12V battery issues (error messages/car charging problems)

[jomo25]

I would think it better to find the issue on why the 12V batteries are dying. Is it bad batteries? Is something discharging them? Every ICE has a 12V battery in them and they are essentially bricks until the battery is either charged or replaced as well. So, this isn't a unique issue. What is unique is "new" 12V batteries dying after only a month (or so) of service.

I dont think redesigning every elec component to run off of 400V or to using a step down converter are viable options in the timeframe we would need a fix.

 

[MitchL]

Just out of curiosity, could they not do neither and just have something to convert the 400V to 12V without a battery, like a voltage convertor? Sorry to be naive but that would seem simpler than having the 12V battery to fail and the issues with partition of the main battery (I believe an early version of the Roadster tried this with even more issues than the 12V battery, if I am not mistaken. Perhaps someone can correct me if so).

DC-to-DC converters do have inefficiencies, but I believe the issue is that Tesla (and other EVs) would like to leave the main contactor (a huge relay that gates the large battery's power) OFF as much as possible. If the car is sitting there idle, and all you need is to keep the computers running for background tasks and other low-power stuff, you're better off keeping the traction battery isolated.

I can see it being a safety feature. Also, from a design perspective, perhaps the thinking is that a 12V battery is the "simplest" technology, and you're supposed to be able to count on it even when the traction battery is sick, to run the computers and provide battery management and diagnostics. It's just unfortunate that on this particular implementation, it's the weak link, not the most reliable part.

/Mitch.

 

[lolachampcar]

I agree that Tesla has purposely isolated the traction battery. When the car is active, it pretty much must use a buck (DC to DC) converter as the "alternator" to charge the 12V system and run the on board electronics. The 12V battery acts as the supply when the traction battery is isolated (the "engine" is off so the alternator is not turning).

So, if we drop the whole traction battery issue and just troubleshoot the 12V system it normally comes down to one of two issues. Either the 12V system is not being replenished or it is being depleted too quickly. MB seat modules are notorious for failing by not going to sleep. They suck the 12V battery dead and your MB car is temporairily like a brick until you charge or replace the 12V battery.

Given that firmware updates are being done to address this issue I would suspect there are too many things being left on when they should not or the buck switcher "alternator" needs to be managed differently. Of course there is always the bad batch of batteries theory which very well could be right. I guess we will know when Tesla fixes the problem.

 

[ElSupreme]

They suck the 12V battery dead and your car is bricked.

Ok, this word is getting thrown around too much. A 'bricked' device is a 100% dead and UNRECOVERABLE.It is useless except for a paperweight, and/or its recycled materials value.

A dead 12V battery will immobilize your Tesla, but it won't brick it. Plop in a new Pb-acid battery and you should be good to go.

 

[mknox]

Question: If the 12v system dies when the car is unoccupied, how do you get in? The only thing I can think of is to pop off the access panel on the nose and boost the battery from the terminals there.

I've wondered about this on my own ICE. My doors are solenoid controlled like the S's, but there is a hidden key in my remote and a keyhole on the driver's door. I tried the key the other day and was surprised to find it doesn't unlock the car. Turn the key and you hear the electric solenoid operate and the door actually pops open (without having to pull the handle). If my ICE's 12v battery dies, I don't know how I'd get in my current car either, and there would be no way I know of to access the battery.

 

[steve841]

Question: If the 12v system dies when the car is unoccupied, how do you get in? The only thing I can think of is to pop off the access panel on the nose and boost the battery from the terminals there.

Thats all you can do.

 

[swegman]

Didn't someone post earlier that TM said the issue is related to a module, and that the protype cars exhibited this problem, but the module was redesigned? If this is true, is it possible that in a zest to get as many cars shipped as possible, the module supplier may have "inadvertently" shipped some of these "bad" modules?

BTW, when I spoke to a sales rep this week about popping out the nose cone, he told me that you get to the charging posts by opening the front hood, hand turning a black knob and removing the plastic shroud.

 

[jomo25]

Ok, this word is getting thrown around too much. A 'bricked' device is a 100% dead and UNRECOVERABLE.It is useless except for a paperweight, and/or its recycled materials value.

A dead 12V battery will immobilize your Tesla, but it won't brick it. Plop in a new Pb-acid battery and you should be good to go.

I agree conceptually. I used 'essentially a brick' as it was used in previous posts. By the definition you posted, then even a dead 85kWhr battery doesn't brick a MS. That battery could be replaced and the car back to working state. The battery bricks. Not the car.

 

[Ceilidh]

So if the issue is by definition a problem keeping the 12 v battery charged, and the 12 v battery is hidden away so the only access is the one for jumping under the nose cone, then should we all be getting home battery tenders and popping off our nose cones to keep our 12v batteries topped off? Should we be charging the batteries separately at night until Tesla fixes the issue? Just wondering what people think. Once I get my car I would rather prevent a problem than end up unexpectedly immobilized. Of course we shouldn't have to, but just until the issue is fixed.

Cheers

 

[FlasherZ]

So if the issue is by definition a problem keeping the 12 v battery charged, and the 12 v battery is hidden away so the only access is the one for jumping under the nose cone, then should we all be getting home battery tenders and popping off our nose cones to keep our 12v batteries topped off? Should we be charging the batteries separately at night until Tesla fixes the issue? Just wondering what people think. Once I get my car I would rather prevent a problem than end up unexpectedly immobilized. Of course we shouldn't have to, but just until the issue is fixed.

Cheers

Since .31 was pushed, I have experienced no further problems with charging...

