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Service Required after 12v battery replacement

Jeecups

Member
Oct 1, 2020
8
0
USA
Hi all,

Kinda of at the end of my rope with my ‘12 Model S (and with Tesla Service.)

Model S started displaying the low 12v message, and, assuming Tesla would charge an arm and a leg, I ordered a replacement from EV Tuning. I installed it following a couple of YouTube videos. It really wasn’t very difficult. Upon connecting the new 12v, I got Service Required errors on the dash and lots of BMS errors in the notifications area on the MCU. The car will not switch into Drive. I’ve attached a picture of the of the errors I’m getting.

Long story short, the car has been to Tesla 3 times now. The first time they said it needed a new 12v. The car worked for a couple of days, then got the same Service Required errors. 2nd time they said they “fixed the pins on the 12v sensor”. Car worked fine for a couple of days then same errors. 3rd time they said it needed a new DC DC converter and gave me a $5k estimate.

I declined that estimate since I’d given them $1200 so far to fix my car and they had failed. Also I knew, thanks to these forums, that the DC DC could be serviced somewhat easily. So this morning I pulled out the DC DC and opened it up. All 4 fuses are good. Nothing seems amiss from what I can tell.

SO... that brings me here. With a dead car that seems to not be getting power to the 12v from the DC DC.

I guess my questions are:

1. Is there anything else in the DC DC that can be tested if I open it further?
2. Does anyone have any other advice before I purchase a used DC DC for replacement?

At this point I’m not confident that replacing the DC DC will fix the issue.

If you read this far, thanks! And thanks for any advice!

1DE777F6-FB2B-49E4-A87E-BD118A941ADF.jpeg
 

wycolo

Active Member
May 16, 2012
3,068
423
WA & WY
'Replacement from EV Tuning' - what is this battery exactly?

What are 'pins on 12v sensor'? Does my 12v sensor have pins? This is the sensor on the neg term, right?

I've put cable extensions on my 2012 ModelS battery so I can easily access 12v battery located right in the frunk. If you had, say, three 12v batts in the frunk you could test drive until the first died and then quickly hook up the second one, etc to see if you really need a dcdc or to test out a replacement dcdc. Happiness is spare 12v batts. :D

With the 12v batt hidden under all that stuff it is almost impossible to service the old cars. Hence my mod.
--
 

swegman

Active Member
Mar 27, 2012
1,580
1,619
Can’t help debugging the problem but I believe if you swap out the DC-DC converter for a used one (not bought and installed by Tesla) you will have to reload the firmware, and I don’t know how you will get Tesla to do that for you. So before you buy a used DC-DC converter look into this issue.
 
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kdday

Active Member
Oct 29, 2016
1,159
2,561
AZ
So one thing that likely might not solve it, but that you should be aware of, is that there are 5 generations of 12v batteries (that I'm aware of) - each of which has a unique configuration setting stored on the car's gateway. I have no idea what happens if you mismatch the 12v battery to the wrong configuration type (I can't imagine it'd cause what you're describing), but just an FYI you should have service make sure the 12vbatterytype config setting matches the battery type you have now.
 
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Jeecups

Member
Oct 1, 2020
8
0
USA
'Replacement from EV Tuning' - what is this battery exactly?

It’s just a regular AGM 12v that’s the correct size and has the terminals in the correct place to match the OEM. The OEM that Tesla uses is basically impossible to find, at least for me.

What are 'pins on 12v sensor'? Does my 12v sensor have pins? This is the sensor on the neg term, right?

I believe that’s correct.

I've put cable extensions on my 2012 ModelS battery so I can easily access 12v battery located right in the frunk. If you had, say, three 12v batts in the frunk you could test drive until the first died and then quickly hook up the second one, etc to see if you really need a dcdc or to test out a replacement dcdc. Happiness is spare 12v

Interesting idea. It might be something to try except that the car won’t switch to Drive even with a fully charged12v.
 

Jeecups

Member
Oct 1, 2020
8
0
USA
Can’t help debugging the problem but I believe if you swap out the DC-DC converter for a used one (not bought and installed by Tesla) you will have to reload the firmware, and I don’t know how you will get Tesla to do that for you. So before you buy a used DC-DC converter look into this issue.

