P3021 Battery block 11 becomes weak

I've got the same issue with my 2007. Any resolve to this problem?

 

welcome! absolutely.

 

I have code P0A80 and code P3021 will this require me to replace the entire HV battery? I took it out and tested all of the individual modules all tested to be 8.03 volts except for one which tested to be 7.36 V. could it be this one module causing all of my problems

 

it could be. the problem with replacing that one module is that it still won't be balanced with the old ones.

there are some great threads here, for the brave of heart, detailing how to balance everything. but even after you've done that, you don't know how long until another module goes bad. current voltage tells you nothing about health.
the only other options are new, $2200. or so, and rebuilt dorman, $1500. or so, but they are iffy as well.

 

So pretty much, time for a new car?

 

You need to replace the failing module. You can replace the failing pack. You could also replace the entire vehicle.

And yes a ~700mV difference means there is a cell in there that is dead dead dead.

What you need is to replace that module with a like minded module. For example, if your pack has degraded to where the average internal resistance is 19mOhms and the module capacity is 2000mAh, you will want to find a used module with pretty much 19mOhms of R and 2Ah of capacity.

This is almost the proverbial needle in a haystack. That goldilocks module exists out there somewhere, but it would be considered a quest to find it.

Sub-ideal solution #1 is to replace the module with one that is kind of sort of close. Buy a few on eBay (probably 3-4) measure and select the best fit, pop it in, and drive away. This will most likely last many years... BUT, it could also be "rejected" just like an organ transplant and die in a few days or weeks. This is what I like to refer to as "playing whack-a-mole".

People have had excellent results with this non ideal solution, repairs that last years and keep on ticking. And for $30/module and your car already open, why not?

Now imagine that instead of trying to find one of a few modules that fit your exact Prius pack, you just had to find 28 random modules that fit eachother? You would have hundreds or thousands of modules and you could measure, record, and categorize each one and group them into like stacks with like resistances and like capacities. Once a grouping had 28 modules, voila, a new reconditioned pack! And this is exactly what the reconditioned pack people do. They have a warehouse full of modules and select 28 like minded modules and put them together.

Personally since it seems you are comfortable with working with the HV battery, I would buy 28 pre-conditioned and pre-balanced modules from an eBay seller or whatever. Let them buy thousands of modules and do the sorting for you. There is an eBay listing out there for a guy in Las Vegas that sells balanced/mated genII cells in lots of 28 and more for Gen1 vehicles do a retrofit. It will cost you roughtly $1K upfront. You know you are only replacing 1 bad module, so you now have 27 good but unknown modules that you can resell on eBay as onesie-twosies for $20 or so a piece, making a brand new reconditioned balanced pack out the door for $500. This should last a very long time, and when you buy in a pack like that, usually there is a warranty (some 30 day, 90day, 1 year, 3 year, or some are just mileage based but require odometer verification etc).

If you want a new car, go get one! But no a repair should work.

 

Wow that's awesome. But I may just try to buy a few of the modules and try that out.

Thanks for all the info 2k1Toaster

 

how many miles on her?

 

The module that is 7.36 volts might not have a failed cell in it. You should try charging it before replacing it outright. Typically a bad module with a bad cell will read less than 7 volts. After you have charged it, you should do a load test on it to see how rapidly the voltage drops and to get an estimate of its capacity. You will need to compress the low voltage module between two 2by4s so it doesn't swell when you charge it.

There might be other problems with block 11 causing the P3021 code. Investigate this first - examine the bus bar closely for corrosion. This might what is preventing the low module from getting enough current to charge to the same voltage as the others.

 

approx. 130,000

 

When I took the battery out the first time to check voltage of the modules I cleaned all the bus bars. I found the code continued after replacing it. I went ahead and just bought a new module. Putting it in today and will see if the code is still there after replacing.
*EDIT Any tips on replacing? Just so I know things to watch for and be cautious of?

 

Try and get the replacement module sort of equal in voltage to the rest of the pack before you install it. Otherwise you will most likely get a code thrown immediately for it being out of balance (the car doesn't expect 1 cell to be replaced while it is off). Sometimes the car will attempt to balance with the code thrown and then you can clear it later.

 

I found one that was VERY close in voltage. Mine had been saying 8.03 V per module. the one I received says 8.06 V hopefully that will be close enough

 

When taking the battery pack apart, make sure it's done after you haven't driven on it for a day. If that battery is still HOT, it will swell up the minute you unbolt it.

Remember that are bolts on the bottom of the entire battery pack, those all have to be removed before you unbolt the pack and let it loose.

I agree the modules with 7.xx volts may not be a failed module, it may just be out of balance.

 

Wow that's good to know for future reference. But since it's not been functioning properly I've not been driving it. Replaced the module though and it's not showing codes yet. Will drive it a bit tomorrow and see what happens. Will update tomorrow. Thanks all for the help and great info.

 

CAN someone tell me where is block 13 located in my 2007 Prius? I attached a picture i took, is it located on the left side where the power supply is at or a the right side where the letter paper is at?

 

No, block 13 would be #3 and 4 module from the ecu end. Not paper e end