Service Hybrid/Voltage Gap/Graphs - GreenHybrid - Hybrid Cars

Service Hybrid/Voltage Gap/Graphs

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  #1  
Old 10-09-2018, 08:51 AM
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Default Service Hybrid/Voltage Gap/Graphs

2011 GMC Yukon Hybrid 193k Miles
have been troubleshooting the last month
infamous PB0dd and MIL codes
using BAFX and Car Scanner (great combo) w iOS
loaded PIDS and been tracking
suspected bad cell(s) or polarity reverse through some discussions
did full 3 cycle discharge/charge/balance w Prolong at 192V/120V/24V
which greatly regrouped 20 battery. Module voltages. That said get whacky anomalies on 3-4 modules and CPA/DPA and Service Hybrid even after rebalance which appears to be from voltage discrepancy.
Looking for next troubleshooting steps if possible before full replacement to know I did all I could.

Graphs are are pretty consistent when issue happens.
graphs: Have high level w all 20 modules and CPA/DPA and then different views w just suspect modules (ones that drop)
appreciate any guidance has been a hell of a learning journey.


(1) Full graph all 20 modules and CPA/DPA
(2) zoom in on drop 1 just suspect lowest modules and CPA/DPA
(3) zoom in on drop 2 just suspect lowest modules and CPA/DPA ( this was at tail of driving when in park sitting in lot)
(4) zoom in on drop 1 all modules and CPA/DPA
(5) zoom in on drop 2 all modules ( this was at tail of driving when in park sitting in lot)







 

Last edited by jhaefele; 10-09-2018 at 09:10 AM. Reason: Added graphs
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  #2  
Old 10-09-2018, 11:33 AM
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Default Re: Service Hybrid/Voltage Gap/Graphs

secondarily, two questions:
what is the definition of Discharge Power Available and should it ever drop to zero like that?
are there PIDS that represent "low volt block" and "high volt block" for the GMC like there are for toyota?
 
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Old 10-09-2018, 08:32 PM
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Default Re: Service Hybrid/Voltage Gap/Graphs

1) Unknown, but they are likely analogous to similar values in the Toyota hybrids. Essentially, given various conditions (temperature, state of charge, block voltage response to current), the power in and out have limits, e.g., if the SoC is near 80%, the car sets a very low charge power available value equivalent as when the battery is near "full", it's not safe to charge it at high current.
2) Unknown, and those values aren't available for all Toyotas. Fewer new models have that value.

The end of the first graph (which is particularly ugly), and the last two graphs say it all. Your battery is toast, and it's typical for the GM hybrids with highly uniform permanent module deterioration, i.e., most modules - even after "reconditioning" - only have 1-2.5Ah capacity vs. the 6.5Ah rating.

Note how you have a huge spread of block voltages, and they are distributed throughout. If you had a problematic module or two, you would see one or two outliers with the rest bunched tightly together.

Essentially, start with the highest block. All blocks greater than 0.3V below the highest are likely bad or at least HIGHLY suspect. Based on the graphs, I estimate that upwards of 15 out of 20 blocks are bad.

You either need to THOROUGHLY TEST ALL 40 MODULES and probably replace about 30 modules, or you need to buy a replacement pack.
 
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Old 10-11-2018, 03:30 PM
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Default Re: Service Hybrid/Voltage Gap/Graphs

Thank you sir... any gut on how long I get away with it like this it’s funny since using prolong I’ve actually been able to get about 2mpg more than I was even w this ridiculous voltage differences. And get a couple “service hybrid” and can tell there’s a blip of a delay during some major drops.... just curious if it will continue down this path and then just finally give up?
 
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Old 10-11-2018, 03:41 PM
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Default Re: Service Hybrid/Voltage Gap/Graphs

It's been on a continual decline for a long time. You're just now seeing the effects. That trend will continue. It might fail in a week. It might fail in a year. Monitoring it as you are will help you assess its health.

Two things have definitely happened:

1) You have maximized the available capacity of all modules.
2) By forcing them all to 100%, you have actually made the imbalance worse. They were "balanced" at 100%, but when the weakest are at 0%, the strongest are likely at or above 70%.

A third possible thing is:

3) Since the modules have wildly different capacities, damage occurred when the deep discharges occurred. The weakest cells (not modules) went into reversal very quickly and a large amount of current was driven through them in reverse. Energizer says that NiMH cells can tolerate about 50% reversal, i.e., a 6.5Ah cell can have 3.25Ah driven through it AFTER it has been depleted of usable charge. Many of your cells are likely at or below 1000-2000mAh.

#1 improves things
#2 makes things worse, but driving and time will help narrow this.
#3 makes things worse - usually quickly.
 
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