Good point. I’ll investigate that. Thanks!
 

tccartier

Supporting Member
Oct 27, 2015
909
951
AZ.
Hi all,

Kinda of at the end of my rope with my ‘12 Model S (and with Tesla Service.)

Model S started displaying the low 12v message, and, assuming Tesla would charge an arm and a leg, I ordered a replacement from EV Tuning. I installed it following a couple of YouTube videos. It really wasn’t very difficult. Upon connecting the new 12v, I got Service Required errors on the dash and lots of BMS errors in the notifications area on the MCU. The car will not switch into Drive. I’ve attached a picture of the of the errors I’m getting.

Long story short, the car has been to Tesla 3 times now. The first time they said it needed a new 12v. The car worked for a couple of days, then got the same Service Required errors. 2nd time they said they “fixed the pins on the 12v sensor”. Car worked fine for a couple of days then same errors. 3rd time they said it needed a new DC DC converter and gave me a $5k estimate.

I declined that estimate since I’d given them $1200 so far to fix my car and they had failed. Also I knew, thanks to these forums, that the DC DC could be serviced somewhat easily. So this morning I pulled out the DC DC and opened it up. All 4 fuses are good. Nothing seems amiss from what I can tell.

SO... that brings me here. With a dead car that seems to not be getting power to the 12v from the DC DC.

I guess my questions are:

1. Is there anything else in the DC DC that can be tested if I open it further?
2. Does anyone have any other advice before I purchase a used DC DC for replacement?

At this point I’m not confident that replacing the DC DC will fix the issue.

If you read this far, thanks! And thanks for any advice!

View attachment 595102

Don't give up :) I'm driving my 2012 signature VIN number 162 everyday. It has turned out to be a fairly reliable vehicle at least as good as any that I've had previously and better than some. There is only one number one. If your car is a signature keep it as a survivor and just buy another one to use as a driver.

Probably not a practical solution but it is a heartfelt one. Still grinning over here!
 

wycolo

Active Member
May 16, 2012
3,068
423
WA & WY
So one thing that likely might not solve it, but that you should be aware of, is that there are 5 generations of 12v batteries (that I'm aware of) - each of which has a unique configuration setting stored on the car's gateway. I have no idea what happens if you mismatch the 12v battery to the wrong configuration type (I can't imagine it'd cause what you're describing), but just an FYI you should have service make sure the 12vbatterytype config setting matches the battery type you have now.

Five generations seems to imply progress ie steps of improvement which I humbly suggest is not the case. TM since 2012 has just stuffed in whatever lead acid 35ah that would fit into the afforded space that Service is able to get their hands on. Some get an AGM but most just get an SLA of some sort. The longevity is likewise a crapshoot.

Tell us more about this 'gateway' and the various configurations stored therein. Do you see this on *your* car, perhaps a newer S with the readily accessible 12v battery? I've never run into it on my 2012.
--
 

kdday

Active Member
Oct 29, 2016
1,159
2,561
AZ
Five generations seems to imply progress ie steps of improvement which I humbly suggest is not the case. TM since 2012 has just stuffed in whatever lead acid 35ah that would fit into the afforded space that Service is able to get their hands on. Some get an AGM but most just get an SLA of some sort. The longevity is likewise a crapshoot.

Tell us more about this 'gateway' and the various configurations stored therein. Do you see this on *your* car, perhaps a newer S with the readily accessible 12v battery? I've never run into it on my 2012.
--
All Teslas from all generations have their car configurations stored on the gateway, including a 12vbatterytype value. It’s not user accessible and generally is only available for setting for those with Toolbox or a Service Center visit. I have no insight into what mismatched batteries and 12vbatterytype configurations do. Perhaps it was causing over/under charging of the battery because the configuration was for the wrong chemistry. I do not know.
 

Alysashley79

Active Member
Oct 4, 2013
1,198
512
Seattle(ish) WA
I had my 12V replaced by Tesla two weeks ago. It requires the firmware (new or same one) to be reloaded just after install so that it talks to the car again. The day I had it replaced they had removed the old 12V and installed a new one JUST as the entire system crashed globally. The tech that was working on it had my firmware in his mobile (he’s also a mobile tech) so he uploaded it OTA since I was out of town and could continue on my journey. My car is 100% driveable....but my trips don’t work. Energy consumption doesn’t work etc.

