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Any reason not to hook up a battery tender to the 12 volt battery ?

aus

Member
Oct 10, 2014
311
44
United States
Most of our trips are 5-10 miles and longer trips are 40 miles each way a couple times a week.
No chargers or accessories attached to the car.
PowerSave mode is on.
.
 

N..8

Member
Dec 20, 2017
202
150
Sanford, NC
"Toto, I've a feeling we're not in Kansas anymore"

Batteries live longer in mild climates. Heat kills.

Then there is the issue of Vampire drain. What settings do people put their Tesla in (always on, power saving, etc). And what accessories do they have plugged in / hard wired (cell phone chargers, radar detectors, cameras, stereo equipment, etc).

Then there are driving habits (short trips to stores/work vs cross country vacations), day vs night, fast vs slow.

Even in 2013 there were people that didn't have an issue with the 12v if they hit all the usage/environmental factors just right.

I guarantee you there are still people that need something better than the SLA battery with no external smart charger. Switching to a more expensive LiFePo4 battery or sticking with an SLA and using a smart charger, either one probably fixes the issue for even the worst outliers.
I can only speak for myself in why I did it. I worked in the Aviation field for years and SLA batteries is all we used. Only receive my Tesla this month but before I read almost every post about the battery system. It wasn't until I received it did I see that the 12v system is in a always on state. I had the car in the garage and I could hear the contact for the 350v to 12v charger clicking on every so often too often for my taste. So I decided to see how much the 12v was dropping before it would charge it back up, took my Fluke and did a few tests. Too be honest it didn't drop really too far on most cases. What got me to thinking was that every time it needed a top off the 350v HV battery would come online and use a step down transformer to charge the 12v battery. I figured that there is nothing I can do for when I'm at work but if I can reduce how many cycles it goes through at the house its a bonus. The SLA battery works really well if you take care of them and while it's in the garage plugged into a trickle charger it's not cycling.
 

Lodo1000

2017 75D AP2 Prem CW
Nov 19, 2017
116
103
Houston
There are too many reports of premature Tesla 12v battery failures to not take notice. That doesn't mean there won't be some cases where the battery lasts 3+ years, but knowing how the battery is over-cycled, and the history of failures, why not help the battery out if you are inclined to? Is it a 'must do', no but it's relatively easy to hook-up a smart tender so....
 
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Naonak

Member
Dec 22, 2015
796
1,153
Kansas
Ok, if you say so. *checks temps in summer 118F for 6 weeks straight in the summer*

I have a radar detector, dashcam, and a 45w USB charger going in my cars.

I don't think it's a matter of "hitting all of the usage/environmental factors just right" but more of a case of "hitting all of the environmental/usage factors just wrong."

Only a handful of people have a problem compared to the ones that don't. So that would indicate to me it's a problem with the individual users/batteries and not a systemic problem.
 

dhanson865

Active Member
Feb 16, 2013
4,610
7,280
Knoxville, Tennessee
Only a handful of people have a problem compared to the ones that don't. So that would indicate to me it's a problem with the individual users/batteries and not a systemic problem.

Have you read Near annual replacement of 12V battery is typical according to Tesla Service Tech or do you just assume anyone not you is a handful that doesn't matter.

There are dozens of other threads like that. Since you don't have access to Tesla's data and I don't your argument comes down to I don't believe it until you prove it and my argument is I do believe it because of all the reported cases.

If that is your attitude we are at an impasse.
 

Lodo1000

2017 75D AP2 Prem CW
Nov 19, 2017
116
103
Houston
I might also be a little sensitive on this topic as my 12v battery was replaced before my new car was even delivered to me. I guess sitting on the showroom floor was a little too much for it.
 
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supratachophobia

Active Member
Sep 24, 2014
3,856
2,683
Columbus, Ohio
Is this still really an issue? I have 3 Teslas, one dating back to 2012, and have never replaced the 12v battery. Maybe Tesla has done it on the sly in the SC and not put the paperwork in?

Never had a single issue with any 12v battery.
Same. I think it had something to do with total 12v load, higher is better for some reason. No raw data, just 120k miles over 2 cars.
 

