About to buy a used prius

Here's more anecdotal "evidence"

http://priuschat.com/forums/gen-ii-...raction-battery-finally-died.html#post1267638

 

This is an interesting story. It is possible to test a battery before it codes to get some sense of whether or not it is up to par, but Toyota will only warranty replace if there is a code. Aspects of it support both sides of our discussion. I tend to believe the dealer's statement though.

 

Please explain.

 

THREE traction battery failures, out of ~ 2 million Toyota hybrids running around the US.

Oh dear. Oh dear oh dear. I bet if you scrounge you will find 20 reports, and then we can say the failure rate is 1/100,000. That should scare off anyone silly enough to consider a Prius, eh ? No doubt much smarter to buy a regular ICE where the transmission repair rate is about 1/100 if my memory serves correctly.*

I hope you understand my sarcasm. But in case you do not, read this: you are a troll, and an idiot.

* addendum: 1% transmission failure might be way too optimistic

http://www.autosafety.org/ford-automatic-4-speed

 

In other words, it depends.

Regardless of how well the ECU tries to optimize the charging rate, ultimately it's the driver and the running environment which determines how many times the battery is cycled. NiMh batteries lose a little of their storage capacity everytime they are used.

 

Those anecdotes are just as valid as the 299999 battery ones someone posted,

I don't hear you complaining about the latter posts.

 

^^ the two are not even remotely similar. The 299k+ thread does not limit itself to cars with that mileage if and only if the original traction battery lasted that long; the thread asks for all significant repair experiences for a car on the road for that many miles. So far every Prius reported to reach 299k miles has done so on its original battery. I do not know of any car that has been junked solely due to a failed traction battery.

In a year or two hundreds of Prius will be reported that have traveled 200k+ miles, and reliable statistics will be derived. For now all we know is that traction battery failure is a rare (much, much less than 1% prevalence) event in the G2/G3 fleet.

Now go think about the transmission failure rate in your car, and the $2500 - $5000 repair that may await you.

 

I don't think my question to Seilerts has much to do with charging rates, since he mentioned the effect of allowed SOC range. You might learn something if you admit you are clueless. Kind of like the first step of AA.

I'm willing to take a guess at what Seilerts will hopefully explain: An uneven battery pack might be seen as a row of soda bottles of varying volumes. If the SOC (percent bottle fill, if you will) is an unweighted average of each modules reported voltage, then a SOC of 80% implies overcharging of the weak module, and a SOC of 40% implies overdischarge of the weak module. Since we know that over and under charging hastens battery death, the pack at ever increasing speed heads to its demise.

Just a guess --- I am likely totally off base.

 

The vehicles with high mileage in a relatively short time are precisely those which do not stress the battery since high mileage indicate a high ratio of freeway vs local miles.

 

^^ I have no idea what your post has to do with my response.

As for your statement, a highway does not *have* to be flat you know. And you are forgetting the amazing battery longevity results reported by taxi drivers. You think they drive mostly on the highway ?

Face it, the Prius battery is amazing, and the car likely the most reliable ever built -- hands down; and the cheapest to run over its lifetime as well. A hummer owner might listen to you, but here you are just sputtering.

 

What I was trying to say is that keeping batteries in the 40%-80% state of charge can, over time, make the batteries appear weaker than they actually are.

The battery computer does very well at keeping all modules at the nearly state of charge, and prevents them from coming anywhere close to being fully charged or fully discharged. It is important to avoid deep cycling the pack, because the chance of reversing the lowest cell increases as SoC declines. Reversing a cell => dead cell => faulty module => P3000 + P301x. In addition, the number of available cycles increases exponentially as the depth of each cycle decreases, all else being equal. Likewise, charging the pack to full with 100 amps of regen will cause the highest cell to overheat and die.

The chart in the Duracell article is very nice, showing how partial discharges leads to lower apparent capacity over time. This is a feature of NiMH chemistry. In the case of the Prius, by avoiding deep cycling, and not having an occasional full discharge/full cycle, it is as if a part of each cell is asleep, making it appear as though amp-hour capacity has decreased. From the Duracell article:

The voltage drop occurs because only a portion
of the active materials in the cell is discharged and
recharged during shallow or partial discharging. The
active materials that have not been cycled change in
physical characteristics and increase in resistance.
Subsequent full discharge/charge cycling will restore the
active materials to their original state.

Thus, the typical reconditioning process used by ReInvolt, hybrid-battery-repair, and others, involves 2-3 full discharge/charge cycles to wake up the dormant cell parts, and recording the amp hour capacity of the final discharge to judge whether or not a module is fit for service. Such reconditioning also rebalances the cells inside a module, a module having 6 x 1.2V cells in series. The easiest (only?) way to balance the individual cells is to trickle charge each module to full capacity.

There is no doubt, modules will age and eventually fail, regardless of any reconditioning process or driving habits. I make no claim that these batteries will last forever. I personally think that 250,000 miles is a reasonable expectation before needing service for a Gen II. But see http://priuschat.com/forums/knowled...ypercycles-prolong-prius-hv-battery-life.html for a discussion of theoretical battery lifetime.

