HV Battery problem

Also, the symptom of the battery indicator going from full to empty and back quickly is a main sign that your HV battery has at least one bad cell. That, and the battery fan running on full are pretty certain indicators. If the battery is bad, then you will experience limp mode.

 

PAO80 is Hybrid battery failure. You have one dead cell or more and or corroded interconnect bus bar connections.
Always accompanied by a battery charge-empty-charge-empty fast cycle on the mfd.

And I hope the transmission has had a fluid change somewhere in its life too. Shame to buy a new pack and then the trans goes.

 

One or more modules is way out of range of the other modules. That's what the Battery ECU is detecting and nagging. Or the buss bars are very corroded where the connections meet. Should be shiny copper not green or dark brown.

And I am referring to changing the transmission fluid. Open the dump bolt. Dump the fluid. Open the fill bolt (do that first) and pump in or funnel from above 4 quarts of Toyota WS transmission fluid. $ 10 a quart.
Very easy. Thousands of posts about that procedure here. Getting almost as popular as a dead 12 volt battery.

Post pics of how it looks and pictures of the magnetic dump bolt end please.

 

Yeah if you didn't change that weak one out then it's almost certainly going to be causing the problems you're now seeing. There may be other weak ones, but that 6.86V one sounds like a definite.

Measuring just the open circuit voltage wont always find a bad cell, often they'll still look healthy enough until you drop a load on them. Even a relatively small load of an amp or two can be useful to make a weak cell show up, they will start dropping their voltage under load much quicker than the healthy cells. Of course if you're going to do anything like dropping loads on cells then you definitely need to know what you're doing around electricity, otherwise it's likely to end badly.

 

Wow thats really cool. Well done. Fingers crossed down here.

 

Nope...still got some soft modules in there.

May be time to bite the bullet and buy a rebuilt pack.

 

I don't think they would even out by themselves. Try discharge the new module to the same voltage as the others with a light bulb. Good luck!

 

Here's what I would at least try if this were me (no guarantees but it makes logical sense and its easy to do).

Drive the car on a flat surface below 42mph and hold in EV mode for as long as possible (trying to run the HV battery down as low as possible) The idea is to get it into the purple bars. Run it until the ECU's automatically fire up the ICE to begin recharging the battery (this doesn't have to be done while driving, you could also do it by simply turning it on and letting it sit. The main focus is to drain the hv battery as low as the ECU's will let you). Then, drive it to a long downhill stretch and coast down the hill in drive (attempting to get the battery to 8 bars). If after this, you have codes, clear them. Drive the car and see what happens.

The idea behind this is to attempt to balance the pack using the cars charging system. I might even do this 2 or 3 times. If it doesn't work, you'll have to resort to more extreme measures of repair/balancing.

I would give this about a 10% chance of helping you.

 

I have to disagree. Assuming all the modules in the pack are in good health, and the problem is that one of the module is too full or too empty as compared with other modules, then going through deep discharging/charging cycles as usnavystgc suggested won't help, since the modules are connected in series in the pack, and in the worst case it will hurt, risking overcharging a module that's too full or over-draining a module that's too empty. The only correct way to balance the modules is to open up the casing to access individual modules and charge up the module that's too empty or discharge the module that's too full. Not trivial and require all the safety precautions and safety equipment. Good luck!

 

I was totally expecting this type of response and its just so overbearingly false I have to respond to it.

For one, how will what I suggest take any module through a deep discharging/charging cycle? The ECU will not allow it to go below 40% nor will it allow it to go above 80%. Since the module in question is presumably overcharged, It could possibly take one module above 80% (but this is a very remote possibility). Even if it takes one module above 80%, the fact that the modules are in series will cause the excess charge to spread throughout the battery over time.

There is not even a possibility that what I suggest will risk "overcharging a module that's too full or over-draining a module that's too empty. If there is, I would like to know what that scenario is.

And to say that the only way to correct it is to do what you say ("open up the casing to access individual modules and charge up the module that's too empty or discharge the module that's too full) is very presumptive.

It always amazes me that when I try to offer a suggestion to someone to help them, someone has to come in and shoot it down right away. And its usually someone that hasn't completely thought things through (as I believe the case to be here).

You can disagree all you want but at least offer a logical argument for your disagreement (with at least some basis in fact).

 

My argument in my post above may be brief but is indeed logical. You can think about it when you cool down. Cheers.

By the way I would love to know how this magic can happen:

 

I'm not mad. Its just illogical. There's no need for me to cool down. Pls state the logic in it for people who may not be as smart as you are or have as great of an understanding as you.

Cheers

 

Its really too bad that the OP came here for help and when he gets someone trying to help, he has to weed thru all the subsequent FUD posts and usually ends up afraid to try anything to fix it.

Sorry OP, I tried to come up with something to help you but the self admitted "Wimpy DIYer" disagrees.

 

I hope to write a reply in more detail soon. In the mean time I dug up the attached Navy training material that should help our US Navy STGC and other interested members refresh his/her memory on how DC electricity and batteries work. Have fun reading! There will be a quiz later. By the way I am glad to see that at least part of my tax money is used to make such nice training material for our military.

 

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