Typical lifetime of 12V battery...

My Gen I's OEM battery lasted 10+ years and my '06 is still on the original. I will use it until it dies just like I did on my '01. If people replace their battery every 4 yrs regardless, we will never get good data on how long they last.

Standing by to get blasted by the "battery police" for this post

 

No need to blast. Some owners want to minimize unscheduled downtime to avoid unneeded negative drama in their lives. Others want to eke out the last bits of life from their 12V battery.

Either approach can work depending upon your personal preferences. I'm in the former group but can understand that an individual might choose the latter.

 

By that logic, we should all run our tires 'till they are flat and our gas tanks till they are empty!?! A few people have been lucky, but batteries usually fail at some point not long after 4 years. With all the problems reported here on PrisuChat why bother?Yeesh.

 

If I lived in AZ or another hot climate I'd probably err on the side of changing early; as it is, I think I'll just measure the battery voltage when I change oil and change it out when the resting voltage approaches 12V

 

This is patrol officer a priori. You, sir, are being issued a citation. You may elect not to contest and to pay a fine or appear in open court to face the charges listed in the citation.

Aside from the normal charges of frugality and common sense (common only to those with an understanding of basic electrical circuits and the maintenance of automobiles), you are being charged with contributing to the delinquency of minors and newbs, as well as the rest of us who may read your post and believe that it is no big deal to wake up one day and find the 12V battery is dead.

I don't want anyone attempting to jump start my Prius, and I really don't want to read another post by someone just slightly worried things aren't working after Uncle Bob and Aunt Betty jumped the Prius with the Town Car while they were inside trying to read threads in PriusChat about what to do next.

(Did I go far enough?)

 

Not everyone or even the majority of Prius owners have problems with their 12V aux battery in less than four years time. Seems to be those who are just "unlucky" and need to tell the world how much Toyota screwed this up.

It is not "luck" for those who have had the original GS Yuasa battery for five or more years. To call it "luck" indicates you lack even basic knowledge of how car batteries are designed and function. Not too late for you and others who share your viewpoint to become knowledgeable - if you want to. Or you can continue to cling onto your misguided beliefs. Which seems to be your personal preference.

I've noticed you repeat the same old worn out argument about bald tires and an empty fuel tank - you're talking apples and oranges. A car battery functions perfectly well for the vast majority of its service life and declines drastically at the end of its life. You seem to believe that it's like tire wear, brake wear, or fuel usage - you're mistaken. Assuming, of course, that the OEM battery hasn't been abused by unnecessary deep cycling.

Some Prius aux batteries last a long time because these cars are driven at least 25 miles per day. This keeps the aux battery nearly fully charged at all times, which prolongs its life.

I responded to your post because the minority must be heard to warn those nervous nellies who peruse this site that they don't need to panic and rush out to buy a yellow top at the first possible moment when their OEM batteries are in good health.

 

In the sub-zero winter weather in the midwest, batteries need to be strong and reliable. It's cold weather that tests our batteries.

 

Wheeewwwww, I set off a firestorm.

 

Seems to me you've been looking for data points . . .

 

This depends on how far you follow the concept of replacing before it fails. Should we change the HV battery using a similar formula as the 12v or the ice water pump or even the transmission, of course not.

Monitoring the state of the 12v battery is all that is required, but using the MFD to do this is for comparison purposes only as it's reading are very inaccurate. On measurements I have checked being consistently low bye up to .5v. This difference can be a 75% charged to completely discharged battery. A reasonably accurate DVM is needed to get any really meaningful results.

In the UK we have a moderate climate "rarely goes above 25c or below -10c" we do have odd times when these temperatures are exceeded. It is not unusual for 12v batteries to last 10 years so why change after 4years

 

A reasonable person would consider the cost of the proposed repair vs. the probability of the failure and the inconvenience caused by it.

The Prius gas engine coolant pump gives plenty of advance warning before it fails, so there is no need to replace the pump until you see the warning signs (typically, coolant weeping from the pump shaft seal.)

