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

I'm in Southern California, I would be happy to discuss replacing your battery. Feel free to give me a call

Avi

 

Toyota's batteries are not new. They are also rebuilt. That's why there is a core charge.

From what I hear, ReInvolt upgrades the first generation batteries with units used in the second generation.

If that's true, I'd go with ReInvolt.

 

Sorry, but that is incorrect. Toyota batteries are NEW. Re-manufactured Toyota parts have longer part numbers such as an 84 added to the end. Also, don't forget most new batteries have core charges.

 

This is news:

Do new Toyota batteries for the NHW11 use the current style modules?

I am very interested in seeing a photo of a module from a Toyota replacement traction battery. In particular, the terminal end to see if they have the thin (original NHW11) or thick terminal mount and the top to see if the temperature probe clips are rotated 90 degrees. Also if the replacement modules have the 'goop' that was retrofitted to the original modules.

Please understand I'm curious as to the source of this information? Did Toyota issue a press release or TIS or hands-on with a Toyota replacement pack for the NHW11?

Do they still sell them as modules and the installer transfers the frequently corroded bus bars and control electronics?

Thanks,
Bob Wilson

 

The new traction battery from Toyota includes the modules and bus bars installed in the battery case. The tech has to move the battery ECU, system main relays, etc. from the old to the new battery case prior to installation.

 

Do you know if Toyota is still using the old-style, modules or the newer ones? The bus bars and electronics are easy enough to handle but the low, internal resistance modules with better heat profiles are critical.

Bob Wilson

 

I should mention that Toyota replacement traction batteries do not have the extra numbers at the end.

Trust me I've had my hands on them:

 

The only difference I noticed was they used different nuts at the buss bar connections.


The nut on the left is from the buss bar of an original battery, the last new battery I installed had nuts similar to the one on the right. The difference being the one on the left is made from two pieces, the one on the right is one piece.

 

Thank you! Great photo.

The temperature probe orientation is the same as the original NHW11 modules. Here is how I tell the difference between NHW11 and NHW20 modules:

Here you can see the temperature probe 'fingers' are rotated 90 degrees in the lower, newer module. Also the terminal end plastic is much thicker and stronger. The 'silver' is some sort of mold release and non-conductive.


The biggest advantage are a doubling of cell-to-cell connections that cut the module resistance in half. This significantly reduces heat concentrations that weaken the terminal seals.


This last photo shows the 'goop' that was added to handle terminal seal failure. Module 33 shows the tell-tale, black "O" ring failure associated with failed modules. This allows the KOH electrolyte to leak out and eat some of the buss bar, the green speck. The black pad is to absorb the electrolyte so a short to the case won't happen 'right away.'

When I choose to upgrade my traction battery, it was working perfectly fine but I knew my used 2003 Prius had been driven hard in Texas. Changing the transaxle oil at 53,000 miles, it was opaque and smelled like paraffin. But I wanted NHW20 modules, not the NHW11 ones:

	Column 1	Column 2
0	[th]NHW11[th]NHW20[th]specification[tr][td][tr]6.5Ahr[tr]6.5Ahr[tr]rated	new Ahr[tr][tr][td]worse[td]better[td]handling heat[tr][td]worse[td]better[td]internal resistance[tr][td]better[td]less[td]new vs used capacity

My Prius studies suggest that the traction battery is 'part of the transmission' and plays only a minor role in vehicle fuel efficiency. There is a measurable effect that disappears within six months after a new traction battery is installed (thanks Patrick.) But six months of improved MPG, 5-10%, is nothing compared to the cost of replacing a traction battery. So I went with a better set of modules from a rebuilder who has inventory and a clue to how to build a quality, rebuild pack. This won't be the first time that a rebuilt part is better than an original replacement.

Once again, I want to thank you for your excellent photo. Seeing the temperature probe finger orientation strongly suggests it uses the old-style modules. Without taking off the cover, I can't tell if it has the 'goop' treatment and without a photo of the module ends, confirm the thicker or thinner terminal seals. So Toyota could have rotated the fingers again in the ZVW30 modules, I don't have an example, yet.

Thanks,
Bob Wilson

 

Yes, I would say that is most likely.

 

I didn't take any pictures with the cover off, however, I did not see any goop or black pads. Also, NHW20 batteries do not have their temperature sensors on the top of the modules, they are on the bottom.

 

Interesting, this is how I learned about it:

Source: Yahoo! Groups

I don't have 'a dog in the fight' but if I had gone with a Toyota replacement pack, I might ask if SSC 40G applies to the replacement pack. It may not as Toyota has been known to put fixes in over time.

GOOD LUCK!
Bob Wilson

 

They look like J.I.S. M6x1.0 flange nuts. The one on the left has a free spinning nut and the one on th right is fixed. They may be had with either a washer or an external tooth lock washer. It is knwn as a Keps nut. It the bottom of the nut serrated to provide a better grip and better electrical contact? If it is, in the US, it is referred to as a "whiz-nut."

 

I've never seen it on new (replacement) batteries and I have a feeling there was a production change early on. I did notice the orange plastic on the buss bars has changed. New buss bars have less holes in them, the same holes the corrosion would grow out of.

 

Not serrated or free spinning.

 

The two piece nut with a captive washer allows torque to be accurately imparted on the styd by the nut without the large physical surface area of the washer as with the later current nut. To achieve the same level of tensioning for the stud a higher torque value needs to be applied to the driver or the wrench.

My previous inquiry was if the later one piece flange nut was serrated.

 

I'm almost certain it wasn't serrated. Next time I come across one I'll take a picture and post it.

 

For those who haven't read it: Luscious Garage | Blog | Prius Battery Rebuild: Yes or No?

I tend to believe those who are independent and in the business. I understand what has happened in her experience. There are a lot of variables in traction battery module certification and testing as well as installation. For example, the NHW11 modules have two 'anchor' posts on the bottom but the NHW20 only one. So I can understand how a single anchor post might get stressed leading to the one bottom crack she mentioned.

I also understand how one competitor might get a lock on modules making it difficult to sustain the inventory and processes needed to build quality parts. She had to make a business decision and deal with the reality of supply and demand. She is good about preserving his methodology:
Toyota Prius Batteries (healdsburg / windsor) $25 - Toyota Lexus Forum - Performance Parts Tuning

She has more experience with him than I so I would go with her judgement first. But I remain puzzled by some of the results of my experiments. Why can I restore full capacity with rehydration and cycling charge-discharge? Also, what are the absolute limits of the "O" rings and pressures? Finally, what are the age characteristics of the plastic case?

My traction battery experiments started four years ago and led me to use a ReInVolt pack rather than trying to rebuild my own because I knew David's operation covered all of the critical elements. He had a large enough inventory to be able to match modules, larger than I could hope to achieve. But Caroline and David Taylor have an order of magnitude more experience than my early experiments of four years ago. There are a host of risks not yet addressed including age effects on the plastic case. The only way to evaluate these risks are to do a population study and Dave and Caroline are in a much better position to make that call.

I continue to learn new things about NiMH battery chemistry and recent, retests of my own, much smaller inventory revealed a previously OK module has failed. But I'm not about to replace my ReInVolt traction battery until there are hard failure systems and so far, no problems. By then, the car may be so old and the replacement options so reasonable, the decision will be easy. So let me sum it up this way.

Three years ago, a rebuilt pack made more sense than living with the known problems of the first generation modules. But knowing how to keep a pack happy (i.e., cool!) means one should be able to extend the a new, NHW11 traction battery life much further than an uninformed owner. These same techniques work regardless of old or new modules. So choose one with a one year warranty and have a happy.

Bob Wilson