Failing battery, inverter, both?

Absolutely! Also check your aux 12v battery voltage, I like to check it with a voltmeter up front in the engine compartment drivers side main 12v fuse box jump pin after its been off for a while. That jump pin is directly connected to the 12v battery and if low, can cause all kinds of ghosts. At resting (vehicle off for at least 15 mins) it should be anywhere between 12.2 to 12.6 volts depending on condition of the battery. When running it should be 14.2v, I don't know why they regulate it for so low a charging voltage, my optima battery needs more like 14.6v to reach 100%. I now use a maintainer to keep it charged up when vehicle not in use!

 

have it load tested at an auto parts store. there is a date code on top, if it is older than 5 years, just replace it.

if not, put it on a charger overnight, and keep an eye on the resting voltage.

is it a new oem hybrid battery?

if all else fails, you can troubleshoot the codes at techinfo.toyota.com

 

Keep us posted as some more time passes.

 

I have been monitoring charging voltage for several years, and can tell you that the charging voltage can be anything from 13.2 V right up to 14.7 V.

Your observation of the charging regime being gentle is congruent with my observations, so if the car is not getting regular and long drive cycles, it is on a maintenance charger.

Another of my observations is that for the charging voltage to get to 14.7 V, it usually means the car thinks the battery is totally flat. Another thing is, if I see the charging voltage is 14.4 V or higher for any length of time, that is my signal to give the 12 V a full charge on my external charger.

If your car is charging the 12 V at 14.7 V constantly, it is a pretty good sign that you need to change the battery. Constant charging at that rate will also impact the fuel consumption.

 

I've noticed that after a drive (10-30mins) and you're back home and ready to check it, wait until the entire cycle is over, (after it's done with all the automatic noises etc.)..if you hook up a maintainer too early, this will confuse it! Example: after shut down within about 3 minutes it will have a rather loud purging sound and also the gas tank vent solenoid goes off, all these things will draw current out of the aux. battery and will bring the voltage down to perhaps 11.9-12.0v! But after they are done it will slowly creep back up to its resting voltage. This is when to hook up the maintainer. BTW, I now use a Schumaker SP3.
I like it because it has a readout of %charge, then when it hits 100% it goes into maintenance mode.. Just use the "jump pin" in front engine compartment drivers side 12v fuse box, First connect the - lead to a strut tower bolt for frame ground, then connect the + lead to the jump pin. That "jump pin" is directly connected to the aux 12v + post so no messing with the battery itself or fumes in the rear compartment etc..

 

The other reason to use a Schumaker SP3 is because the leads are totally dead when first connecting the leads! This I believe is very important because with 5 ecu's running all the time, you could zap one or more by hooking a live charger to it. Especially if it sparks! ecu's do NOT like sparks...

 

So at that point, I'd expect there to be some codes thrown. Have you read the codes after the drive? Usually, you would get something like C1241 and others when that happens. How is your inverter coolant pump? If it looks to be working when you check it, maybe it is intermittently failing.

 

Run through the test procedure for the C1241, which will also get you checking the BCPS (brake control power supply) in the back among other things.

I noticed that the C1241 trips well before there are any inverter faults.

You are looking for the reason the DC/DC is dropping the 12 V power.

My hypothesis is that the inverter cooling pump is not working well enough to keep the inverter cooled enough, but not so far out of spec that it trips inverter overheating DTCs.

 

P3000-123
Abnormal signal response from the battery ECU, often associated with a high-voltage battery system malfunction.

Possible causes include: HV battery system, Battery ECU

you had the dealer replace the hv battery correct?
how old is the 12 volt ? what brand?
when I see a glob of codes from my car I know my hv battery is failing

P3024 Possible Causes Faulty HV battery assembly Faulty Battery ECU

 

Have the tools ready to disconnect and reconnect the 12 v negative battery cable in case you get the triangle of death. Practice this before you get the triangle of death then you will be prepared. You may find order and peace if you are prepared. If the triangle appears before you remember your training remain calm a 12 v reset may limp you home.

 

Yes, I agree, it looks like it is barely doing anything.

I'm not sure making such an assumption is even a good idea let alone that, in general, making assumptions is a bad way to diagnose a problem.

Umm, actually P3000-123 doesn't say possible causes are HV battery system, Battery ECU, it says those are trouble areas:

P3000-123
Detection Item: HV Battery Malfunction

DTC Detection Condition: Abnormal signal input from battery ECU (HV battery system malfunction)

Trouble Area:

• HV battery system
• Battery ECU

While it is tempting to go all Chicken Little when you see the words HV Battery, it is a good idea to look at the big picture.

The key with P3000-123 is to focus on the detection condition, where you will see that it simply is the HV control ECU is telling the driver that it heard from the battery ECU that there was a problem. This could be because the inverter is not performing, for example.

Second point, the codes were cleared and did not return. It may be that they were residual from a previous event and not current.


Rather than get side-tracked, my inclination would be to change the inverter coolant pump (or have it changed), as it seems to be hardly doing anything at all.

After doing this I would redo the same hour-long drive (if possible) while logging and see what transpires.