In the case of the inverter coolant pump, there is no advance warning, so I suggested that owners replace the pump before 100K miles. Of course, since then, Toyota came up with the LSC.

Replacement of the traction battery and the transaxle will cost into four-digits. Unless the inconvenience caused to you by that failure approaches that cost, it makes sense to wait for the failure before action is taken.

If you are able to make your 12V battery last 10 years, then no worries. However I would say that most owners are not so fortunate.

Suppose a 12V battery costs US$200 and has a normal lifetime of 6 years. If you live in an area with cold winters and you decide for preventive maintenance reasons to replace the battery after 4 years, then you have given up 1/3 of the battery's potential life.

Assuming a $200 cost, you've potentially given up $66 of value. In exchange for that, you get to replace the battery at a time and place of your choosing, rather than waiting until it actually fails. You also get to explore the various alternatives for a replacement battery and buy what you think is the best combination of performance and price. Finally, you get to avoid that particular reason for having a no-start incident which will save you lots of time.

The alternative to that measured approach is to wait for the failure to happen. Perhaps the failure will happen when the car is driven by your wife or daughter who has no idea what to do and you are not around to help. Then a well-meaning Good Samaritan offers a jumpstart which results in disaster, the inverter is destroyed, and you get to pay a four-digit repair bill.

Or, as was the case with an associate of mine, the failure happens when you are around but no other car is available, it is a weekday morning, you are in a rush to get to work, so you end up paying for towing as well as a premium price at your local Toyota dealer for the battery plus installation, resulting in a $400 bill.

 

In the Illinois sub-artic, sub-tropic plains, our climate "rarely goes above 40c or below -25c." That's about a 115 degree difference and it really tests batteries (among other things!). I just changed out a 660 CCA ("cold cranking amps" in our lingo) that was registering only 230 -- on a very nice late Summer day. It was having difficulty recovering enough power to turn over a warm V-6 after doing three stops in a one-hour span. I was amazed to find it was the original (Toyota) factory battery from 2005. I feel pretty good about having batteries last four or five years. Seven gets me all tingly. Ten is beyond belief in these parts.

 

Patrick you are guilty of selective editing, you mist out the middle paragraph of my post stating that monitoring of the battery was required, a bit like checking the dipstick to see if you have any oil.

 

I did not intend to overlook that.

If you will spend the time to frequently monitor 12V battery voltage first thing in the morning before the car is made READY, then that is certainly helpful. Judging from other posts I have seen, I would say that some members who like to measure battery voltage are not aware that this must be done after the battery has rested overnight. It does no good to measure voltage immediately after the battery has been charged.

 

I fully understand what you are saying, but the Prius battery does not have to crank the engine, and I did state that batteries in the UK last longer probably because of the climate. So one size does not fit all, and monitoring the battery would give warning of impending failure.

 

No doubt. I'm not looking for an argument with you. You are doing a better service by pointing out the truly moderate climate in the UK which is much better on batteries.

I suppose I needed to find the "smiley" thingie where it shows a tongue planted deeply in the cheek!

 

??? Question on mode of failure ???

I monitor 12V battery on every trip with my PriiDash program. The car is turned "IG-ON" and the lowest voltage is recorded when the brake pedal is depressed (and as a result often times the accumulator pump runs and draws extra current from the battery), before the power button is pushed to go to "READY" mode. But the question remains that whether the battery would deteriorate over at least a few days before it dies to give enough warning for me, or it would work fine in one trip and die suddenly before the next trip without any warning. Comments?

 

The normal failure mode of a lead acid battery of whatever type, is a slow fall in voltage measured after standing for some hours (over night). This normally takes a few years. there is a failure mode of a shorted cell that can happen quickly at any time but this is much more rare.

There is a problem however that is more common than both the above and, that is some electrical load being left on. This is not a problem with the battery but with the driver and does not give any warning and applies to any vehicle.

If the car has to be left without being driven for a couple of weeks either disconnect the battery or leave it on some form of trickle charge.

 

Original 12V battery, 118,000 mi, mostly highway at 49 mph. Garaged at night.