Techstream shows battery voltage and SOC not in sync

My battery charge display would sometimes show only 1 bar and randomly I would throw a generic P300 and P080 code.
If I unplugged the battery module to reset it,( without the engine starting to charge the battery),when I power up the car the bars on the display would jump up to show a full charge.

I realized at that point my SOC ( state of charge) in bars on my display was not showing to be in sync with the actual HV battery voltage. The bars seemed to stick sometimes throwing the codes.

Since the HV battery module senses the battery voltage by using 14 inputs, and the input voltages are reading normal, but the SOC did not follow the voltage changes in the charge and discharge cycles. I am assuming the module is bad.

The HV battery module seems to communicate % of battery SOC to the can bus system instead of battery voltage.
I am assuming the module is bad, guess I will try changing it but I probably need to check the CAN BUS Pins on the battery HV Module and Main module first to see if the fault could be by a bad can bus connection.

My question is, if all connections between the modules are good, when the battery voltage and SOC of the battery are not staying in sync, would that be a problem in the HV battery Module?

 

I meant my car was throwing a P3000 code not P300

 

Thanks Brian for your input.

The ECM has a set time it takes to do some readings like 02 sensor readings, not sure about SOC I have over 330k miles on my Prius and that is because I know how to recondition the HV Batteries, People act as if it is rocket science, but it is all volts and amps simplified, you have to have enough of both and they need to be balanced since all cells are in series and one bad one can effect the whole package be it low volts or low amp hr capacity.

I am not sure what is normal when the car is charging right, but when the SOC can be high when the voltage is low and lower when the voltage is high, something is not communicating to the charging system what it needs to do to maintain the HV charge.

My display can show no bars with my battery fully charged so I suspect a module or a wiring issue like short or bad connection in either a module of the 4 that control the charge, or in the CAN BUS wiring.

Today I did a bus check with Techstream, it showed all the modules that work to manage the HV charging and all were shaded red which meant no communication. So since changing the HV battery ECU did not fix the problem and I have a HV controller ECU coming to replace, if that does not fix it , next will be troubleshooting the CAN BUS communications.

You can't get up to 53mpg one day, then randomly throw the death code and get in the 30s mpg, then another day get 53 again and it be a battery issue.

I will figure this out, no doubt to me, I do not give up. When I do I will post the solution here. But people that always jump to condemning batteries only do it because these systems are too hard for most people to troubleshoot so as a first resort they condemn the HV battery.
I will come back here when I figure it out, it has been so hot and humid I have not felt like troubleshooting wiring yet in this weather, just doing component changes of the most likely problems for now as a process of elimination. The modules are cheap and if not needed I will always have a back up. I have rebuilt the combination meter on this car too, before when I bought it, it would not even start. It has been a great car.

 

I think I am chasing symptoms, not the problem as far as the SOC not matching the actual battery charge. I troubleshooted the CAN BUS and voltages are good.
So anyway I found a problem just by happenstance yesterday.

In the past when I did not have this HV charging problem, out of curiosity with the ignition off I had checked the high voltage terminals from the battery at each of the 2 relays to vehicle ground. I just wanted to know if the HV battery was grounded to the frame for safety purposes. It was not, it was totally isolated logically as you would expect.

So yesterday as I was screwing around after checking the CAN BUS, I set my meter to 1000v, had the safety plug unplugged and with my meter negative lead to ground I touched the positive lead to each HV battery cable at the relays, so one cable comes from the positive of the battery and one from the negative on the side facing the front of the car
I was getting voltage readings from ground at each terminal, one a higher voltage than the other.

I noticed when touching the negative meter lead to vehicle ground and the positive lead to the battery negative cable, I was reading negative voltage which meant positive from the battery was shorting to vehicle ground somewhere.

Touching the positive meter lead to the positive cable from the HV battery and the negative meter lead to ground, I was getting a positive voltage reading, which meant HV battery negative was shorting to ground somewhere.

The 2 different voltage readings of different polarity to ground were because the battery was split into 2 packs by the safety plug being unplugged. So since the only other wires connected to the cells were the monitoring wires I determined that is where the leak was traveling through to vehicle ground somewhere further down the line.
,
Prior I had tried 3 different HV battery modules that I had, 2 had been tested one was the original and nothing changed, so I knew the leak was not battery module to ground.
While watching the HV battery voltage to ground I unplugged the plug on the rear side of the battery to the battery ECU, and the voltage dropped out rather quickly, at that point I knew I needed a wiring diagram to isolate which wire(s) in the plug were carrying the short(s) to ground.

I know that one thing the module output plug feeds is the battery cooling fan, but it seems to be working fine tested using Techstream. I will isolate the wires next to see where the shorting is.

One thing I did not mention with all my babbling is the HV reading to ground would very slowly start dropping after the ignition was turned off, this I recognize as a solid state type leakage because it seems like a resistive short, not immediate like a dead short to ground.


It is possible I could have a bad HV control module with an internal short, or a wire feeding it is grounded to frame and the short is traveling through some of the solid state components like a capacitor back to the HV Battery module.

The reason I write so much so detailed is so if others have this issue they can glean more about the troubleshooting process. Sorry it is so much to read.

I will follow up on this soon I have an HV control module being delivered soon, I will try replacing it before I do further wire tracing, in the case my HV control module is the problem,
that would seem logical as the problem in a non Murphey's Law world..

 

I just saw your instructions today Friday, codes were cleared while troubleshooting yesterday, and have not driven the car to set the P0A80 code again, I can tell you the code sets intermittently with random readings in the freeze frame but I am no expert on all aspects of freeze frame data reading so it is possible I could be missing something, just that nothing stood out as abnormal when the Code sets.
I have not wanted to drive the car to set the code, as I have to put everything back in place so the cooling works and I was troubleshooting the wiring yesterday.
I feel I am onto something with this HV short to ground within the charging system so I am going to finish the process and if it does not fix the problem I will work on getting and uploading the freeze frame data. Right now my time working on this is limited. But thanks a lot for your help and communication, two heads are better than one.

 

I am slow catching up on your very helpful post responses, but that makes sense kind of like how it takes time driving to set 02 codes for emissions.

I sometimes think I could design a better component troubleshooter as most codes are vague and some are set by other issues, not what the code designates. Like the replace battery pack code is generic.

My charging issue is causing my AC and my TRAC system to also throw codes because of the inverter control problems