2012 Prius V: SOC Dropping Intermittently And Instantly And Throwing P0A80 Code

2012 Prius v, 209k miles

Last year I replaced two hybrid battery blocks that failed. Two months ago I replaced two more hybrid battery blocks that went bad. I also replaced the voltage sensing harness and primary ground cable because of corrosion. Things have been working well and suddenly, 1,500 miles later, this has started.

Yesterday, cranked up and turned on Dr. Prius. SOC was 58%. I pulled out of the driveway and suddenly the dash lights lit up and my SOC dropped to 27%. It was showing an active P0A80 code. I cleared the code and things started working. About 30 minutes later, it did the same thing.

Today while driving we stopped for about 20 minutes. Dr Prius was showing the SOC at 70%. As I pulled out, the dash lit up and my SOC dropped to 27%. I cleared the code and things started charging. This time the Delta SOC (red) started increasing as we were driving. You can see where I cleared it.

Later I hooked up my Techstream. All block voltages were fine. SOC was 56%. Suddenly, it threw another P0A80 code and my SOC dropped to 26%. Block battery voltages dropped down into the 15 volt range, but there were no significant differences between the voltages.

I am at a complete loss as to what to check next. We're leaving in 6 weeks for a 6,000 mile trip...and I can't leave home like this! Video link attached.

Any input or suggestions would be appreciated.

Thanks!

 

Brian,
Thanks. I will hook techstream back up and try to find that data. I have never looked at/for freeze frame data before...hopefully I can find it! I'll update afterwards. Thanks again!

 

OK, I pulled the freeze frame data related to the P0A80 Code. At this point I am counting on the great minds here to analyze this...because I don't have a clue! I did note that all the block voltages looked OK (to me). Thanks!

 

Yes, I had cleared the last P0A80 code because we were driving and power to the wheels was very low. When I did the sensing wire replacement I did use a used harness that was corrosion free. I also had to replace the sensor module (below is a link to that post with pictures. It was so bad the board in the module was corroded. I have also rebuilt the primary hybrid ground cable that runs from pack 1 and plugs into "something" at the end of the batteries (next to the sensor module). At this point, I would like to replace that cable as well. I am certain all the battery nuts are tight as I had went over them twice.

We live on the Gulf Coast, on the water, so humidity and high temps are the norm. Last year I was checking the spare tire (just an air pressure check) and found about 6" of nasty water around the tire. Everything down there was wet...and I guess that moisture would have also got into the battery. Could be why I've had such a corrosion problem. I did find the source of the leak so we are now remaining dry.

The ground cable (since I don't have things opened up yet); does it plug into the battery ECU? I will start searching for a ground cable and ECU.

Please know how much I appreciate your help.

Link to my previous post:
P0AFC... Terrible Wire and Voltage Module Corrosion | PriusChat

 

Brian,
The battery ECU...is that the part with the relays on it?

Would this be it?
10-15 TOYOTA PRIUS BATTERY ECU RELAY CONTACTOR VOLTAGE SENSOR 89892-47020 MODULE | eBay

 

ChapmanF,
Thanks for joining in! I am keeping my laptop in the car so that if the event happens again, I can capture that freeze frame data (before clearing the code).

Is the module you are referring to the one I linked to below? Thanks!

Travis

2010-2015 TOYOTA PRIUS POWER MANAGEMENT CONTROL ECU MODULE 89681-47250 OEM | eBay

 

Thanks for the update and corrections...appreciated! Yes, sensor module was replaced (I'm glad the link to my previous thread proved beneficial). I do not own or have access to a grid charger for balancing the pack.

Is it possible the cable corrosion could have made its way from the battery ground cable into the contactors/relays? It seems I remember reading in the past about those sticking/failing?

I hate the thought of just throwing parts at a problem...but at the same time I realize there are many things that could have triggered these events. Outside of something else (which it could be...), is this my list of potential part failures:

Ground/negative cable (from battery to contactor/relay),

Contactor/Relays assembly:
10-15 Toyota Prius Gen 3 Hybrid Battery Fuse Relay Box Module G92Z1-47020 | eBay

Power Management ECU (under the dash):
2010-2015 TOYOTA PRIUS POWER MANAGEMENT CONTROL ECU MODULE 89681-47250 OEM | eBay

Over this weekend we will be driving the Prius quite a bit. I will be watching it closely and will report back here if there is another event. We're scheduled to depart in six weeks for our fall trip to Montana...so my time is getting short. I certainly don't have a problem pulling the battery and rechecking everything as well as buying any needed or suspect parts.

Brian & Chapman... again, please know how much I appreciate your knowledge, input and guidance! Thanks!

Travis

 

@ChapmanF, @Brian1954 ,
I do not have a repair manual...but I will look for one to see the troubleshooting steps.

Well...It through another P0A80 code today. It was sitting idle (in ready-mode) for about 10 minutes. When we got back in the car dash lights were lit up. Kathy quickly pulled out the laptop and we hooked it up. I pulled the freeze frame data, attached, and took a look at it before saving the file and clearing the code for our drive back home.

I did note there was a huge difference between the #2 block voltage and everything else; about 1.5 volts less than everything else. I would think that would be enough to trigger the code. What do y'all think?

Travis

 

Brian,
It may come down to buying a new system. Kathy and I pulled the battery out this afternoon (only took about an hour). All batteries tested static between 7.94 - 7.99. One tested at 7.93 ( and was not the one that showed low on the freeze frame data. Tomorrow we will load test each pack.

I did a close inspection of the negative battery cable and it is trash all the way to the orange terminal. See pictures. I do think buying any used negative cable is a gamble...since the corrosion can't be seen unless the insulation is stripped back to expose the wire. I did remove the orange connectors from both cables (see pictures). I am going to order a used positive cable, cut to length and add a copper ring terminal. I will then take the orange connector I removed from the negative cable and attach it to the modified cable. That will allow it to plug in properly and will give me the assurance the cable/terminals have no corrosion. The orange terminals ends are mirror images of each other so they are not interchangeable. That is why I will need to swap ends on the new modified cable.

I removed the negative contactor/relay. One of the terminals shows signs of heat (dark discoloration). So I do believe something got warm. Possibly related to the failing negative cable. Also the blade where the cable connects also has some corrosion...but is really hard to see how much.

Tomorrow we will load test each cell and see what shakes out. I will also be looking closely at the recently replaced voltage sensing wires and module.

I am attaching a few pictures of the removed orange terminal ends and such.

Travis

 

I did find one of the packs on block # 2 to be much lower than everything else. I load tested it and the voltage drop was considerable compared to the other 5 tested.

So, considering the badly corroded negative cable and the heat-discolored pin on the negative relay, plus the weak cell, I can't help but believe there is a cumulative effect here. So, beyond this... @Brian1954 recommended just buying a new battery and be done with it. So that is where I am at at this point in time. However...

I started searching for a new Toyota battery. My local dealer quoted me $4,500 plus installation. LOL. That is more than half of the value of the vehicle...on a good day. So I have searching for batteries. I've contacted a number of Dealers that people have mentioned...no one will sell me one outright (they must install it). So I have turned to looking at the various sellers with the round/tubular battery systems. One that I have seen several times is @2k1Toaster . Some sound pretty good. But I don't know...unsure if any are truly a good thing or if their hype is just lipstick on a pig!

I am continuing my search, but I would certainly welcome any recommendations. Thanks!