Testing 185k mile battery
 

My Yukon hybrid was been awesome for 185K miles, but recently repeatedly has coded P0AC4 Hybrid Powertrain CM Requested MIL, P0A80) Replace Hybrid Battery Pack, and P0BBD Hybrid Battery Pack Voltage Variation Exceeded Limit (Current). It also did the various crazy lurching and other funny issues. I have unplugged Hybrid Battery, replaced 12V battery, but still get repeated codes although seemingly driving "ok". I was confident the battery pack was going bad, and ordered a new GM one, which has come in today.
Since inquiring minds want to know, and as I am an industrial electrician and qualified (and worked for 40 years at the Delco Electronics plant where and in the department that a lot of the research on these and the Impact were done), I opened the battery pack and to my surprise recorded 318 VDC across the pack. Now I am wondering if I actually have battery issues or a control issue. Is 318 VDC higher or at normal levels? I don't have the equipment at home to do full testing and discharging, but want to feel ok to pick up the new battery.

Re: Testing 185k mile battery
 

Not sure why you started another thread. Did you just not like my response? :)

As you likely know, a battery or a cell's voltage tells you almost nothing except confirming that you don't have a COMPLETELY dead cell. An old worn-out 12V battery may show a very healthy 12.6V just sitting there, but the moment you hit it with a 100A load tester (or try to start a car with it), it falls flat on its face with massive voltage drop due to one or more nearly dead cells... that still hold SOME charge at rest.

All it takes is a single cell to render a pack unusable. A single cell failure of a 240 cell pack will make a difference of about 1.2V... that's a 0.4% difference at the nominal voltage. You'll never spot it at the pack level (resting voltage can easily be anywhere between 304 and 324V). You have to measure all 40 modules or 20 blocks directly to confirm you don't have a dead cell. Most meaningful results are obtained after at least 24 hours of sitting... preferably 48.

The cells are rated for 6500mAh. The voltage only tells you their approximate State of Charge (SoC), but it tells you nothing about their actual capacity or ability to deliver/receive current. With 100% consistency of data presented on this site, every GM 2-mode hybrid has experienced a progressive and massive capacity loss. This is likely what's happened to you... your 6500mAh battery is only able to deliver less than 500mAh of usable capacity due to massive AND consistent deterioration.

You can use Android phone/Torque Pro and OBDII bluetooth reader to test it in a manner similar to what I described in your other thread:

https://www.greenhybrid.com/forums/f...results-31736/

You can look at the deep dive into this battery:

https://www.greenhybrid.com/forums/f...ry-pack-31796/

Alternatively, you can connect 3X light bulbs in series to the pack. Use the safety plug for on/off. Discharge the battery with 100W light bulbs until the pack measures about 264V. Record all module voltages UNDER LOAD at that level. You will likely see substantial voltage variation, which confirms your battery is shot (they should all be within 0.1V of one another if the pack is at least semi-healthy).

Re: Testing 185k mile battery
 

Thank you for your knowledgeable and quick reply. I started this thread because I was not sure anyone would notice my question at the end of another thread, and I needed a quick response since I am taking my old battery in tomorrow morning to get my new one and not have to pay the core charge. I hadn't seen anywhere that the battery voltage could be over 300 V so that was why I was asking for clarification. Thank you again.

Re: Testing 185k mile battery
 

NOMINAL is 288V, but you never actually see one that low in the resting state unless they are completely and truly depleted of ALL usable (and unusable) charge - true 0% SoC.

Assuming:
1) healthy battery
2) parked with the SoC very near the bottom limit
3) sat for MONTHS/YEARS

A battery MIGHT read as low as 296V.

Given your high mileage, and the consistency in the nature of the failures, it's likely that you're vehicle isn't unique. It has likely failed in a highly similar fashion. It's possible that I'm wrong, but the data supports a high probability of failure.

Re: Testing 185k mile battery
 

Installed my new GM battery pack yesterday and WOW! I thought my battery was ok since it would Autostop, run on electric, and average 19.4 mpg all the time in city. The new battery has me in Autostop all the time and in electric a lot more in town. The guys here are right about the battery pack is pretty much gone before you start getting codes. Looking forward to seeing if mileage average goes up, gotta pay for that $3150 some way. Actually, was a no-brainer since it is such a nice truck and everything works.
Thanks to everyone on this forum that shares information, especially S Keith, Jaime, and others.
Dealer told me this battery pack was the only one available in the country excepting dealers who may had one on the shelf. Is there anyway to determine date of manufacture from serial number or nameplate? Since GM requires a $1000 core charge I was afraid I was going to get a rebuilt unit but I can tell you this one is brand new.

