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12v Always On Project

Zachb1

Member
Jul 20, 2021
10
0
Los Angeles
I love my car fridge & freezer for my Model Y. It uses about 30watts when running the compressor (not always on). Yet the car must be in camp mode or sentry-mode set to ON in order to keep the fridge going when I leave the car.

I want to install an always-on 12v socket. This one includes an inline fuse of 20A (way more than I need). Link here.

Does anyone have any suggestions for how to get this wire into the cabin? I know there's a firewall, and I've seen more users break open their console in the cabin to "tap" into an already present wire. Has anyone seen other details how to get this wire from the 12v in the hood of the car -> into the cabin? Very curious if this is something I can do or if I'd need a proper mechanic that works on Teslas.

Thank you!
 

jcanoe

Active Member
Oct 2, 2020
3,482
3,532
Maryland
If the Tesla vehicle is in sleep mode and you are drawing power, i.e. 30W from the 12V battery to run the fridge , this would more than double the 25W standby drain on the 12V battery. This may reduce the life of the 12V battery; currently these 12V batteries seem to require replacement after ~2 years.
 

GtiMart

Active Member
Nov 13, 2019
1,390
1,222
Quebec City, Canada
Yeah, I'd be wary of that too. I think you can also hook under the back seat straight to the 12V converter but that probably turns off when the HV battery disconnects. I would just buy a portable battery that would charge when the car is awake from the standard 12V plug and otherwise provide power to accessories when the car sleeps. But I know this doesn't answer the OP's question...
 

Watts_Up

Active Member
Mar 4, 2019
3,712
2,691
In a galaxy far, far away
Does anyone have any suggestions for how to get this wire into the cabin? I know there's a firewall, and I've seen more users break open their console in the cabin to "tap" into an already present wire. Has anyone seen other details how to get this wire from the 12v in the hood of the car -> into the cabin? Very curious if this is something I can do or if I'd need a proper mechanic that works on Teslas.
There are different options for getting a constant 12 V inside the car:

- You can try to review some TMC threads or Youtube videos dealing with the installation of accessories, such as audio amplifiers.
Some users were able to localize a wire under the central console, but Tesla makes often some changes
and this was not always working for every one depending on the factory date.
And also sometime this solution was not working after a new software release.

- You can search for some youtube videos for tow hitch installation requiring a 12 V for the trailer plug.
The solution was to drop a wire under the battery and having a wire going under the car
using one of the rails supporting the propulsion battery to hide and protect the wire,
and to have the wire reinterring inside the car from one of the rear red light wires hole.

- Another option is to use the hole in the firewall used to have the steering wheel axial for the Right Hand Drive version.
The hole is closed by a plastic cover located under the front passenger footrest.

- An option that I used is as follow:
I installed a camera under my front license plate, connected to a display on top of my dashboard,
so I can see the cars coming from my left when I exit from my garage because the visibility is very poor.
I needed to pass a video wire but I wanted as much as possible to make any holes.
I found in fact a way to slide my wire under the top of the right finder about where the side view mirror is located.
The wire passes then along the door frame and the wire goes under the rubber going all around the door.
I found in fact a location where there was two pieces of metal soldered together and there was a small gap
that I used to put my wire so it would not be too compressed when closing the door.

About connecting the cooler directly to the car battery, I would use an isolator and a motorcycle battery,
to avoid draining the 12 V battery while be able to keep the second battery charged.
Having a separate battery allows you also to carry and keep the cooler outside of the car.


By the way, what kind of cooler do you use?

I was considering getting one of those Igloo Thermoelectric 40 Qt Cooler but I wonder if a Mobicool Compressor Cooler would be preferable?
 
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Watts_Up

Active Member
Mar 4, 2019
3,712
2,691
In a galaxy far, far away
I want to install an always-on 12v socket. This one includes an inline fuse of 20A (way more than I need). Link here.
I installed such socket extension to the 12 V battery, so I can recharge my phone, laptop, or OneWheel skateboard, inside the frunk even when the car sleeping.
I would recommend using some extra nut, the battery bolts are long enough, so there is no risk to disconnect the battery when installing or removing the extension.
(And also, if I need to bring the car for service, I prefer to remove any additional wires, to avoid any warranty issue).
 