Tesla says it needs the newest firmware to be manually uploaded from service. Did they try that? $1200 for what seems like a probable firmware issue seems steep.

fwiw the day they did my 12v and their system was down they couldn’t pull my cars warranty up to prove it was under Tesla’s used warranty so I agreed to pay $279 for battery and labor to install after their system came up if it wasn’t covered (it was)

I’ve seen other posts by people that have put in lithium batteries and Tesla blames everything under the sun on the 3rd party battery. Could that just be the case here?
 

wycolo

Active Member
May 16, 2012
3,068
423
WA & WY
Lithium 12v batteries will be scorched since TM superimposes intermittent spiked voltages on top of the usual 14.5vdc charging voltage. At least they used to do so; it is not sure when they stopped doing this nonsense if they ever did stop it. WARNING!!

What is that $1200- for ???

> Perhaps it was causing over/under charging of the battery because the configuration was for the wrong chemistry. I do not know. [kdday]

Lead acid of all types can be charged just fine by Teslas. No fear of over charging since Teslas over draw the poor little 35ah 12v to such a great extent. I've never seen UNDER charging but this could result from only driving short distances or else letting the car sit unused.

Could be that TM has profiles for each type of lead acid battery and that the car will not run unless this is carefully matched when you switch 12v types of lead-acid. On my 2012 my 12v battery failures neatly coincided with Service visits so I've been spared ever having to deal with this issue. But in a few weeks when I finally relocate the 12v to the frunk I guess I will find out, maybe have to get Service to come 75 miles or do an OTA adjustment. Such joy awaits. :)
--
 

Jeecups

Member
Oct 1, 2020
8
0
USA
Lithium 12v batteries will be scorched since TM superimposes intermittent spiked voltages on top of the usual 14.5vdc charging voltage. At least they used to do so; it is not sure when they stopped doing this nonsense if they ever did stop it. WARNING!!

What is that $1200- for ???

> Perhaps it was causing over/under charging of the battery because the configuration was for the wrong chemistry. I do not know. [kdday]

Lead acid of all types can be charged just fine by Teslas. No fear of over charging since Teslas over draw the poor little 35ah 12v to such a great extent. I've never seen UNDER charging but this could result from only driving short distances or else letting the car sit unused.

Could be that TM has profiles for each type of lead acid battery and that the car will not run unless this is carefully matched when you switch 12v types of lead-acid. On my 2012 my 12v battery failures neatly coincided with Service visits so I've been spared ever having to deal with this issue. But in a few weeks when I finally relocate the 12v to the frunk I guess I will find out, maybe have to get Service to come 75 miles or do an OTA adjustment. Such joy awaits. :)
--

For clarity, I never replaced the 12v with a lithium battery. I replaced with an AGM battery from EV Tuning

As to the $1200:

The first 400-ish was for diag and to replace the EV Tuning battery with an OEM battery. I didn’t really think that was the root cause, and that was confirmed when the same error messages occurred a couple days after getting the car back from Tesla.

The remainder was the 2nd visit when they “diagnosed” the car for 6 hours and then “adjusted the pins on the 12v sensor”. This was with the OEM Tesla battery they’d just put in the car. Again, after this visit, the car ran fine for a couple of days before displaying the same error messages.

The 3rd visit is when they told me it needed a DC DC and gave the $5k estimate, which I declined.

So, even if the battery profile needs to be precisely matched to the exact battery, I would think that would’ve happened on one of the 3 visits.

Anyone have any advice on testing the DC DC to see if it’s converting and delivering power to the 12v?
 

murphyS90D

Member
Jul 2, 2016
646
455
Horsham, PA
Connect a voltmeter to the 12 volt battery and observe the voltage while driving with the headlights on. If the voltage is above 12.7 volts the battery is being charged. I have a 12 volt socket expander in a cup holder in the console. It provides 3 sockets but more importantly they are vertical. I have a voltmeter, designed to plug into the socket, in there. When charging the voltage goes up to 14.5 volts.
 
