Hacker News Reader

Comment by cmrdporcupine | Hacker News Reader

Our Outlander PHEV has this. Full 12amp outlet, can run power tools, appliances, etc. And has the advantage of being a PHEV so acts as a gas generator once the (admittedly small) battery depletes. It's nice too, there are two outlets; one in the cabin so the kid can charge her laptop on road trips, and another in the back so I can bring my table saw etc. out into my field and run it off the car.

Only available in the top trim, unfortunately.

Inverters that do this kind of thing are available as third party adapters for most EVs. I can get one for my Volt that runs off the 12v accessory battery hookup in the back.

View on HN

It's sad that pretty much all EV cars already have all the hardware necessary to do this - most cars have the hardware to power their charging socket to whatever voltage/current/frequency they want.

All it would require is a firmware update and someone to splice a socket onto the end of the charging lead.

I don't think that that is true.

The inverters are designed for power and cost efficiency, so I'd say it is unlikely that are capable at outputting anything other than the high-voltage, high-frequency power intended for the electric motor.

The electric motors in most EVs are 3-phase, 400V motors. I expect them to operate at quite high frequencies for efficiency (I'm not sure about that though).

So I expect that 115V/50Hz or 230V/60Hz is just way outside of the design envelope of car inverters.

Yes it would be very difficult to go from the full 3 phase AC, that runs the drive train, to 120v or 220v 2 phase AC.

Third party adapters that do this usually run off the 12v DC accessory battery, which already is hooked up to a DC to DC converter from the car's LiOn battery. Going from 12v DC to 120V AC is obviously already a very solved problem.

That would be very inefficient, and I also doubt that the build-in 12V DC-DC converter is capable providing the current required to run the inverter.

So, since it requires retrofitting anyway, it would make much more sense to have an inverter running directly of the high voltage battery.

I guess this all comes back to my original statement: Currently available EVs certainly do not have suitable electronics for 115V or 230V output. It will require hardware retrofit, not just a magical software update to make it work.

> I also doubt that the build-in 12V DC-DC converter is capable providing the current required to run the inverter.

that's not how it works; the current is provided by the 12v battery, not the charging inverter.

Now, obviously the charging inverter isn't going to keep up for long, but as far as high current is concerned as 12v car battery can usually provide around 400-700 amps if given the proper leads, with a capacity of (typically) at least 45aH.

that's a lot of juice. even with the inverter inefficiency you should be able to get some fairly major work done if the inverter can supply the amperage -- especially if the EV systems are working alongside to maintain the battery.

>That would be very inefficient

absolutely.

>So, since it requires retrofitting anyway, it would make much more sense to have an inverter running directly of the high voltage battery.

that'd be nice, but I think EV groups would rather you wear out the cheaper replaceable battery with the erroneous usage. Sure, the loads still load the EV battery, but those charge/discharge rates can be more closely monitored or denied all together -- something that'd be harder to implement if the inverter had straight access to the ev primary battery.

I didn't realize EVs still have a 12V battery, I always assumed 12V accessories are ran directly of the DC-DC converter.

Thanks for pointing that out!

So I'm not even sure in my Volt if the 12v battery even powers the accessories directly, because it's at the _back_ of the car, not up in the front by the accessories.

It's super handy for boosting other vehicles.

> The inverters are designed for power and cost efficiency, so I'd say it is unlikely that are capable at outputting anything other than the high-voltage, high-frequency power intended for the electric motor.

You could use the motor inverters for this, if only they weren't already connected to the motors. You can't have your wheels spinning just because you want to hook up an AC device.

Instead you'd use the charging inverter. Large modern chargers are combinations of MOSFETs, capacitors, and inductors, which are all components where the power flow is reversible. There is also an isolation transformer which the motor drive inverters don't have, and is important for detecting potentially dangerous faults.

This isn't true with say your laptop charger, since it's input stage typically uses diodes rather than MOSFETs for the initial rectification, which means you couldn't run the whole thing in reverse to make AC off your laptop battery, even with new firmware.

>Our Outlander PHEV has this. Full 12amp outlet, can run power tools, appliances, etc. And has the advantage of being a PHEV so acts as a gas generator once the (admittedly small) battery depletes. It's nice too, there are two outlets; one in the cabin so the kid can charge her laptop on road trips, and another in the back

Sounds a lot like the feature set of the hybrid Sierra that GM made for a few years back in the '00s.

> I can bring my table saw etc. out into my field and run it off the car.

And this is more or less the sales pitch they made for it.

I think most trucks have this feature now. My tacoma has a couple outlets in the bed as well. I've seen it on a few different american truck brands too.

It's been a handy feature for me

Baseline trim Toyota Sienna has this and it isn't even an electric vehicle. Very simple, very useful feature.

Nope, not nearly the same. That's not full 12amp (which parent post claims for Outlander PHEV). Per Sienna manual, the 120V outlet is limited to 100W (less than 1amp). http://www.tsienna.net/power_outlets-322.html

For this level of power, you can get a 12V DC to 120V AC adapter that works on pretty much any car.

Yeah, the Outlander's outlet is 1500W. So around 12 amps @ 120v.

https://www.youtube.com/watch?v=Ka9XNNu2uZ4

(Ad shows 220v, as most Outlander's sold have been overseas)

Reply on news.ycombinator.com