 

[mknox]

should we all be getting home battery tenders and popping off our nose cones to keep our 12v batteries topped off?

I wondered if one of those trickle chargers that plugs in the 12v power port (aka cigarette lighter) would work. Does this port remain connected when the car is off?

 

[strider]

So if the issue is by definition a problem keeping the 12 v battery charged, and the 12 v battery is hidden away so the only access is the one for jumping under the nose cone, then should we all be getting home battery tenders and popping off our nose cones to keep our 12v batteries topped off?

Here's the definitive question. Has any car that was shipped w/ 4.0 or above had a problem w/ the 12V system? My car was shipped w/ 4.0 and we've had sleep mode active and have not had a 12V problem (1 month and 1,200 miles old). I believe that the problem was related to 3.x code not putting the computers to sleep which drained the 12V battery. Repeated cycling of the batteries combined w/ insufficient charging wore the batteries out prematurely.

So if the answer to my question above is no, then my hypothesis would be correct and that Tesla gas fixed the problem with 4.0. If the answer is yes then Tesla still has some work to do and I will be installing a Battery Tender lead into the frunk.

 

[jerry33]

I wondered if one of those trickle chargers that plugs in the 12v power port (aka cigarette lighter) would work. Does this port remain connected when the car is off?

Even if it did, the wires to the power port are usually tiny. I wouldn't use one for that purpose.

 

[mknox]

Even if it did, the wires to the power port are usually tiny. I wouldn't use one for that purpose.

Presumably, the circuit is protected by a fuse. I've seen (but never used) portable battery packs that you carry in the car and if your battery goes flat, you plug it into the lighter socket, wait 15 minutes or so, then crank the car over. They also sell solar "battery maintainers" that you throw up on the dash (to catch the sunlight) and plug into the lighter socket. I figure if these products are on the market, and all you need is a trickle to maintain or boost the 12v, it might work...

 

[jerry33]

Presumably, the circuit is protected by a fuse.

I'm not sure how carefully that fuse is chosen.

I've seen (but never used) portable battery packs that you carry in the car and if your battery goes flat, you plug it into the lighter socket, wait 15 minutes or so, then crank the car over. They also sell solar "battery maintainers" that you throw up on the dash (to catch the sunlight) and plug into the lighter socket. I figure if these products are on the market, and all you need is a trickle to maintain or boost the 12v, it might work...

If it's only one or two amps you're probably okay as that will be about the same as a cellphone, but I have little confidence in the power port. I don't know if the Telsa one is on when the car is off. If the plastic piece is easy to get off, the jumper terminals are really the best solution. Maybe someone can make an extension with the terminals in the frunk so you can plug a Batteryminder in with minimal hassle (not have to remove the plastic piece. I expect that it's not designed to come off daily.)

 

[Doug_G]

I would think it better to find the issue on why the 12V batteries are dying. Is it bad batteries? Is something discharging them?

Early versions of the firmware didn't maintain the energy balance in the 12 battery, especially when the car wasn't operated for a long time (e.g. transport). As a result some cars with the old firmware arrived at their destinations with flat 12V batteries. The problem with flattening a 12V battery is you have a finite chance of damaging one of the cells. I once killed a car battery just by leaving the headlights on by accident.

If the 12V battery survived being flattened then no problem; recharge it and away you go. If it was damaged then it may kinda work or not work at all; either way it needs to be replaced.

As I understand it the 4.0 firmware fixed this problem.

 

[jomo25]

Early versions of the firmware didn't maintain the energy balance in the 12 battery, especially when the car wasn't operated for a long time (e.g. transport). As a result some cars with the old firmware arrived at their destinations with flat 12V batteries. The problem with flattening a 12V battery is you have a finite chance of damaging one of the cells. I once killed a car battery just by leaving the headlights on by accident.

If the 12V battery survived being flattened then no problem; recharge it and away you go. If it was damaged then it may kinda work or not work at all; either way it needs to be replaced.

As I understand it the 4.0 firmware fixed this problem.

Fine. This is official? I'd love to hear it from Tesla or in the release notes.

 

[FlasherZ]

I'm not sure how carefully that fuse is chosen.

I've used a compressor on the 12V power port that draws about 5A (it's cord-protected with a 7A fuse)... that's as far as I've stretched it.

 

[tezco]

...Model S cigarette lighter socket (fused at 15 amps).....

Reported elsewhere....

 

[dlmorgan999]

Here's the definitive question. Has any car that was shipped w/ 4.0 or above had a problem w/ the 12V system? My car was shipped w/ 4.0 and we've had sleep mode active and have not had a 12V problem (1 month and 1,200 miles old). I believe that the problem was related to 3.x code not putting the computers to sleep which drained the 12V battery. Repeated cycling of the batteries combined w/ insufficient charging wore the batteries out prematurely.

So if the answer to my question above is no, then my hypothesis would be correct and that Tesla gas fixed the problem with 4.0. If the answer is yes then Tesla still has some work to do and I will be installing a Battery Tender lead into the frunk.

My car arrived yesterday (w/4.0 firmware). I had lots of fun driving it, and last night I put it on the charger and scheduled the pending 4.1 update for installation. This morning I came out to a car with warnings of "Car needs service" and "Car may not restart". After fiddling with it for a bit, I also saw a warning that the 12V battery is low. In any case, I can't drive it right now and I called Tesla for service. For what it's worth, in the short time that the car stayed active, I was able to determine that it did update to 4.1.

As an additional point of information, my car was put on a truck on 12/26/2012 and was delivered on 1/4/2013.