In most cases using a Jumpstarter/jumping from another vehicle ,without lifting the negative cable, would probably work and be safe; however, not knowing why the 12V died, i like to error on the side of caution. After the contactors close ,I would wait a couple of minutes before removing Jumpstarter or jumper cables. I am pretty sure you would only need to wait until you hear the pumps start after the contactors close, which is just a few seconds? What needs to be operational is the DC-to-DC converter to supply 12V power. When I disconnected the negative cable after the car transitioned out of sleep state, the car was drive-able and seemed to be fully functional. I did get an onscreen error that the 12V battery was disconnected (which was true). After returning home, I would charge and analyze what happen to the 12V battery before reconnecting it to the car.
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Model 3 12v Battery issues, monitoring, Aftermarket replacement
- Thread starter hcdavis3
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- 12 volt 12 volt battery
DonTom
Member
I wonder if the Tesla even uses the chassis ground for the 12 volts. I can tell you that my Zero motorcycles uses a floating ground. The bikes doesn't use the frame to complete any electrical circuits. So to even measure any voltages, I use the headlamp low in place of a frame ground.Hey gang, the edit time elapsed, so need to start a new post. My wife asked how exactly to 'start' the car, and I didn't have an answer. By the way, I added a yellow zip-tie to the cables, to fish them out easily, in case they hide, since I removed the part where one of them plug to the cap. Super easy to open now, and I have the battery there, so no worries anymore.
After you open the frunk, I have the following questions:
1. It should be 99.99% safe to just jump the battery like an ICE car, without the need to remove negative cable, no? But is it best to attach negative to the battery itself, or to a chassis ground, like on an ICE car? And yes, always attach positive terminal first, then negative (either to ground, like on ICE cars, or battery terminal, depending what the experts say). Or is the negative terminal absolutely has to be removed, and attach the jumper terminal there? Then turn on battery pack as a jumper.
2. After car is energized, and you open the door, what's next? Can you remove the jumper pack at that point? Or do you need to actually put the car in D, before removing jumper device? Please provide details. Thank you.
In EV cars, I don't think they ever use the frame for the HV stuff as that could be very dangerous if they need to use metal tools to pry open a car after a serious accident with people still in it. You don't want a ground to be able to short tools to, if the hot is accidentally contacted with a metal tool. . But I do not know about the 12 Volts. When I change my battery I will check to see if the negative side is going to the frame. But I would NOT use the frame in an EV if I didn't know for sure that it went to the battery negative. And while it could even be positive ground for 12 VDC, I would expect it to use no frame ground at all. And I would assume such in an EV if I didn't know, since that is the way even my electric motorcycles are.
After you once have the car on, I assume the DC2DC will keep the 12 volts on regardless of the battery. I don't know when the DC2DC comes on, but it is on for sure when you're ready to drive. Perhaps I can test for that also, when I change my 12 V Tesla battery. I will then report back here.
-Don- Reno, NV
JCtx
Member
Awesome! Thanks Don
. Just to know at which point the car is energized, and we can remove the jumper device. And I fully agree with your assessment of chassis ground; makes a lot of sense. But out of curiosity, please see if you can trace the 12V negative battery terminal. So the only question left is if we jump the battery with the negative cable connected or not. My take is there's no need to remove it, and here's why. Let's assume the 12V battery had a short; it'd have damaged the car already, no? But if it didn't damage it, it shouldn't damage it when just jumping it to energize the contactors, no? The worst that could happen is that the contactors are not closed, so at that point, we'd have to proceed to remove the negative cable, no? By the way, it's extremely rare to see a full short of a 12V battery. If anything, maybe one cell or two, but the battery still has power. Not having to remove the negative cable would simplify jumping the car a lot, especially for women. Or guys not mechanically inclined
.EDIT: Hey Don, can you please tell me if you can engage all clips after you reinstall the battery cover? I couldn't engage the ones next to the frunk rubber seal. None of them. I could hear them wanting to engage, but pop back out. If I press any harder, I'd break something. The whole thing feels extremely flimsy. Just want to know if my car is the only one. The cover is safely in place, since the side and top ones did engage. Maybe something changed for 2021? Oh, and had 1 clip missing; need to ask Tesla for one. Thank you.
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DonTom
Member
My "jumper device" do you mean a small battery pack in parallel with the dead 12 V battery?
Hard to say what will happen when the DC2DC converter is shorted. It depends on the design. Some could just turn off automatically, if they have current limiting, which is not uncommon these days, but I would not bet on it either.
-Don- Reno, NV
JCtx
Member
Yeah, I have exactly this one: https://www.amazon.com/gp/product/B015TKUPIC/ref=ppx_yo_dt_b_asin_title_o06_s00?ie=UTF8&psc=1 . Much safer than using a second battery and jumper cables. If you reverse the cables, nothing happens. And I'm 99.99% sure that our DC2DC converter has the same 'short' protection, hence not having to remove the negative battery cable. I'd like to ask that to a Tesla factory tech guy, so we know for sure if it'd be safe or not to 'jump' the dead battery still connected.
JCtx
Member
Hey guys, I need to buy a 'booster pack' for the Tesla; the one I linked above is for my large 12.1:1 CR 32V V8 car, which needs a lot of juice. For the Tesla, a much smaller one would suffice, right? A link for a proven one for this task would be great. Mine is heavy, so something lighter would be better. Thank you.
