Display battery bars stick, HV battery charging normal.

I reconditioned my battery pack, it is very strong now as far as AH capacity. My display will stick at 3 bars and sometimes at 1 bar and won't go back up even though the hybrid battery is charging properly.

If I unplug the Battery ecu to reset it, it makes the bars un stick and show a charge almost full. Then if I let the car sit with it on and the ac running, it very slowly starts losing bars and it will either stick again at 3 bars or go down to 1 bar, if it ever moved from 1 bar it never goes above 3 bars.
So anyway the battery module is not the problem because I replaced it and it does the same thing. But the Battery module is causing the issue, maybe because of signals it is getting, it freezes up.

I was messing with till dark, it was then I noticed although my 12v battery had a charge of over 12 v, the interior lights seemed dim, then when I pressed the start button and the computers all powered up, the lights got real dim even though my voltage at my 12 battery was holding over 12 volts..

I quit because it was dark out, but I am wondering if the problem might be my 12V cable going up to the fuse box has resistance or a bad connection so all my computer modules when powering up are not getting the volts they need to operate.

But what is confusing is when the inverters buck module kicks in 14 volts to charge the 12 v battery, It seems that would eliminate the low voltage problem. I guess it depends on where the bad connection is if there is one and where the inverter taps into the 12v cable.

One of my hybrid battery cables going to the safety switch had some corrosion on the terminal, when I stripped the casing off, the whole wire had green corrosion.under the orange rubber . I am wondering if that can be going on in my battery cable that goes the length of the car. Guess I will find out when I get some daylight. I am just grasping straws till I get my Techstream program running on my Laptop.

 

To certain people who wear their nerves on their sleeve
Nobody has to read this, I am just using this app to brain storm for my own feedback an analysis of a problem I am having. Most people will not have the patience or understanding to tolerate logic. But if I solve this problem, people will understand the process and hopefully it will help them if I diagnose it.
My Gen 2 Prius battery level on the display will stick if it drops below 4 bars which only happens when the car is not moving, turned on, and the batteries energy is being used . Otherwise the car works normally getting over 50mpg with throttle response you only get from a good Hybrid battery, it stays mostly right at the bar below the first green bar while driving.


There is no corrosion at the battery ECM , or on my HV battery, or components inside the pack anywhere, I plated the copper connectors with nickle. I am way ahead of that obvious corrosion problem in the HV battery on troubleshooting. I drove the car today and got over 50 mpg so my battery is not the issue period. A healthy battery with a good AH capacity can be felt in the throttle, barley pressing it will get a quick response unlike the slower reaction the ICE gives. My throttle is very responsive before the ICE accelerator triggers the ICE throttle body.

It only discharges to 3 bars or less and sticks, if the car is sitting in park, and turned on, with the AC on. , works great while driving.
I suspect the inverter might be the problem as my inverter pump went out and I did not realize when it happened, it overheated one very hot day with the AC on.

I watched the battery voltage while in park, car turned on, ac on, first cycle, it kicked in charging at 209 volts and kicked out at 240v and the next time it kicked in at 209v and kick out at 220v . Whatever regulates the HV battery charging when in park appears to be erratic.

When you are driving, the charge discharge cycles do not allow the bars to ever drop below 4 bars so the display's battery bars function normal , no sticking.

I believe when the HV battery voltage drops too low below (4 bars) while in park, before the inverter starts charging, that triggers the HV Battery ECM to lock the bars for whatever reason. Maybe it is designed that way, it is not the module at fault as it has been replaced and made no difference with this issue.
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Although the HV Battery ECM communicates with other control modules through the CAN/BUS to manage the HV battery, the HV Battery ECM seems to be the module that actuates the display battery bar level. Because resetting only it, affects the battery level display

The display only sticks when the car is not moving and the battery bars drop below 4 bars but
If I let it charge up, reset the battery ECU and drive it, it works perfect, drove it 60+ miles to several stops and never had any an issue, but then while driving the bars have never dropped below 4 bars.

This is not a simple fix or I would not be on this website trying to find a solution so maybe others having this problem could be helped.

The hybrid battery does have a low ( AH capacity/or low voltage threshold) where it will trigger the triangle of death. But there are other problems that can cause the Hybrid Battery to show weakness such as not properly being charged which can also be an intermittent problem in the battery management system. Even a dirty battery blower can cause the battery to throw a (replace Hybrid battery pack code).

