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Discussion Starter · #1 · (Edited)
I just got back from the service after 2 weeks ago error "service high voltage charge system" pop up in the morning, after a long ride on mountain road and ramp parked over night. First thing I thought it is the cooling level or sensor but today I got the car to dealer service.
The good new is that everything was ok, the level of cooling, the sensor and what it had triggered the error was low AC "freon" wich I understand if it ain't supply enough air to cool down the High Voltage battery, it will trigger the error.
So, I changed the AC freon and after that I was told it needed 2 software update. That's when the bad news come in.
The fault cannot be clear without update, but with this update I was told that I might have some loss in range. So i read that some Ampera owners have got this problem, I hope not me. I understant it's not the reballancing cells update, as that one was done on 2013 Volt recall. Maybe the car is just relearning my driving style but some says it will completely discharge at 8.8 - 9 kwh after update. Currently I was able to pull about 9.5-9.8kwh.
Now my car is charging and I will see if this update affect my range.
 

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It is my understanding that some of the procedures done on the Volt/Ampera may result in a resetting of the car’s programming that calculates the ev range. I would recommend that you drive the car through a number of full charge/full depletion cycles so that the Battery State Estimate Algorithm can calibrate itself using data gathered from the throughout the entire "usable window" of power.

How many cycles? At least one person suggests up to 12 cycles. The Chevy Volt Owners Facebook group has one participant who is a Volt tech. Here are a couple of his postings that speak to the need to recalibrate your car’s range estimate programming by carrying out a number of full charge/full discharge cycles.

Note especially the second item, where he recommends up to a dozen cycles AND that it helps accelerate the learning process by waiting two hours before plugging in to recharge and leaving it plugged in for two hours after it reaches full charge.


" Jaryd Carvell->Hi friendly neighborhood Volt tech here! As I have tried to explain to so many people in this group. The recall (GM Program #:N172130462 Issued:Mar 28, 2019) is to correct your vehicle from improperly balancing the cells over time. The balance of those cells is part of what is used to calculate the GOM. When they reprogram the module 2 things happen. The vehicle starts to properly balancing the cells again, and the battery capacity learned values are reset. Over the course of multiple charge/discharge cycles the cells properly balance, and then the module relearns the capacity and the GOM adjusts accordingly. If your GOM goes up or down it means that the car had not been properly balancing the cells for quite some time. This process happens much slower without full discharge/charge cycles and so some people the adjustments happen much quicker than others. Also not all vehicles have the same cell imbalance. Even with the bad software some vehicles were staying close to properly balanced and others were quite a bit off. If yours was one that was close to correct, not much will change after the recall. If your cell balance was off, the more it's going to change after the recall. This is why some people noticed almost no change and others have had a change in the GOM. This is also why some people have seen the change quickly and some it took a while. Complete discharge/complete charge cycles will accelerate this learning process. Oh and one more thing, the 2013-2015 volts have 9 battery temp sensors but really only need 6. There is also software included in the recall that allows the vehicle to ignore up to 3 of the redundant temp sensors if they fail, rather than having to replace them. So there are multiple reasons to have this recall performed."

" Jaryd Carvell Hi friendly neighborhood volt tech here! ... If they did the relearn procedure..., it can be up to a dozen full discharge/charge cycles. It also helps if you leave it discharged for 2 full hours before plugging it in, and once fully charged leave it plugged in for 2 more full hours. This will accelerate the learning process."

The suggestion to wait 2 hours before plugging in brings to mind a point made in Steverino’s kWh Used vs. Battery Degradation FAQ regarding the adjustments the computer may make to the SOC estimate when the car stops for a while during the day’s travels. The computer uses the time to gather additional data to refine the estimation of the battery state of charge. IOW, if the computer can make a slight adjustment to the SOC estimate it is using to calculate range when you stop to run an errand in the middle of the day’s driving, it may also be able to make a similar adjustment to its data for the "fully depleted and am about to plug in to recharge" SOC estimate if you don’t plug in immediately, but instead wait a couple of hours... and the same for the "it’s now at full charge" SOC that it uses for the "full charge SOC" reference if you let it remain plugged in for a while after reaching the full charge point.
 

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Discussion Starter · #3 ·
Thank you "wordptom", very helpful article. I just did a full charge last night and GOM show 61km of range instead of 66-67 what I had before the update. The most important thing is the kwh used, I will see after a full discharge. Before the update my GOM was a bit off, most of the time for the first 40% of the battery, on short stops it looses 1 kwh in 1km maximum after start from a 10-15min stop. Most of the tie,after using 50%, my GOM show me 1bar more, sometime let me discharge 8.8kwh other tiem 10.2kwh, so it was king of fuzzy.
So, I understand that this update actually wil not decrease the percentage of usable battery capacity, instead, it reset the method of calculation and learning process.
Thanks again!
 

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I’ve been driving my 2012 Volt for over 8 years now, and had the cell balancing procedure done last November, after which I drove my Volt through 11 full charge/full depletion cycles so that the Battery State Estimate Algorithm could calibrate itself using data gathered from the throughout the entire "usable window" of power.

I used an OBD reader and the mygreenvolt app to view the raw SOC at full charge when I unplugged from the wall, and the raw SOC at the point where the system switched to gas (or as close to that moment as I could stop the car and view the numbers, keeping in mind that once the car is in CS Mode, the generator is running and the SOC is subject to change).

My records indicate the averaged value of the "full charge" SOC for my 2012 Volt was 87.8%, and the switch to gas SOC value was 22.3%. The "usable window" for the 11 cycles averaged 65.35% of full capacity (Wikipedia says the Gen 1 Volt usable window is 65% of full capacity). The kWh Used ranged from 9.1 to 9.6 kWh, averaging 9.39 over those 11 cycles. Math says 9.39/65.35% = 14.4 kWh current full capacity, or my 2012 Volt’s full battery capacity is ~90% of new after 8+ years of driving.

I rarely drive more than 10-15 miles per day, except for long summer road trips, and recharge daily, so I rarely observe the kWh Used in a full charge more than a few times a year. I think my "normal" had been ~9.6-9.8 kWh before the procedure was done. The variation during those 11 cycles was from 9.1 to 9.6 kWh (average 9.4), so there might have been some reduction. Range achieved in December/January varied widely, from 39.8 to 21.6 electric miles (64-34.8 km), but that could have been a seasonal cold weather effect. At the beginning of this July I drove 42.8 ev miles (68.9 km) on 9.6 kWh Used in a full charge, and my GOM today is reading an estimated 43 ev miles (69.2 km), which seems not bad for an 8 year old Volt with an estimated 10% loss in full battery capacity over the years!

Keep in mind if you try viewing your own SOC readings that the data you gather is not that precisely measured (to one decimal point, at best), so these values are approximations only.

I will also admit that my habit is to plug in to recharge as soon as I arrive home... it is very hard to remember to wait 1 or 2 hours before plugging in to give the computer additional time to gather more SOC data at that SOC level so that it can use that data to "fine tune" the Battery State Estimate algorithm.
 

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Discussion Starter · #5 · (Edited)
Thank's again for all the details, seems like your habbit is like mine, /i drive around 20km/day and I plug in the car every night, but I think that habbit was what made the Gom read wrong after short stops. I attached my SOC at 100% charge (90.2) and I also test with yvoltcapacity and I have 40.9Ah left so not bad at all. I have 91k km first register 06.2014 (2012 production year)
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I will do 12 full charge/discharge cycles and see how it goes, hope I get my old range and usable kwh. So far, are you happy with your update? I haven't got a choice after I get "service high votlage charging system" that was caused by low cooling freon on AC.
 
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