There is a whole thread on this issue. There are plastic supports under that trim piece that break really easily. Totally a fail on design by Tesla. There are 3D printed parts that fix it and work amazingly well. I do not have a 3D printer so I used an online service to print mine. Worked great. Here is a video of the fix —
And the thingiverse part model
Model 3 frunk reinforcement part by joanquro
And the thingiverse part model
Model 3 frunk reinforcement part by joanquro
DonTom
Member
I would guess that it is even safer to leave the old battery connected. Even if it has a shorted cell in the old battery, it most likely won't be a dead short and the voltage will still come up to the voltage of your GB40 when properly connected. But it is somewhat of guesswork, as batteries can fail in different ways.
Another guess I have is the DC2DC converter is activated as soon as the car is ready to drive. Perhaps a foot on the brake pedal or putting the car in gear.
I received my new 13 volt lithium battery today, but I don't have an error message or any problem yet with my stock 12 VDC battery. I have the new battery in the Frunk along with a 10 MM open end wrench. I have not yet decided if I should replace the battery with the new one or just wait until there is an indication that I have a bad 12V battery.
But even if I do NOT replace it, within a few days I will do some testing with the 12V battery just to find out when the DC2DC comes on and to see if the neg side uses the frame ground, if there is a frame ground in there that I can get to.
I have a few other projects to work on first.
-Don- Auburn, CA
Another guess I have is the DC2DC converter is activated as soon as the car is ready to drive. Perhaps a foot on the brake pedal or putting the car in gear.
I received my new 13 volt lithium battery today, but I don't have an error message or any problem yet with my stock 12 VDC battery. I have the new battery in the Frunk along with a 10 MM open end wrench. I have not yet decided if I should replace the battery with the new one or just wait until there is an indication that I have a bad 12V battery.
But even if I do NOT replace it, within a few days I will do some testing with the 12V battery just to find out when the DC2DC comes on and to see if the neg side uses the frame ground, if there is a frame ground in there that I can get to.
I have a few other projects to work on first.
-Don- Auburn, CA
JCtx
Member
No wonder I couldn't lock the damn thing. Ha ha. But mine doesn't lock below AND above; just the 3 clips at each side, which is more than enough IMO. At least that extra part would solve the issue below the cover. Hey, do you happen to have a link to that thread? Couldn't find it. Hopefully somebody is making that part, and I can just buy it, since I don't know anybody with a 3D printer. I'm sure somebody messed with my car, since the 12V positive (red) cover was broken, the frunk flimsy (those broken parts), and a white pin missing. Not a big deal, but no sense in trying to make Tesla fix that, no? They probably wouldn't even know what the hell I'm talking about. Ha ha.
DonTom
Member
I don’t think so. That looks quite different than the replacement. If you watch the YouTube video you can see exactly what breaks and what the 3D printed part replaces to fix it.
Let me see if I can find the thread. I could not find someone making it. Just the models so I had it printed. It was not cheap to print with the highest quality heat resistant plastics but it was a perfect repair. I wonder if you can find someone on the site with a printer who would be willing
JCtx
Member
Thank you. Somebody with a printer should make them and sell them here, or on eBay/Amazon. I don't plan to call Tesla since a replacement would crap out again the first time you push on the damn thing. I want that design in black, and made with good plastic, like ABS. You don't need anything special for that IMO.
DonTom
Member
I did watch the video, and that was what made me ask. It looks like the entire bar is replaced, not just the little cheap plastic thingies. But I still am not sure.
If the ebay thingy isn't for that, what is it?
-Don- Auburn, CA
JCtx
Member
If any of you find those clever parts for sale anywhere, please post a link . I'd like to buy a pair, to at least engage the clips next to the frunk. Thank you.
. I'd like to buy a pair, to at least engage the clips next to the frunk. Thank you.Hi folks, I know this is an old thread, but I had a hard time finding just a regular replacement 12V battery, so I thought I would post the number I eventually found that worked for me. It's a group size 51R, from AutoZone, Duralast # 51R-EFB. The posts were in the right place and the right sizes, and it even had the same vent ports on the sides. I transferred the vent fitting on one side and the little red vent plug on the other side from the original battery. It was about 2mm shorter than the original though and I had to put a spacer under the battery hold down to keep it from bottoming out before it got tight. Also, this is a regular lead acid battery, not AGM like the original or Optima batteries. It cost me $220. All in all, I would say it's a serviceable replacement, not fancy like an optima or the lithium option, but available and a bit cheaper. I'll post right away if I run into any issues with it.
I wonder what EFB is? I preemptively looked for a 51R in the Winter, since I had hit 2 years. I found a Duracell 51R, flooded, not AGM. I don't think the OEM battery is AGM. Anyhow, the Duracell is at Sams Club, and probably Walmarts as well. It's only $104 at my Sams:
Okay, went to the Hankook battery site, and EFB is Enhanced Flooded Battery, which gives 3x the life of regular MF, Maintenance Free, batteries.
The Atlas battery is the one I underlined. Note, it's a MF, maintenance free, not an AGM. Also, note the that the 3 batteries marked as "for Tesla", two are MF, and one is AGM, so it's not unique nomenclature for the Tesla battery. A MF is not an AGM.
The Atlas battery is the one I underlined. Note, it's a MF, maintenance free, not an AGM. Also, note the that the 3 batteries marked as "for Tesla", two are MF, and one is AGM, so it's not unique nomenclature for the Tesla battery. A MF is not an AGM.
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