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Zachb1

Member
Jul 20, 2021
10
0
Los Angeles
I would recommend using some extra nut, the battery bolts are long enough, so there is no risk to disconnect the battery when installing or removing the extension.
(And also, if I need to bring the car for service, I prefer to remove any additional wires, to avoid any warranty issue).
Thanks for all the information! Seems like there are a few options to get power into the cabin. I'm using a Icego 20L off amazon. I'll post some pictures. I had it in the trunk but the wife had problems with truck real estate being taken up... and I noticed the frunk gets insanely hot in the direct sun. So I actually managed to fit the cooler perfectly under my daughter's car seat base. I kid you not -- I'm using rolled up towels to position the fridge perfectly so the lid opens and doesnt strike the car seat base, or the center console.

As others mentioned concerns about the 12v -- from what I understood, the inverter should assist the 12v as needed. Should I be worried about the battery being drained at 30w peak // maybe 10w average over the hour? If it does drain, I assume the inverter should charge it.

Then there's 12v battery health with the extra job I'm putting on it. The way I see it -- it's a really crummy battery anyways. Lead has it's own problems and also can only drain 50% from what I understand before it's in trouble. I don't know much, but given lead's bad rep, I was considering swapping it out with a Lithium 12v instead.

I guess there's two questions:

(1) Will the lead battery die from a phantom load such as what i'm describing? Or will the inverter see the voltage drop and just charge it.
(2) Will such a load shorten the life of a lead battery down to something dramatic, like 2 months vs 2 years. If so, maybe a lithium 12v will be fine with the load.

I have a 700Wh battery bank -- it's just so nice and cost such a pretty penny, I'd hate to just throw it into the car to bake in the sun. The car can get 100 degrees, maybe 120. This power bank is a LiFePO4 battery -- so im not sure if the heat will kill it before the charging does. From what I've read, these power banks -- heat is the worst thing for them.

That being said, I wonder what the diff is between a power bank getting hot and dying prematurely, and a lithium 12v in the frunk. I'd imagine they both get hot. Maybe my powerbank worries are mute.
IMG_6717.jpg
IMG_6721.jpg
 

jcanoe

Active Member
Oct 2, 2020
3,482
3,532
Maryland
The Tesla 12V battery powers the Tesla 12V systems when the Tesla is parked. The 12V battery has no problem powering the Tesla when the computer is active, i.e when Sentry Mode is turned on. When the Tesla is in sleep mode the Tesla uses ~25W, when not asleep, i.e when Sentry Mode is active the Tesla uses ~225W. The Tesla vehicle will charge the 12V battery as required. The Tesla vehicle will need to charge the 12V battery more frequently if drawing 25W (nominal) + 30W (Igloo cooler) = 55W instead of only 25W. When Sentry Mode is active the 12V battery may need to be topped up (charged) every 2 hours or so. When only supplying 25W the 12V battery may only need to be topped up every 24 hours. When supplying 50W the 12V battery may need to be topped up every 10 hours.

The Tesla 12V battery is a deep cycle battery (has thicker plates) than a standard 12V automotive starter battery. A starter battery is designed to float at 90% to 100% state of charge. A deep cycle battery can sustain a much deeper discharge without damage.

The variables that impact the life of a battery include: load, exposure to extreme temperatures (especially high heat) and vibration. Some types of battery cannot withstand a deep discharge without permanent damage. The 12V battery currently used in the Tesla Model 3, Model Y lasts ~2 years in normal use. Why some of the Tesla 12V batteries fail within the first year while other examples are able to be in service much longer is not clear. (This is not unique to Tesla's 12V battery. On the Chevy Volt the 12V AGM type battery used in that vehicle is known to fail within the first year or two, yet sometimes the Volt's 12V battery will last beyond seven years.)

Something to consider; if you add a non-standard 12V circuit to the vehicle this would probably void the warranty at least for the 12V components.
 
