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MASTER THREAD: Powering house or other things with Model 3

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1. What does everyone think of this idea. Like I say, the little inverter works fine off of the 12 volt accessory so the current demand numbers are valid.
No issues with this. But if the only thing you will be using this for is the fridge, you will be better off using a 12v fridge as inverters are not terrible efficient, say only 50%. And as you noted you can avoid camp mode by wiring to the battery. If you do this be sure you include a fuse and make sure you can disconnect whatever you plug in - just use a standard 12v outlet.
2. If I get a “replace the 12 volt battery” message, can I reset it myself.
No. This is something that needs to be taken car of sooner than later.

3. I am assuming the car, even when asleep, will enable the DC to DC converter to replenish the 12 volt battery yes???

Yes
 
No issues with this. But if the only thing you will be using this for is the fridge, you will be better off using a 12v fridge as inverters are not terrible efficient, say only 50%. And as you noted you can avoid camp mode by wiring to the battery. If you do this be sure you include a fuse and make sure you can disconnect whatever you plug in - just use a standard 12v outlet.

No. This is something that needs to be taken car of sooner than later.



Yes

Thanks for the quick response. Agreed that a 12 volt fridge would be better but we already have the fridge and it works well with that little inverter.

Re your answer to “2. Can you explain that a little more. So no I can’t reset it with a reboot??? And do you mean it would have to be reset by a service centre? Just to be clear. This is not happening. This is just preemptive in the sense that connecting directly to the 12 volt battery may cause this fault.

Thanks.
 
Just don't count on getting a USB port on a new Model 3 or Y. ;)

Screen-Shot-2021-11-12-at-7.37.59-PM-e1636774739573.png


 
Re your answer to “2. Can you explain that a little more

When the car tells you it is time to replace the battery you cannot simply charge and reset. The 12v battery is required for the car to function, so the car constantly monitors its health. When it detects it is time to replace the battery you have a couple of weeks (roughly) before it fails - although they have failed faster. Once it fails your car becomes a great big brick!

When you see this message it is telling you it is time to make an appointment with Tesla to get the battery replaced, or to do it yourself (check out YouTube). When the new battery is installed the car will see a good battery and will not present the warning - there is nothing to actually reset.

Increasing the load on the battery will only cause the DC-DC converter to come online more often to top off the battery.
 
When the car tells you it is time to replace the battery you cannot simply charge and reset. The 12v battery is required for the car to function, so the car constantly monitors its health. When it detects it is time to replace the battery you have a couple of weeks (roughly) before it fails - although they have failed faster. Once it fails your car becomes a great big brick!

When you see this message it is telling you it is time to make an appointment with Tesla to get the battery replaced, or to do it yourself (check out YouTube). When the new battery is installed the car will see a good battery and will not present the warning - there is nothing to actually reset.

Increasing the load on the battery will only cause the DC-DC converter to come online more often to top off the battery.
Ok. I thought that was what you meant but thanks for explaining it. My concern was that the additional drain on the 12 volt battery would make the car think there was a problem with the battery when there really isn’t. My guess, in this case, is if I simply turned off (unplugged) the load that message would probably go away after a couple of charge cycles.

Thanks for the informative discussion.
 
Increasing the load on the battery will only cause the DC-DC converter to come online more often to top off the battery.
This is not correct. The Model 3/Y and the facelift S/X actively monitor the battery charging power. If you are drawing a significant load directly from the battery terminals, it will cause an error because the car thinks the battery is absorbing an abnormal amount of power. All significant loads should be taken from unused circuits on the Body Controller or directly from the PCS terminals.

I don't know how persistent the error is or whether it will clear itself after the abnormal load is removed.
 
If you are drawing a significant load directly from the battery terminals

I understand what you are suggesting but how would it know what is coming from the battery terminals? Doesn’t all the power being consumed on the 12v system come from the battery terminals? Also, when a battery is being charged the amount a battery consumes is a function of what is supplied to it, such as using a 1A, 5A, 10A etc. charger. So again, since the charging amperage is static, until the battery nears a full charge, again how would it know?

Please explain as I would like to understand better.
 
