Gen II Prius Individual Battery Module Replacement

I can go ahead order/replace the bad module #8. Do you think I should replace any other modules? The pack is 12 years old and as far as i can tell the blocks are very unbalanced. Under load the voltage drop seems to be >.20V on average. I am hoping for at least two years of trouble free service.

 

#8 is the obvious failed module, there may be more after you test the entire pack.

I don't think you'll get 2 years of trouble free service on a 12 year old pack, unless you do a complete rebuild of the pack and all the modules to have a significant amount of capacity remaining.....after a complete rebuild, you "might" reach 2 years

 

In my case do you think it best to individually cycle each module and measure its remaining capacity? Then replace the weakest cells?

 

Yes, definitely cycle each module. When you are done cycling everything and you've identified the bad/weak modules, then replace them all. Once the pack is complete, I can help you balance the entire pack in 24 hours.

 

Ok, will do.

 

Make sure you clean all the corrosion off the buss bars, you'll have lots of it. Soak it in some vinegar overnight.

 

Yes. There was a surprising amount of corrosion. I already got all the bus bars and bolts off. I just need to soak it in vinegar. There is also a strong electric smell, is this normal? Can i use modules from a gen 3 2015 Prius. I found some at a very reasonable price and they are bound to be better than anything from a gen2 prius. Also at what settings should I cycle the cells? 7250Mah, down to 6v three times. Would a house fan be enough to keep the pack and cells cool?

 

You probably don't want anything from 2015 because they would be much stronger than the rest of your 200k miles pack. What you want to get is something of similar age with very little variable differences. Similar capacity remaining, IR similar etc. As these modules get older (yours are coming around 12 years), they will have a higher discharge rate compared to the newer stronger modules. So it's important to keep the discharge rates the same so the pack doesn't go unbalanced.

If you can get 28 2015 modules, that would be ideal and you don't even have to mess with reconditioning and you'll get another good 6-8 years of service. BTW, do you know how to tell the module year of production? Just because someone tells you it's 2015....you probably need to know how to check.

IMPORTANT NOTE: Do not soak the terminal nuts, only soak the copper buss bars in vinegar.

 

You can get more accurate info from @MTL_hihy or @TMR-JWAP our other members about the needs of cooling and charging using a hobby charger. I have a Reaktor 1000w 30A unit waiting to be opened LOL

 

Replacing the entire pack with one from a newer model would be the best solution. But, the car is not worth much anymore and i have a 2013. If i remember correctly you can check in the serial number and the letter. On your recommendation i will order some gen2 cells. Is there anyway to measure internal resistance? It's a shame that no one besides toyota produces these cells and only one company makes replacement modules. Hopefully they will come down over time. I wonder if lithium pouch cells could be adapted to work in the prius. The BMS only uses 40% of the entire capacity and with modern cells it could prove to be a viable alternative. I doubt i'll need much cooling. I'll be charging them at 50w and discharging them at 5w. Do you know if the new gen4 packs are backwards compatible?

 

I don't have the document that shows the actual dating of the modules, someone will probably post it again. It's been posted many times. But mainly the 4th letter in the serial number tells you the year. Starting in 1999 A, 2000 B, 2001 C.....and so on. Some hobby chargers have an IR setting/measurement or you can buy something on Ebay that measures it.

Gen4 is the same if you choose the base model with nimh modules.

When charging, make sure the modules are CLAMPED down and there's enough cooling. When I charge my packs outside of the car, I have the exact same setup as the car's cooling system. The OEM Fan and Duct work leading to the battery. It's lots of air flowing to cool it down.

 

I just put in the battery and after a little trial and error it started. I just needed to clear the codes and car started right up. I did balance the cells and limited charging to 6500Mah due to the swelling and the heatwave in socal at the moment. I was able to speed up the process significantly by discharging with a light bulb. Another cell is likely to fail within a year, but i was amazed at how much capacity improved by the third charge. As a plus i could probably replace the module within two hours now and got to buy new tools.

 

Having the battery clamped together is very important when charging, that would have helped with the swelling. The cooling is also another factor to look at next time you do this.

When there's a heatwave, best to keep the charging to night time hours. The heat during charging is not good for the batteries

 

I am PRAYING someone is still watching this thread. I am going to try and be as detailed as possible.

I have a 2006 Prius with over 310,000 miles on it. a few months ago I had a bad cell that I bought online and replaced it and everything was perfect. NOW however I checked all the cells and they are ALL at 8.2 Volts, but the hybrid battery will NOT hold a charge. If I am driving a flat road it seems ok-ish but going up any type of hill or pressing hard on the gas pedal the battery will go even from green to purple as quick as you can sneeze. I unplugged everything related to the hybrid battery and reset the computer. Drove to work ( from north east PA to NJ by giants stadium ) and multiple times the battery went to purple. I am SOOOOO confused and lost as what it could be. If anyone can help or offer advice that would be AMAZING. My personal email is matthewd2472 at hot mail dot com. for some reason I don't get any updates if someone replies here.

 

take the battery out, let it sit 7 days. The bad ones will lose it's voltage. Replace with KNOWN good modules and charge/balance the battery

 

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Ed. How many of those dt6 chargers did you use for project?

Thanks

 

Being awhile! Where have you being brother?!

 

Jeff! You are a guru.
How many if those chargers are you using, and how much did they cost you?

Thanks

 

I like to quick responses John!
Learning tremendously with your comments.
Thanks do much