I’m pretty sure my 12v message remained in the screen until it was replaced (about 2 weeks in my case).
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"Proactive" 12v battery replacement - good idea or overkill?
- Thread starter joebruin77
- Start date
It will use almost as much energy as sentry.
Sentry's energy use is mostly overhead used to keep the HV power system on, not compute processing power. You'll see something like 175w instead of 200w.
Realize in the modern world you can easily do computer vision for motion detection in only a watt or two.
Regarding the subject line of this thread, I find it funny that people question proactively getting a new 12 V battery. I did it a year ago or so, and have zero regrets. It cost like $100, for a $60,000 car, to make sure that it continues to operate without 12v battery problems. My understanding is that a sudden failure of that battery is far more complicated to remedy in our cars, versus an ICE car. I will always get a new 12v every few years proactively as long as I own a Tesla. Short money for peace of mind.
RayK
Active Member
And in the past, the failure of the 12V battery sometimes came up rather unexpectedly (i.e., you were never given a warning of its imminent failure). With some software update(s), there's now a warning and steps taken to minimize the chance of you getting temporarily locked out. I changed mine when it was almost 4 years old. Not because of any message or problem, but merely to avoid being a statistic of Murphy's Law when I was planning a trip out of state.
Oh, I certainly don't question it ... it's the smart move.
But for me, I just decided to play chicken with mine and see who blinked first. If I lost and the car shut down suddenly, well, that would've been on me.
So the battery blinked first, this week, actually. Took 4 years & 3 months for me to get the "12V must be replaced soon" alert -- but I already had one on my workbench, sitting on a trickle charger. Less than 10 minutes later and new battery was installed.
Pretty pleased - 51 months is pretty healthy even for an ICE car battery!
When I was considering whether to buy an M3, getting stranded was my greatest fear about the car. One of the first things I did when the car arrived was to buy the A23 battery and stuff it into the tow bar receptacle.
Or you could read the manual for the car and see that it's no worse than an ICE can and often easier.
OK, I admit, I have not read the manual regarding the 12v battery. But I have read posts on this forum. It seems that if the 12 V battery dies unexpectedly, I may be completely stuck. In any ICE car that I’ve ever owned, when that has happened, you just get somebody to jump the car and you’re on your way. Again, my understanding from reading this form is that if the 12 V battery dies unexpectedly, I won’t be able to get into the frunk easily to jump the car. (“Easily” is the operative word.) Do I have this wrong?
stopcrazypp
Well-Known Member
If you have "someone to jump" you can pop the frunk with the jumper cables, so I'm not seeing how it is significantly different. Also if you were already driving the car, the car would keep the DC-DC alive so it is unlikely to die on the road in a way you can't keep operating the car (only if you park and the car sleeps).
The main difference isn't ICE vs EV, it's that the car doesn't have a physical key nor manual frunk release in the cabin, so you don't have a physical way to open the car (or the frunk) without 12V power of some sort. But there are other ICE cars like this too (I believe some Porsches are an example, you have to find the hidden release in the wheel liner to pop the frunk if your 12V is dead).
Here's a link to the section in a Model 3 manual titled "Jump Starting"
Model 3 Owner's Manual | Tesla
Learn how to properly tow and jump start the vehicle in the unlikely event your vehicle runs out of range.
www.tesla.com
Ehhhh I don't know.. I haven't seen that in my experience.
I have seen my car be awake doing Cabin Overheat Protection, or maintaining the 12v battery (I don't drive much so the car can be asleep for days). When it does this even though the car might be awake for several hours, I only lose about 1% HV battery (according to TeslaMate).
I'm pretty sure I'd lose a lot more if Sentry was running, in fact when I've driven to work and it IS on I can be sure that I will lose 2-3%+ over the course of the working day.
YMMV though.
It’s amusing to me how people buy a relatively expensive car like a Tesla and then insisting on driving the 12 volt battery into the ground like it’s a badge of honor. In 40 plus years of driving, I’ve never had a battery slowly wind
Down and nicely let me know it’s done. It’s always been a hard failure with no warning and the most inopportune times. Like a few others I’ve learned to be proactive. And I have seen teslas become inoperative with a dead 12 volt. I had to jump my in laws model S because of this. I proactively replace my batteries at 4 years. Teslas, bmw i3 and Pacifica. In one tesla and the Pacifica, no warnings but when tested out of the car, both were near death in a manner of speaking. The Pacifica battery had started to swell and that failure kills the car (same for i3) it’s 100-200 bucks. Cheap insurance and peace of mind.
Down and nicely let me know it’s done. It’s always been a hard failure with no warning and the most inopportune times. Like a few others I’ve learned to be proactive. And I have seen teslas become inoperative with a dead 12 volt. I had to jump my in laws model S because of this. I proactively replace my batteries at 4 years. Teslas, bmw i3 and Pacifica. In one tesla and the Pacifica, no warnings but when tested out of the car, both were near death in a manner of speaking. The Pacifica battery had started to swell and that failure kills the car (same for i3) it’s 100-200 bucks. Cheap insurance and peace of mind.
Well, Model 3 must be the first then.
It was a curiosity item for me to see when and how the car would pick up on it.
Have to understand - Model 3 isn’t my primary car right now. It doesn’t go anywhere that isn’t very local - long distance driving is done in either the S or X. I also have a jump box in the frunk in case it did conk out suddenly.
So why not do a little experiment and see how the car reacts?
Turns out … perfectly. Exactly as one would hope. Detected an issue, kept the contactors open until I replaced it, and I already had one on the workbench. Less than 10 minutes to replace the battery.
I wouldn’t recommend everyone do this, of course …. But in my case, why not? Biggest risk was that I’d have to pop the trunk with a 12V battery and jump the car. Not a big hassle at all.
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stopcrazypp
Well-Known Member
Both of your observations have the car sleeping most of the time (especially the latter one). He is talking about if the car was kept awake 24/7 as it does with Sentry. From the other thread, it appears that even Cabin Overheat does not keep the awake the whole time, it wakes the car at certain intervals to do a temp check. It only keeps the car awake if it's actively cooling the car.
Depending on the ambient temperature it will stay awake to try and keep it under 40C (or lower). In some cases, in direct sunlight, that means it will be awake for several hours, until the temperature drops and/or its out of direct sunlight.. Likewise I can see in TeslaMate that my car occasionally wakes up to maintain the 12v battery for ~2 hours at a time.
johnny_cakes
Member
I got the 12v battery replaced by Tesla this morning. It's been over 7 hours now and my car still won't sleep. I did take it for a drive but it's been sitting in the garage for ~5 hours out of the 7. Sentry is off. While cabin overheat protection is on, this never prevented my car from sleeping in the garage before the 12v battery warning came on. Usually about 15 - 30 minutes of idle time was enough to get it to sleep. Anyone know if I need to do something to restore the sleep behavior to the way it was before the 12v battery was replaced?
johnny_cakes
Member
It can easily take 24 hours after a battery replacement for it to sleep. It needs to fully charge the battery, and then run a bunch of tests on it. They are not shipped fully charged.
Driving or not will make no difference to this timing. It's not like a ICE car, there is no different charging that occurs while driving.
Driving or not will make no difference to this timing. It's not like a ICE car, there is no different charging that occurs while driving.
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