Naonak

Member
Dec 22, 2015
796
1,153
Kansas
Have you read Near annual replacement of 12V battery is typical according to Tesla Service Tech or do you just assume anyone not you is a handful that doesn't matter.

There are dozens of other threads like that. Since you don't have access to Tesla's data and I don't your argument comes down to I don't believe it until you prove it and my argument is I do believe it because of all the reported cases.

If that is your attitude we are at an impasse.

Yes, and that's a 3 year old thread. They've changed both the battery type and I believe the charging algorithms since then. So my original statement stands. Is this really still an issue?

I'm not doubting the veracity of it originally, but if you think Tesla remains static and changes nothing in response to problems, then we are at an impasse.
 

dhanson865

Active Member
Feb 16, 2013
4,610
7,280
Knoxville, Tennessee
Yes, and that's a 3 year old thread.

bzzz, wrong, you haven't read it then. Sure page 1 is from 2015 but pages 19 to 23 are from 2017 not to mention the pages in-between that covered 2016.

Let me give you another clue, go to page 1 of this thread and it also started in 2015. Imagine that you are in a supposedly 3 year old thread complaining that another thread is supposedly 3 years old.

It's the longer thread with more content and you are here in a shorter thread with less content saying nothing is happening.
 
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Naonak

Member
Dec 22, 2015
796
1,153
Kansas
Where have I said nothing is happening? You keep saying I've said this - please quote me where I've said this. You seem to have trouble understanding what you are reading. I'm sorry about that. I'm not sure how much more clear I can make it.
 
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dhanson865

Active Member
Feb 16, 2013
4,610
7,280
Knoxville, Tennessee
Where have I said nothing is happening? You keep saying I've said this - please quote me where I've said this. You seem to have trouble understanding what you are reading. I'm sorry about that. I'm not sure how much more clear I can make it.

I'm saying read the messages in that thread that you complained is 3 years old and you will see numerous Tesla owners describing their recent replacements that occurred in 2017. You keep asking "Is it still an issue?", I point you to posts that say it is and somehow you complain that posts from 2017 are 3 years old.

If you can't read the posts from 2017 in that thread and gain knowledge from them you surely don't expect me to make cliffs notes for you?

Start at Near annual replacement of 12V battery is typical according to Tesla Service Tech post 361 and read until you get to the end of the thread if you truly want to know if this is still an issue.

Or at least acknowledge that your statements were self conflicting either: A. You didn't read the whole thread or B. it isn't 3 years old or C. don't reply further. Any way would have saved us the last few replies.
 
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Naonak

Member
Dec 22, 2015
796
1,153
Kansas
I'm saying read the messages in that thread that you complained is 3 years old and you will see numerous Tesla owners describing their recent replacements that occurred in 2017. You keep asking "Is it still an issue?", I point you to posts that say it is and somehow you complain that posts from 2017 are 3 years old.

If you can't read the posts from 2017 in that thread and gain knowledge from them you surely don't expect me to make cliffs notes for you?

Start at Near annual replacement of 12V battery is typical according to Tesla Service Tech post 361 and read until you get to the end of the thread if you truly want to know if this is still an issue.

Or at least acknowledge that your statements were self conflicting either: A. You didn't read the whole thread or B. it isn't 3 years old or C. don't reply further. Any way would have saved us the last few replies.

Thanks for encouraging me to read those posts starting at the beginning of 2017.

Out all those posts, there were exactly 2 people who had their battery replaced prematurely. 1 that was kind of iffy and wasn't clear on when/why it was replaced. There were several (3 or 4) that had it replaced at the 3 - 4 year mark, which is not unreasonable, and a number of people saying they have had zero problems, and finally, 1 person who clearly had a problem with the vehicle causing the battery to discharge.

So based off what I've read in that thread that pointed out, it would appear this is no longer an ongoing issue and the problems have been resolved going forward, just as I suspected.

Tesla has changed the battery type (to a DCS+), changed the hardware that charges the battery in the HV pack, and has also changed the charging algorithm, thus rendering this problem non-existent as a design issue.

Shocker.
 
