Is there no easy way to extract DC power from the traction battery?

The "system" that keeps the traction battery charged likely would be "upset" if anything was connected directly to the battery that caused the charging and discharging characteristics to change more than a tiny bit.

Second, an "inverter" with a 240 VDC input is kind of rare and expensive.

Third, 240 VDC is more dangerous to work with than 240 VAC.

I think it has been discussed here before but never got past the discussion stage.

 

Let me rephrase your question, there is no obvious safe way to connect to the HV battery to power an inverter.

Toyota went to some lengths to completely isolate the HV battery when the car is off, so first responders are not killed.

If I was intent on using the HV battery to power an inverter I would study open source J1772 devices that currently safely allow high voltage DC connections. (Your car would take the role of the EVSE and the inverter would be the vehicle side) That would be as safe as the Prime.

https://en.m.wikipedia.org/wiki/OpenEVSE

 

For an overview of the ways people who are currently doing it are doing it, and answers to several of your questions, you can refer to this knowledge base thread:

Electric power from a hybrid, connecting inverter to the high-voltage system | PriusChat

An added inverter is generally connected 'downstream' of the system main relays, so the expectation that the battery is isolated when the car is off isn't violated.

(An inverter typically will have some capacitors on its input that will continue to put voltage on the orange wiring for a few minutes after the relays open. But then, that's also true of the inverter under the hood.)

Taking your title rather literally, at 200+ volts, it is all too easy to extract DC power from the traction battery! You can quickly demonstrate by making one wrong move while working around it. That's why Toyota worked so hard on the isolation and interlocks.

 

Huh, I thought somebody already did this.

Most of the batteries actually put out between 245 to 355 VDC depending on the model. 2017-2022 Prius Prime is 351.5VDC, although the 1st gen Prius Plug-in's battery puts out 207VDC (these values are all nominal). The highest I've ever recorded on my PiP was 222VDC, although fully charged it was typically 221VDC. Toyota already builds in 2 inverters as well as a DC/DC converter and all are already monitored and controlled through ECMs. I'd try to see if you could access one of them. For instance there is the inverter for the AC and/or heat pump unit (if it has one) and a separate one for each motor (although the newer hybrids use e-Axle and are integrated).

 

'easy' is a loosely defined term

 

Inverters with DC input voltages in the range of 300-400 Volts are NOT rare. They are commonly used for strings of solar panels.
Yes, working with higher voltage DC is dangerous.
Connecting safely to the traction battery is a challenge that I'm trying to crack.

 

I think @bwilson4web did some experimenting a few years ago.

 

Well, Sam posted that a couple years ago. There were solar panels then too, and inverters to go with 'em, but I think his point was you have to look harder to find one of those to put in a car than to find compact 12 VDC input inverters, which are all over the place and are cheap.

Post #4 in this thread has a link to another thread that's a more centralized place this discussion goes on.

 

What do you want to get from this inverter?
What is the output voltage? What is the output power?

 

I'd like to run the critical parts of my house during an outage:

• Refrigerator
• Microwave or induction hot plate
• and the latest addition: heat pump (20 Amp at 240 Volts)
• I may have to forgo this last and use a 1500 Watt resistance heater, but my generator transfer switch does not go the the bedroom outlet.

I already have a 240 Volt transfer switch installed. The power panel is in the garage, so it is all very convenient.

 

People hooking inverters to the traction battery have generally limited the inverter capacity to the amount of power the car can replenish while sitting READY in Park. For the non-plugin Prii that has been about three kilowatts. Some larger hybrids were determined (PlugOut Power used to publish a handy list) capable of around five kilowatts.

Note this is nowhere near the maximum capacity of the engine and drive train, which can be dozens of kilowatts driving down the road, but it is the limit when the car is stationary and running the engine to supply charge.

Powering the heat pump could be a stretch.

 

In Japan, this is implemented. Many models of hybrids and electric cars are equipped with devices for transferring energy from the car to the home's power grid. This is due to the fact that due to tsunamis and earthquakes, Japan villages lose power supply. Prius will allow you to power a house for several days from one tank.
Link to the site in Japanese, but you can turn on the translator mode.
もしもの時は電源に。エコで燃費がいいクルマ「プリウスPHV」 | フェーズフリージャーナル

 

I bought one of these systems and it worked great: PlugOut Power LLC

 

Yes, Randy has been a long-term, if intermittent, presence in the inverters-from-the-traction-battery market, as covered in our thread on such things:

Electric power from a hybrid, connecting inverter to the high-voltage system | PriusChat

He used the name ConVerdant Systems at first, and one of those inverters has a review linked from that thread. He bowed out for a while and came back as PlugOut Power selling some new hardware for a few years (where the inverter and transformer were in separate cabinets). As of about a year ago he bowed out again, having sold the last of those units.

According to his web site, looks like he found a supplier back around November and is now shipping another batch of newer hardware.

Which system did you buy? One of the original ConVerdant ones? Or one of the later PlugOut Power ones? Or one of this latest new batch?