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Discussion Starter · #1 ·
Just bought a 2015 Avalon Hybrid with 9000 miles Dec 24, twice the battery has gone dead. Once when I was setting up the blue tooth in the garage with all the car doors closed? Last night when I went to town visiting for 1/2 hour. Came out and the battery was dead. Is this a problem for the Avalon's?
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I'm new to the TAH world, but I'd say no, this isn't a general problem. If the car has been sitting for an extended period of time (9k miles in 2 years? not a lot of driving), it's possible the battery hasn't been fully charged in quite a while (the 12V battery is charging only while the car is driven).

Your 2015 should still be under warranty, so you could take it to any Toyota dealer and inquire. However, I'd do the following first.

When I bought my 2014 TAH, with 12k miles, first thing I did was install a Battery Tender "Fused ring terminal quick connect" to the battery. I then used my Battery Tender Plus to bring the 12V battery to a full charge. It charged for 15+ hours before shutting off (obviously had been sitting at the dealer for some time!) . After driving the car every other day for a couple of weeks, varying length trips, the car was charging the battery to the proper level. I connected the charger again, this time only charged for 2 hours.

I bought our 2013 Ford Cmax with 41k miles on the clock. The first time I attempted to charge it, the Battery Tender Plus couldn't bring it to a full charge after 30+ hours! I took the car back to the selling dealer, they replaced the 12V battery free of charge.

I now have 2 hybrids and a full-electric Leaf. I've installed quick connects on all 3 cars' 12v batteries, and every month, each one gets fully charged. Since all 3 cars are driven regularly, the charge rarely takes more than 2-4 hours, but it's nice to top it off with a "full" charge every month to 6 weeks.

You can purchase a BatteryTender Plus, if you're interested, for around $50, IIRC. Good luck!

PS: You might want to add your location to your signature. This way the reader will know the climate you're living in, which, in this case, would affect the life of your battery.
 

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Discussion Starter · #3 ·
Seems a few people suggest this, to me this is unacceptable. I am 67 now and have owned a lot of vehicles, never have I had to use a battery tender. Vehicles have sat for days and never needed any attention. Has Toyota gone on the cheap route with there 12 volt batteries?. One person sais he replaced toe OEM battery with an Odyssey AGM battery because of a failing Toyota battery. My car is kept in a heated garage, driven daily 15 to 20 miles on short errands.
 

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pasaint: "...My car is kept in a heated garage, driven daily 15 to 20 miles on short errands..." If you're driving the car every day, the 12V battery should maintain adequate charge. If it doesn't, something is wrong. Batteries are cheap: have it load tested to prove its ability to hold a charge. With a healthy battery, you should NOT have to do what I do (I'm OCD about battery life!)

I would also advise you, though, regardless of car brand, to periodically take your car on an extended drive...20+minutes, highway speeds, to get crankcase oil up to full operating temp. to burn off moisture/acid that builds up with short trips. Also, to completely heat up and dry out your exhaust. The extended drive will also assure your 12V battery is adequately charged.

Heat kills batteries. Modern cars are electricity hogs., and sadly, 12v battery technology isn't keeping up (FYI, VW/Audi batteries are averaging 2-3 years, according to hundreds of posts on TDIClub). I use the battery tender to assure zero chance of a 12v battery failure when I'm away from home. The inconvenience of battery failure is unacceptable.

I'm 62. I've owned several makes of automobiles. For 46 years, I've followed this advice, and I firmly believe I'm keeping my cars in tip-top shape. Oh...and I've never had a battery failure "on the road."

Good luck as you find the cause of your battery failure. (Where do you live?)
 