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tomas

Out of warranty...
Oct 22, 2012
4,251
3,834
Chicago/Montecito
So one thing that likely might not solve it, but that you should be aware of, is that there are 5 generations of 12v batteries (that I'm aware of) - each of which has a unique configuration setting stored on the car's gateway. I have no idea what happens if you mismatch the 12v battery to the wrong configuration type (I can't imagine it'd cause what you're describing), but just an FYI you should have service make sure the 12vbatterytype config setting matches the battery type you have now.
I had my 12v replaced by mobile service 2 weeks ago. Tech replaced battery, and then reprogrammed something. I asked what, and he said that there were service menu settings for different generations of batteries, and “if he didn’t change the setting, I’d be needing another 12v battery in a couple of weeks”. Makes me wonder about the DIY videos. This is first replacement I know of on my 2012.
 
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random155

Member
Mar 18, 2019
876
450
NJ
I had my 12v replaced by mobile service 2 weeks ago. Tech replaced battery, and then reprogrammed something. I asked what, and he said that there were service menu settings for different generations of batteries, and “if he didn’t change the setting, I’d be needing another 12v battery in a couple of weeks”. Makes me wonder about the DIY videos. This is first replacement I know of on my 2012.
Really good to know. Im a DIY guy but after reading this thread, I'll have to splurge and have Tesla replace my 12v when it goes. That sucks.
 

Jeecups

Member
Oct 1, 2020
8
0
USA
Connect a voltmeter to the 12 volt battery and observe the voltage while driving with the headlights on. If the voltage is above 12.7 volts the battery is being charged. I have a 12 volt socket expander in a cup holder in the console. It provides 3 sockets but more importantly they are vertical. I have a voltmeter, designed to plug into the socket, in there. When charging the voltage goes up to 14.5 volts.
Connect a voltmeter to the 12 volt battery and observe the voltage while driving with the headlights on. If the voltage is above 12.7 volts the battery is being charged. I have a 12 volt socket expander in a cup holder in the console. It provides 3 sockets but more importantly they are vertical. I have a voltmeter, designed to plug into the socket, in there. When charging the voltage goes up to 14.5 volts.

Good suggestion. Thanks!

Dumb question, but does the DC DC only supply power to the 12v while driving (like an alternator)? I have it off the car now, in pieces since I was checking the fuses. Is there any other thing that’s testable with it off the car?

Just removed the 12v to put it on a charger and it read less than 4v. Gonna get it charged up and see if the car will even power on and be driveable. If so, I might try the socket voltmeter idea.
 

Jeecups

Member
Oct 1, 2020
8
0
USA
The DC to DC supplies power whenever the car is on. It also comes on 4 or 5 times a day when the car is parked.The loud clicking sounds that you hear are the contactors connecting the HVB to the car.

So I fully charged the 12v and reinstalled. Car powered on (MCU powered up, AC was blowing air, all lights work etc...) In the hour or so after I put the fully charged 12v in the car while I was screwing around, the voltage dropped to around 10v. DC DC never clicked on. Eventually the 12v lost enough voltage to power most of the car functions.

Seems like the car isn’t even telling the DC DC to turn on.

Honestly going to sell it cheap at this point. I’m done throwing money at it and done dealing with Tesla service advisors that look down their nose at my audacity to have an 8 year old car.
 

tomas

Out of warranty...
Oct 22, 2012
4,251
3,834
Chicago/Montecito
So I fully charged the 12v and reinstalled. Car powered on (MCU powered up, AC was blowing air, all lights work etc...) In the hour or so after I put the fully charged 12v in the car while I was screwing around, the voltage dropped to around 10v. DC DC never clicked on. Eventually the 12v lost enough voltage to power most of the car functions.

Seems like the car isn’t even telling the DC DC to turn on.

Honestly going to sell it cheap at this point. I’m done throwing money at it and done dealing with Tesla service advisors that look down their nose at my audacity to have an 8 year old car.
Can understand the frustration. Where do you live? If there are other service centers in the area, maybe try one of them? It’s interesting that some people have had such bad experiences and I’ve only had good ones across 8 years, 3 cars, 2 states. I suspect it must be variable by SC. in some areas there are also 3rd party businesses repairing Teslas. Or even Tesla owners with equipment and DIY cred who would help. It would be a shame I’d you had to punt when this seems repairable.
 

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