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Zachb1

Member
Jul 20, 2021
10
0
Los Angeles
The Tesla 12V battery powers the Tesla 12V systems when the Tesla is parked. The 12V battery has no problem powering the Tesla when the computer is active, i.e when Sentry Mode is turned on. When the Tesla is in sleep mode the Tesla uses ~25W, when not asleep, i.e when Sentry Mode is active the Tesla uses ~225W. The Tesla vehicle will charge the 12V battery as required. The Tesla vehicle will need to charge the 12V battery more frequently if drawing 25W (nominal) + 30W (Igloo cooler) = 55W instead of only 25W. When Sentry Mode is active the 12V battery may need to be topped up (charged) every 2 hours or so. When only supplying 25W the 12V battery may only need to be topped up every 24 hours. When supplying 50W the 12V battery may need to be topped up every 10 hours.

The Tesla 12V battery is a deep cycle battery (has thicker plates) than a standard 12V automotive starter battery. A starter battery is designed to float at 90% to 100% state of charge. A deep cycle battery can sustain a much deeper discharge without damage.

The variables that impact the life of a battery include: load, exposure to extreme temperatures (especially high heat) and vibration. Some types of battery cannot withstand a deep discharge without permanent damage. The 12V battery currently used in the Tesla Model 3, Model Y lasts ~2 years in normal use. Why some of the Tesla 12V batteries fail within the first year while other examples are able to be in service much longer is not clear. (This is not unique to Tesla's 12V battery. On the Chevy Volt the 12V AGM type battery used in that vehicle is known to fail within the first year or two, yet sometimes the Volt's 12V battery will last beyond seven years.)

Something to consider; if you add a non-standard 12V circuit to the vehicle this would probably void the warranty at least for the 12V components.
Thank you -- great info here. Interesting to know that the car will top off the 12v running my load maybe every 10 hours. The 30w estimate was given as a constant load, but the fridge in my car doesnt run non-stop. So I'm imaging the average load being half that, maybe 15watts per hour. That all to say, I think it'll be safe to drain the 12v with a cable such as this. With the inline fuse, my only challenge will be getting the wire through the firewall. Hoping Watts_Up's suggestions will work to fish the cable through the hood -> cabin.
 

Zachb1

Member
Jul 20, 2021
10
0
Los Angeles
- Another option is to use the hole in the firewall used to have the steering wheel axial for the Right Hand Drive version.
The hole is closed by a plastic cover located under the front passenger footrest.
I opened the hood and found this cable in the hood. This is on the driver side of the hood. The yellow section of the cable runs into a circular hole. I wonder where that circular hole goes. There's no plug or anything cover the hole -- probably the size of a quarter or half-dollar.
 

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Watts_Up

Active Member
Mar 4, 2019
3,712
2,691
In a galaxy far, far away
The 12V battery has no problem powering the Tesla when the computer is active, i.e when Sentry Mode is turned on.
I might be wrong, but what I observed is that when Sentry is on, or when you are driving,
the inboard DC/DC charger is running and delivers then 13.5 V to act the same way
as the alternator of an ICE car, so the 12 V battery don't get discharged.
 

jcanoe

Active Member
Oct 2, 2020
3,482
3,532
Maryland
I might be wrong, but what I observed is that when Sentry is on, or when you are driving,
the inboard DC/DC charger is running and delivers then 13.5 V to act the same way
as the alternator of an ICE car, so the 12 V battery don't get discharged.
You are right. I don't know what I was thinking. When Sentry Mode is active the DC-to-DC converter is powering the 12V systems, maintaining the 12V battery. The 12V battery does not power the Tesla vehicle 12V systems when the vehicle is powered on.
 

Zachb1

Member
Jul 20, 2021
10
0
Los Angeles
You are right. I don't know what I was thinking. When Sentry Mode is active the DC-to-DC converter is powering the 12V systems, maintaining the 12V battery. The 12V battery does not power the Tesla vehicle 12V systems when the vehicle is powered on.
My goal is to avoid using sentry because of the power draw in having the computer running. It really adds up during the day. If I can tap the 12v and the onboard charger keeps it happy at sleep, then it’s a win win!
 

