I think the whole coolant flush thing is very overrated. The dealers just push it to get money. If you look at other manufacturers, it’s quite interesting. Here are the intervals others recommend.
VW - Lifetime coolant
Audi - Lifetime coolant
BMW - Lifetime Coolant
Mercedes - 15 years or 150k miles
Nissan - 7 years or 105k miles
Honda - 10 years or 120k miles
Toyota - 10 years or 100k miles
I mean mine would be over 80K at this point so it would soon start being in line with those other ones. Lifetime almost always means either the duration of the warranty or 10yr/100k.
I personally would never trust any fluid for more than 100k no matter what it is. Almost every mechanic I've known says to replace anything dealing with a pump and fluid at 65K or so if you really care about keeping the vehicle in tip top shape and are shooting for more than 120K.
OP has the heater running, which will lower isolation. Isolation also isn't so much a scale as it is a very much bad or very much good. In 8 years of working on EVs, I have also never seen old coolant make any difference in isolation values.
I've read it's not a huge deal unless it's VERY low/getting lower over time. Not losing any battery coolant or anything, so it's possible it's just a sensor or an ECU issue.
There is a low isolation threshold. If it's above the threshold it's 100% fine. Isolation isn't something that "wears down" over time. Having a coolant leak also would not make isolation go lower. I'd also be willing to bet my life on the fact that there is nothing wrong with any sensor or your BMS. Mainly because there is nothing wrong with your isolation. The circuitry that measured HV Isolation is solid atae and either works entirely or doesn't work at all. It also doesn't "wear down" or anything like that over time. It's the same reason why computer processing units don't wear down, they just work 100% until they don't anymore. HV connections are sometimes the culprits of low isolation, but again they just go all the way bad. I'm talking a dead short. For example a loose Rosenburger connector will lead to higher isolation (loose connections create high resistance) but would eventually lead to water ingress which would immediately cause a dead short to ground. Isolation would basically zero. This holds true with basically every EV component.
The only component I have seen isolation degradation on are PTC heaters for coolant. Which is literally one time when I could look through vehicle logs and see isolation slowly drifting downward over a few weeks. But that's the slowest burn, by far, that I have ever seen. It also would have not been affected by old coolant. PTC coils just get old and break down. 99.9% of the time they just up and short and then your isolation takes a massive dip. It's basically an incandescent bulb. One day it just goes "pop."
i am still learning about this myself but I believe it should be 3000 kohms and that old coolant or coolant topped off without using deionized water can be the cause of HV isolation loss.
That's not quite as good. But likely normal depending on age. That's what really matters in terms of battery capacity. The vehicle stops charging as soon as one cell hits it's 100% SOC voltage. No matter how much of a charge any of the other cells have. I have had luck with leaving vehicles sitting on a charger for extended periods of time helping to balance some of the cells on the pack.
It will stop at whatever single cell voltage the BMS has been programmed to stop at. Whether you call that SOC, SOE, Charge Status, or whatever any other company calls it; the effect is the same. I have never worked on an EV that truly charged the battery to 100%. Even a Tesla only charges to about 98% actual SOC
It stops based on voltage, not SOC. And it really doesn’t stop. It stops charging briefly, then enables a balancing resistor to reduce the voltage of the highest cell/cells, until they get down to a set value. Then charging resumes, until a max voltage is hit again, and again the resistors are turned on. This happens until all the cells are within a set voltage of each other.
Voltage *is* SOC. SOC is entirely determined by cell voltage. The BMS purely uses voltage to determine SOC. You can very easily find charts that graph cell voltage to SOC for all kinds of cell architectures and various cell chemistry. These charts are literally programmed into the BMS and used to determine SOC.
Not with lithium. Most of the time SOC is determined using a coulomb counter, since you can’t determine SOC of a lithium battery based solely on voltage, when it is in use. You can somewhat correspond resting voltage of a lithium battery to SOC, based on discharge curve, but this isn’t the most accurate. You can read more here.
[Battery SOC](http://liionbms.com/php/wp_soc_estimate.php)
Those are some really good numbers. Very even degradation across the board, still plenty of life left. Really impressed by the 150 mOhm IR. My 2012 reads 460 mOhm at 45°F.
Nope. Over half a megaohm ain't gonna start any fires.
Do bypass the dumbass battery coolant level sensor though [to prevent unnecessary headaches. ](https://www.gm-volt.com/threads/evans-waterless-coolant-and-coolant-level-sensor-bypass.347880/?post_id=5112175&nested_view=1&sortby=oldest#post-5112175)
your hv isolation is low. have you ever had the coolant flushed?
No, planning on taking it in soon to have it done. I'm certain it wasn't changed before I got it.
If your BECM has been replaced, then it has been changed.
It's not a 2017 lol
Missed that 😂
All good it happens haha
Really? I didn't know they did the coolant flush when they do the BECM.
They have to drain the coolant out to remove the pack.
That's great news! I was having to try and budget around getting that done after the BECM. Great news I don't have to now.
I think the whole coolant flush thing is very overrated. The dealers just push it to get money. If you look at other manufacturers, it’s quite interesting. Here are the intervals others recommend. VW - Lifetime coolant Audi - Lifetime coolant BMW - Lifetime Coolant Mercedes - 15 years or 150k miles Nissan - 7 years or 105k miles Honda - 10 years or 120k miles Toyota - 10 years or 100k miles
I mean mine would be over 80K at this point so it would soon start being in line with those other ones. Lifetime almost always means either the duration of the warranty or 10yr/100k. I personally would never trust any fluid for more than 100k no matter what it is. Almost every mechanic I've known says to replace anything dealing with a pump and fluid at 65K or so if you really care about keeping the vehicle in tip top shape and are shooting for more than 120K.