I understand what you are suggesting but how would it know what is coming from the battery terminals? Doesn’t all the power being consumed on the 12v system come from the battery terminals? Also, when a battery is being charged the amount a battery consumes is a function of what is supplied to it, such as using a 1A, 5A, 10A etc. charger. So again, since the charging amperage is static, until the battery nears a full charge, again how would it know?

Please explain as I would like to understand better.
And further to that, if there is a number that causes a fault, what’s the number to stay below. I’m looking for 12 amps max continuous, and probably closer to 10 amps.
 
I understand what you are suggesting but how would it know what is coming from the battery terminals? Doesn’t all the power being consumed on the 12v system come from the battery terminals? Also, when a battery is being charged the amount a battery consumes is a function of what is supplied to it, such as using a 1A, 5A, 10A etc. charger. So again, since the charging amperage is static, until the battery nears a full charge, again how would it know?

Please explain as I would like to understand better.
It's doing current measurements, and when the total drawn from the battery and the total of the known fused circuits (Tesla Model 3 uses electronic resettable fuses so they can measure everything) don't add up, it can throw an error.

The other forum mentions this and explains why people spend so much time trying to figure out another way to connect things to the car rather than directly to the 12V battery:
Here's how to safely tap 12v power for add-ons
 
I understand what you are suggesting but how would it know what is coming from the battery terminals? Doesn’t all the power being consumed on the 12v system come from the battery terminals? Also, when a battery is being charged the amount a battery consumes is a function of what is supplied to it, such as using a 1A, 5A, 10A etc. charger. So again, since the charging amperage is static, until the battery nears a full charge, again how would it know?

Please explain as I would like to understand better.
This video explains it pretty well and he tries to make it understandable for non-engineers.


Basically, there are no traditional fuses in the current Tesla cars and they are using current shunts to measure all the 12V circuits in the car, with MOSFETs that can cut off the power to any circuit that's misbehaving. The 12V battery is one of those circuits, so the controller knows exactly how much current is flowing in and out of the battery. There are also MOSFETs that can modulate the charging current to the battery, but that particular mode may not be used, they may just have the PCS modulate the voltage of the 12V bus to control the 12V battery charging. While the car is running, the power being consumed is not coming from the battery, it's coming from the DC-DC converter portion of the PCS (Power Conversion System), just like it would be coming from the alternator in an ICE vehicle. The main difference is that an ICE vehicle is not aware of the difference between how much energy is being consumed by different accessories versus charging the battery, versus aftermarket loads.
 
And further to that, if there is a number that causes a fault, what’s the number to stay below. I’m looking for 12 amps max continuous, and probably closer to 10 amps.
The 12V socket in the center console can definitely safely supply 10A. 15A will definitely trip. There is probably an allowance in the trip curve for higher startup current for something like an air compressor.
 
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This video explains it pretty well and he tries to make it understandable for non-engineers.

That was a cool video, thank you! The point not addressed, which I think goes back to the OP's question, has to do with direct connections to the battery. If we connect an air compressor, refrigerator, etc. directly to the positive and negative terminals of the battery, with a fuse for safety of course, will this not be outside of Tesla's monitoring system since the draw will come directly from the battery?
 
That was a cool video, thank you! The point not addressed, which I think goes back to the OP's question, has to do with direct connections to the battery. If we connect an air compressor, refrigerator, etc. directly to the positive and negative terminals of the battery, with a fuse for safety of course, will this not be outside of Tesla's monitoring system since the draw will come directly from the battery?
When the car is awake, the draw will be seen by the car because the car is maintaining the voltage of the battery. The current from your load connected to the battery will pass through the VC-Front module from the PCS which is providing energy from the traction battery. It will see that load as an excess charging current. When the car is asleep, it will drain the battery more quickly than normal and the car will have to wake up and recharge the battery. If the battery does not maintain a certain voltage when the charging current is removed, the car may not sleep at all. The fact that the battery voltage is dropping when it shouldn't is another reason to throw an error.

For a transient load like pumping up one tire, connecting directly to the battery is reasonable. Anything longer term like a refrigerator or electric cooler should draw power from a proper load circuit on the body controller. Tapping the subwoofer circuit in the trunk is a reasonable choice for a load like a cooler.
 
