12V battery

[John K]

Had to replace my wife’s battery in her car, had unclip wiring harnesses, pop a computer off mounting bracket, and other miscellaneous junk.

Hoping the CT 12v battery is not buried under a bunch of stuff. I always had a mental block changing batteries, for some reason, always considered it a boring task.

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[JBee]

I'd expect the auxiliary battery to be lithium like in the plaid. It's unlikely that it will have to be replaced as often as a lead acid battery. I expect it to be in the frunk somewhere, next to all the auxiliaries so access shouldn't be too bad. At a minimum they will have some sort of battery health monitoring that will make it easier to diagnose and then service.

I'm also expecting to see Teslas new wiring architecture, with comms bus over power tech, that will reduce wiring considerably.

 

[Crissa]

Tesla is getting better about not burying the accessory battery, access in the Model 3 was pretty tight. But today they've made the clips much simpler to get into.

-Crissa

 

[ajdelange]

Of course I have no idea as to where the battery will be in the CT. In other Teslas it is in the frunk - well behind the frunk actually. To get it out you have to remove several bits of plastic surrounding the frunk rim, then take out a dozen bolts and remove the frunk (its a tub). At that point the battery is pretty accessible held into place with typical hardware. There should be You Tube videos on how it's done.

As for longevity: as you may know there have been problems with short lifetime of the 12 V battery. Some owners have replaced the lead acid stock battery with a Li ion battery made by Ohmu. Quite expensive but the surprising thing is that the warranty is only 3 yrs - not that much better than what one gets out of a good lead acid.

 

[Friday]

Over on the *** forums (first letter m, second letter m and last letter e), 12V aux battery problems appear to be bricking vehicles. I've seen threads on the TMC forums describing when the 12V goes weak or flat. Lots of weird problems.

The 12V battery seems to be the Achilles heel in the EV architecture at the moment.

 

[ajdelange]

All the brains in the cars are powered by it as are lights, windows, fans, door and trunk lid actuators... so there is a lot of load on it. Plus in the Tesla's at least it is a bitty battery - more like a motorcycle battery than a car battery (but of course it doesn't have to crank). Thus it gets subjected to lots of deep charge/discharge cycles. This is stressful and probably what is responsible for the failure. A bigger battery would be a first step. Seems silly to have a 3 year battery in a car whose traction battery is expected to last 7 - 10 years if not more. Going to lithium is, IMO, a good move.

 

[Hunter Sawyer]

The CT might not have a 12v battery. Tesla is (or was) hoping to introduce their flex circuit to the Model Y in Berlin. This circuit brings down around 90% of the wiring and has no need for a 12v system.

 

[John K]

Gone are the days of maybe a bracket, a clamp and two terminal posts to swap the battery out.

Also, gone are the days of a $45 battery replacement. The battery location and effort needed is one of the areas to be checked when the CT is received. Brake assembly is another area I check. While brakes are simple, I like to review and gives me a chance to review how many cv boots needing to be watched.

I do a once over when car is pristine because doing it after 60k miles has buildup to contend with. Checking while new is unwrapping a gift. With 60k racked up, a chore.

 

[ajdelange]

If there is no 12V system what will run the 12V loads?

Tesla had talked at one time of eliminating the battery and running everything on the DC/DC converter. The obvious problem with that is that if the main battery goes dead you can't charge it as there is nothing to operate any of the controls with. With the current system as long as the 12V battery is alive you can.

 

[ajdelange]

Gone are the days of maybe a bracket, a clamp and two terminal posts to swap the battery out.

That's all that is required to swap the battery in the MX. Now as noted earlier you have to take out the frunk to get to the point where you can see those parts.

Also, gone are the days of a $45 battery replacement.

If you want to replace with the Ohmmu they certainly are.

 

[Crissa]

The 12V battery seems to be the Achilles heel in the EV architecture at the moment.

The DC/DC board going bad does the same thing... some things work, others don't, it is only logical if you know.

-Crissa

 

[Mini2nut]

Changing out a defective 12v Battery was a PITA on the early Model S sedans. Watch and enjoy the frustrating process…

 

[John K]

Changing out a defective 12v Battery was a PITA on the early Model S sedans. Watch and enjoy the process…

I’m a third of the way through and already starting cursing.

 

[John K]

40% through, obviously the wrong video tagged. This cannot be a 12 volt battery replacement….

I am a firm believer engineers should breakdown to all consumable parts. I bet a lot of changes would be done.

 

[John K]

I’m angry now, my dog will only get two treats instead of three. Who am I kidding, he gets four.

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