2007 GEN 2 - weak HV battery but the modules are ok

Hello,

I have a strange problem with my Prius, and since I live in Eastern Europe (Romania), we do not have many proficient hybryd mechanics, so... here is my problem:

Couple weeks ago, when driving arround the town, I got a ABS, VSC and (!) sign. I noticed that the brakes were a little weaker. I pulled over, restarted the car and the problem vanished. Everything went ok for few days, than it happened again. Same procedure got me rid of the warning lights and the brakes were ok.

3 days ago, driving in the city, and the ABS, VSC and (!) apperared. Also, there was the red triangle and check engine. I read about the failing 12v battery and checked it, it is ok, healthy and sound ( I checked it at a local automotive battery shop, where they have some special diagnose tools for batteries, they told me it is top notch. After some 30 minutes I started the car again and all the errors were gone.

Yesterday I drove arround 180 miles to a nearby city. I was cruising at arround 60 mph and accelerated to 70 in order to pass a slower vehicle. Than it happened: the ICE revs went up, and I felt a sudden loss of power. Also, the red triangle and check engine light appeared and, on the mfd, the red car with !. The charge status on the MFD turned to the last two purple bars. Pulled over, restarted but the warning lights remained there. Drove again, and the battery was charging much more slower, and if I hit a speed above 60mph it started to deplete. Also, when a hill was reached, the battery discharged and I ended up going uphill with only the ICE, making a lot of noise and just barely crawling.
Reached destination, and returned after some 2 hours. All the errors dissapeared, but the weak battery simptoms continued, and there are present to the day. No more errors on the obd reader (I use Torque) nor on the dash.

I remembered I had home an Chinese OBDII reader, so the next day I pulled the codes, and only one was found: P3190 (power train). Another odd issue is that, when I check the HV battery voltage via the torque app, it shows some errors. some of the modules show a normal 16-17v voltage, and others (actually 10 of them) show -322,5 V.

I considered it has to do with some HV battery cells giving up, even if I did not hear the cooling fan, as I read it should happen when a HV battery fails and starts to overheat. Took out the HV battery today and checked the voltage, all seem ok. Also, I did a load test for one minute on each cell, with a 110W load (2 H7, 55w bulbs) and did not find any strange voltage drop, results below:

cell initial voltage/ voltage alfter load / voltage drop
1 7,87 7,69 0,18
2 7,87 7,69 0,18
3 7,87 7,67 0,2
4 7,87 7,66 0,21
5 7,87 7,66 0,21
6 7,87 7,66 0,21
7 7,86 7,66 0,2
8 7,86 7,65 0,21
9 7,85 7,64 0,21
10 7,85 7,66 0,19
11 7,86 7,65 0,21
12 7,86 7,65 0,21
13 7,85 7,66 0,19
14 7,86 7,65 0,21
15 7,86 7,66 0,2
16 7,85 7,65 0,2
17 7,86 7,65 0,21
18 7,85 7,65 0,2
19 7,85 7,65 0,2
20 7,85 7,65 0,2
21 7,86 7,65 0,21
22 7,85 7,64 0,21
23 7,85 7,65 0,2
24 7,85 7,65 0,2
25 7,85 7,65 0,2
26 7,86 7,66 0,2
27 7,87 7,66 0,21
28 7,88 7,69 0,19

The battery pack seems to be ok. What could have caused this? The car starts ok, drives ok, but when I hit a hill, the battery depletes very quick ( in a matter of 0.8-1 mile). When I go downhill it charges ok, I see even green bars if the descent is longer than 2 miles, but it seems that it charges slower than it did before.

Other things I checked were the 12 v battery, the hybryd coolant pump, all work fine.

I suspect 2 possibilities:
1 - I have a battey ECU failure, but then why does it not throw codes?
2- being a 2007, 168.000 Miles, the battery could be worn, so it can't hold the charge? but then, why did it happen all of a sudden? Would a regeneration of each cell help?

What do you think?

 

Well, I will have to check on that.
Would a low capacity battery benefit from a cell regeneration/rebalance? Or it would be pointless?

 

Is there a way to check the fan without powering the car? I do not remember to have heard it ever. If battery is weaka,it should heat up when beeing pushed to the limit I recon

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I remembered something, when I openwd the battery, there was some corosion on the bus bars (copper plates) and on the nuts. Can that be a sign of a bad battery or is somewhat normal? Does it help to clean that corosion?

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I've just ch checked' no corrosion at the orange connector...
Could all these be symptoms of a bad battery ECU?


iPad ?

 

Unfortunately no. I am programmed tomorrow for a scan at the local Toyota dealer, let's see what cods will they pull. Anyway, I am determined to do a battery regeneration by using rc chargers and hope things will be better then.


iPad ?

 

So... Been to the dealer. He tested it for couple hours bit no code popped. Road tested twice. First time we went uphill and when the battery emptied, it continued on the gas engine. Sluggish as a snail, as everybody knows they go on gas only. Put it on tester and then again road test, the battery got full charge. So he told me that the inverter is ok,it charges the battery.
They sent me home and told me to come back when the errors reappear on dashboard.
One more interresting thing, he daid that given the mileage and the oil consumption, could be that the ICE is too weak to charge the battery when i go uphill? And that is why it wont charge uphill?

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Happened again...

 

Dealer has opening for schedule only next week. Does this freeze frame data remain saved somwhere until then, or I should hurry somehow?

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Thank you for your patience and goodwill, I will Clean those. The cleaners are available locally. Would these i probe the power of the engine?


iPad ?

 

All these errors that I get... could it simply be the HV battery and nothing else? The simptoms seem to be similar to what other people from the forum get when their battery is finished. The guys from the Toyota dealer alre clueless in what to do, tommorow they will check the p 3190 error by doing a compression test. But they stated clear that the HV battery does not have anything to do with this issue, altought the HB Battery sign on the MFD is pretty clear...