Correct, that's why my system is overbuilt, but the question was about overheating over time. Transient load over a few seconds won't cause significant heating as you know
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How many amps can you get from the 12V system for emergency situations?
- Thread starter marcmerlin
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My LG fridge uses a linear motor for the compressor instead of an induction motor. It should have much lower inrush and because it is variable capacity, it should run longer cycles making it better for running from an inverter.
I have not done any measurement on it however.
Great work marc. I live in Tx where we do not have many utility outages but I sympathize with you anyway.
I have not done any measurement on it however.
Great work marc. I live in Tx where we do not have many utility outages but I sympathize with you anyway.
Correct, that's why my system is overbuilt, but the question was about overheating over time. Transient load over a few seconds won't cause significant heating as you know
I built a variation of your design. Plan is to upgrade the wiring from 12 gauge to 1/0 gauge wire and run the wiring with glans through the box when I get a bigger inverter. I also noticed on your blog you increased the resistor value. I haven't used it it yet with the Tesla so it was easy enough to change out. I ordered 150 ohm 100W resistors. With 150 ohms it was unable to energize the relay so I tried running them in parallel since they came two to a pack. Even at 75 ohms it wouldn't pull down the relay.
However, my variation gets arounds that by adding a momentary switch that switches in and the resistor and making the relay latch off the inverter side of the relay. Works well and it physically takes the resistor out of circuit in the event the relay fails to switch. It also allows me to use the 150 ohm resistor for extra safety against having the Tesla breaker trip on the current surge. (I also had a spare diode in the parts box and added flyback diode on the relay. Likely overkill. Flyback diode - Wikipedia)
Here is a picture with the original 1.8 ohm resistor. Running on my bench with 12V 30A power supply to test out. The way it works is that you keep the switch off - press and hold the momentary switch and charge the inverter and after that you can release it and you have about 3 seconds to throw the switch, before the inverter capacitors leak down below 10V or so. Since I take the ground for the LED from the switched side of the relay you'll know if it worked because the light on the switch lights up.
Nice build, you don't screw around
Given that I may very well never actually use my build (i.e. a real half or multi day power outage), I didn't work too hard on mine past what I posted, but about the resistor, I found out that my inverter, would sometimes charge too quickly even with the resistor and trip the DC/DC system, or maybe my DC/DC system trips more easily now, so that's why I put a bigger resistor now.I found I had issues during software upgrades where the DC/DC turned on and off a bunch of time and would eventually trip.
I've also added a simple inline switch before the resistor so that I can turn the entire thing off and it won't try to energize unless I actually need it.
Nice build, you don't screw around
I found I had issues during software upgrades where the DC/DC turned on and off a bunch of time and would eventually trip.
I've also added a simple inline switch before the resistor so that I can turn the entire thing off and it won't try to energize unless I actually need it.
My thinking was in the event that I need this thing the last thing I want is to break the Model 3 at the same time!
Brock-WI
Member
We just finally purchased a model 3, adding to our 2013 Leaf with 110,000 miles and is now the kids car. This is a great thread. and a bunch of associated threads.
I have done similar projects going back 20+ years using ICE vehicles with big alternators. Our situation is a bit different as we have 3kw of solar, 8 Trojan L16's and a Xantrex XW6048 (6000 watts @ 48volt) split phase grid tie inverter. Most of our house is on the downstream side of the grid tie inverter with a dedicated panel with larger things like the geothermal, 2 electric cars, electric dryer being on the main panel. How I use our system is using a 2000w sine wave inverter from which ever vehicle to feed a iota DLS-5413, basically a 13 amp 54 volt battery charger that feeds our big 48v lead acid bank which in turn feed the main 6000w house inverter. So in a grid down situation I can idle a car (2003 VW diesel TDI with a 120a alternator) or set the Leaf to run mode or as a last resort run a Honda 2000i, which ever feeding the 48v charger. Basically dumping a steady 720 watts in to the bank, which is less than what we usually pull in a grid down situation. At 12v that is about a 60 amp load. Similarly I use a 12v 100w light bulb to charge up the inverter before the hard connect, but I do it manually, I like the idea of automating it just in case the car shuts it off for some reason and then it comes back on.
So if I understand this correctly, and correct me if I am wrong, it looks like the 12v lead under the back seat can supply 200 amps, I only need 60 amps. I can't directly connect to the 12v aux battery near the frunk in the model 3 becasue there must be an intermediary charge controller between the main 12v supply and the 12v aux battery? In other words it's not like a #4 direct wire or something is between the HV 12v output and the 12v aux battery?