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Ok, let's start here.
1. You have two batteries. A 12V one and NiMeHi traction, aka hybrid battery.
2. 12V battery is charged continuously as needed. It is charged from traction battery. There is a converter that does this. So driven or not, 12V is maintained at specific level.
3. 12V is a power backup battery for all onboard computers and AC system, excluding electrical AC compressor. Also, supplies power to stereo system.
4. If 12V is not being charged, it means 2 things: traction battery does not have enough charge to charge it or DC converter is not working.
I am not sure what OP refers to as "dead" battery. Dead as in dead or dead as in discharged?
Is it OEM Panasonic battery? Those are VERY GOOD quality batteries and last LONG time. Mine is still functional going on year 11 of use.
No, those batteries are NOT cheap to replace as they are AGM deep cycle batteries and run close to $200 aftermarket.
OP, do you have nav system? If yes, in link in my sig there is how to access diagnostic menu on hybrid vehicles. From there, you can scope your battery state.
Are battery cable terminals clean? Otherwise, I am suspicious there is a parasite drain off 12V.
 

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Ok, let's start here.
1. You have two batteries. A 12V one and NiMeHi traction, aka hybrid battery.
2. 12V battery is charged continuously as needed. It is charged from traction battery. There is a converter that does this. So driven or not, 12V is maintained at specific level.
3. 12V is a power backup battery for all onboard computers and AC system, excluding electrical AC compressor. Also, supplies power to stereo system.
4. If 12V is not being charged, it means 2 things: traction battery does not have enough charge to charge it or DC converter is not working.
I am not sure what OP refers to as "dead" battery. Dead as in dead or dead as in discharged?
Is it OEM Panasonic battery? Those are VERY GOOD quality batteries and last LONG time. Mine is still functional going on year 11 of use.
No, those batteries are NOT cheap to replace as they are AGM deep cycle batteries and run close to $200 aftermarket.

OP, do you have nav system? If yes, in link in my sig there is how to access diagnostic menu on hybrid vehicles. From there, you can scope your battery state.
Are battery cable terminals clean? Otherwise, I am suspicious there is a parasite drain off 12V.
"...driven or not..."? Doesn't the car need to be driven for the NiMeHi battery to charge the 12v battery?

I haven't looked closely at my 12V battery, it doesn't appear to be AGM deep cycle, I'll check it tomorrow when it returns home. If it is in fact AGM, am I harming it by using a BatteryTenderPlus to recharge periodically? Dealer tech told me "no problem".

Neither my Cmax nor my Leaf have AGM batteries, both about $120/each, and that was why I was thinking they're not expensive.

Thanks for the clear post. I'm going to check my own diagnostic menu when the car returns home.
 

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Yes, car needs to be driven to charge traction battery. But it is a very large battery and, normally, has enough capacity to maintain 12V battery charge when vehicle is not driven. I am aware of several TCH owners that had their cars stowed for several months and had them start without any issues. So for your application, traction battery should be plenty charged to maintain 12V charge. Unless you parked car with only lowest level of charge possible for traction battery AND ran stereo with subwoofer off 12V for long time. Then sure, you'd drain 12V - but then your car simply will not start. As in - HSD will not go into ready mode.
 

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ukrkoz: I appreciate your input on this. I've been driving VW diesels for 7 years, and learned that the capacity of the OEM 12v batteries was more than adequate, although lifespan was 2-3 years, especially in hotter climates. The alternator, although large capacity, just didn't do a very good job of keeping the battery charged. (I'm aware of the down side of constant over-charging!) That's why I resorted to using the BatteryTender to top them off every 4-6 weeks.

Now I'm learning about the 12v systems in the hybrid/full electric world. Evidently I won't be having a similar issue.

Specific to the Avalon Hybrid, AGM battery: Based on your experience, I won't be needing to use the BatteryTender at all. Thanks.

FordCMax, Leaf: Lead acid batteries. I've found that every 3-4 weeks, when I plug in the BatteryTender, it goes to full charging status, as the battery is less than 80% charged.
 