Watts_Up

Active Member
Mar 4, 2019
3,712
2,691
In a galaxy far, far away
I'm using a Icego 20L off amazon.

As others mentioned concerns about the 12v -- from what I understood, the inverter should assist the 12v as needed. Should I be worried about the battery being drained at 30w peak // maybe 10w average over the hour? If it does drain, I assume the inverter should charge it.

I guess there's two questions:

(1) Will the lead battery die from a phantom load such as what i'm describing? Or will the inverter see the voltage drop and just charge it.
(2) Will such a load shorten the life of a lead battery down to something dramatic, like 2 months vs 2 years. If so, maybe a lithium 12v will be fine with the load.

I have a 700Wh battery bank -- it's just so nice and cost such a pretty penny, I'd hate to just throw it into the car to bake in the sun. The car can get 100 degrees, maybe 120. This power bank is a LiFePO4 battery -- so im not sure if the heat will kill it before the charging does. From what I've read, these power banks -- heat is the worst thing for them.

That being said, I wonder what the diff is between a power bank getting hot and dying prematurely, and a lithium 12v in the frunk. I'd imagine they both get hot. Maybe my powerbank worries are mute.
To answer to the question (1) I suspect that the DC/DC Converter will be running higher than usual and you might get a failure alert requesting to get a new 12 V battery.
And getting a new battery would have any effect to solve this issue.

And for the question (2) as you mentioned it, a 12 V battery should not be discharged below 50% of its capacity. This is why refrigerators running on batteries in a boat or a bus
have an interface to control the battery status whose function is to stop the refrigerator if the battery is discharged and to let the refrigerator to restart only when the battery is charged.

Using a 12 V lithium battery seems to be an expensive solution, well you are right you could reach may be 10% of the capacity, or you could double the size of the original battery.
But how often are you using your refrigerator? It would be different if you have a Patrol car with a lot of radio equipments.

I would not recommend playing too much with the 12 V battery as it is a weak point on any electric car. You could run a tire pressure pump for a little bit
but running a refrigerator all the day long might create problems.

It is why having a separate motorcycle battery, that could be charged at night when you are at home could be simple. Or using an isolator to charge the secondary battery,
but avoiding to drain the primary battery.

As you mentioned it, I noticed that you are using an Iceco 20L Refrigerator. I try finding some information about the compressor used for this portable fridge.
It seems to be made by Danfos, it is a DC Compressor (Model BD Micro BD1.4F) and you are correct about the power of 30 W to 50 W.
I found an Amazon comment of a user, using a Wattmeter, reporting a daily consumption of about 700 Wh or about 30 Wh.
In fact, I am a little bit puzzle because I would assume that a refrigerator is only running about five minutes and stop for ten minutes, or run about one third of the time?

I noticed that you already use a battery pack BLUETTI Power Station EB70 700W, so does this battery pack is sufficient for your daily need?

Note: You mentioned the high temperature inside the car in middle of the day when parked. I wonder if you have any tinted windows, glass roof sunshade, or windshield sunshade?
To provide a better sun protection, I also cover the outside of the front windshield and half of the roof, and also the rear window and half of the roof with two large external sunshade covers.
These provide an additional insulation avoiding the sun baking the car canopy.
 
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bradtem

Member
Dec 18, 2018
24
5
Sunnyvale, CA
One thing I have considered is indeed to have a SLA battery, around 200 wh should suffice for the night, but you don't want to run it dry so 300wh (or about 30ah) might be about right. These are available for wheelchairs and cost around $60. The question is how to hook it up to the accessory port. You don't want to draw more than 12a so you want to limit current for charging it. The isolator shown above will disconnect if voltage drops too low from the port (which it usually does not in a Tesla while the DC->DC is on) so what's the best circuit which will charge the lead-acid if it's low, keep it at float voltage if its not and provide power to the fridge? These fridges should come with a port to let you connect a backup battery to them. ICE cars need it even more.
 

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