Need some advice re: replacing dead traction battery in my 2001

Bob so your still sold on the ReInVolt yes/no ?

 

In July 2012 I was faced with the same decision on the traction battery in my 2001 Prius (97,800 mi.) The dealer quoted $3500. I found an ad on the local Craigslist which is still running (PRIUS HYBRID BATTERIES / SLO 748-3962) and decided to get the rebuilt battery ($1775 installed). So far it has worked out fine. Actually my gas mileage seems to have improved slightly (was 43.2mpg, now 44.7mpg). You could probably contact the guy directly if you need some advice, he seems pretty knowledgeable.

 

Yes . . . mine continues to work perfectly fine. As well as another one down in Blountsville that I helped install.

I did abuse it last summer with a forced charge in 95F+ weather and got an understandable, thermal alarm. The weakest module pair narrowed to one pair but after 24 hours, it resumed the normal cycling between 3 or 4 pairs. It would have been worse with the old style modules.

Caroline at Lucious Garage is a well respected leader in independent Prius maintenance. That she ran into a problem with "Battery Boy" as a supplier may be unique to the California market. From a technical standpoint, there are things I had looked at but ran out of time and resources to resolve. One critical area are the mechanical characteristics of the plastic case. Without a large population of modules handled in a consistent manner, I am hesitant to say we know every aspect. But when it comes to the terminals, I would much rather have an NHW20 or later style module over the original. The newer style runs cooler and heat is the enemy.

In a perfect world, Toyota would sell new NHW11 replacement packs using their most advanced modules. But we see no evidence, yet, that is the case. We can speculate about the modules in Toyota's replacement packs but the fingers over the temperature probe well are 'old style' so I suspect new manufactured but hotter running, old style modules.

Bob Wilson

 

Please either join Fuelly.com or go to Fuel Economy and start tracking your tank-by-tank mileage. Patrick Wong shared his data after a traction battery replacement and the data suggests there is about a 3-4 month interval of improved performance, ~5%, before it levels out again. You are one of the few who has a new traction battery and able to record and share the data. Six months would be enough but a year would be perfect so we could see the seasonal variations.

Also, I hope Avi might share any additional details about the modules in the Toyota pack. In particular anything that might give a manufacture date or insights about the 'goop' Toyota had put on the early batteries.

Thanks for sharing,
Bob Wilson

ps. Although I recorded my mileage after the ReInVolt swap, I could not find any appreciable change in MPG. But my original battery was OK and the used modules had already passed through the 'new' phase to used. I was not expecting improved mileage.

 

I rebuild and sell Gen II traction batteries. As someone noted in this thread, matching discharge current isn't as important as matching module voltages. When I swapped out my Gen II battery with 180K miles, the newer one provided little, if any, fuel savings. It was hard to find a difference in performance between my old battery and the newer one.

As a test, I had some "failed" modules from batteries I've swapped out that were just "laying around." I decided to make a "melting pot" traction battery as all of the modules were mismatched. The difference in the highest to the lowest module voltage was 800mV.

Again, I wasn't able to notice a difference in performance with regards to fuel consumption. However, the major difference I noted was the heat! This battery heated up very quickly, it would stay hot for a long time and even when the car is parked the temps rose much more than my previous battery. What I've learned early on is that the traction batteries in the Prius are like cooking chickens or turkeys. Even after you shut the heat off, the temperature still rises!

That being said, I installed this battery in August and it's still in my car now. Putting them into one traction battery has leveled out the module voltages but the heat is still there. I made my own custom CAN device and programmed the battery fan to use a more aggressive approach in cooling the traction battery. By the time the battery gets to 104 degrees, it's already at level 6. I do this because above 104 degrees your CCL starts to decrease. With the new software, I'm able to keep the battery under 104 degrees. This is a picture of screen installed on my Prius. It has many different pages than just the one pictured here (I interfaced it with the OEM buttons on the steering wheel, the up and down arrows, so it's kind of hidden on how to operate it) :


Now that the temperatures have gotten cooler, the battery doesn't get as hot but I'm sure once April/May rolls around, the battery temperature will increase very easily. So for my own car, I have no problem using modules that other people or myself can't use because I can keep it cool enough where it isn't a concern. I'll just keep doing that until I reach 1,000,000 miles on my Prius Sure, I will most likely end up with a module that will fail, probably cell reversal, and I'll have to replace it. However, rebalancing and matching cells pretty much ensures that you will have a battery that lasts for a long (relatively speaking) time.