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12V Battery dead on 2017 XSE

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swampboy

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Discussion starter · #1 · (Edited)
I had to have a boost to get the car going today. i got in the car and nothing worked, no lights, horn, no instrument panel. So i tried hooking a battery pack that you use to boost ICE cars and nothing happened. I left it connected for 30 minutes and nothing. My neighbor offered a boost and my car immediately worked after the boost. Lucky the boost point is under the hood, because the hatch cannot be opened if the battery is dead unless you crawl inside and release it manually after you remove a small panel.

I can't figure out why the battery pack didn't work. It was fully charged and I had used it to start a friend's 2009 Sienna just a short time ago.

Next stop is the dealer to find out the condition of the 12V battery.
 
#2 ·
swampboy said:
I can't figure out why the battery didn't work. It was fully charged and I had used it to start a friend's 2009 Sienna just a short time ago.
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You killed it. The HV 12v batt is not capable of jump starting another car. You're lucky you didn't fry something. Get a new 12 battery, but be ready to get gouged at the dealer. Just be sure its the correct type with a venting tube fitting.

Now you know why you're not supposed to use jumpers on a HV.
 
#6 ·
I have a 2017 XLE pre-owned certified from the dealer. They had to jump the battery because it was sitting in the showroom for a while. They gave it to me, and within a week, my cranks got slower and slower, to the point where I was concerned about not getting it started one day. So I called the dealer. I had jumpers and a booster with me just in case I need them. I didn't. But I took it in, and they ran a test with codes on it, and finally got it to "fail." It was still under the original factory warranty and certified warranty. So I got a free battery. I think it should have been free regardless of a warranty since it sat in their dealership for weeks/months(?) before I got it, and wasn't responsible for the dying battery. But anyway, win/win. ;) As a precaution, I make sure to turn off the radio and any lights that are on (headlights/internal lights) before shutting it down.
 
#8 ·
bumbobee said:
Can someone clarify for me here? The hybrid cars have another battery that dies and you need to replace?
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Have you read the owner's manual? Yes, there's a 12Volt battery under the deck board in the cargo ares, it can be run down or die and need charging or replacing, it provides power for hardware/electronics(ECUs) that needs power before starting even though it doesn't provide power to start the ICE, if the 12V battery is dead, the system won't srtart, this is detailed in the owner's manual.
 
#10 ·
It's a vented AGM battery, I priced one for our '15 Prius at $130, but since it never needed to be replace, I never bought one, I think most Prius Chat owners went with aftermarket batteries, OEM HV 12V batteries are $165-$220.
 
#11 ·
Yes, the hybrid does have a 12V battery in the trunk, you can jump from the hood. Hyundai Sonata hybrids have the same thing in their trunk, that's were you have to jump it. Dealer replacement are $350 from Hyundai... you can get the same battery for some $160 (with the hose connection), but it is a special order shipped to the auto store in 2-3 days. Usual lifetime of these 12V in a Hyundai is 6-8 years as they are away from heat and not cranking the car.

These 12V batteries run the electronics, mainly the computer. No computer, no start. You can jump them in case you somehow drained it as someone stated on the Hyundai hybrid site. They were running the radio with the car off for hours. And yes, one Hyundai dealer told a customer they had to be flat bedded to the dealer. It is a smaller battery with less amp hours then regular car batteries. So don't let a dealer say it's a "special battery", its just a special size with a hose connection. About $140 to $200 depending on quality.
 
#12 ·
Some notes on the 2018 Hybrid 12-volt battery from the OM42B81U manual:

■Charging the 12-volt battery
The electricity stored in the 12-volt battery will discharge gradually even when the vehicle is not in use, due to natural discharge and the draining effects of certain electrical appliances. If the vehicle is left for a long time, the 12-volt battery may discharge, and the hybrid system may be unable to start. (The 12-volt battery recharges automatically while the hybrid system is operating.)
■When recharging or replacing the 12-volt battery
●In some cases, it may not be possible to unlock the doors using the smart key system when the 12-volt battery is discharged. Use the wireless remote control or the mechanical key to lock or unlock the doors.
●The hybrid system may not start on the first attempt after the 12-volt battery has recharged but will start normally after the second attempt. This is not a malfunction.
●The power switch mode is memorized by the vehicle. When the 12-volt battery is reconnected, the system will return to the mode it was in before the 12-volt battery was discharged. Before disconnecting the 12-volt battery, turn the power switch off. If you are unsure what mode the power switch was in before the 12-volt battery discharged, be especially careful when reconnecting the 12-volt battery.
●Some systems may require initialization

P.S. If I read an earlier post right, no where in the manual does it say you can jump start the 12-volt battery from the traction battery and I would suspect that would be highly dangerous. That battery is rated about 650V at maximum.
 
