Auxiliary 12 v battery for refrigerator

[JamesG]

I want to charge a 12v battery because the 12v outlets shut off when the screen is off and therefore the appliance won't run all day. The voltage of the outlets are 13.6. how can I protect the Telsa electric system. I think a 10amp fuse and a cut out relay are not enough. Can I use a solar controller. The refridge draws 2.5a and I plan to get at least a 30 amp hour auxiliary battery.

 

[vandacca]

There is a 2nd 12v outlet in the trunk (behind the driver-side, 3rd row seat) that I believe is on at all times. Not sure if that works for you.

 

[cantdecide]

The front seat 12v outlet is on 24/7 in my car (dashcam records all night)... which is different from my S.
Can you confirm that your car does this? Does the 12v turn off when the car sleeps?

 

[efxjim]

I have been running a similar fridge in my S for over 3 years. I feed the fuse for the 12v adapter from an all ways on source (electric seat fuse). My fridge has 3 settings for how low it will pull down 12v battery in the car. I leave it on the middle setting and have never had any ill effects. I'm sure it will cause the battery to not last as long but three years has been more than I expected. If I do not use the car for more than 12 hrs or so the fridge will start to warm up since the battery has dropped in charge. As soon as I wake the car it comes back on.

 

[FlatSix911]

There is a simple modification to the Model S to allow the 12V power outlet to always be switched on.

Ingineer said: ↑

BTW, it's a simple matter to keep the 12v outlet in the console live all the time if desired. It's just a simple relay in fuse box #2 (the one on the passenger side under the removable cowling cover - see owner’s manual). Simply make up a jumper consisting of short piece of 14AWG or better wire with a couple of male 1/4" spade terminals. Pull the front most passenger side relay out and insert the jumper into the now exposed 1/4" female receptacles, and you're done, the 12v outlet is now on all the time. You can quickly change it back anytime by removing the jumper and reinstalling the relay.

 

[JamesG]

The front seat 12v outlet is on 24/7 in my car (dashcam records all night)... which is different from my S.
Can you confirm that your car does this? Does the 12v turn off when the car sleeps?

The manual on page 123 says:

"12V Power Socket

Your Model X has a power socket located on the front of the center console. An additional 12V power socket is located in the rear trunk. Power is available whenever the instrument panel and touchscreen are on "

But you seem to be correct that the 12v power is on when the car sleeps

 

[JamesG]

There is a simple modification to the Model S to allow the 12V power outlet to always be switched on.



View attachment 179843 View attachment 179844

Thank you. How do I get a map of the fuses in the X

 

[JamesG]

I have been running a similar fridge in my S for over 3 years. I feed the fuse for the 12v adapter from an all ways on source (electric seat fuse). My fridge has 3 settings for how low it will pull down 12v battery in the car. I leave it on the middle setting and have never had any ill effects. I'm sure it will cause the battery to not last as long but three years has been more than I expected. If I do not use the car for more than 12 hrs or so the fridge will start to warm up since the battery has dropped in charge. As soon as I wake the car it comes back on.

The manual on page 123 says:

"12V Power Socket

Your Model X has a power socket located on the front of the center console. An additional 12V power socket is located in the rear trunk. Power is available whenever the instrument panel and touchscreen are on "

But you seem to be correct that the 12v power is on when the car sleeps

 

[JamesG]

Upon further investigation I find that the cigarette lighter turns off after a while.

I could do what Ingineer does if I was sure the big battery is always charging the 12v. Otherwise it might go dead running the fridge.

The 2 ideas I have to isolate an auxiliary battery is:
1. Get an ac inverter and plug in a battery charger. Cumbersome.

2. Find a controller similar to a solar controller. Is there a solar controller that will accept 13.6 v input.

 

[deonb]

Will the Model S wake up in quick cycles to keep recharging the 12V battery? Let's say you continuously draw 10 Amps from it - it will need recharging every hour. Will that actually happen?

 

[JamesG]

Will the Model S wake up in quick cycles to keep recharging the 12V battery? Let's say you continuously draw 10 Amps from it - it will need recharging every hour. Will that actually happen?

I don't know. I'd like to know. I have an X

 

[FlatSix911]

Upon further investigation I find that the cigarette lighter turns off after a while. I could do what Ingineer does if I was sure the big battery is always charging the 12v. Otherwise it might go dead running the fridge.

The 2 ideas I have to isolate an auxiliary battery is:
1. Get an ac inverter and plug in a battery charger. Cumbersome.
2. Find a controller similar to a solar controller. Is there a solar controller that will accept 13.6 v input.

No need to isolate the battery - the HV traction battery will charge the 12V battery as needed.

Will the Model S wake up in quick cycles to keep recharging the 12V battery? Let's say you continuously draw 10 Amps from it - it will need recharging every hour. Will that actually happen?

Yes, just keep your Tesla plugged in when at home.

 

[JamesG]

No need to isolate the battery - the HV traction battery will charge the 12V battery as needed.



Yes, just keep your Tesla plugged in when at home.

 

[JamesG]

@ flat I am still hesitant to connect the auxiliary battery directly to the Tesla electric system. With an alternator car it would be no problem.

 

[deonb]

Yes, just keep your Tesla plugged in when at home.

Uhh...

If I can plug in the Tesla somewhere, I can plug in whatever device I wanted to plug into the 12V inverter.

 

[JamesG]

Uhh...

If I can plug in the Tesla somewhere, I can plug in whatever device I wanted to plug into the 12V inverter.

Uhhhh. What about when you can't plug in the car

 

[deonb]

Uhhhh. What about when you can't plug in the car

That's my exact point - I want to be able to use the 12V when I can't plug in the car. I could care less about running a converter at the time the car is plugged in.

@Fiat was saying it's fine to plug into 12V, as long as the car is also plugged in. Which is the least useful use case imaginable.

 

[JamesG]

Plugging a 120 v inverter into rear cigarette lighter with a smart charger connected to aux battery in rear trunk.

 

[Drewflux]

If you find a small dc-dc charger such as the solar charger you suggested that would work too. I assume your inverter has a low voltage cut off ciruit built in.

 

[JamesG]

If you find a small dc-dc charger such as the solar charger you suggested that would work too. I assume your inverter has a low voltage cut off ciruit built in.

I would love to find a DC to DC charger. No cut out relay because the Tesla 12v outlet shuts off when the car is off