Classic Hybrid Battery Gone "Bad"

Hi Holly,

The DTCs logged are consistent with a failed battery module. It is not a trivial matter to replace the module and this action is contrary to Toyota's repair philosophy - so the dealer techs will not do this. The replacement module may not work well with the rest of the battery so there's some risk in implementing that solution.

The least expensive solution in the short-term is to purchase a salvage traction battery and have it installed by your dealer. However there's no assurance as to how long the salvage battery will last or for that matter whether it is good to begin with.

$3,200 is a lot to pay for a new traction battery considering the age and odometer reading of your car.

Good luck with your decision.

 

Hi Holly,

The gasoline engine is quite reliable. With your Prius model, I would be more concerned about failure of the following systems: transaxle, inverter, electric power steering, catalytic converter, MFD, front struts/rear shocks. Failure of any of the first four will result in a four-digit repair invoice at the dealer; a new transaxle will be a $6K charge.

 

yea there was a 01 prius with 300 k highway miles on it so the gasoline engine is the least of your worries.

we had classic owners that had transaxle problems before HV battery problems arises.

 

No. One day the car is fine. The next day your dashboard resembles a Christmas tree and you can hear strange drivetrain noises.

Speaking of the transaxle, have you periodically replaced the transaxle fluid using 5 qt of Toyota ATF T-IV and also replaced the engine and inverter coolant fluids per the maintenance schedule?

Sorry, but an older, highly complex vehicle like Classic Prius has the potential to be highly expensive to maintain post-warranty, unless you can DIY and install salvage parts as needed.

Regarding the "background" story on your post #1, did any warning lights appear besides the master warning light (red triangle)?

Regarding the BRAKE light appearing two weeks ago, did the dealership determine the reason for that light coming on?

Regarding your question about your independent mechanic's inability to retrieve DTC, this is because Prius has multiple ECUs that can produce DTC: engine, hybrid vehicle, skid control, electronic power steering, traction battery (to name the most likely). This will confuse a regular OBD-II code reader, so you need to rely upon a Toyota dealer service dept or an independent that specializes in Toyota vehicles and owns the correct diagnostic laptop or hand held tester. Certain of the ECUs can produce three digit subcodes that provide additional detail regarding the failed component; a regular OBD-II code reader has no ability to retrieve the subcodes.

 

There are not a lot of choices with a bad traction battery. One member of "Prius Technical Stuff" tried module replacements but what happens is the next weak module fails. There are 38 so it doesn't take long.

A salvage traction battery is possible but it is a 'pig in a poke.' You don't have anyway short of the word of the seller that it is OK, much less, how much life it has left in it. Even now, we don't have a good protocol for measuring the capacity of modules except to remove them and individually test them.

The price of a new NHW11 battery is high but it also returns the car to service. Find another way to spend $4,000 for a car that gets 52 MPG (in my case) or even 45 MPG, the GreenHybrid average.

We have seen some transaxle failures associated with a 'humming' due to shorted windings of MG2.

I checked the distance but 552 miles from Huntsville is 10 hours, one way just to travel there. There is one excellent Prius mechanic in that area but he may have work limitations that prevent him from helping on this one.

Check with the dealer and maybe he'll let you use the old vehicle as part of a down payment on a 2009. But this puts you back in the car-payment mode. Still, with the price of gas down, between now and about the end of February, you have some 'negotiating' room.

Now if you have an interest in self-maintenance, it is possible to keep an old Prius running for a long, long time. However, this is not for everyone.

Bob Wilson

 

Here'sy 2 cents. I'd get a battery off ebay, get your car running, then sell it or trade it in on a new Prius.

 

How does the Prius HV battery warranty apply in your state? If not at all. I would be tempted to buying as newer battery as possible from salvage. Since you have another car, time is not of the essence, and it may be really fun disassembling the HV baterry and determining the healthiest modules. This way you'll have some extra spare modules. I suppose also determining good modules would require some research and building a load bank. By just comparing modules, good ones should be quickly recognizable. As for selling or keeping after repair that's of course your choice. As Pat said, for a new battery (guaranteed by dealer) for $4000, is not a bad price.

 

You may be willing to negotiate with Toyota Customer Experience Center 800-332-4331 for a cost share. Such efforts have had some success in the past.

