10 minutes. The first time I tried turning on my 2012 Volt for ~10 minutes while plugged into my L2 charger, I then drove until the battery was fully depleted, and got 10.6 kWh Used, the first time in over a year and a half that my Volt used more than 9.9 kWh per charge.
 

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30% warranty

Hello....... Your next steps has already been addressed. After the resets, If you drive a route that you have good baseline data (ie EV miles driven, speed MPH, temp, accel ect) and still see reduced miles then you would need to see the dealer with more then that good data.

I still have not seen anything from GM that says that if you get 20% degradation in two years(or even 3-4 years) it does not matter cause it is still under 30% and basically too bad. If this is the real hard Truth it should be out there, as even most all of the dealers do not know this. But two people on this site have mentioned getting this answer from GM (or at least people in GM) in the below thread.

I was done to 32-27 EV miles but that was at about 50MPH. Not sure what your speed is. With 40-41 EV miles it will be tuff to get any body to hear you with out real data from the SOC equipment mentioned in some threads. And EV miles driven. It seems that some batteries may be better then others.

The 10.9-11 KWhrs (maybe 10.8)on my car has been very consistant for about 4 months. But I run the charge down every day.



http://gm-volt.com/forum/showthread.php?196274-Do-you-know-when-your-battery-warranty-will-be-honored-by-GM


So, my 2013 Volt, bought new in October 2012 and now with about 41K miles, ~95% electric, has always given me 10.4 - 10.5 kWhr before going to generator. A little over a month ago, I noticed that it went to generator at 9.9 kWHr. A9.9 and 10.1 kWhr.

Do I have degradation? a bad battery module? Currently I am getting only about 40 - 41 miles range. Could this have caused the problem?
 

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I have almost the same issue - except....

My 2013 Volt, purchased in Aug, 2012 started doing the same thing during the winter. I was getting under 10kwh a fair number of days in a row and started to worry about it. Now that summer is back and that I have actually fully depleted the battery a few times, I am hitting about 10.1 to 10.2 again. I will be really happy to see some 10.4's but I am not expecting that to happen.

My mileage is suffering too right now because of new Pirelli P7 LRR tires so I am only seeing a range of about 36-37 miles vs. about 40. I do a lot of short trips and top off from about a 50% charge on a normal basis. I am noticing a very small downward trend but this year is certainly hotter where I live compared to the last 3 years and last winter was fairly mild compared to the last 3 so I had a lot of days were it was not cold enough to hit ERDTT so I drove battery only for a much longer period of time.

I am going to take a few day trips on 50mph highways in the next few weeks so I expect to do some consecutive daily depleting and maybe it will start rising to 10.4 again.

As the car is now 4 years old and has about 26,000 miles on it, mostly electric, I would not be surprised to see a 5% degradation occurring but the problem is, between weather, traffic, small changes in habits over the past 4 years, some wear and tear, it is really hard to nail it down specifically to just degradation.

I would at first try a few full depletions and full charges before getting too excited about it, even if it means skipping a charge or two and relying on ICE to be able to use up the battery all the way two or three days in a row.
 

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As a fellow '13 owner who had this problem due to a faulty software reprogram (see http://gm-volt.com/forum/showthread.php?198114-Going-to-dealer-any-ideas-on-my-Volt-s-strange-issues), I can attest that a lowering of the kWh used meter combined with measurable range loss equals problem.

My driving is very similar on most days so it was easy for me to note the change. I actually made a spreadsheet of a full 30 days of usage with kWh used + actual EV range. This clearly demonstrated the problem.

Honestly, it was a royal PITA to go through this process and--unfortunately--I was basically a guinea pig while GM tried to figure out the cause (it took 6 weeks of my car in the shop + multiple failed attempts to solve it). Shortly after my car was fixed, a TSB was released on the problem. GM did give me a $250 gift certificate for the trouble, however. Kudos to them for their commitment to Volt owners.

My advice, get your Volt advisor involved and make a daily log of the issue. There are tests that can be performed to show battery health and degradation--which I did not have--and it's probably unlikely you do also. However, this car contains more code than a naval battleship and it is bound to get corrupted from time to time.
 

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Do you happen to know what the tsb number is and what they did to fix it?
 

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I can attest that a lowering of the kWh used meter
A "meter" implies it's measuring. It's not. It's a guestimate based on assumptions. That's why its called a display, not a meter.
 

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Hello .. It seems that it should be more than just a lucky guess/guesstimate if EV miles driven and KWHRs drop as I and others have seen. The below words indicate some sort corrections are going on to get the KWHR used. EV Miles driven under a baseline course being the best measurement without SOC tools.

From the FAQ thread by Steverino From GM fellow:
"An indirect state of charge (SOC) measurement will occur when you turn the car OFF and it sits for a bit but that measurement won't show up on the display, only the estimate gets displayed. The SOC of a Li-Ion cell cannot be directly measured accurately by any non-chemical means, (by some sort of “sensor” for instance) so the Volt always uses an estimation.

However, even while ON there will be times where a more accurate detection (not a direct measurement) of existing SOC can be made, and if significant enough, a correction CAN be made that would therefore be reflected in the displayed kWh readout. The displayed "kWh used" value may vary depending on the number and levels of these corrections that took place during the trip cycle (last time of full discharge/recharge). "


A "meter" implies it's measuring. It's not. It's a guestimate based on assumptions. That's why its called a display, not a meter.
 

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my 2014 Volt was reading low kwh earlier this year; around 10.2 for a full charge. Now its showing 10.5kwh for a full charge; but I don't drain the battery completely very often; so perhaps it is resetting its estimates slowly. When new, the guestimate was more like 10.6kwh or 10.7kwh for a full charge. Also see my updated post; http://gm-volt.com/forum/showthread.php?233273-battery-degradation-indicators
 

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Do you happen to know what the tsb number is and what they did to fix it?
"EV Range Estimation Changes More Than 5 Miles After The Vehicle Sits For More Than 2 Hours" -- any 2013 MY Volt that has had HPCM2 reprogrammed since Feb 1 2015 (and until October 12 2015) may experience the issue. Mention Bulletin #PIC6138 and they will need to reprogram HPCM2 once again.

Note that this TSB deals with a very specific issue -- a faulty reprogram of HPCM2 during the months listed. If this was not you, I'm not sure if it would be helpful but might point to a software-specific issue.
 

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Well, I understand the estimated range is a guess based on driving history, but the kWhr used should be a direct measurement of energy flowing out of the battery. I have never seen it vary much in the past, just 0.1 - 0.2 kWhr perhaps. Moreover, I'm sure my range is less than it has typically been for the weather conditions and my driving style.
As you know, your range will depend on the 5Ts: terrain, temperature, technique, traffic and tire pressure.

From my data of 32 times where CS mode was initiated when the battery had been expended, the average was 10.6 kWh, with the 10.1 and 10.9 defining the limits of the range. I have a 2014 (bought new in June, 2015) with the 17.1 kWh battery. I record every trip and the majority of recharging is with a partially depleted battery charge. I currently have 263 entries and 25,164 miles on the odometer, 29.6% of them EV miles.

I don't think that you have to worry about your battery capacity yet. I would begin to be concerned when you consistently switch to CS mode when the battery reaches ~9.5kWh (you are no longer seeing the 10s). That may indicate a battery beginning to age. Even then, GM apparently won't invoke a warranty repair until you can show a 30% degradation (26 mile range). (I'm not sure that that % is written down anywhere.) And you have 7 more years of warranty coverage (assuming that you bought the Volt in 2013).

So, relax and enjoy your Volt.:D
 
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