I suggest you Google "inverter precharge circuit" as it seems you need more background that are much better explained than by existing resources than what I can provide.
-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
MASTER THREAD: Powering house or other things with Model 3
- Thread starter Vines
- Start date
-
- Tags
- powerwall solar home
I suggest you Google "inverter precharge circuit" as it seems you need more background that are much better explained than by existing resources than what I can provide.
I am not familiar with that brand but any decent 12V input pure sine inverter should work. Just don't skimp on battery cable gauge (I suggest 1/0) as it's high current at 12V.
You should also follow @marcmerlin's writeup for more detailed steps.
Last edited:
I see now. Thanks a lot. I was a bit surprised that MM used 1.8 Ohm, though I guess that still limits the heating rate to 100 Watts (barely). Any reason not to go with a 20 ohm power resistor, or even larger, and make the precharge current really small?
Additionally, I am thinking I would be a bit more comfortable incorporating at normally off relay on the 14.8 volt side. Do you feel like that would dissipate too much energy/heat in the long run?
One last thing, I am thinking that in an abundance of caution and very much not wanting to take any chance of tripping the dc-dc converter in the model 3, it would be good to have a fuse, breaker or relay that trips at high current in the 14.8 volt side of the dc power that goes to the inverter. What would be the appropriate spec for that, that would protect the dc-dc converter? I would love to get a specific recommendation for that that would be compatible with the things I am running and a SUDOKEJI 1500W Pure Sine Wave Power Inverter
Here are the specs of what I plan to run:
1. Normal Fridge. 120 watts when on, 500 to 1100 Watt peak power for a second or so when compressor starts.
2. Small Fridge. 80 Watts when on, 500 to 600 Watts peak power for a second or so when compressor starts.
3. Chest Freezer. 90 Watts when on, 200 to 300 Watts peak power for a second or so when compressor starts.
If two things came on at the same time by coincidence, or the capacitors somehow temporarily drained, or ..., I am thinking it would be very much preferable to have a breaker trip on the 12 volt circuit to the inverter, rather than to have the Tesla dc-dc converter shut down.
Here are the specs of what I plan to run:
1. Normal Fridge. 120 watts when on, 500 to 1100 Watt peak power for a second or so when compressor starts.
2. Small Fridge. 80 Watts when on, 500 to 600 Watts peak power for a second or so when compressor starts.
3. Chest Freezer. 90 Watts when on, 200 to 300 Watts peak power for a second or so when compressor starts.
If two things came on at the same time by coincidence, or the capacitors somehow temporarily drained, or ..., I am thinking it would be very much preferable to have a breaker trip on the 12 volt circuit to the inverter, rather than to have the Tesla dc-dc converter shut down.
That is a very cheap inverter. I have this one. The quality is very good and has 1,500W peak output even though the continuous rating is 800VA.
https://smile.amazon.com/Victron-En...6T8MW4F/ref=sr_1_2&qid=1587439295&sr=8-2&th=1
I also use a breaker like this close to the 12V tap point on the car.
https://smile.amazon.com/ZOOKOTO-Ci...100+amp+circuit+breaker&qid=1587439607&sr=8-1
Thanks. That does look really good. Do you know if that has pre-charge circuitry built in that would limit the current draw when you first plug it in to a 12 volt source (and it begins to charge the capacitors)?
20 ohm would be fine. It just takes a bit longer to precharge but I doubt you would notice. You can use a relay but it's more common to use a circuit breaker with manual switch since it's simpler.
If you are concerned about starting power then you should look at low frequency inverters that have a single large transformer instead of a several small ones but they are generally significantly more expensive and heavier than high frequency inverters like the one you are looking at. You can search for "low frequency inverter" to more info. AIMS seems to be a popular brand for low frequency inverters but I have not used one. Alternatively, you can add soft start kits to your fridges that would reduce the starting power required.
As for breakers that can react to short power surges, you may need a fast 15A breaker on the 120V AC side since high current DC breakers are mostly thermal breakers that don't react to short power surges.
I do not have a precharge circuit. However, I use an Anderson type connector between the breaker and the inverter. When I connect the inverter, there is no voltage present and I use the switch on the breaker to make the connection. I don't know how much in-rush there actually is. My shunt meter is also connected to the breaker protected side, so there is no reading until the voltage and current has settled.
I don't use this setup with my Model 3. It is connected in close proximity to the 12V battery in my RAV4 EV. That car uses basically the same DC-DC converter as a 2012 Model S.