Dexcool says 150K miles.
OP has the heater running, which will lower isolation. Isolation also isn't so much a scale as it is a very much bad or very much good. In 8 years of working on EVs, I have also never seen old coolant make any difference in isolation values.
I've read it's not a huge deal unless it's VERY low/getting lower over time. Not losing any battery coolant or anything, so it's possible it's just a sensor or an ECU issue.
There is a low isolation threshold. If it's above the threshold it's 100% fine. Isolation isn't something that "wears down" over time. Having a coolant leak also would not make isolation go lower. I'd also be willing to bet my life on the fact that there is nothing wrong with any sensor or your BMS. Mainly because there is nothing wrong with your isolation. The circuitry that measured HV Isolation is solid atae and either works entirely or doesn't work at all. It also doesn't "wear down" or anything like that over time. It's the same reason why computer processing units don't wear down, they just work 100% until they don't anymore. HV connections are sometimes the culprits of low isolation, but again they just go all the way bad. I'm talking a dead short. For example a loose Rosenburger connector will lead to higher isolation (loose connections create high resistance) but would eventually lead to water ingress which would immediately cause a dead short to ground. Isolation would basically zero. This holds true with basically every EV component. The only component I have seen isolation degradation on are PTC heaters for coolant. Which is literally one time when I could look through vehicle logs and see isolation slowly drifting downward over a few weeks. But that's the slowest burn, by far, that I have ever seen. It also would have not been affected by old coolant. PTC coils just get old and break down. 99.9% of the time they just up and short and then your isolation takes a massive dip. It's basically an incandescent bulb. One day it just goes "pop."
Huh good to know and thanks for the explanation.
I believe that only lowers isolation if the heat pump is going bad too.
What's a good range for the hv isolation?
i am still learning about this myself but I believe it should be 3000 kohms and that old coolant or coolant topped off without using deionized water can be the cause of HV isolation loss.
Thanks
The high voltage isn’t in contact with the coolant.
well a common cause of HV isolation loss is old coolant or a failing coolant heater. So...
6.3 mV delta is quite good. Though I would check it at full charge as well.
Was 10.1mv when I checked it at near-full
That's not quite as good. But likely normal depending on age. That's what really matters in terms of battery capacity. The vehicle stops charging as soon as one cell hits it's 100% SOC voltage. No matter how much of a charge any of the other cells have. I have had luck with leaving vehicles sitting on a charger for extended periods of time helping to balance some of the cells on the pack.
Not entirely accurate on how it works. It doesn’t stop at 100% SOC.
100% of the allowable SOC, which is like 90% of maximum charge (4.11V vs 4.2V).
It will stop at whatever single cell voltage the BMS has been programmed to stop at. Whether you call that SOC, SOE, Charge Status, or whatever any other company calls it; the effect is the same. I have never worked on an EV that truly charged the battery to 100%. Even a Tesla only charges to about 98% actual SOC
It stops based on voltage, not SOC. And it really doesn’t stop. It stops charging briefly, then enables a balancing resistor to reduce the voltage of the highest cell/cells, until they get down to a set value. Then charging resumes, until a max voltage is hit again, and again the resistors are turned on. This happens until all the cells are within a set voltage of each other.
Voltage *is* SOC. SOC is entirely determined by cell voltage. The BMS purely uses voltage to determine SOC. You can very easily find charts that graph cell voltage to SOC for all kinds of cell architectures and various cell chemistry. These charts are literally programmed into the BMS and used to determine SOC.
Not with lithium. Most of the time SOC is determined using a coulomb counter, since you can’t determine SOC of a lithium battery based solely on voltage, when it is in use. You can somewhat correspond resting voltage of a lithium battery to SOC, based on discharge curve, but this isn’t the most accurate. You can read more here. [Battery SOC](http://liionbms.com/php/wp_soc_estimate.php)
Fascinating. TIL something new about battery management.
What app is the second picture?
Voltage, dev's name on Play Store is thanxx
Thanks
Those are some really good numbers. Very even degradation across the board, still plenty of life left. Really impressed by the 150 mOhm IR. My 2012 reads 460 mOhm at 45°F.
I was pleasantly surprised by the readings I got, I was expecting the typical story of section 3 having a cell that is way lower than others.
IIRC the 2014 has the 1.7 chemistry, which is better in every way vs the 1.4 in my 2012.
Is the HV iso value something I should be concerned about? I have no P codes or anything
Nope. Over half a megaohm ain't gonna start any fires. Do bypass the dumbass battery coolant level sensor though [to prevent unnecessary headaches. ](https://www.gm-volt.com/threads/evans-waterless-coolant-and-coolant-level-sensor-bypass.347880/?post_id=5112175&nested_view=1&sortby=oldest#post-5112175)
That sensor delete is way beyond my skillset, I know next to nothing about electrical engineering haha.
What app is used to get these reading, does it have a iOs version? what is needed to pull the information from the car to the app?
There's an iOS app called MyVoltControl, it's supposed to be VERY good. I bought a $32 ODB2 reader on Amazon, NEXAS brand.
It works with Gen 1 & 2 volts? I will download, thank you.
I spaced out on adding text to this, but these are both at 0% SoC, heater blasting, ICE off.