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Model 3 completed dead in my garage. 12v the issue? Mobile service can’t come for a WEEK! what should I do?
- Thread starter ethanfl79
- Start date
Rice&Curry
Member
you can buy the battery from Tesla, pick it up and if you are comfortable you can install it yourself. Lots of YouTube videos on how to do it yourself.
If it’s under warranty, I’d let them deal with it. To be honest.
But the battery is cheap from Tesla, so if you want to DIY, I’d get the battery there.
I’d guess first step would be to see if you can get the hood open (following the directions online) and check the voltage of the battery.
How old is the car? Is it the original 12v battery?
But the battery is cheap from Tesla, so if you want to DIY, I’d get the battery there.
I’d guess first step would be to see if you can get the hood open (following the directions online) and check the voltage of the battery.
How old is the car? Is it the original 12v battery?
If the app activates the hood, doesn’t sound like it’s the 12v battery.
You have a multimeter and can measure the voltage?
You have a multimeter and can measure the voltage?
I read that the app can if your 12v has a small amount of juice left and it’s via Bluetooth. I had to be close to the car for it to work. It can’t open the trunk or do anything else though. I had to press it twice for the frunk… and the little white light in the frunk is flickering.
No I don’t have one unfortunately.
I’d get the windows down, leave driver door open and put it into tow mode… just in case… if you can, and while you still have power
I can’t do any of this. Doors don’t open, windows don’t come down.
The taillights are flicking. When I lock/unlock the car via the app, the honk sound is very faint, but car doesn’t lock or unlock.
Car is acting all weird. Pretty confident it’s the 12v out of juice.
If that's true then why do so many owners with dead 12v batteries report that their car shuts down? They typically have to pop the trunk by shorting the wires behind the tow hook port.
Have I misunderstood?
Krisja
Active Member
If you can reach the 12V battery, connect a battery charger, leave it for a couple of hours, try to open your car and drive to the nearest Tesla SeC or a place where your battery can be tested/ replaced.
I did it this way with my neighbours MG
I did it this way with my neighbours MG
stopcrazypp
Well-Known Member
The Tesla early warning that keeps car awake only works if it was able to detect 12V failure while car was awake. If the 12V battery failed while the car was asleep, it wouldn't be able to throw the contactors to connect the HV battery.
pnwadventures
@bpr1de on Instagram
If you have frunk open:
- Emergency 12v jump starter pack to get it on and running;
- Drive it to any place that will do a 12v swap for you -or- bring compatible replacement home and DIY
I was under the impression that all the 12v equipment in the car was powered directly from the 12v battery... and the 12v battery is recharged constantly by the HV battery, but if the 12v dies, so does all of the 12v equipment. That's not true?
My understanding is that all 12V stuff is powered by the 12V battery, as in, the "-" terminal is connected to ground, the "+" terminal is connected to 12V, and everything that's powered by 12V is connected to that "+" terminal. But that's not the only thing on that bus.
The architecture of the 12V battery circuit is bog-standard. In an ICE, the alternator in the car feeds a rectifier/charger that is also connected to the 12V bus. When the ICE is running, it spins the alternator which more-or-less keeps the 12V battery charged up. So, say that on this hypothetical ICE that we're talking about the 12V bus is using, say, 20A or something. When the car gets turned on (first click on the key) the battery supplies 20A plus whatever the starter motor needs to turn the engine over, thus discharging the battery a bit. When the engine starts, the alternator starts doing its thing, recharges the battery, and then, as the car is driven around town, supplies roughly 20A to the 12V bus both to keep the battery charged and keep everything else running.
Just so we're clear on this: If the alternator in the above scenario fails, it's possible to make it some distance down the road with the battery supplying 20A, so one can make it to a service center before the battery runs out of charge again and goes kaput. (Various shade tree mechanics have discovered this over the eons.)
On a Tesla, it's not much different. Instead of an alternator, there's a DC->DC converter that goes from the HV battery to the 12V bus and keeps the battery charged, as well as providing operating current.
What I don't know is whether or not that DC->DC is available at all times or if the car has to be some species of "on" in order for it to work. I suspect the latter.
Now, lead acid batteries can fail in interesting ways. A lead-acid battery's cell generates around 2V; six of them in series gives one the nominal 12V that people expect. (Fully charged, around 13 or so; fully discharged, 11 or so). Say that one one discharges the battery so it's in danger of going flat. (With an ICE, this is called, "leaving the lights on when one didn't mean to."
The six cells don't typically have exactly the same charge, there being manufacturing variations. At some point, then, one of the cells will become completely discharged while the rest are working. The voltage across this cell becomes flipped. If, at this point, one starts charging the battery again, that, "flipped" cell may not recover. So, instead of having a 12V battery, one has a 10V battery. There are a significant bunches of electronics that are designed for 12V and Won't Work at 10. Or will barely work. And if more than once cell gets flipped, that's all she wrote, you got 8V.
Thing is, as lead-acid batteries age, one of the things that happens is that individual cells can develop defects that cause them to self-discharge. You can see where this is going, a dead battery out of the blue. So, measuring the voltage across the battery is a Good First Step to make sure that it's the bus voltage that's messed up and not something else, like, say, a blown fuse.
However, there's a bit more than that. In the case of an ICE, a smart mechanic snags one of these multi-testers on a cart that repair shops keep around for this purpose and verifies that the charging circuit is running correctly. There's fuses on that charging circuit; dead alternators, due to bad or loose belts or just busted diodes, burned windings, and so on are Things. So, the first guess that the problem is a dead battery is generally a good one (and pretty common), but it's not the only thing that can happen. In fact, putting in a nice, fresh battery with a dead charging circuit will get one some miles down the road and the blame thing will simply fail again. Murphy says it will be in The Middle Of Nowhere, rather than, say, in your garage.