To operate some of the electrics and electronics in the event that the main battery is disabled - i.e. so that main fuse blown at highway speed does not equal no power to steering, headlights, airbags, etc.
It's more than just for convenience if it's thirty-nine C below zero outside and the house heating system controls are electric.
But yes, a small emergency generator could run the critical items without also eventually disabling the evacuation vehicle. Some plugin hybrids like the Outlander have a 15A x 120 V outlet, but Mitsubishi doesn't sell home battery systems.
n2mb_racing
Active Member
If you have two model 3s, use one for backup power, save one for evacuation transportation....
Worth noting that it is a pretty small amount of power. To run a chest a chest freezer takes about 1 kwh per day. So in a 5 day power outage you can save all you food from being ruined using just 7% of your 75 kwh model 3 battery.
If you run your 12V down you will be dead in the water.There is supposed to be a low battery warning but more than one report of no warning. I just replaced my with an Ohmmu Li Ion built specifically for the M3. There are several videos on Youtube and the 12V and how to change it out for the M3 and also all the functions that are powered by the 12V. Almost everything but the motor(s). The Ohmmu is a very impressive replacement for the OEM. Guaranteed for 48 months, one report of 5 years and 150k+. 100% refund. Delivery overnight.
Last edited:
--n2mb seems to make the most sense here--any confirmation of what he claims?
I have an old Prius and years ago I read in a Prius forum similar to this one how to hook up a 1200 watt inverter to the 12V battery, leave the car on and the drive pack will automatically keep the 12V charged and now and then the ICE will kick in and recharge the drive pack. Last fall it worked perfectly several times and once for four days. It ran the Fridge, LED lights, several computers & etc. I know this is different but the Prius drive pack is tiny compared to a Tesla so it seems it could work.
Methinks the issue brought up several times here about energy returning to the grid does not apply if the 12V battery is connected to an inverter and an extension chord goes into the limited household appliances (NOT the house's panel--as I did with Prius) My pure sine wave inverter (to run electronics) did cost 3-$400 for 1200 watts.
I still have the Prius for that purpose but could of course get a 2000 watt $1500 dual fuel inverter/generator and be done with it. During the 4 day outage many neighborhoods around me in N. CA had the drone/chugging sounds and smell of exhaust from all the generators running
The dual fuel is more expen$ive but has less noxious exhaust than gas or diesel
Last edited:
n2mb_racing
Active Member
--n2mb seems to make the most sense here--any confirmation of what he claims?
I have an old Prius and years ago I read in a Prius forum similar to this one how to hook up a 1200 watt inverter to the 12V battery, leave the car on and the drive pack will automatically keep the 12V charged and now and then the ICE will kick in and recharge the drive pack. Last fall it worked perfectly several times and once for four days. It ran the Fridge, LED lights, several computers & etc. I know this is different but the Prius drive pack is tiny compared to a Tesla so it seems it could work.
Methinks the issue brought up several times here about energy returning to the grid does not apply if the 12V battery is connected to an inverter and an extension chord goes into the limited household appliances (NOT the house's panel--as I did with Prius) My pure sine wave inverter (to run electronics) did cost 3-$400 for 1200 watts.
I still have the Prius for that purpose but could of course get a 2000 watt $1500 dual fuel inverter/generator and be done with it. During the 4 day outage many neighborhoods around me in N. CA had the drone/chugging sounds and smell of exhaust from all the generators running
I think I was wrong about that working on the model 3. It will only work on the Model S/X. The charging current for the 12V battery on the Model 3 seems to be too low to be useful. On the Model 3 you'll need to go right to the DC/DC converter.
I have a dedicated backup battery (non Powerwall) at the moment, I can use my Tesla to charge that safely to power the house. It's more expensive, but I really don't want to brick my $60K vehicle. I prefer to use that to charge another battery or device that runs the inverter. I can do it without lifting the frunk or the trunk or any wiring.
n2mb_racing
Active Member
n2mb_racing
Active Member
Wow, apparently we might not need to do this much longer.... The charger already in our Model 3/Y might be able to produce AC power.
Tesla quietly adds bidirectional charging capability for game-changing new features - Electrek
Though, I don't really understand that schematic. Why would it support three phases? I don't know if model 3s outside the US support three phase power charging...
Tesla quietly adds bidirectional charging capability for game-changing new features - Electrek
Though, I don't really understand that schematic. Why would it support three phases? I don't know if model 3s outside the US support three phase power charging...
Similar threads
