P3013 but block 3 voltage is good

4 years ago, I installed a NewPriusBatteries kit in my 2005 Prius. I've since put close to 60,000 miles on it and the modules had held up strong, that is until a month ago. During a long drive, I started getting P3011, P0A80, P3000, and maybe more. I tested resting module voltages using a voltmeter, and module 1 was 1.5v lower than the rest: a clear sign of trouble. So Nick was nice enough to provide me with a new module 1; he advised that since my pack is still relatively young, the capacity difference should not be too great.

Although he warned me it would take some cycling and acclimating, I kept getting my red triangle, even after lots of driving, but thankfully, no limp mode or pulling over required. Sometimes it's every 5 minutes while driving, sometimes it has gone over half an hour. It has never done it while idling. Module 1 continued to read 1.5v to 2.0v lower than the rest when charging but surging above the rest when discharging (which makes sense because it's new and has slightly more capacity than the others).

But it gets weird. What codes does it throw every time since I replaced the module? P3013 and P3000, every single time. Why would I get P3013 if it's module 1 with the voltage difference? When I monitor live voltages while driving, module 3 never shows any sort of imbalance whatsoever, including at the precise moment the code is triggered.

And it gets even more puzzling. Today I switched modules 3 and 5, to see if the code would remain P3013 or change to P3015. This would tell me whether module 3 really has a problem or not. Sure enough, it behaves exactly the same and still throws P3013 and P3000 every time.

I would think this is a voltage sensor wire issue, but then how come no voltage fluctuation is shown in the readings? There is absolutely no anomaly in module 3 voltage compared to the rest, whether while charging or discharging. Module 1 still shows big differences but I have not once gotten code P3011 since putting the new one in.

So what do I do now? I could ask Nick for a new wiring harness. I could do a module balance by connecting all 14 in parallel (placing a lightbulb as a load between positive terminals of modules 1 and 2, to limit the current since there's bigger potential vs. the rest of the pack).

But I don't know if either of these things would solve the problem.

My car gets me everywhere fine, but I have to use my Car Scanner app constantly while driving, to keep clearing the P3013 and P3000 codes, sometimes every 5 minutes.

 

This is an aftermarket battery pack from newpriusbatteries, each block is one module. There are 14 modules, each with twice the voltage of a factory module.

 

That's what I mean by surging higher: the voltage is higher when discharging and lower when charging. Which is expected.

I am counting from farthest to nearest to the ECU, per instructions for a gen 2 Prius. Module 1 (the newly replaced one) is the farthest (passenger side of the car) and module 14 is the nearest (driver side). And I've confirmed this because in the past when I've gotten codes, they always correspond to this numbering scheme. The failed module one was obviously under voltage as confirmed by my multimeter, and it was code p3011. In the past I had a poor connection between modules 4 and 5, and I got p3014.

 

An update:

The problem is still here, no change whatsoever. While driving, at seemingly random times, codes p3000 and p3013, with no other hybrid battery codes. I have done the following:

• Replaced the battery ECU
• Replaced the voltage sensor wiring harness
• Switched module 3 and module 7 (to deduce if module 3 is actually failing or not)
• Cleaned and rearranged bus bars, making sure the contact side is very smooth and flat.
• Switched out the supplied serrated terminal nuts with the original Toyota non-serrated built-in-washer nuts, as the serrated ones were biting into the nickel-plated bus bars and sensor wire rings. How this could effect voltage readings I don't know, but I did it anyway.
• Torqued all nuts to 48 inch-pounds.

I'm at a loss because I have replaced or swapped every part of the system I can think of, so how am I still getting the same p3013 code? Is my HV control ECU bad? This is the ECU that has the p3000 code, which is a generic code that means "go check the code on the battery ECU". The battery ECU that has been completely replaced. So I'd be surprised if an HV ECU could cause this problem.

One important point as well, is that before replacing module 1, I never had code p3013. Afterwards, it's the only code I get (aside from a brief period of "breaking in" the new module where I was getting p0a80 and some others. But these have been absent for two months.)
How could module 1 cause a module 3 code?

 

The freeze frame data shows all voltages normal (within half a volt) except module 1, which is sometimes as much as 1.5v higher or lower than the rest. However, I can watch voltages live as I drive and see module 1 very different from the rest, but with no codes being triggered. Additionally, sometimes the p3013 code triggeres when even module 1 is at the same voltage level as the rest. Why would the Prius be fine with a 1.5v discrepency for great lengths of time, but then sometimes throw codes for a different module? The p3013 appears randomly. Sometimes I drive for an hour with no code, sometimes it pops up every 2 minutes. There has never been any sign of any voltage anomaly with module 3.

The reason I have not swapped module 1 is because the replacement has a newer plastic bracket design that does not allow it to fit in any other position in the pack; it's shaped as an end piece and won't fit bus bars correctly.

The next thing I'm about to try is starting up the car with module 3's sensor wire disconnected. If I receive code p3013 (and probably p0a80 and more), then I know the module wire numbering is as expected. If I receive a different code, then I know something is screwy with the wire numbering.

 

So apparently the Prius calculates module voltages in an advanced way that I do not understand. I previously thought it would take each pair of sensor wires and simply measure the voltage potential between them. 14 modules, 15 wires, therefore there are 14 adjacent pairs of wires, each a voltage potential of ~14.4v.

However, my experimentation shows there's more than meets the eye. I completely disconnected the sensor wire corresponding to module 3, re-tightened the bus bar, and then started the Prius. The only trouble code I received was P3030, which indicates a complete disconnect somewhere in the battery system, which makes sense I suppose. But on the Techstream live data, all modules were still reading nominal voltages, including #3. That is, until for a second, module 3 showed close to zero, (~0.03 or so) and module 4 showed ~30v. Then it returned to normal levels of ~15v for all modules.

This tells me that the Prius doesn't just read voltage potential between each pair, it must also read larger voltage potentials between multiple modules, then divide those results to get a "second opinion", which it averages with the individual pair readings? Anybody know exactly what calculations the Prius is doing to get its module voltage readings? In any case, this makes me think module 1 could in fact be causing a module 3 code somehow. Still a lot of question marks around it though. Like why does it sometimes not care about the large voltage imbalance for an hour, then sometimes throws the code every minute?

I will try to find a way to switch module 1 to a different position... Perhaps I could make it module 14 since it is an end-piece and might be able to fit (like I said above, the plastic frame design makes it fit with bus bars or terminal wires in only one direction so I can't just put it anywhere in the pack). I could even make some high-gauge wire connections instead of bus-bars, just to connect it for the sake of experimentation.