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When the car is awake, the draw will be seen by the car because the car is maintaining the voltage of the battery. The current from your load connected to the battery will pass through the VC-Front module from the PCS which is providing energy from the traction battery. It will see that load as an excess charging current. When the car is asleep, it will drain the battery more quickly than normal and the car will have to wake up and recharge the battery. If the battery does not maintain a certain voltage when the charging current is removed, the car may not sleep at all. The fact that the battery voltage is dropping when it shouldn't is another reason to throw an error.

For a transient load like pumping up one tire, connecting directly to the battery is reasonable. Anything longer term like a refrigerator or electric cooler should draw power from a proper load circuit on the body controller. Tapping the subwoofer circuit in the trunk is a reasonable choice for a load like a cooler.
I’m the fridge guy and wanted to thank you for a great explanation. We are changing plans somewhat and after doing some testing in camp mode have decided that we’ll just use the accessory plug. I think a little 9 amp DC to DC battery charger charging a buffer battery will work. Supplementing with solar could be a challenge because of shade. But I’ll figure it out. Using the accessory plug takes the stress out of it and that way we are staying within Teslas guidelines.

Thanks again. O
 
I have one other question. Mostly related but different end game.

With a model Y, when camp mode is on, does the charge line on the 7 pin connector stay activated? The charge line is the pin at the 1 o clock position. It’s job is to charge the trailer battery while driving down the road. I’m assuming that Tesla has about 13.3 volts on this pin while travelling down the road pulling a trailer. I wonder if this pin stays active while in camp mode.

Moderator, this is kind of only semi related to the original question. If you like I can ask a separate question in the towing forum. I probably should anyway.

Thanks.
 
@miimura

I re-watched the video and wish to confirm something I think I heard. It sounds like the high voltage system, and thus the DC-DC converter is engaged anytime the car is anything other than asleep. So any of the following will turn the high voltage system on: Sentry Mode On, Summons Standby Mode On, Climate Control On…

Correct?
 
@miimura

I re-watched the video and wish to confirm something I think I heard. It sounds like the high voltage system, and thus the DC-DC converter is engaged anytime the car is anything other than asleep. So any of the following will turn the high voltage system on: Sentry Mode On, Summons Standby Mode On, Climate Control On…

Correct?
Yes, I believe that is correct. It may be possible for the HVDC to go to the DC-DC and not to the rest of the car like the A/C compressor, heater, and drive units, but I'm not positive on that.
 
I have Solar City panels which are now managed by Tesla

I have applied for a Power wall but cant get one because they will only sell one with additional solar panels and i don't have any space available on roof

So I need to power my fridge, internet, comp, and one 32 inch screen
Also have a sleep apnea set up that needs power

SCE shuts my power off when the wind blows now

I have decided to try a Goal Zero 3000x

Will see if I can use the home integration kit to hook up 4 fuses when power goes out

the kit taps into 4 fuses and you manually switch over the lines you need to battery when power goes out

If it works i may increase the battery with an add on home battery kit

My question is how to charge if my power outages go longer than 1 day

Can I use my tesla or my Smart For two electric to charge the Goal Zero? I have one 200 watt panel that I will use and plug into battery

is any body else using their cars to help out at home when the power goes out?

Thanks
 
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I have Solar City panels which are now managed by Tesla

I have applied for a Power wall but cant get one because they will only sell one with additional solar panels and i don't have any space available on roof

So I need to power my fridge, internet, comp, and one 32 inch screen
Also have a sleep apnea set up that needs power

SCE shuts my power off when the wind blows now

I have decided to try a Goal Zero 3000x

Will see if I can use the home integration kit to hook up 4 fuses when power goes out

the kit taps into 4 fuses and you manually switch over the lines you need to battery when power goes out

If it works i may increase the battery with an add on home battery kit

My question is how to charge if my power outages go longer than 1 day

Can I use my tesla or my Smart For two electric to charge the Goal Zero? I have one 200 watt panel that I will use and plug into battery

is any body else using their cars to help out at home when the power goes out?

Thanks


(moderator note)

Moved your post into an existing thread on this topic.