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While I was visiting a party at a remote location with no connection to the power grid there was a generator running to power a couple of lights after sun-down. The generator is noisy and stinks and it got me thinking: We did have a couple of cars right next to us. Chademo supports bidirectional charging.

Are there any affordable and portable options for such cases to extract power in a form that normal household devices running on 230V can be connected?

Edit: I am aware of 12V/230V inverters. Actually I own one. But the 12V battery of cars have low capacity, so I specifically ask about using the high-voltage battery of purely electric cars. E.g. the charging connector Chademo that most Asian manufactured cars have supports bidirectional charging and can thus use the high-voltage battery. But can I convert that to 230V AC?

EDIT2: The Chademo-Specification to charge electric cars allows for "vehicle to grid" decharging. So the idea is e.g. that you can charge your vehicles battery during the day with solar power and then power your home at night from the car's battery, effectively using the battery as a buffer (or in the even more advanced version not just YOUR home, but the whole grid). E.g. Princeton Power Systems sell a charging station that provides Vehicle to grid. Now hat I was thinking about was a something similar, but much much smaller device, so that it is portable and affordable. But effectively it should plugin to the chademo port, have an inverter and provide a 230V power outlet. (I used chademo as an example here, maybe there are other/better ways).

  • They use generators in remote locations for a reason, it is the only viable solution. – Moab May 27 '18 at 13:44
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The obvious but unsatisfying answer

First, let me answer the question you actually asked:

Are there any affordable and portable options for such cases to extract power in a form that normal household devices running on 230V can be connected?

Yes, one could use a conventional inverter that's designed for conventional internal combustion engined vehicles. Such inverters convert from 12VDC to 120 or 240VAC and 60Hz or 50 Hz, depending on the region.

However that's not going to be what you would likely want for a number of technical and economic reasons. In this answer, I'll describe the current (if you'll pardon the pun!) state of technology for both pure electric and hybrid vehicles, why that's relevant to your question, and what the future might hold.

How electric cars work

All hybrids and most pure electric cars use permanent-magnet synchronous motors (PMSMs). These include the BMW i3, Chevrolet Bolt EV, Opel Ampera-e, Chevy Spark EV, Ford Focus EV, VW e-Golf, Nissan Leaf, Fiat 500e and Kia Soul EV. The remaining electric cars (Tesla, Toyota RAV4 EV, Renault Zoe EV) use induction motors (that is, motors which do not contain permanent magnets). PMSMs and induction motors in this application are driven by a variable frequency AC power supply, almost always polyphase. The source for their energy is, of course, batteries which produce only DC. This means that the DC output of the batteries (which are typically in the 360VDC range) must be converted into the synchronous AC power needed by the motors. Such a circuit is generically called an inverter and it's notionally the same as the inverter mentioned in the previous section. So since these inverters are already built into the car, problem solved, right? Well, no.

Electric car inverters

The inverters for electric cars are designed to work with multipole motors at varying frequency, none of which is likely to make a typical household appliance happy, because they're designed for a specific voltage and frequency (e.g. 240V, 50Hz). Many small electronic devices, such as laptop computer chargers or mobile phone chargers are rated to work at multiple voltages and frequencies, e.g. 240V 50Hz or 120V 60Hz, but would not likely fare well if fed by 250Hz as might be generated by an electric car's inverter.

Longer term

Your question is not unusual, and some vehicle manufacturers are paying attention. For instance, some non-electric Ford pickup trucks (and maybe others) already provide an inverter with up to 400W output for use charging computers, mobile phones or battery-powered tools. I have read that electric versions of some pickup trucks will be similarly equipped. One could also, with sufficient knowledge and expertise, design and build one's own separate inverter for an electric vehicle, but this would almost certainly void any vehicle warranty and might interfere with the power electronics responsible for keeping the batteries in good condition.

Summary

So for all of these reasons, the answer today is that other than conventional inverters designed for 12V operation, there aren't really good options, but that future generations of vehicles may well have such capability built in.

  • Thanks for the details, but still: What is wrong about carrying a portable inverter and hook it up more or less directly to the car's high-voltage battery? Probably through a chademo connector which is designed to also allow discharging? – yankee May 29 '18 at 15:06
  • You asked about affordable and portable devices. To my knowledge, a very few of the type of devices you mention (CHAdeMO or CCS to "house power") exist, but none are available outside of Japan and even there only as pilot or trial programs generally. Search for V2G (vehicle to grid) or V2H (vehicle to home) on the web to learn more. There's no inherent insurmountable technical hurdle -- it's probably mostly due to very little demand that such devices are not more generally available. – Edward May 29 '18 at 15:25
  • OK, I'll accept that this is just not available today, but it is likely some time in the near future and hope I can eventually change the accepted answer ;-). – yankee May 30 '18 at 16:11
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There are plenty of power converters from 12V to 230V out there.

But keep in mind, that a 50Ah car battery contains an energy of 50Ah*12V=600Wh. If your 230V devices draw 100W, the battery will last for 6h. If they consume 200W, it's only 3h.

Now, those converters are not lossless, and may take additional 10-20% of power. And you do not want to drain a starter battery completely. Do not take more than 50 % for to be able to start the car.

Oh, and finally, a 2000W blender needs a 2000W converter, not just 150W.

  • 1
    Actually, there is Peukert's law for high current draw meaning you get only a fraction of the battery capacity, and also old batteries may have less than 50% of the nameplate capacity available. For a 50Ah battery, I wouldn't plan to take more than 50 Wh of energy from it, especially if it's old. – juhist May 27 '18 at 15:58
  • It seems I did not stress the term "electric car" enough. Most current electric cars (Hyundai IONIQ, Nissan Leaf, any Tesla,...) have batteries with 25-60kWh. I can run the 2000W blender that you quote (that must be a HUGE blender!) for a minimum of 10 hours continuously on such a battery. I edited my question to be clearer. – yankee May 28 '18 at 13:39

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