PS: This can be a one man job, used a 3' x 4' piece of 3/4" plywood slid in the back to the battery pack and lifted each end up onto it one end at a time. Then slid it to the back, and directly onto the folded down tailgate of my pickup truck.

Re: Testing 185k mile battery
 

The bar code on the pack should read "Primearth EV Energy" with the 5th digit of the serial number being a year code. "V" is 2018.

If you can remove the cover or see the serial number on the end module, the first 4 digits of the serial yield the DDMY of manufacture. M is 1-9, X, Y, Z and "Y" would be "T" for 2018.

In the Toyota world, modules are made generally 1-3 months before a pack is purchased, e.g., the new Prius pack I bought last week had modules made 11/12/2018. This can be skewed due to manufacturing surges. Toyota had a supply issue last year, and they supplied enough packs to catch up to the point that it wasn't uncommon to see packs as old as 4-5 months before purchase.

With the lower volume of the GM hybrids, I wouldn't be surprised if the "new" pack was made > 6 months ago.

Glad to hear you got it sorted. Glad to hear you got it $1K below MSRP. Glad the dealer didn't give you a ration of sh!t about selling it to you.

EDIT: Would LOVE for you to go through the exercise of using Torque Pro to log a discharge and post it here... :)

Re: Testing 185k mile battery
 

It1GMC that was a good move to buy a NEW pack. I sure wish that I had held out and bought a Brand New battery myself. I bought a rebuilt pack that I have installed and I am not seeing the huge drive-ability improvement that I expected...................I have done some testing on the old pack and it is at less than 25% of original capacity. If this rebuilt one actually has New modules (like they told me it does) then it should be noticeably better? My idea was that I wanted the truck to drive like it did when it was new. My dream is completely shattered.............................

Re: Testing 185k mile battery
 

a good benchmark is to run it at 25mph and see how many miles it will go??
make sure you warm up the batteries first.

there is a mod to run it to 29mph before the engine turns on maybe mine was modified to start at 29mph ???
two miles in EV mode is the Baseline for a new battery

so if you only go:
2 miles = 100% capacity
1.5miles = 75% capacity
1 mile = 50% capacity
0.5 mile 25% capacity
0.1 miles 5% capacity

Re: Testing 185k mile battery
 

I have the perfect test spot with a big hill going down to the local dam recreation area. The road by the river is at least a mile long (maybe more) / 25mph speed limit and perfectly flat. I will try that this weekend if I get out that way. I understand that there are a lot of factors such as if it is completely warmed up, the heated seats/heat/AC is being used etc etc I might try a couple of passes to see if it is fairly consistent though with everything turned off and completely warmed up................ It would be pretty cool to try to establish a way for people to see how their GM Two Mode compares to others.I have a feeling that my oversize wheels and tires may affect my EV mode duration negatively but we will see. All you guys out there find an equivalent spot with a long hill to charge and then a long slow speed flat stretch and report back with results? Who is good a doing spreadsheets? We will need to do a data base for the other poor souls that drive these dinosaurs.....Haha

Re: Testing 185k mile battery
 

On what do you base this? There are too many variables to consider and too many unknowns to make this consistent, let alone meaningful.

Re: Testing 185k mile battery
 

GM claims it will do 2 miles straight EV mode alone in the user manual
from the original user manual printed in 2007..'
another good indication for a weak battery is a poor translation from battery to engine mode. when normal pressing of the acceleration or 29mph mark..
it should be a seamless... switch over. no lag or hang time...

this happened to me on an suv i test drove nearly caused an accident as I was not expecting this to happen..
it was a 2009 4*4 with 115k miles on it.. I think the battery was damaged from sitting on the lot too long..
115k should be in good working shape..
did not buy since it would have blew the budget since the service 4x4 was on and the battery needed replacement.... they were asking 13,500 for it 14,900 total

I test drove a 2012 with 94000 miles and it ran fine it had other issues i was not interested in fixing it would have put me WAY over budget.. ( oil sensor issues ) it was 15,600 total

Re: Testing 185k mile battery
 

LOL

"Depending on the state of battery charge, the vehicle can travel up to two miles in EV mode." This is meaningless as a measure of any kind. It's even disqualified at the outset: "Depending on..." Here's that that sentence really means:

"If you manage to drive the SoC to the absolute maximum of the usable range, which is almost impossible with normal driving, and you drive like a kindly old grandmother with no surplus power consumption, you *might* get 2 miles of pure EV mode."

