12V battery what is the use

[jerseygirl18]

Curious, my MX is in a typical garage in SE Fla. Right now the temp is unseasonably hot in the high 80's occ. 90..giving a 5-10' increase in the garage...what is too hot for the car batts? And will the a/c or whatever comes on to cool the batteries..come on automatically by sensing the batteries need to cool down...or is that a manually operated effort?

 

[ajdelange]

Automatic.

 

[Tam]

...what is too hot for the car batts?...

1) For the main manual, the manual says:

"Temperature Limits
For better long-term performance, avoid exposing Model X to ambient temperatures above 140° F (60° C) or below -22° F (-30° C) for more than 24 hours at a time."

...come on automatically by sensing the batteries need to cool down...or is that a manually operated effort?

As @ajdelange mentioned: Automatically

You can also attempt to manually turn the battery's heater on by turning on the cabin heater and look at your phone app on the "Climate" page, if there's a snow icon, the battery heater is on, if there's no snow icon, then it's not that cold for the battery to have its heater on.

There's no such similar above procedure if you want to manually turn on the battery's cooler. It's automatic with no icon indicator.

2) For 12V battery:

It has no thermoregulation at all because it's cheaper to sacrifice a 12V battery than to equip a similar above heater/cooler system for it.

Typical 12V battery can freeze at about 32F to -58F (0C to -50C) depending on its state of charge, its frozen liquid expands and it becomes irreparable.

Its favorite temperature is about 80F (26.7C).

Damage could start at 110F to 125F.

 

[rreedd]

Actually (lol) a lot of the parts in the car run off 12 V. I believe the idea was to get rid of it totally but they finally didn’t. The Y may not have one but since 75% of the parts are the same as the 3, maybe it will?

Wonder if the pickup won’t have a 12 V?

It’s definitely a weak point since it has to be replaced every two years or so (just had my X’s replaced (under warrantee, of course)).

I am intrigued by the 2 year replacement comment. I am just past my 2 year mark on my X and I just woke up to a dead car. I cant even get into the car and it is plugged in to my home charger. About to call for roadside assistance.

 

[ajdelange]

I went ba=ck and looked at the OP. It asked what the 12V receptacle was for and most everyone interpreted this as asking what the 12 V battery is for.

Someone suggested that the 12V receptacle is for portable stoves, refrigerators, TV's, kettle's etc. No it's not for those as it has only a 15 A fuse on it which limits it to 180 W. Before plugging anything other than the smallest appliances (chargers) into it check that the draw will be under 15 A.

 

[mswlogo]

I'll second everyone else's statements. The entire car runs off of 12V. Pretty much the only thing I think that doesn't are the wheels and possibly heater core.
The 12V accessory outlet is for all sorts of items. The USB ports are slow charging, for example, if you want faster, you need to use a aftermarket 12V USB charger.

The car could still have a 12V Outlet and have everything run off 12V without a 12V battery by just using a step down transformer from the main battery (which it already has to charge the 12V battery).

But the 12V battery is a safety feature. In the event of an accident the main battery may get disconnected, by design for safety. But the 12V battery can stay connected to make a call, open a window or a door, put in tow mode, car itself could phone home (Tesla) for accident and upload data, keep TeslaCam alive. You name it. Think of 12V as a small backup for when you lose Main Power.

 

[shinytop]

Back in the day the original VW had the battery under the back seat. Then and now I believe any access to the battery that requires more than a minute is a glaring example of bad design. Removal of the frunk with 12 bolts holding it in is ludicrous. (Pun intended.) Battery replacement should be forever free just because of that.

 

[ShawnA]

Maybe the next time the frunk tub is out, cutting a little door to the 12V battery may be in order...
(Or perhaps a week or two after the warranty expires...)

Shawn