 

I'm sorry your thread got hijacked with the intricacies of battery quality. But I am very happy to hear that you are enjoying yourself! For me it was like learning how to drive all over again. What you describe is just what you should expect. The HV ECU will optimize battery use to keep your battery gauge right in the middle, 5-6 bars, once the car is warmed up. When you first start the car, the battery is the primary source of propulsion, to limit the emissions from the cold engine, but that means the battery may drop down to 2-3 bars quickly if you are going from a cold stop to an expressway in a short period of time. If your battery gauge gets into the green 7-8 bars, then the computer will use the battery more for propulsion to bring it back towards the middle in order to have headroom for regenerative braking.

 

The whirring sound is almost certainly normal. You should be able to repro it if you pump the the brakes repeatedly even while stopped w/the power off.

Yes, the ICE idles somewhat roughly w/engine RPM going up/down when the ICE is cold. It's normal.

Don't worry too much about the SoC display. It might be difficult to get it to turn green or go all the way to the top unless you go down a long steep grade or hill. I never used to hit it much w/my old commute and area but I am easily able to hit it w/where I live now due to a long downhill section I usually have to go over.

 

Welcome to the club!

My first experience with the Prius was when my parents purchased a new one in 2006 (at my suggestion and in part due to the crazy Colorado/federal tax credit at the time). Their Prius is up to around 50k miles and there have been no major problems (although it did need about 20k of body work after I crashed it into an SUV at 30mph - thankfully no one was hurt).

Last year, after I graduated and it was time to buy a car for myself, I chose to purchase a 2007 Prius with 45k on it for $14k. A year later and 13k miles more and I'm at 58k with no major issues. I've had three oil changes, the pedal reshaping (free warranty recall), and I've had the inverter coolant pump replaced (no failure - replaced for free as part of the LSC). I've also replaced a tail light bulb (which is stupid easy), replaced the previous owner's crappy "Goodride" tires with Hankook Optimo H727s (which I would highly recommend), had an alignment, replaced the air filters (cabin and engine), had the brakes cleaned, installed new headlights (Philips Xtreme Power - they're brighter than the OEM bulbs which were actually still fine), replaced all the interior bulbs with LEDs, installed LEDs in the center console, and put a Parrot Bluetooth car kit in.

So far I've probably spent $1000 on my Prius on maintenance and upgrades, although a lot of that is stuff that I wanted to do (Bluetooth, interior LEDs, better headlights) rather than stuff that actually needed to be done. The only things I actually had to do were a tail light bulb, 3 oil changes, two air filters, and the tires. All of which is scheduled maintenance.

Overall this is a pretty damn cheap car to own. My complaints are pretty minor. The brakes make the typical barking sound that 04-07 Priuses do, which fortunately doesn't affect brake operation. Also, there's kind of a 'crunching' sound sometimes when I go over bumps, which could be either my front springs getting older or the TSB about the transmission mounts. In either case it doesn't affect the ride or handling. You can't expect perfection from a 4-year-old car with 60k miles on it.

Take care of your Prius and you can expect a car that will be cheap, trouble-free, and last a long time.

More responses below.

There are two braking systems on the Prius - regenerative and friction. The brake computer balances the two systems. Regen is used for light braking. Heavier braking results in both regen and friction braking. Below about 6mph, if you activate the anti-lock brakes, or if you brake hard then you get just the friction brakes.

Light braking should result in a slight higher-pitched "whine" sound. As you slow down to around 6mph or less you may notice that the brakes get more 'grabby' and hear some crunching noises. That's the normal transition from regen to friction braking. The system tries very hard to minimize the transition but it's sometimes pretty noticeable, especially if your brakes are cold or wet (which is more often the case on the Prius because they are used less). The obvious benefit of regen is better fuel economy, but it also dramatically reduces brake wear. Expect your brake pads/shoes to last at least 100k (although you still want to have them inspected regularly), which is much longer than in a traditional car.

Like on most cars, the gas engine will run a bit rougher when it's cold. I do notice that the idle speed seems to wander a bit on my engine on cold days until it warms up.

Engine startup shutdown will be a bit rougher when the system is colder. You may notice a "thud" when the engine starts up or shuts down. There are many different system modes that are managed by the computer and it generally does a very good job of hiding this. Most of the time when I'm at a stoplight if I have the A/C or heat on it's very difficult to tell if the engine has shut down.

The good news is that you don't need to worry about any of this. Trying to predict when the engine will run or not is pretty hopeless. In general, if the engine is warm and you have the heat/AC off or on a low setting and if the state of charge is high enough and you're and not accelerating, the ICE will shut down. On colder days it can take a while for the ICE to get warm enough for this to happen. On hot days the A/C can drain the battery pretty fast, causing the ICE to start.

Also, the Prius tries very hard not to rev the ICE when it's cold, which (as on any car) creates additional wear. This can also be reflected as more sluggish acceleration. You can help the computer out by going easy on the gas for the first few minutes.

