2008 Swapped two traction battery cells, then got 3001 code.

My sons 2008 Prius with 203K miles got the dreaded red triangle of death last week, temps were -15F.

I disconnected the 12v battery and charged it (hoping that was the issue), ran the car and the red triangle came back on. Used the Dr. Prius app and found that block 8 was bad 14.3v vs 16.x on all the other blocks of cells.

Pulled the battery, removed the two block 8 cells, shifted everything to the left so that the replacement cells would be block 1 incase my replacement cells would be bad. I have an older traction battery from a 2005 Prius that was wrecked. The replacement cells had been sitting for 10 months. Got everything back together and went for a test spin.

For the first three miles everything was great. All blocks except the newly replaced block 1 were showing 16.6 or so, block 1 showing 15.3 (but it had not had a chance to charge). According to the Dr. Prius app everything was still in the green.

Red triangle came back on, I pulled over, Read the Battery codes: 3000, 3001 then reset them, and the Red triangle light went out. I could hear the battery fan on high, and looking at the Dr. Prius app, the traction battery was at 35% and going down. The car must be in limp mode because it would not accelerate very quickly. I was about 3 miles from home so I turned around and kept driving back watching the traction battery go from 35% to 33, 30, 28, 26... I made it home at about 23%. Stopped the car, put in in park, turned it off.

Started it back up, no red triangle, no codes... Held the brake and gas and could see the traction battery was charging.. When for a 2 mile test ride and it seemed normal, no issues, battery kept charging. I'm in WI, the temps were about 25F.

I could not find any anyone reporting a 3001 error code. I see this happens in Gen1 Prius, and it seems to be a Battery ECU issue. It looks like for gen2 3001 is also traction battery ECU issue.

Tomorrow I, I will take another look at the battery pack and ECU to make sure I do not have a loose wire.

One issue I had when putting the cells back in the battery. The cells must have swollen with use, it was very difficult to fit them in and bolt them in from the bottom. I had to use two long 24" clamps and the white plastic outer cover to squeeze them together to bolt them in. Also I believe this battery pack has been worked on in the past, I can see markings on some of the cells.

Any suggestions on the 3001 code, or anything else would be appreciated.
The two cells I used to replace the two bad ones are definitely better, but the 3001 and limp mode has me a little worried.

Thanks in advance for any help.
-andy

 

SFO, thanks for the quick reply.
I went back in this morning to double check all connections, just as I was finishing I found a cell sensor clip on the ground, thus I need to go back in and make sure I have all the temp sensors installed... Ug.

Question: Since I'm pulling the battery again, would it make sense to split up my two replacement cells.
When I ran Dr. Prius yesterday:
Banks 2-14 all were very even at around 16.6v.
Bank 1 (the one I replaced, after shifting everything down), was in the green but at 15.3
I'm hoping this will even out eventually.

Would it make sense to split my two replacement cells and put one in bank 2, so I would end up with
16.0 in bank 1 and 16.0 in bank 2, and 16.6 in banks 3-14?

Or am I better leaving the two replacement cells in Bank 1.

Thanks
-andy

 

Thanks for the information, I will put a replacement cell in block 1 and block 2. Currently I don't have the equipment to balance and recondition, so I will test and monitor.

Is there any downside to leaving the OBDII module plugged in all the time? I like your idea of monitoring and having the option to reset the codes.

Thank you for your help.
-andy

 

Update on the Traction Battery cell swap.
I put in the two 2005 replacement cells in Bank1 and Bank2. Replaced all bus-bars and nuts with new ones I purchased on Amazon.
Tried to balance the two replacement cells by discharging with an automotive light bulb, for about 15-30 minutes, until the voltage dropped to 5.6 volts, waited 20 minutes, then charged back up with a Battery Tender trickle charger, would run for 60-75 minutes until the voltage hit about 8 volts which is what the rest of my cells read. I discharged / charged twice.

Put it back in the car, ran for 30 miles, no issues. Ran the Dr. Prius app the whole time and the largest Voltage Diff was about 0.5V
Here is a picture from Dr. Prius.



Interesting that Internal Resistance varies from 25 - 28 ohms. Every time I have ran Dr. Prius on this car or any other Prius, I would always get internal resistance of 19 ohms. I'm not sure if this is from the new bus bars or something else.

The car seems to be running great.

Thanks again for all the help and suggestions.

-andy

 

Nickle. From Amazon:
Hybrid Battery Bus Bars & Nuts set, compatible with Toyota Prius (2004-2015)

 

Good point, after future research I see that it 0.xx ohms, so I'm assuming I am seeing 0.25 - 0.28 ohms.

Thanks for the clarification.
-andy

 

One more note about the internal resistance.
I just checked the Dr.Prius recorded file .CSV, and it shows that all cells started with an internal resistance of 0.19.
Further into the ride, then all went to 0.20, then 0.21 then started to vary a bit.
I'm not sure if this what triggered the change, I assume it was the cells charging / discharging. When I test again I would expect them all to be 0.19 on a cold traction battery.

 

Thank you for the clarification and explanation!
-andy

 

I though I would post an update: 1/25/2021

After 10 days on the replacement modules and 1K everything is good so far. No RTOD, no engine codes.
MPG are around 38-41 which is typical for a Wisconsin winter.
Delta SOC is at 0, and voltage Diff is staying under 0.4v
My only concern is internal resistance is bit higher than I would expect 20 - 28 miliohms.
I will try and post an update in 6 months.
-andy