MY 12V inverter capacity?

[bdambrosio]

Anyone know the capacity of the MY 12V inverter?

I used the 12V system on my previous MX to run an inverter to supply power to run critical appliances during PGE outages last year - worked great, on MX the inverter used to charge the 12V battery has 50amp capacity, and runs whenever the 12V needs charge, whether car is on or off. (You have to connect directly to the 12V jump-start location, can't use cigarette lighters). That means you can pull up to 600W continuously for days (I ran my house refrigerator, rooftop cell signal booster, some lights, phone chargers, etc for 2 days, main battery charge level dropping about 10KWH per day).

Good news - the 12V in my new MY is even easier to get to. Anybody know if the charger is the same capacity, and, like MX, runs as needed whether car is 'on' or not?

btw, this may void the warranty, and in any case is dangerous on top of it, I DO NOT recommend anyone try this!.

 

[MrTuna]

I do not. Is the 12V the same size? That might be a hint but not proof of how it works.

 

[E_R_N]

I tried to find this out too. I want to do the same as much as the manual is all "dont do it" bla bla as long as you dont overload it, its not different than running the car accessories. The other thing I thought of was the rear hitch wiring. There should be 12v b+ there to charge a trailer battery and if you have a pretty dead trailer battery you could easily be pulling over 20 amps, 8 to run the brakes, a couple amps for the lights and then the battery can take massive amps if it is dead. Not sure if tesla has some sort of current limit set on that circuit

 

[E-curb]

I tried to find this out too. I want to do the same as much as the manual is all "dont do it" bla bla as long as you dont overload it, its not different than running the car accessories. The other thing I thought of was the rear hitch wiring. There should be 12v b+ there to charge a trailer battery and if you have a pretty dead trailer battery you could easily be pulling over 20 amps, 8 to run the brakes, a couple amps for the lights and then the battery can take massive amps if it is dead. Not sure if tesla has some sort of current limit set on that circuit

Good idea on using the trailer hitch wiring -- does not require modification of the vehicle. Wouldn't there be a 12v fuse protecting this circuit? The rating of that fuse would put an upper limit on maximum safe amperage.

 

[E_R_N]

Good idea on using the trailer hitch wiring -- does not require modification of the vehicle. Wouldn't there be a 12v fuse protecting this circuit? The rating of that fuse would put an upper limit on maximum safe amperage.

Tesla doesnt have normal fuses like you would see in any other vehicle so it leaves it a mystery still but there has to be some current protection of some sort. When I decide to get serious I was going to hook up a trailer and see what kind of a load it would take to break the circuit open but I havent had the need yet to go through the effort,,, since I dont have a trailer hitch at the moment.

 

[bdambrosio]

For what it's worth, I did a bit more research, and found the 12V battery in the Y is smaller than S/X (only 45AH), and the inverter in the 3/Y is integrated into other components, a redesign from the S/X. So most likely the 3/Y capacity is considerably less than 50a.

 

[Darmie]

For what it's worth, I did a bit more research, and found the 12V battery in the Y is smaller than S/X (only 45AH), and the inverter in the 3/Y is integrated into other components, a redesign from the S/X. So most likely the 3/Y capacity is considerably less than 50a.

May be the reason the Model 3 12V battery goes out more often then the S/X..

 

[rrolsbe]

The following is for Model 3 cars with lead acid batteries, I assume it might be the same for Model Y vehicles without the new smaller batteries. Some of this might not be totally correct and is from memory. Tesla does not recommend connecting anything directly to the 12V battery or the posts under the rear passenger seat. The DC-to-DC that provides power to the 12V bus and charges the 12V battery can output around 200A; however, only about 8 amps is delivered to the 12V battery posts through the front body controller. People have attached accessories to the battery posts and the posts under the rear seat and there are several threads on this forum that discuss the topic. You can connect to the cigarette lighter but that is limited to around 12A continuous. If only 8A is available, the battery would eventually be depleted if over 8A were being drawn. Things could have changed since my research or some of the above could be incorrect. Please feel free to correct any misstatements.

 

[e645824]

There are several places to tap into in my Tesla 2021 MYLR to power an inverter. But the general guidance from Tesla seems to be not to do it. However, here are some of the ones that I found:

• 12V cigarette port
• 12V lead-acid battery terminals
• 30A subwoofer power port
• 13-pin trailer connector
• 12V port under the rear seat (200A ?)
• 400V battery cable under the rear seat

The 12V port under the seat seems better than the lead-acid tap-off approach. The following person used the 12V under-seat point and tested his pure sine-wave inverter in his (2019?) Model 3 with a 1300W microwave and said that it worked:

https://marc.merlins.org/perso/cars...ncy-Power-Source-In-Case-of-Grid-Failure.html​

For other 12V places, there is this note, "However, once an unexpected very high load, like 80A is detected (on the 12V line); the Telsa goes into an error state. " from here http://www.aprs.org/FrankenVolt.html

The 13-pin trailer connector doesn't provide enough current (it uses 13 and 15 gauge wires) according to Wikipedia 13-pin Jaeger ISO 11446 connector.

And tapping into the raw 400V battery directly is very tempting, but lithium batteries are persnickety (just ask a Chevy Volt) and it isn't recommended without a sophisticated battery management system in the loop. And the danger of instantaneous discharge of 80 kWh of energy (80 kWh = 288 Mega Joules).


I have two usage cases for an inverter:
1. on a road trip and wanting a cooler (but I'd just get a 12VDC cooler instead of a 120VAC fridge)
or
2. a grid power outage and needing to power things temporarily at home (refrigerator, etc.)

The sad thing is that for #2, my MYLR is the perfect mechanism since I could power things in my house for MONTHS. Power for 1 day, then drive to the nearest operational SuperCharger, charge the car, then come back home and power for the next day. This is perfect, but Tesla is trying really hard to prevent this.

I'm afraid that this is one area where GM, Ford, Chrysler, etc. are going to eat Tesla's lunch by actually providing functionality that everyone seems to want. I don't need V2H (to power my entire house), just a couple of kW to prop-up the refrigerator and etc. until the lights are back on. I can't afford solar+batteries for my house right now. Sure, I "should" get a Yeti 6000X, but I have a $60k battery-on-wheels sitting in the driveway that I can easily recharge at a SuperCharger indefinitely.

Scott

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MYLR | Red ext | White int | 19" | 5 seats | tow | no FSD | made/delivered Oct 2021