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dhanson865

Active Member
Feb 16, 2013
4,610
7,280
Knoxville, Tennessee
Thanks for encouraging me to read those posts starting at the beginning of 2017.

Out all those posts, there were exactly 2 people who had their battery replaced prematurely. 1 that was kind of iffy and wasn't clear on when/why it was replaced. There were several (3 or 4) that had it replaced at the 3 - 4 year mark, which is not unreasonable, and a number of people saying they have had zero problems, and finally, 1 person who clearly had a problem with the vehicle causing the battery to discharge.

So based off what I've read in that thread that pointed out, it would appear this is no longer an ongoing issue and the problems have been resolved going forward, just as I suspected.

Tesla has changed the battery type (to a DCS+), changed the hardware that charges the battery in the HV pack, and has also changed the charging algorithm, thus rendering this problem non-existent as a design issue.

Shocker.

Yeah and if you had done that to begin with we could have shaved how many wasted messages out of this loop?

OK so late 2016 or newer Tesla's maybe better at keeping a 12v happy by way of a change to the main HV pack. What makes you think there isn't still an issue with all the 2012 to 2016 cars that are pre change? Do you know about a recall campaign on all those cars that I haven't heard about?

Assuming that campaign doesn't exist, and hey what about all those out of warranty or soon to be out of warranty cars, doesn't it seem prudent for a Tesla owner that has the older setup to use a smart charger or buy a LiFePo battery (choose between the cost of time dealing with an external charger or money to make the problem go away)? Especially if they don't live near a Tesla Service Center.

I'm saying the DCS+ battery alone without the HV pack change isn't a fix. That's just a minor parts tweak. A welcome tweak, a small improvement, but not the root cause and so not the root fix.

I still live over 200 miles from a Tesla Service Center and I tend to buy used cars and/or keep cars past warranty. So to me this thread is about the big long term picture for all Teslas and knowing that some TLC is required to avoid the tow truck.
 

Naonak

Member
Dec 22, 2015
796
1,153
Kansas
Yeah and if you had done that to begin with we could have shaved how many wasted messages out of this loop?

OK so late 2016 or newer Tesla's maybe better at keeping a 12v happy by way of a change to the main HV pack. What makes you think there isn't still an issue with all the 2012 to 2016 cars that are pre change? Do you know about a recall campaign on all those cars that I haven't heard about?

Assuming that campaign doesn't exist, and hey what about all those out of warranty or soon to be out of warranty cars, doesn't it seem prudent for a Tesla owner that has the older setup to use a smart charger or buy a LiFePo battery (choose between the cost of time dealing with an external charger or money to make the problem go away)? Especially if they don't live near a Tesla Service Center.

I'm saying the DCS+ battery alone without the HV pack change isn't a fix. That's just a minor parts tweak. A welcome tweak, a small improvement, but not the root cause and so not the root fix.

I still live over 200 miles from a Tesla Service Center and I tend to buy used cars and/or keep cars past warranty. So to me this thread is about the big long term picture for all Teslas and knowing that some TLC is required to avoid the tow truck.

Man, you are just really reaching for a reason to be right, aren't you?

So if I had done that to begin with, my conclusion would have been the same, as would the post...

"Is this still really an issue?" If you had bothered to actually read the thread you linked to, we'd have saved this back and forth, that's for sure. You could have said "Nope, we don't appear to have an issue according to this thread." But instead, you decide to go on and on about a problem that apparently doesn't exist any longer.

If the 2012 - 2015 cars haven't had a problem by now, then they aren't going to have a problem related to THIS particular issue *boggle*. That's assuming your assertion is correct, which I find it to be highly suspect to begin with. If the 2012 - 2015 cars were still having an issue, you'd think we'd have heard about it by now, here coming up on 2018 in a few days... yet in the past year we've heard virtually nothing about it.

So there's one of two likely possibilities:

1. The cars that were going to have a problem, have had their problems and have been fixed.
2. The problem only affected a small number of cars to begin with and the defect was corrected at the factory for newer cars. Older cars are fixed as they present for problems related to premature discharge of 12v battery.