On the flat, without tricky driving you can't really control the battery charge level and you shouldn't try. The only time you should normally see green (7 or more bars) is after going down a long hill. You can expect to see purple (2 or fewer bars) after using the A/C a lot, letting the car sit stopped (but in "Ready") for a long time, or while going up a big hill. The computer will not generally let you overcharge or undercharge the battery unless you do something stupid like trying to drive a long distance after running out of gas (which for some reason people on this forum seem to do) or leave the car in neutral for a prolonged period of time. Even then you usually haven't done any serious damage, although I wouldn't try either.

Remember that the Prius is not really an electric car, and
recharging/discharging the battery pack is not 100% efficient. Normally, you can expect the ICE to run for anything other than slight acceleration. Also, expect the ICE to run any time you are at highway speeds. When the battery has a high state of charge (8 bars is around 80%) you can expect the engine to run less. When the battery is low (no bars is around 40%) you can expect the engine to rev quickly and the car to accelerate more sluggishly. Hills excluded, usually you won't notice either since the computer tries very hard to keep you from getting to either extreme.

Great job! I only see around 46 on mine because it's been cold out lately and I'm a bit of a lead-foot. Stop-and-go and short trips hurt the Prius, although not as much as in a traditional car. You should know that MPG is a poor scale because it becomes misleading at the high end: smaller differences in fuel usages result in larger differences in MPG. So everything that affects your MPG in a normal car - including things like temperature, driving style, trip length, speed, and other factors - will look like a bigger change in the Prius. A 10% efficiency reduction in a 20MPG car makes it get 18MPG (2MPG less), while a 10% reduction in a 50MPG Prius makes it get 45MPG (5MPG less).

You don't need to be a hyper-miler to get good economy in the Prius. Keep your speed reasonable on the highway (60 MPH is ideal and efficiency starts to drop off pretty fast over 75 MPH). On the highway, cruise control will deliver the best MPG unless you're willing to invest some effort to practice hypermiling techniques.

In the summer, keep your A/C reasonable. If you can, keep the A/C off and open the windows to air out the car for the first few minutes. At higher speeds (45 and up) keep the windows shut because the drag will hurt your economy more than the A/C will.

In the winter, keep the heat off for the first few minutes. It won't blow hot air anyway until the engine heats up and you're just delaying the process. If you happen to live in a more mild climate or don't mind freezing your butt off, keep the heat off for the first 10 minutes or so until the engine gets hot enough that it can shut off while the heat is still running.

Check your tire pressure and make sure it's at the recommended value. Under-inflated tires kill your MPG and are dangerous too. Your Prius has TPMS that will warn you if the pressure is way out of range, but it needs to get 25% or so low before the light will come on. It's better to check it at least monthly with a manual gauge. Some owners here get better mileage by pumping up the tires higher, but you sacrifice traction, ride quality, and tire wear by doing that. For me, it's not worth the 3MPG or so you get.

Frequent quick deceleration is bad for your MPG. Any time you brake more than the regen can handle (light to moderate braking), the friction brakes are used alongside or instead of the regen system and energy is wasted. Look ahead to see if traffic lights are red or will soon be and ease off the accelerator. Plan your deceleration as soon as you can so you can brake as lightly as possible. This will improve your MPG and also save wear on your brakes. With practice, you can end up using your friction brakes only at low speed (below 6 mph the Prius always uses the friction brakes) and when you need to stop quickly. Sometimes people may give you odd looks when you do this but getting to a red light faster doesn't do anyone any good. If you pay attention here you will start to notice light patterns on your regular commute and you can actually anticipate the red lights before you see yellow (many people already do this). In my city the crosswalks have countdown timers and yellow happens on "0" (except late at night), which is very handy for this.

Have fun, drive safe, and enjoy your car! I certainly do!

 

I've heard WA described as a partial-CARB state. This is consistent with the warranty booklet of my 2010, which lists 12 states on the CARB pages, but then breaks out PA and WA for different (i.e. less) warranty coverage.

 

What do you mean by the brake systems cycling when you turn the car off? Usually the only sound you hear is the coolant system running fluid in the thermos on a GenII. My pump has never failed on me some I don't know what they sound like when going bad.

 

That is probably the muffler bearings that need lubrication.. jk, its most likely normal. For the record, I just sold my 2005 Prius with 222k miles on it with very little maintenance needed to get to that point. Other than normal stuff, its a great car! Even the normal stuff (brakes, spark plugs, etc.) go farther between changes than traditional vehicles...escpecially a Land Rover!:welcome:

 

Congrats on your new ride!

So, my wife and I bought ours at the end of October and have put 11K on it so far with the only issue being an HID headlight, a story that is covered by others on other threads.

The one thing that I've noticed and meant to mention on the 200K thread is that the Prius changes your driving habits. So, some of the wear and tear you might see on other cars is not likely to happen with the Prius. Specifically, if you used to drive a car hard or fast you might no longer see front end suspension repairs or engine repairs you might encounter with a sports car.