My battery is 77 KWH in the car. You can't use the last 20% for V2L, and the V2L inverter is not particularly efficient. The net results is that starting at 100% and going to 20%, you can get about 50 KWH from the V2L car port.
Due to the V2L low efficiency especially at low draw, you do not want to let it idle with a topped off inverter battery. You would wait until the inverter drops to, say, 50%, then plug in your V2L, top it up to, say 80%, and stop it.
E-GMP EV, right? I missed this efficiency issue when I was planning how to use my V2L, and only caught it in January during my first power outage with it. A lot of the efficiency issue is actually just having the EV on, and probably not isolatable to the V2L inverter. Also did not know about the 20% threshold, which was awkward when I discovered it at 39% SoC in combination with the low efficiency (I have a DCFC near my house that is on a separate segment of the electrical grid, so I just had to drive out and top off)
I think these EVs lose around 1% per hour when running a 200W background load, on top of having the car started up.
I need to add something to add 120/240 to the V2L. Charger + AIO + buffer battery or Autotransformer. Not sure yet which way to go.
One feature of this method is that you can drive the car to a DC fast charger (one that has power when you don't), top it up, and bring it home to run the house. This is the equivalent of buying gas for the generator.
For the ~5 power outages the past two years here, at most 1 of these power outages also hit the closest DCFC to me.
There wasn't even a special line at the DCFC when I was topping off during the power outage. Maybe since there aren't that many people using V2L to backup their house.
Last year I bought a generator to deal with the power outages. It's much easier to use V2L in a typical power outage.
I can leave the EV backfeeding the house while it sits quietly in the garage. Portable generator is not fit to run unaccompanied during a storm. Also, a portable generator is pretty inefficient at multiple layers itself. Unless you charge a battery, you have idle losses at low output. You also likely have to burn off some gasoline before putting the generator in storage.
You could of course do both -- gas generator into a 120V EVSE into the car. And then you can keep going with either gas available or with DCFC available, without needing a house battery. The 120V EVSE unfortunately will be kind of wasteful unless the car can charge > 1.5 kW (the car probably draws 200W-400W while charging).
Sure, in a SHTF power outage where I need to fight raiders for gasoline and there are no DCFC, maybe the tri-fuel generator is the way to go.
600 watts may not sound like a lot, but it is 600 more than nothing. And with the refrigerator load also removed from the battery bank,. it did charge up nearly 2 KWHs before I shut down the generator for the night.
This. Having been through a lot of power outages recently, the first 250W is huge. So is the first 1.8kW (which lets you cook / make coffee). And you only need that 1.8kW for maybe 10 min, for the kind of cooking you're doing in a power outage if all you have is a few kWh of backup power.
My main beef with V2L is that the most common ones (I think mciholas and I both have E-GMP EVs) don't branch out from single phase inverters, and 120V only is annoying for backup power.
Keep in mind the 100A minimum service we have in the US is like enough for a whole apartment building in some countries. Some places have less power for whole apartment than we're required to have for just the kitchen 120V circuits.