There is no LONG TERM picture for this issue. It's either an issue that presents fairly rapidly, or it doesn't. That is, quite literally, the point of the problem. Premature discharge and failure of the 12v battery. If the car isn't killing the battery unnaturally early, then there's no problem. IF it is, then the problem presents almost immediately. If you don't have a problem immediately, then you don't have a problem as related to the context of this discussion.

A CPO comes with a 50k warranty. You'll encounter the problem before then on a CPO, Tesla will correct the issue, and away you go. More likely, though, Tesla will correct the issue on the CPO servicing before they even sell the vehicle. I doubt you're going to buy a CPO that has the issue, unless there is some other factor at play that is not within the scope of this discussion (like the one guy in the thread you linked to).
 

Naonak

Member
Dec 22, 2015
796
1,153
Kansas
When did you buy your CPO? 2.5 years is not an unheard of timeframe for replacement of 12v batteries. I've replaced many 12v batteries in ICE cars in that amount of time, some less. I've also had 12v batteries last for 6+ years in ICE cars. It's just luck of the draw as far as that goes.

The problem here is premature (I'd say 1 year or less) 12v battery replacements, followed by repeated replacements. A single replacement in 2.5 years is not indicative of a problem. If you've only replaced a battery once in your car, that's not a problem, that's just the battery lottery like any other car on the planet.
 
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tga

Supporting Member
Apr 8, 2014
3,955
2,796
New Hampshire
When did you buy your CPO? 2.5 years is not an unheard of timeframe for replacement of 12v batteries. I've replaced many 12v batteries in ICE cars in that amount of time, some less. I've also had 12v batteries last for 6+ years in ICE cars. It's just luck of the draw as far as that goes.

The problem here is premature (I'd say 1 year or less) 12v battery replacements, followed by repeated replacements. A single replacement in 2.5 years is not indicative of a problem. If you've only replaced a battery once in your car, that's not a problem, that's just the battery lottery like any other car on the planet.
Car was built 10/14, traded 2 years later. I bought it 12/16, 12V battery warning happened 3/17 or so. SC told me there was no history of 12V replacement.

You said
More likely, though, Tesla will correct the issue on the CPO servicing before they even sell the vehicle.

Yes, if a 12V warning occurs during the CPO process, they'll fix it. My point was buying a CPO doesn't mean the 12V battery won't fail shortly after purchase, since mine did. Whether this is still an issue remains to be seen. I won't complain if I get another 2 years on this 12V battery.
 

Brass Guy

Active Member
Jan 5, 2014
1,157
947
Holbrook, MA
I just read this whole thread. Interesting comments - aside from most of this last page.

Regarding the several efficiency comments I read earlier, wouldn't it be more efficient to charge the 12v through an external trickle charger rather than use energy from the HV battery? It seems going through the HV battery (energy originally comes from the EVSE, through the car's charger, into the HV battery, out of the HV battery, through the DC-DC converter, to the 12v) is a lot more loss-y steps than using a 12v battery tender. I don't know how efficient the chargers are, but a round-trip through the HV battery alone brings that efficiency down to about 80%, doesn't it?

For my car, I don't think I'll bother with this. I was one of the lucky ones. My first 12v lasted nearly 3.5 years, about 93k miles. That also got me thinking, since it only cycles when not being driven, perhaps my higher than average driving patterns contributed to its longevity.
 
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N..8

Member
Dec 20, 2017
202
150
Sanford, NC
Brass, I agree with you and believe people who do not have a whole lot of issues with their 12v are the ones who have higher mileage. It's to bad that Tesla didn't make it so while the car is plugged in it would use a smaller trickle charger for the battery. I added mine and so far the highest wattage that it's pulled was about 180 watts most of the time it's about a 40 watt pull.
 
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SteveS0353

Member
Aug 23, 2014
365
54
San Diego, CA
Spot on. The 12V battery only cycles when the car is parked and "off". Cycles kill the 12V battery, so driving a lot or using a tender when parked and "off" does the same thing to limit the 12V battery cycling.

I'm at nearly 60k miles on a new car I picked up in Fremont in July 2014, and have had no issues with the 12V battery so far in 3.5 years.
 

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