Possible New Prius Owner - Some Advice, Please

In some sense it's both of these. NiMH batteries deteriorate due to both calendar aging and also cycle life aging.

We don't have a lot of information on calendar life in hybrid applications, but in stationary applications from the power and telecommunications industry it is estimated to be at least 15 years, ad possibly even 25 years. See: http://www.cobasys.com/pdf/tutorial/Considerations-for-NiMH-in-Stationary-Apps-battcon05paper.pdf

Cycle life on the other hand is more related to the miles (km) driven, but is also strongly influenced the terrain and type of duty, which influence the depth and frequency of cycling. (BTW, "cycling" refers to the charge and discharge cycling of the battery).

Both types of aging are influenced by temperature, but as Calendar aging doesn't involve any heavy use of the battery the temperature would be considered as ambient air temperature. For cycle life however, working the battery hard in cases like driving in mountainous terrain at high ambient temperatures will definitely impact the lifetime.

I would not agree with the premise that even a low km battery will only last 10 years.

 

Both, not being cute. Time is always a factor in battery life but the conditions that the battery is exposed to will determine if your battery gives service to or near the max lifetime that can be expected or its life cut short. Heat, cold, how often it is DEEPLY discharged and if so left uncharged, how often is it cycled( intermittent use can be very hard on rechargeable batteries) ...then there is the physical damage that can occur, a severe bump can damage the batteries connections or the individual cells themselves, excessive vibration can cause the same thing over time. In short any rechargeable battery will achieve its longest useful life if used regularly, not allowed to get to hot, not discharged too deeply(especially important to not let it set deeply discharged for long periods of time) not over charged and not subject the any hard knocks or lots of vibration.

RAL

 

This is not an easy question to answer. there are thow's that have done 250,000 miles+ on the original battery and gen1 Prius owners (2000/2003) still running on the original.

Prolonged exposure to high temperatures seems to bring about early failures, one of the reasons Toyota take the cooling air for the battery from the cabin (vent on the drivers side rear seat) on the assumption that the driver will have the aircon on in hot weather.

Under normal circumstances I would suggest 150,000/200,000 miles would be a reasonable estimate. In certain states in the US the battery is guaranteed for 10 years 150,000 miles.

Continuous use in mountains is also recognised as a use that can bring an early demise. Of course there have been earlyer failures for no apparent reason, and I now this does not apply to you but most countries have at leased 8 year 100,000 mile guarantee.

John (Britprius)

 

The Prius battery is never deeply discharged "at leased the traction battery". The traction battery level of charge is computer controlled, never being discharged below 40% never charged above 80%, and generally being held close to 60%

John (Britprius)

 

BTW el-man, you didn't answer my earlier question.

Roughly how many km per year do you drive and what is the approx fuel economy (in either L/100k or km/L) of the proposed alternative vehicle.

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IF everything is working correctly. I read that Mountain driving can cause the system to charge to 100% capacity at times. Also remember that computers can fail in some subtle and quirky ways....if things change, "odd it never put the full 8 bars in before and now it does sometimes" you best check it out.

RAL

 

The full 8 bars is only actually a charge of 80%. The bar graph display only shows the working range of the Prius battery:- 40 to 80%.

When 80% is reached on a down hill section of road the engine will appear to rev. This is not the engine running it is MG1 spinning the engine at speed to use up energy produced by MG2.

A strange thing then happens if you put your foot on the accelerator the engine slows down, take your foot off the engine speeds up, the opposite of normal operation. When you come to a stop the engine will continue to spin to bring the charge down in the HV battery to below 80%.

John (Britprius)

 

Again if all is working correctly. Mine never has never been to 8 bars, 7 bars very rarely . Once it shows 8 bars there is no way to know how much over 80% it is no????? The Prius is a good design but all man made systems can fail, add a computer to that....... ....... Don't you think its wise to check the systems health if something has changed, 8 bars regularly rather than the 6 it displayed before????
I am new to the Prius world but not new to high dollar rechargeable battery systems. They can be damaged rather quickly once they start to be operated outside their "sweet spot".

RAL

 

Sorry RAL, you've lost me, I'm not sure how this relates to the current discussion. You seem to be referring to some particular case here, but it's not the case of the OP. Is this some change that has recently effected your Prius, or is it some other case that's recently been posted here, or is it just a hypothetical case?

 

My car see's 8 green bars regularly as I clime and descend a lot of hills (not mountains).

If the state of charge of your HV battery fluctuates rapidly from two purple to 8 green and back rapidly this is a sure sign of impending battery failure, but that is not what you state.

The system stops charging the battery at 8 bars it does not continue to charge or over charge. When I say 80% this is a nominal figure it may go 81% or 82% but certainly no higher. Under what conditions does your car show 8 green bars? Is this at the bottom of a hill?

John (Britprius)

 

EL man asked a question about battery life, the factors affecting it is what this was about. Overcharging rechargeable batteries being a real life shortener. Mr Britprius pointed out that the Prius computer is programmed to prevent that from occurring . I was merely pointing out that man made systems can and do fail and it is wise to check the reasons for changes in operation and/or display rather than just assuming the computers got it.

RAL

 

RAL. You're referring to a specific case of someone who previously never saw more than 6 bars SOC, but now suddenly sees 8 bars regularly. I just wondered where this case came from?

Edit: Ok I get it now. This is a hypothetical case of loss of battery capacity causing SOC anomalies.

 

Ral in your previous post you say you car has never been to 8 bars and rarely 7 then you go on to say should you get your car checked out because it 's going to 8 bars.

In your avatar you show you have a 2012 Prius, how many miles has it done as it would be reasonable to assume a new car will not roll as easily as a car that is run in for a number of reasons. Again when the car is run in it is reasonable to assume it will regen more "because it rolls easyer" and charge the battery more up to it's cut off limit.

John (Britprius)

 

John thanks for your replies. We seem to have gotten offtrack a bit......I was answering a question about factors that affect battery life, overcharging being a big one. You pointed out that the Prius has programs to prevent this. I am not having a problem with my car, my point was when something changes on your car, display or performance that is prudent to find out why rather than just running it and perhaps damaging the expensive battery pack. The 8 bar 6 bar was just an example of a change. My apologies for being unclear .

RAL

 

To the OP, you've already received a lot of specific advice about your potential purchase.

I simply would add, that I think you are being wise in being cautious and questioning the reality of potential traction battery replacement.

Of course my "New Prius" is warrantied in my area for 10 years or 160,000 miles, but if I keep my Prius for that length of time or beyond, I'm very much going to approach it as if I have to live with the expectation that the traction battery could fail at any given time. Therefore I will hopefully be able to have the money set aside for that eventual possible replacement....be that 5 miles past warranty...or in year 11, 12, 13 or beyond.

If budget concerns are a reality for you NOW....as much as I do like the Prius and as much as I believe you could buy it and perhaps get multiple additional years without a problem I think I would have to default to don't do it. IMO any Prius in which you have surpassed the warranty period on the battery has to be handled as if battery failure is a possibility at any time and if that reality would result in considerable hardship? Then perhaps it's not the right vehicle at the right time.

 

Ral we all sometimes do not make ourselves understood as we would wish. I now understand what you were trying to establish. The Prius has more than one system to prevent overcharge but would point out if it did the dashboard would no doubt light like a Christmas tree because all the systems are closely monitored. If one battery module goes out of range by 0.2 volts or more up or down thats 0.033 volts per cell in a module, fault codes are issued and warning lights lit.

John (Britprius)

 

so ? how is it going ?

 

I guess you can update your "other non-hybrid" bit in your profile.