I can always tell how much someone knows when they always point to the HV battery as the problem. Most people think the inverters are bullet proof. If they were they would not need a cooling system for heat

You can have one diode go out on a standard Chevy alternator, it will still charge the battery but if you start using a lot of power draining accessories like the AC and lights, it will not have the amp output needed to keep the battery charged in those conditions so your good battery will keep getting a low charge and might seem like it is bad. When it was actually you lost 1/3 of the amperage from your alternator.

A Prius HV battery charging system may be a little more complicated, but the inverter in a Hybrid replaces the alternator, it also uses diodes, converting AC to DC to charge the battery, also an alternator has a voltage regulator and a Hybrid inverter also has a voltage regulation that keeps the HV battery in it's operating range
I have replaced every module involved in the battery management except for the Transmission/ traction module. That leaves 2 other possibilities, either a bad connection somewhere, or a bad inverter.

My problem is specific only when the car sits not moving whether in park or drive, if it sits long enough to allow the bars to drop below 4 bars, the bars stick at 3 or below regardless of the actual charge of the battery, and the only way to un stick the bars is to reset the HV battery ecm.
The bars otherwise never drop below 4 bars as long as the car is kept moving and not allowed to sit still long enough to allow it to drain below 4 bars.

It could also be possible the amp output of the inverter could be weak so when the motor idles, with the AC on, it allows the battery to dip below it's voltage threshold long enough to cause the problem, but when the car is driven and the engine is spinning faster, the inverters amp output can rise enough so the battery never drops below the threshold that causes the sticking bars issue.

I will probably buy an inverter and test that theory.

Just because the inverter will charge the battery, that does not mean it has the amp output to keep up with the drain of the ac when the Condenser fans kick in if the charge of the battery is lower in range and more energy is needed from the inverter that it can output.

You can charge a 12v car battery with a 1 amp charger but it will take more time, if you put a temporary 2 amp drain on it the voltage will dip where if you had a 5 amp charger on it, the voltage would not dip..

I believe the threshold going from 4 bars to 3 where my problem happens, might be because my inverter does not have the amp capacity at idle to maintain the 4 bar threshold, because it has lost some of it's charging capacity in amps at idle.

What makes this complicated to diagnose is your brain wants to believe the battery level meter and it does seem to be accurate, except before sticking.
So lets say the inverter is maintaining the proper lowest charge threshold of the HV battery as it cycles, but it is designed that as the battery discharges, if your inverter outputs the proper amps, that rated Amp output prevents any lag or lowering in the base voltage below the 4 bars, happening the second it kicks in. But if your inverter is not putting out the proper amps, the voltage might drop below the 4 bar threshold before recovering with the charging, causing the problem.
It does not happen when driving because the higher rpm's increase the amp output of the inverter and keeps the voltage lag from ever happening. So I never drop below 4 bars and the display never locks, because higher rpm's are making the inverter meet it's amp output to prevent any lag.

I noticed after a stop, getting back in the car, turning my ac to high caused a a lag in my throttle response and a drop in my battery level that recovered after turning the ac down.
This would fit with my analogy of more drain that AH capacity the Inverter could compensate for because it is weak is leading to my problem of losing that good threshold to prevent either my bars sticking, or the red triangle. As it happened when i was starting out without my rpm's up and with my ac on high.

I am just trying to diagnose different symptoms and how they all could happen. I am at the point I realize nobody on here can help me mostly because the ones who could need to have their hands on it.

I find writing down things as I think them, and reading it back helps me to recirculate the thoughts in my head where I can confirm some and discount others And repeating myself is a programming technique. Some people do not get it on the first shot, I have always been slow to absorb things, but good at storing them for future use when studying things.

I have gone to bed before after trying to figure something out and giving up at the end of the day tired and worn out. Then the next day when I woke up it was like my brain was working on it while I slept and I had a clearer picture of what to do, and sometimes the solution just by sleeping on it. This has happened numerous times, reading what you write helps keep the calculations and thoughts going sometimes even when you are asleep.

I feel sorry for people who have zero patience, I find slow and steady wins the race. Never give up trying and you will never fail







When the car is being driven, there are no charging problems, only when it is not mo