POLL is your battery replaced or inverter

2010 Prius (Level 4) with 115,000 miles of highway driving - at times some decrease in miles per gallon (I think due to the new tires), but I just had a tank at 52.4 mpg; no battery problems to report.

 

184,000 2007 Touring no problems at all

 

No prob 130000 mile 2006 Gen2 Prius

Note that the Gen2 Hybrid Battery survey on-going is in its last month of being open for votes:

GEN2 survey link-
It might be useful to track hybrid battery life of Prius Chat participants. Even though the survey results will probably be biased towards folks having battery issues, we might be able to discern trends.

INSTRUCTIONS: Everyone with a Gen2 Prius is welcome to answer the survey.

Read more: http://priuschat.com/threads/hybrid-battery-survey-gen2-prius-2004-2009.132362/#ixzz2oDb5pesA
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Maybe you should have split it into gen2 and gen3?

I've completed the UK JD Power reliability survey with result due next year. I wonder if the UK Prius will be top of reliability again? Last year they reported one or two issues.

The gen3 isn't bomb proof like it's made out.

 

Well this is a difficult one:

• 2003 Prius, ~120,000 miles - upgraded traction battery, November 2010, no problem before or after. Done to take advantage of relative low prices and upgrade to a lower, internal resistance traction battery format.
• 2010 Prius, ~50,000 miles - no problem since taking delivery May 2009.

I had to vote "no problems" although I've done some extreme testing and gotten one battery warning.

Bob Wilson

 

What did that extreme testing consist of?

 

2007 Level 5 with 76,000 miles and Ive had no problems with the hybrid battery or inverter. Actually, I havent had any problems with anything at all, period. So different than the General Motors vehicles I drove for over 17 years...

 

• repeated, floored acceleration up a hill in 95F (35C) weather followed by maximum regeneration, descending the hill
• testing startup, traction battery, maximum duration in 95F (35C) weather to measure the fuel effects followed by a forced charge (done with rebuilt battery using NHW20 modules)

Most of my early tests were conducted using the original NHW11 module, traction battery. These and analysis of failed modules, revealed how heat is the enemy. But I didn't know this until testing revealed what was going on.

Bob Wilson

 

2010 Gen III package 4. 85,000 miles from March 2010 to present. No issues with the traction battery nor the inverter.

 

152k miles on a gen2 (February 2006) T-Spirit. Only issues a drip from the water pump bearing at 78kmiles (parts and most of the labour paid for by Toyota out of warranty) and an exhaust heat shield which fell off at 115k miles. Car was on it's third set of tires when I traded it in. Lifetime MPG 56(UK), 47(US), with last 50k miles on Nokian all season tyres.

Replaced late September by a Prius Plug In, currently 6k miles. Current mileage 69MPG (UK) 57.5 (US) with approx 10% electric use. Electric range and MPG have dropped now temperatures 0-10 Celsius, 30-50 Farenheit from aaprox 13.5 miles to 11, but am also now running on Nokian Snow tyres.

 

So not too indifferent to the 10 hours of hammer my car got. Up a 1 mile steep hill fully loaded with passengers and luggage and then desend said hill pushing displayed charge level to full causing the car to try and burn off charge - often resulting in it running on electric with quite good acceleration upto 40 mph. The car would often go about a mile on electric only before the HV level came down and the engine switched back on.

It was coming down a long 2 mile hill where I had the weird high pitched noise and that same hill 6 weeks (or so) later when my inverter blew.

I'm now convinced it was a build up of heat over the 10 hour working day that caused the problems in my car. I know others say that New York cabs run 24/7 and have no issues. I again think that's why they might be ok - they don't have time to cool down.

We had a fleet of cabs that were run 24/7 with no issues, but if someone was off ill or on holiday and the van was parked up for a day or so, it was a real bugger to start it again (and not just a 12v problem) if it had high miles on it. Perhaps the cycling of extreme heat internally, followed by cool down over night is caused the failures?