#14 ·
Edwin617 said:
That's not true. I've done it several times.
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Perhaps rdgrimes is right (again)? Apparently, Toyota does not recommend jump starting other vehicles with the hybrid's 12v battery. On page 601 of the OM42B81U manual under the "Notice" subsection of "If the 12-volt battery is discharged", it is written:

To prevent damaging the vehicle The exclusive jump starting terminal is to be used when charging the 12-volt battery from another vehicle in an emergency. It cannot be used to jump start another vehicle.
Click to expand...
Emphasis added
 
#15 ·
marcuslaw said:
Edwin617 said:
That's not true. I've done it several times.
Click to expand...
Perhaps rdgrimes is right (again)? Apparently, Toyota does not recommend jump starting other vehicles with the hybrid's 12v battery. On page 601 of the OM42B81U manual under the "Notice" subsection of "If the 12-volt battery is discharged", it is written:

To prevent damaging the vehicle The exclusive jump starting terminal is to be used when charging the 12-volt battery from another vehicle in an emergency. It cannot be used to jump start another vehicle.
Click to expand...
Emphasis added
Click to expand...
No. He isn't right if I, in real life, have proven this to be false. It is possible to jump start from the 12v battery directly. I've done it. 2-3 times. I work as a valet parking manager, and I've used my 12v battery directly to jump start at least 2-3 vehicles this past winter. And I live in New England.
 
#16 ·
Edwin617 said:
No. He isn't right if I, in real life, have proven this to be false. It is possible to jump start from the 12v battery directly. I've done it. 2-3 times. I work as a valet parking manager, and I've used my 12v battery directly to jump start at least 2-3 vehicles this past winter. And I live in New England.
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Well, you're both right. Toyota says not to do it as he quoted from the manual. But you did it and got away with it a few times. That doesn't change the fact you aren't supposed to.

In your valet job I suspect the cars weren't completely dead and a booster pack would have worked too. But I bet neither would work on a totally dead car that had been sitting for days or months and you'd have killed your battery that's no bigger than a garden tractor one.

So I'd suggest having the valet company supply you with a jump box or two because I doubt they'll replace your battery when you eventually do kill it.
 
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#17 ·
Edwin617 said:
No. He isn't right if I, in real life, have proven this to be false. It is possible to jump start from the 12v battery directly. I've done it. 2-3 times. I work as a valet parking manager, and I've used my 12v battery directly to jump start at least 2-3 vehicles this past winter. And I live in New England.
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LOL. Yes he is right. So is Toyota and what their manual states. Just because you've done it a few times doesn't mean it is safe for your vehicle. It's hilarious that you say you've *proven* Toyota's recommendation to not boost is wrong based on your extensive unbiased independent trials. But by all means, boost as many cars as you like and try to prove Toyota wrong. That'll teach em.
 
#18 ·
Edwin617 said:
No. He isn't right if I, in real life, have proven this to be false. It is possible to jump start from the 12v battery directly. I've done it. 2-3 times. I work as a valet parking manager, and I've used my 12v battery directly to jump start at least 2-3 vehicles this past winter. And I live in New England.
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You are risking both damaging a relatively complex hybrid engine system and, in going against Toyota's recommendation, potentially being denied warranty coverage.
 
#19 ·
Edwin617 said:
No. He isn't right if I, in real life, have proven this to be false. It is possible to jump start from the 12v battery directly. I've done it. 2-3 times. I work as a valet parking manager, and I've used my 12v battery directly to jump start at least 2-3 vehicles this past winter. And I live in New England.
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No doubt you'll be the one griping here when your 12v batt dies prematurely, leaving you stranded. Just be aware that the 12v batt in the hybrid models was never intended to be used for cold cranking a large ICE. Its basically a motorcycle battery. Also be aware that the 12v batt is on a 1000w fuse, (83 amps at 12v). Cold cranking can suck hundreds of amps.
 
#20 ·
rdgrimes said:
No doubt you'll be the one griping here when your 12v batt dies prematurely, leaving you stranded. Just be aware that the 12v batt in the hybrid models was never intended to be used for cold cranking a large ICE. Its basically a motorcycle battery. Also be aware that the 12v batt is on a 1000w fuse, (83 amps at 12v). Cold cranking can suck hundreds of amps.
Click to expand...


No I won't. I'll just buy a new battery. Thanks for your concern though.
 
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