Again, a Tesla isn't much different, except that if the charging circuit is a goner, there are many possible causes, just like the ICE, but, of course, different ones. The DC->DC might be dead; I've heard of loose wires (!); and if the Pyro Fuze is gone, well, ain't got no HV in that case to charge that 12V battery.
To the OP: There's Request Service, and there's Roadside Assistance. The former often has weeks before they can see one; the latter involves speedy trucks and/or flatbed tow vehicles. One Day, some six months after getting our M3 back in 2018, the SO got into the car, put it in reverse, and largest collection of error messages you ever saw lit up the screen. She called me, we dinged roadside assistance, and, in an hour or so, a guy with a tow truck showed up. When jumping the car didn't work he somehow got the car out of our garage, onto the flatbed, and off to Tesla, with the SO in the passenger's seat.
Long story short: It was the pyro fuse, likely due to a short in the pagoda wiring harness. The moral: Roadside assistance works faster when you've got a non-driveable car.
Good luck!
The architecture of the 12V battery circuit is bog-standard. In an ICE, the alternator in the car feeds a rectifier/charger that is also connected to the 12V bus. When the ICE is running, it spins the alternator which more-or-less keeps the 12V battery charged up. So, say that on this hypothetical ICE that we're talking about the 12V bus is using, say, 20A or something. When the car gets turned on (first click on the key) the battery supplies 20A plus whatever the starter motor needs to turn the engine over, thus discharging the battery a bit. When the engine starts, the alternator starts doing its thing, recharges the battery, and then, as the car is driven around town, supplies roughly 20A to the 12V bus both to keep the battery charged and keep everything else running.
Just so we're clear on this: If the alternator in the above scenario fails, it's possible to make it some distance down the road with the battery supplying 20A, so one can make it to a service center before the battery runs out of charge again and goes kaput. (Various shade tree mechanics have discovered this over the eons.)
On a Tesla, it's not much different. Instead of an alternator, there's a DC->DC converter that goes from the HV battery to the 12V bus and keeps the battery charged, as well as providing operating current.
What I don't know is whether or not that DC->DC is available at all times or if the car has to be some species of "on" in order for it to work. I suspect the latter.
Now, lead acid batteries can fail in interesting ways. A lead-acid battery's cell generates around 2V; six of them in series gives one the nominal 12V that people expect. (Fully charged, around 13 or so; fully discharged, 11 or so). Say that one one discharges the battery so it's in danger of going flat. (With an ICE, this is called, "leaving the lights on when one didn't mean to."
The six cells don't typically have exactly the same charge, there being manufacturing variations. At some point, then, one of the cells will become completely discharged while the rest are working. The voltage across this cell becomes flipped. If, at this point, one starts charging the battery again, that, "flipped" cell may not recover. So, instead of having a 12V battery, one has a 10V battery. There are a significant bunches of electronics that are designed for 12V and Won't Work at 10. Or will barely work. And if more than once cell gets flipped, that's all she wrote, you got 8V.
Thing is, as lead-acid batteries age, one of the things that happens is that individual cells can develop defects that cause them to self-discharge. You can see where this is going, a dead battery out of the blue. So, measuring the voltage across the battery is a Good First Step to make sure that it's the bus voltage that's messed up and not something else, like, say, a blown fuse.
However, there's a bit more than that. In the case of an ICE, a smart mechanic snags one of these multi-testers on a cart that repair shops keep around for this purpose and verifies that the charging circuit is running correctly. There's fuses on that charging circuit; dead alternators, due to bad or loose belts or just busted diodes, burned windings, and so on are Things. So, the first guess that the problem is a dead battery is generally a good one (and pretty common), but it's not the only thing that can happen. In fact, putting in a nice, fresh battery with a dead charging circuit will get one some miles down the road and the blame thing will simply fail again. Murphy says it will be in The Middle Of Nowhere, rather than, say, in your garage.
Again, a Tesla isn't much different, except that if the charging circuit is a goner, there are many possible causes, just like the ICE, but, of course, different ones. The DC->DC might be dead; I've heard of loose wires (!); and if the Pyro Fuze is gone, well, ain't got no HV in that case to charge that 12V battery.
To the OP: There's Request Service, and there's Roadside Assistance. The former often has weeks before they can see one; the latter involves speedy trucks and/or flatbed tow vehicles. One Day, some six months after getting our M3 back in 2018, the SO got into the car, put it in reverse, and largest collection of error messages you ever saw lit up the screen. She called me, we dinged roadside assistance, and, in an hour or so, a guy with a tow truck showed up. When jumping the car didn't work he somehow got the car out of our garage, onto the flatbed, and off to Tesla, with the SO in the passenger's seat.
Long story short: It was the pyro fuse, likely due to a short in the pagoda wiring harness. The moral: Roadside assistance works faster when you've got a non-driveable car.
Good luck!
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The DC-DC is available when -
- the car is on or driving
- the car is awake
It is NOT on when the car is sleeping. The loads are powered by the 12v battery directly.
The car will wake occasionally to check the state of the battery (and who knows what else) and stay awake to charge if needed.
If the car does detect a bad 12v, it will keep the dc-dc on all the time.
A charger for a few hours or a battery booster should “start” the car if the battery is at fault. As long as the fault is not a dead short in the battery.
Just an update, last night I completely removed the 12v battery from the car. There was a strong smell of sulfur in the garage and the 12v battery had bulging sides and was hot to the touch in areas.