Also Toyota talked about battery refurbishment in a press release

Toyota: Reconditioning Can Extend Hybrid Battery Life

But I have not heard of that program actually happening in the real world.

With appropriate caution and skills, a salvage HV battery and yours could be combined into the best 38 modules, which would hopefully have a long service life.

However if you cannot go any of these routes, Paprius4030 may offer the best plan. Good luck and keep us informed please.

 

Hi Bob,

I wanted to comment on this. IIRC that member lives in hot Florida, and relatively high ambient temps year-round don't help battery longevity as electrolyte loss is accelerated. I agree that the concept of replacing one failed module is not going to result in a long-term solution.

Recall Florian Steiper's approach of replacing six modules at once: the two modules from the failed module pair plus two modules on either side of the failed pair, under the theory that localized heating would prematurely age the adjacent modules so for preventive reasons replace them all at once. He's reported good luck with that approach. Of course ambient temps in Germany are lower than in Florida and that may also help.

 

There have been two module replacement experiments with different results and I wish we had better documentation for both experiments. Meanwhile, I'm hesitant to recommend this approach to folks who don't have the equipment, understanding of series batteries or a work area. I could be wrong and the original poster might yet volunteer that she has these resources and/or the time and energy to acquire them. If so, I'd welcome her at PTS and we could begin the experiment.

Bob Wilson

 

I would go the ebay route. It is an older, high mileage car. It does not need a new battery. A used one should get you another 50k miles. It is a gamble, but you are also gambling on the transaxle, etc. A used battery is a $1500 gamble. A new battery is a $4000 gamble.

 

I have no specific Prius insight regarding single module replacement, but speaking from general terms, partly drawing my professional background as a semiconductor reliability guy:

Replacing a single module is essentially a bet that is was a significant outlier compared to the rest of the pack. If true, and if it has not harmed the neighbors by heat, you might do well.

However, if the module differs from the rest of the pack only by normal manufacturing and (local environment) heat history variation, then more modules are likely to follow rather soon.

My impression--others can correct--is that for your generation of Prius and your likely usage scenario, the failure is not enough earlier than expected to warrant optimism on the single module path.

So if you really want to keep the car, a salvage battery seems a better bet, if you can find one for which there is good reason to think it is quite a bit earlier in its usage history than yours.

 

Hi Archae86,

The earlier generation Prius batteries had higher resistance cell-to-cell connections. This is why the point was brought up. Its also probably why the Florida Prius had the battery become defective at 150K miles. This was one of the improvements between the first and second generation - reducing battery interconnect resistance.

 

Please forgive my ignorance of the battery/charging system but doesn't the series design put more load on an entire bank when a single module gets weak? If a single module is failing then the cells in the whole bank are going to be driven to a higher state of charge to compensate (and at a slightly increased current per cell, correct?) In doing so their lives would be shortened as well, correct?

 

Hi Shawn,

A separate ECU is dedicated to monitoring the Prius traction battery. This resides within the traction battery enclosure.

Voltage sense wires run to each module pair, so that the traction battery ECU is constantly monitoring the voltage of 19 module pairs in the case of Classic (and 14 module pairs in the case of 2G).

The battery ECU expects that the various module pair voltages will track very closely to each other. If one module pair voltage drops down below the others (due to a failed module) then the ECU will log DTC P3006. It may also log a DTC that identifies the specific failed module pair, as was the case with the OP's vehicle.

Since the battery ECU is keeping track of the health of each module pair by constant voltage monitoring, then if a module pair incurs a failure, this will become immediately apparent to the driver (via master warning light aka red triangle and hybrid vehicle or traction battery icon appearing in the MFD).

Regarding your question about whether a failed module will lead to premature deterioration of the other modules due to overcharging, I think this is unlikely since the battery ECU is monitoring module pair voltages and will not allow excessive voltage to develop. The battery ECU communicates with the hybrid vehicle ECU so that the appropriate charging voltage is produced via MG1 and the inverter.

 

Thanks for that explanation, it makes more sense now.

 

I know when your battery goes bad, you will hear the fan turn on all the time, even when the battery is not hot. And if you ask me, I would go with the new battery, so that way you KNOW it will work, and not go bad in a few weeks after paying all that money.