There are multiple other factors that can cause "poor transition" that have nothing to do with the hybrid system.

"115k should be in good shape" - based on your experience? Based on how you think things ought to be? Have you seen the data posted on this site? No one has ever posted any meaningful data that says their battery is okay at any mileage.

I just had a 2008 Prius battery fail at 55K miles. How do you explain that? According to your wisdom, it "should be in good shape."

Anyway, at this point we're just polluting an otherwise useful thread. I suggest that once you have something meaningful to bring to the table, start your own thread.

Re: Testing 185k mile battery
 

battery that went flat duh aka left un-used

it happens with lead acid batteries... that is why when you buy a new one you want it to be fresh ..


and on the 4x4 I test drove it had issues staying in auto stop while parked it had been sitting on the lot for a month.. some sucker bought it a week after..
the battery I have was replaced at some point s/n L02XK

Re: Testing 185k mile battery
 

My record on a flat road in slow traffic is just over 7/8 Mile EV. Barely using the pedal to go, mostly creeping.

2 miles down 3% grade with tailwind maybe

Re: Testing 185k mile battery
 

dnt1010, I'm about to order a battery pack myself. How did everything go swapping it out? I have the sierra hybrid, so it might be a bit more difficult.

Re: Testing 185k mile battery
 

coop it is a very straight forward swap in the Tahoe and should be about the same in a Sierra. The pack is heavy for one person to handle (without scraping up your vehicle) 2 people recommended. I still have not made it out to the testing area to see how far it will run on EV mode, kind of lost interest since the Tahoe is driving very well without any issues right now. Gained about 1 mpg on average since the battery swap so it did make a small difference.

Re: Testing 185k mile battery
 

The Sierra may be a bit tougher than my Yukon, as I loaded it in the back on a piece of plywood straight off the tailgate of my pickup truck tailgate and slid it right into place on the plywood. only has like I think 6 bolts or nuts, and the wiring is pretty simple as well. Just unplug the cutout plug and test the terminals before unbolting the 2 power wires. I disconnected my 12 volt battery too just for good measure, and in case the ECM needed reset to learn the new battery. (Don't know if that is needed but didn't hurt anything, other than making it hard to reset the time on the radio clock, directions are on the forum here somewhere if you have that issue)

Re: Testing 185k mile battery
 

Thanks for the reply, right now I'm getting 16.6 mpg and no codes. When I first got the truck 3 years ago I was getting 18.6. Hopefully it will continue running great. I'm 50/50 on keeping it and giving to my son when he turns 16 or selling it after I replace the battery as it should give someone more peace of mind they wont have to pay for it. The Dealership offered me $500 for it when I took it in to get it looked at.

Re: Testing 185k mile battery
 

$500.00 LOL yeah that sounds like a dealer. I have been checking mpg a each fill-up since hybrid battery replacement. 18.8 mpg over the last 1600 miles compared to 17.1 mpg over the previous 7000 miles with he old battery. IF the battery continues to contribute to mpg by that margin as a constant then should have battery payoff at around 200,000 miles LMFAO. Maybe when Ocasio Cortez and Bernie get in office they can do another "Cash for Clunkers" program and we can cash out of all these dinosaurs. In the meantime my ole HO makes me smile every time I stick it in her (I mean the key of course) :shade:

Re: Testing 185k mile battery
 

hitting 26-28MPG consistently on the highway here at 58MPH with CC.




city hard to say since there is too many variables... but seen upwards of 22-23 mpg
16-22mpg would be the consistency range




24MPG combined averaged over the last 2200 miles driven


I recommend Chevron or Texaco Premium fuel 91-93 octane. this will maximize MPG
I been to a few other stations and they never gave me the 91octane I paid for I can tell by it down shifting in to 3rd gear at 58mph which does not happen on chevron fuel 91 octane..


Sometimes I get that start up lag but It only seems to happen while running the A/C mostly that is a 4.5KW or 5KW a/c compressor.. (based on the wire size going to the a/c)

the total load with the A/C on is in the 6-8KW range with the fans and everything going at the same time...

this start up lag can be easily avoided by using M gear mode....
the lag it self generally happens when the auto stop gets confused anyways i always do try to synchronized my self with the green traffic lights.. since they use traffic light link here