Gen II Prius Individual Battery Module Replacement

Well against everyone's advice and maybe because I like to learn things the hard-way I decided not to balance the batteries (not reassembling the interior). So it sounds like I will know if this works for me or not after 15-120 test miles (or 3,000+), right?

In the meantime I am going to play with the Android Torque app with the custom PIDs to see if I can monitor the voltage of the packs. Oh and air up my bike tires

 

John - do you know somebody in manchester, connecticut area to do a individual module replacement. its battery block 11. p3021.

 

I'm afraid I know a number of people in Manchester, but that is Manchester UK not US sorry.

John (Britprius)

 

Can't wait for a detailed write up. Hopefully with more pictures. I checked the voltages on my cells and found one at 6.4. but now am trying to figure out where to go from here besides ordering a new cell.

 

Thanks, I think I will try a load test first since its the easiest to start with. I will buy the thunder t6 as you recommended when I get the money.
I have a question. You numbered all your cells. Which one is considered number one?. I marked all mine and marked my number one closest to the maintenance plug.
In the meantime im going to soak some of the the terminal in vinegar to get the corrosion off since they pop out of the buss bar.

 

ok I load tested each cell with a 55 watt halogen bulb. I alligator clipped the bulb to the positive and negative of the cell than put my meter on the terminal. These are the readings I got. Cell #14 needs to be replaced but am suspicious of 1 and 28. what do you guys think?

1) 7.41
2) 7.53
3) 7.59
4) 7.55
5) 7.53
6) 7.56
7) 7.56
8) 7.56
9) 7.55
10) 7.55
11) 7.55
12) 7.57
13) 7.56
14) 6.21
15) 7.56
16) 7.56
17) 7.56
18) 7.57
19) 7.56
20) 7.57
21) 7.58
22) 7.58
23) 7.54
24) 7.56
25) 7.56
26) 7.56
27) 7.57
28) 7.41

 

If I were you I would replace 1 and 28 as well - you have gone through so much trouble already, why not do them all together at once?

 

I would balance charge them all except module 14 as then you can make a decision knowing the capacity of all the modules.
It is noticeable that number 14 is in the middle of the pack, and is likely to have run warmer than the outside modules and dries out faster.
It would be a good idea to shuffle the modules when rebuilding center modules to the outside of the pack.

John (Britprius)

 

I think I'm going to take both your advice. Replace all three and shuffle the centers to the outside. Thanks so exciting

 

How long do you leave the 55W bulb on the cell while testing?
On my battery any cell will keep dropping in voltage as long as it is being tested.
I suspect two cells that are lower than the others. But the range is only 7.89 to 7.62; almost all of the cells are 7.85.

 

My '04 has 220K on it now and I am just beginning to see indications that my battery may be getting "tired". I found it down one bar (at 5 instead of 6) just traveling on level freeway and then later saw it at 7 with no more than a mild reduction in speed. I try and take it easy and am trying to make myself always idle for a half minute before starting out (up a hill).

Regardless of the above, I see battery work in my future. I am capable of taking on the balancing task and have a friend that has done a good deal of this on Honda Insight batteries. My other two choices are a new battery from Toyota or a rebuilt one from one of the aftermarket suppliers like Reinvolt. At 220K, and particularly with my mild driving habits, I am not inclined to buy a new one unless the cost difference indicates. So I guess my question, and it should be appropriate for followers of this module string, is: Is a nine year old high mileage battery, even one obviously driven mildly, worth rehabilitating with either balancing and possible select module replacement? Or do I need to open it up and record all of the module voltages, inspect for leakage/corrosion, etc. first? Thanks.

 

The symptoms you described, changing a couple of bars, doesn't sound like impending failure by any means, although maybe you have watched this develop over time. 220K miles is certainly a good long run.

I would suggest getting something like Priidash going, and using its data logging feature to plot the cell voltages, and have a look at what is happening. The software's author has posted examples of that. (You can also do that in varying ways with the other Prius scan tools often discussed on PC.)

If you see more than one cell that is starting to vary from the others, then I would imagine that complete replacement would be the way to go, unless you wanted the learning experience of cell swapping, and could have the car down for a period of time.

 

Thanks for the Priidash recommendation. I had looked at it and did not realize that it could send individual cell voltages. That would be far easier than removing the battery and notedly safer. I have a laptop and can locate the OBDII cord. I'll await stronger indications of distress however, before proceeding.

 

Priidash is a very useful driving aid and does give HV battery information, but feel a mini VCI with techstream may be better for your application in the long run.

Being able to check fault codes and clear them along with brake bleeding and flushing to cover just some of it's uses may be of more help if or when you finally strike trouble.

I am in no way degrading Priidash an extremely useful tool for a different application. As the equipment required in both cases is at minimal cost you may prefer both.

John (Britprius)

 

I just wanted to say thank you. I am currently 300+ minutes into my first cycle.

I could not figure out the Thunder T6 at first and actually charged them twice before I found out you need to be on the DISCHARGE>CHARGE Screen when you Hold Start. Hopefully they won't spaz out on me for taking them up to a healthy 8.x volts.

I too made the mistake of just swapping one module without balancing. I took the time to rearrange the pairs to make good groupings but I learned the hard way, 120 miles, that that was not adequate enough.

Hopefully in 3.5 days I can wire them in parallel and sync 'em. Until then I have 3.5 days to practice some soldering for the wiring harness in my head.

Thank you.

Here's to another 209k miles...

 

Hey did you end up replacing #6 and #27? Were you able to get them all to 7250 mAh before the equalization process?