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Well that's cheapskates at Nissan and Ford saving money on production. What we have in Toyota hybrids is basically marine type high capacity - not high crank - battery suitable for very deep discharge multiple times. Yeah, the OEM ones are rather costly to replace - around $400 - but there is aftermarket alternative and several of them.
Just in case, it also has a thermistor glued on top of it and vent.
From my experience in TCH forum, they start going bad around 8-9 yrs of exploitation. We did have some odd cases of them fail in couple years but statistically insignificant numbers.
So either you have a dud, sorry, happens, or you have parasite draw from one of the devices that runs off 12V exclusively or 12V charge system has some fault in it.
Just FYI, we had an owner that discharged his traction battery by sitting in parking lot with ac turned on and gear shifter in Neutral. When in Neutral, traction battery can not be charged, moving or not (its charge level is monitored by ECM and when it falls down to two bars, ICE starts and recharges battery).
 

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Well that's cheapskates at Nissan and Ford saving money on production. What we have in Toyota hybrids is basically marine type high capacity - not high crank - battery suitable for very deep discharge multiple times. Yeah, the OEM ones are rather costly to replace - around $400 - but there is aftermarket alternative and several of them.
Just in case, it also has a thermistor glued on top of it and vent.
From my experience in TCH forum, they start going bad around 8-9 yrs of exploitation. We did have some odd cases of them fail in couple years but statistically insignificant numbers.
So either you have a dud, sorry, happens, or you have parasite draw from one of the devices that runs off 12V exclusively or 12V charge system has some fault in it.
Just FYI, we had an owner that discharged his traction battery by sitting in parking lot with ac turned on and gear shifter in Neutral. When in Neutral, traction battery can not be charged, moving or not (its charge level is monitored by ECM and when it falls down to two bars, ICE starts and recharges battery).
To clarify, I have had zero issues with my TAH 12v battery. pasaint started the thread, and I agree, quite probably has some sort of parasitic draw.

Any reason for pasaint to consider that, with only 9k miles on his 2015, his car's 12v battery was weakened by sitting idle too long? Are the AGM deep-cycle batteries prone to issues with sitting idle? My experience with deep-cycle marine lead-acid batteries is that they require a battery-tender type device or they'll go bad if left idle.
 

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My bad.
No, as I said, we have several TCH owners that left their cars stowed for 2 and more months without any problem. Toyota actually recommends starting the car every 2 weeks when stowed. As it's same battery in TCH and in my 2012 HiHy, I am sure it's same one in TAH.
They are not used for cranking, that's why they last so long. Of course, clean terminals a must... Threshold is 11.7V, if it goes below, battery is considered to be replaced.
I also came across new trend - using 12V LiIo pack instead of AGM acid battery. Whatever gives large capacity for long term continuous small draw. Then you do not need to worry about vent connection. Though again, several owners chose to not worry about vent at all and simply installed deep cycle sealed battery. AGM of course, as it has very little acid. They found a better priced option for that.
Logically, I'd consider parasitic draw the least viable option. As 12V is continuously "supported" by traction battery. So any draw off it should actually kill traction battery, unless it is safe guarded and when traction reaches minimum charge allowed, 12V is cut off and then draw discharges it. That could be the case.
 

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Speaking of 12V reliability. Here's post from another site from my buddy Litespeed:

Re: 07 TCH - needs engine overhaul
Quote:
Originally Posted by fredo48
Thanks for your suggestions. Will see what they say but will buy some oil, too. I will repost if Toyota comes through but I am sure they wont.

ukrkoz is right. Ignore those guys and just check your oil. Mine has always used oil too. But, never enough for the dealer to rebuild it. Mine uses around 1.5qts to 2qts. now in 7500 miles. I just check it once a week and if it's a little low, I just "top it up".

The battery should be the farthest worry from your mind. I used to worry about it. Not anymore. It's looking like mine will make it to over 300,000. Still on the original 12v battery and original pads and rotors too.

Bottom line, if it runs good, runs smooth and does not put out a cloud of smoke while your driving... Ignore the dealer and everyone else, just add a little oil every now and then and enjoy it.

__________________
2008 TCH Magnetic Grey on Black

271,000 miles
 

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Thanks for the continued feedback. I've learned a lot from this discussion.

