Cut Those Bills!

[stompe]

http://cars.aol.co.uk/2014/01/11/ex-mechanic-uses-toyota-prius-to-power-home-during-storm-blackou/

[Grumpy Cabbie]

I'm sure I posted something similar a few months back. It's as simple as plugging a 1000w sine wave inverter directly to the 12v Battery and then running the car in Ready mode. Whilst it will power items UPTO that level, items such as fridges that can cause surges when they switch on can cause problems. There is also talk that using an inverter can over stress the 12v charge circuits.

The other problem none of these articles relate in much detail is that the car has to be running all the time. Not sure about you, but I don't fancy leaving my car running on my drive.

I guess it's ok in an emergency or if you fancy tinkering at your own risk.

Certainly wouldn't be wise to tap into the 200v DC of the HV Battery though! Fast way to meet your maker!

[cootuk]

easier just to get a petrol generator and run the output into a socket - after pulling the main house fuse.

[FROSTYBALLS]

Think for some areas of the UK, the Prius would also need to be equipped with a flotation device.

[IanIanIanIan]

The cable used to back feed a house from a generator is known as a 'suicide cable' for a reason.

[geo13647]

The cable used to back feed a house from a generator is known as a 'suicide cable' for a reason.

Very dangerous, and totally illegal. Get a qualified spark to fit some additional sockets in key areas & feed them with the generator through an approved consumer unit, using a proper weatherproof incomer.

[cootuk]

That takes the fun out of it...

[stompe]

Lol it was only meant tongue in cheek.But the way energy prices are, you never know!

[timberwolf]

Lol it was only meant tongue in cheek.But the way energy prices are, you never know!

You imagine a future where domestic fuel costs will be greater than vehicle fuel cost?

A 1000 Watts at 115 V = 500 Watts at 230 V. An electric kettle is usually rated at 3000 Watts. So if the power went out you wouldn't even be able to have a cup of tea powered from your Hybrid generator?

[Fecn]

A 1000 Watts at 115 V = 500 Watts at 230 V. An electric kettle is usually rated at 3000 Watts. So if the power went out you wouldn't even be able to have a cup of tea powered from your Hybrid generator?

Just to clarify a little on that 1000 Watts is 1000watts no matter what voltage it is at - Watts is a measure of energy (such as how much power is needed to boil a cup of water) and doesn't directly relate to any particular voltage/current (you can measure petrol's energy content in watts per kg etc....)

Having said that, as voltage drops, more and more Amps are required to get the same number of watts down a piece of wire.

1000W @ 1000V = 1 Amp

1000W @ 230V = 4.16Amps

1000W @ 115V = 8.7Amps

1000W @ 12V = 83.3Amps

1000W @ 1V = 1000 Amps

The max you can pull from a UK 240V outlet is 13Amps or 3120 Watts

Unless you have a 3KW inverter then you're not going to be able to use a standard kettle... and even if you did, then the inverter will attempt to pull around 290Amps from the Battery continuously - No Battery is ever going to like that - it would be like running two starter motors at the same time for 10 mins at a time. I'd be surprised if the DC-DC converter on the Prius is capable of delivering much more than 30Amps continuously rated (based on that being more then enough to run all the 12V electrics, plus charge the Battery at the same time) - Assuming 30A from the converter then you're getting around about 400W of devices that you can run from your car.

I say all this as a man who owns 5 different inverters, a few 210Ah deep-cycle batteries and even a 2.8KW generator (all from a previous life with a motorhome)

[Grumpy Cabbie]

Lol it was only meant tongue in cheek.But the way energy prices are, you never know!

You imagine a future where domestic fuel costs will be greater than vehicle fuel cost?

A 1000 Watts at 115 V = 500 Watts at 230 V. An electric kettle is usually rated at 3000 Watts. So if the power went out you wouldn't even be able to have a cup of tea powered from your Hybrid generator?

It would still be 1000watts assuming you get a 220v inverter. Sure it wouldn't boil a kettle - you could use a pan on your gas hob. But it could keep a small fridge going, or an extension lead to run your boiler and a few lights.

I'm sure some of those without power for a weekend or more over the New Year would have loved to have a few electric lights burning whilst all their neighbours had candles.

It's not an ideal solution. It was an emergency solution.

[timberwolf]

Thanks Fecn. Obviously I have forgotten whatever they tried to teach me at college! :)

A watt is watt therefore if people have hooked up a 1000w inverter it has the potential to draw up to 83 amps through the DC-DC converter?

The Aux power socket only has a 10 or 15 amp fuse so they are presumably bypassing this 12v output.

[Fecn]

Thanks Fecn. Obviously I have forgotten whatever they tried to teach me at college! :)

A watt is watt therefore if people have hooked up a 1000w inverter it has the potential to draw up to 83 amps through the DC-DC converter?

The Aux power socket only has a 10 or 15 amp fuse so they are presumably bypassing this 12v output.

If the DC-DC converter can deliver power that quickly, then yes - however, I very much doubt that it can deliver power that quickly. Think of the situation as filling a bucket of water from a hosepipe. The Battery is the bucket, the DC-DC converter is the hosepipe. The hosepipe fills the bucket at a rate of 10 litres per minute, which is the maximum continuous power that you can pull - However, for short amounts of time then you can pull 50litres/second from the bucket. - It doesn't matter how quickly you try to empty the bucket - it will still fill at the same rate (which is the max power that the DC-DC converter can deliver).

Yes - they'll be going directly onto the Battery terminals with a 1000W inverter - need big thick cables and meaty crocodile clips for one of those. (Should be able to get around 120 - 1500W peak from the 12V outlets though - I have a little 75w inverter which I keep in the car for charging my laptop.. http://www.ringautomotive.co.uk/uk/products/Cars/In-car+Power/Compact+Inverters/REINV75+ )

In general small fridges will only pull a couple of hundred watts continuously, but will need a good burst of power for when the compressor starts up - As such, a high wattage inverter (~1KW or more) is needed for running even a small fridge. Anything which heats up (kettle, toaster, fan heater, oven etc) will burn through far more power than the DC-DC converter could ever hope to supply and is a no-no.

If you've got low energy lighting in your house though, you can probably light the whole place up without a problem.

[timberwolf]

In a standard Prius, without the 1000w inverter, when the car is in READY mode, the DC-DC converter must be able to supply all 12V needs of the Prius and still be able to charge the 12V Battery and in the caseof the Gen 2 the emergency backup brake capacitors. I would have guessed all the 12V needs, lights, computers, hydraulic brakes, demisters, entertainment, sat-nav, etc would add up to more than 30 amps?

[Fecn]

back of an envelope calculations....

Headlights = 2 x 60W = 120W, 10A

Side Lights = 2 x 5W = 10W, 1A

Brake Lights = 2 x 21W = 42W = 4A

Read Demist = 120W = 10A

Fans/Blowers = 60W(on max) = 5A

Computer = 6W, 0.5A

Entertainment = 24W, 2A

Power steering = ??? (but only a momentary load when you're moving the wheel)

Brakkes = ???? (but again, only a momentary load)

Aircon = runs directly off the HV Battery on my Auris.

My 30A was only a guess... mostly based on the fact that you don't want to charge lead acid batteries too quickly or they produce lots of gas. If they're speccing like-for-like with Alternators then 50-60A would be more likely.

[timberwolf]

On the "problem" Auris, the keyless entry activating can use 600mA. I would think that there are many computers or ECUs in a modern car.

I also thought post #7 was interesting regarding charging but it seems to have been indirect measurement.

http://priuschat.com/threads/how-long-can-i-leave-my-prius-c-without-it-being-started-or-driven.106752/#post-1582867