I was so hoping I could adjust how I have this setup mounted to fit in the frunk as it would be great in an outage to just drive to family's house and run a cord from the frunk to critical loads in the house.
Thanks again for all the useful information!
So far we LOVE the car.
I have done similar projects going back 20+ years using ICE vehicles with big alternators. Our situation is a bit different as we have 3kw of solar, 8 Trojan L16's and a Xantrex XW6048 (6000 watts @ 48volt) split phase grid tie inverter. Most of our house is on the downstream side of the grid tie inverter with a dedicated panel with larger things like the geothermal, 2 electric cars, electric dryer being on the main panel. How I use our system is using a 2000w sine wave inverter from which ever vehicle to feed a iota DLS-5413, basically a 13 amp 54 volt battery charger that feeds our big 48v lead acid bank which in turn feed the main 6000w house inverter. So in a grid down situation I can idle a car (2003 VW diesel TDI with a 120a alternator) or set the Leaf to run mode or as a last resort run a Honda 2000i, which ever feeding the 48v charger. Basically dumping a steady 720 watts in to the bank, which is less than what we usually pull in a grid down situation. At 12v that is about a 60 amp load. Similarly I use a 12v 100w light bulb to charge up the inverter before the hard connect, but I do it manually, I like the idea of automating it just in case the car shuts it off for some reason and then it comes back on.
So if I understand this correctly, and correct me if I am wrong, it looks like the 12v lead under the back seat can supply 200 amps, I only need 60 amps. I can't directly connect to the 12v aux battery near the frunk in the model 3 becasue there must be an intermediary charge controller between the main 12v supply and the 12v aux battery? In other words it's not like a #4 direct wire or something is between the HV 12v output and the 12v aux battery?
I was so hoping I could adjust how I have this setup mounted to fit in the frunk as it would be great in an outage to just drive to family's house and run a cord from the frunk to critical loads in the house.
Thanks again for all the useful information!
So far we LOVE the car.
n2mb_racing
Active Member
Sounds right. Might be better to put the inverter in the trunk, rather than the frunk, to keep the 12V wires short.
You summarized correctly, you can only get 200A from under the seat, the frunk battery is definitely behind a low amp charge controller and should not be used for anything more than a few (<5) amps for any extended amount of time.
As for wiring, I put the inverter in front of the right passenger seat, because of how massive the 200A cable has to be.
Marc
Brock-WI
Member
Thanks, given the connection point being in the back passenger seat a 1 foot jump down to the floor, maybe with a Anderson connector so it could just be plugged in would make the most sense. I was just trying to think of a way to run the extension out without leaving a door or window open in case of rain, maybe sneak it back in to the trunk and then out that way? Or is there a better option?
You can easily run a 120/240V extension cord out of the door with the door closed. My car is in my garage though, so I don't care either way
Maybe sneak a 120/240V cord from the output of the inverter under the carpet along the door sills and thru the 'firewall' into the frunk or thru the grille.
How are you going to cool the inside of the car with the inverter running?
It would b really neat to just connect to the HV near the front motor and use a high voltage inverter.
Ultimate would be to use one phase of the front or rear drive inverter.
How are you going to cool the inside of the car with the inverter running?
It would b really neat to just connect to the HV near the front motor and use a high voltage inverter.
Ultimate would be to use one phase of the front or rear drive inverter.
n2mb_racing
Active Member
Cabin overheat protection should handle that.
I think the ultimate would be a fake Chademo charger that gets the contactors to close and then pulls HV DC from the charging port. No modifications required! Though, I have no idea if the car would allow current to flow out...
n2mb_racing
Active Member
Yeah, once battery longevity improves. Right now the battery is too expensive per kwhr to be feasible for V2G.
Are you sure?
Tesla poised to unlock vehicle-to-grid abilities with 'bi-directional' charging systems
says
"There's logic to allow DC to flow out the battery pack. So you can supply an external grid-tie invertor with that and let it do the rest of the magic. Making it part of the HPWC would make a lot of sense in my view, but I am not an EE."
then a later post says maybe not
and then the article further says it may be possible on current cars after all (maybe with very small mods)
you don't need a two way inverter, as long as you can get DC out of it from the charge port, that's enough to plug into some battery-less powerwall and do V2G
I understand the car cannot generate and output AC, but the DC can be run backwards, can it not? If so, as I wrote earlier, you could get DC from the charge port, and plug that into a battery less powerwall that would convert that DC back into AC and sync up with the AC from your house.
Or am I missing something?
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