(thread drift) 1.5 to 2 quarts every 7500 miles? There's no way I'd keep a car that burns that much oil. I've owned many cars, and none have burned more than .5 quart during their 10k miles oil change interval. (I've been full synthetic Mobil 1 since 1983, always a 10k oil change interval, and NEVER an oil related problem. I must be lucky...)
 

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Discussion Starter · #15 ·
Thanks for all the info guys, I learned a ton of info. I am taking the Avalon to the Toyota dealer tomorrow, there is a bulletin for software update on the radio periodically shutting off on the 2015. I am asking for a load test also, hopefully they can dedicate 1-2 hrs for the test as mentioned earlier in this post. If some of the suggestions about battery maintenance mentioned in the thread are necessary I will be trading the Avalon. Like I said earlier it is unacceptable a car needs to be driven weekly on a 30-40 mile run to maintain the 12 volt battery. Worst case I may purchase an AGM or a LiIo battery if the dealership wants to replace the OEM battery and they prorate it.
thanks again
 

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Sorry to pick, but please read post #13.

ukrkoz' posts clearly indicate that your Avalon already has an AGM (as does mine...I checked last night...YAY!), and that your issues are probably NOT battery related, but parasitic draw.

The information I posted (#2) in response to your initial post is only relevant to traditional deep-cycle batteries, which I have in my Ford CMax and Nissan Leaf. Therefore, you can IGNORE my advice re: batterytender charging every few weeks.

Properly set-up, you should enjoy many years of problem-free 12v battery!!!!

I hope your dealership can find and solve your problem. Good luck!
 

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Discussion Starter · #17 ·
I don't always comprehend the tech issues, no need to apologize. I would rather someone correct me than not understand what's going on. I also hope to have many years of trouble free hybrid ownership.
I have a 2007 Tundra with 86K on it and have never had any issues at all with the truck. That is what led me to try an Avalon. After I come from the dealership tomorrow I will give an update.
 

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pasaint: My curiosity is killing me. Did you learn anything from your dealership visit??? (Also, what state do you live in?)

(I, too, owned a Tundra, 2005, put 85k flawless miles on it, loved the truck. Now dealing with 4cyl Toyota engine, researching oil change intervals...for almost 40 years, always went 10-15k miles, full synthetic on VW/Audi 4 and 5 cyl [300hp turbo], never an oil issue in 160-190k miles. Aware of sludge issues on 2006-2011 Camry Hybrids...)
 

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Discussion Starter · #19 ·
Sorry for the delay, when I took it to the dealer they had no idea what a load test was. I tried to explain it to them , but they didn't want to hear it. I guess its a new generation with new technology. As they were doing the battery test I spoke with a salesman who seemed quite knowledgeable about my issues. He went on to tell me about how small the batteries are now, not much bigger than a tractor battery. I had noticed how small the battery was in the Avalon prior to our conversation. When the service dept. got done with the battery test there was nothing wrong with it, [imagine that]. The battery hasn't died for a couple of weeks now. I refuse to drive on a longer trip once a week or what ever they recommend just to keep the battery charged, the car is still under warranty for quite a while. If the problem persists I will keep taking it back to the dealer. That's all I can do for now. I live in NW Pa. The car is kept in a heated garage.


Talk to ya soon
 

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Thanks for the update.

Is your battery the original Panasonic AGM battery?

Sorry they didn't know what "load testing" is all about. For normal 12v batteries, that are used for everything, you need to know how the battery responds under the stressful "load" of start-up draw. Normal 12v batteries can appear adequately charged, but when subjected to "load", voltage drops below the necessary voltage to start the car.

Keep us posted. Maybe your continued usage will indeed keep the battery up to its expected level of charge.

Questions: 1) Which battery does the TAH draw on to start a cold engine? 2) Is the 12v battery indeed a "deep cycle" battery, only for accessories, or will the TCH draw on it for startup?
 
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