A nice 2 hour commute down the highway, even in heavy traffic, isn't going to cause the extreme conditions. Perhaps the more solid build of a diesel engine DOES actually help when it comes to the heat involved in a car used hard for 10 hours a day?

 

M

 

Understand no one knew about the limits I'm sharing until we did some experiments that were inspired by early postings in "Prius Technical Stuff." We did not know about the traction battery thermal issues and the 12V DC-to-DC characteristics until folks started taking some metrics:

* * * Original / response * * *
. . . Up a 1 mile steep hill fully loaded with passengers and luggage and then desend said hill pushing displayed charge level to full causing the car to try and burn off charge - often resulting in it running on electric with quite good acceleration upto 40 mph. The car would often go about a mile on electric only before the HV level came down and the engine switched back on.


What you are describing is what I call "heat pumping" and is an artifact of Prius operation in hilly country. Going up the hill and asking for more power than the engine has, the Prius will draw upon the traction battery. This causes what we call 'I squared R' losses in the traction battery. The heavy current causes ohmic heating of the traction battery modules. But the real kicker is going down hill.

The NiMH batteries get hotter during charge, it is an exothermic reaction common to all NiMH batteries. So descending the hill with the car in "D" and/or gentle brake, puts one heck of a charge on the batteries and the very act of replacing the charge further heats the battery . . . significantly. I've measured a 5C increase just doing a 'forced charge' where you hold the car with the brake and floor the accelerator.

There is a way to avoid this problem:

1. Ascend a hill on engine power only - with our NHW11 Prius on an 8% grade hill, 55 mph is a perfect speed and never over 65 mph. With the 1.8L, ZVW30, hold the speed constant going up or even slack off if there is evidence the traction battery charge is going down. In a perfect world, monitor the traction battery current and if the discharge is more than 10A, try to slack off or slow down. Short, 10-15 seconds, are OK but much longer and the traction battery is going to get warm and eventually hot.
2. Descend a hill in "B" (engine brake) - this mitigates over-charging the traction battery which reduces how much heat is pumped in during the descent. As an added bonus, I don't have to use the brake on an 8% grade to hold the speed limit. If the speed slacks off, shift briefly into "N" or "D", and then back into "B". But if you are using the brake to descend and not in "B", you will put extra charge on the traction battery and it will get hotter and age.

It was coming down a long 2 mile hill where I had the weird high pitched noise and that same hill 6 weeks (or so) later when my inverter blew.


The inverter has three parts: (1) MG1 power, (2) MG2 power, and (3) 12V DC-to-DC power. Any one of these could have caused the failure and without the part, I would not hazard to call it. However, we do know the Prius has some 'good new' and 'bad news' with the 12V battery.

A Prius will start with a dead cell in the 12V battery. Then the car will run and happily dump power into the failing 12V battery heating the 12V DC-to-DC power supply. Heat is the enemy and I have long suspected many inverter failures come from: (1) reverse connected, replacement 12V battery, and ; (2) running on a 12V battery with a failed cell.


I'm now convinced it was a build up of heat over the 10 hour working day that caused the problems in my car. I know others say that New York cabs run 24/7 and have no issues. I again think that's why they might be ok - they don't have time to cool down.


This is why I am still looking for a Prius cab owner to see if they would collaborate on getting some metrics. Without data, we can speculate until the cows come home . . . with data, we'll know.

* * * end quote * * *

I've seen enough failed, Prius modules to know the problem is excessive heat. The terminals have an "O" ring that seals the units. But when they get too hot, the "O" ring weakens and lets electrolyte and gas escape. The gas is hydrogen and oxygen, the water in the electrolyte. This dries out the module, reducing the 'wetted area' and eventually the remaining spots get so hot they melt the plastic-mesh separator and short the cell. But translating the physics of what is going on into operator procedures to avoid this problem . . .

Bob Wilson

 

2005 Gen 2 Prius, replaced 12v battery at approximately 70,000 miles.

 

I'm guessing he meant if the HV battery has been replaced

 

2008, package III, 109,000 miles, no problem with HV battery or Inverter.