Serious Business: Getting AC electrical power from my Prius

First, for a full discussion of the limits of using the traction battery directly see:

PriUPS-getting electricity FROM your hybrid vehicle

You can also do a lower power (1kw) system more simply off the 12 volt supply as you noted:

Prius - UPS Project

JeffD

 

The "traction battery" (the 200V one) is not lithium, it's NiMH.
Without a -LOT- of messing about, you can't connect to the traction battery. Even if you could, the car would have to be running, and you would have to have electronics to convert the 200VDC to whatever you need (I presume you're after 120V AC 60 Hz).

If you're running from the 12V system, the max. recommended current is around 50 Amps. That's still a fair amount of power, but if the car isn't running, the tiny 12V battery will be drained very quickly. You have to leave the car in "ready".

The 12V battery will be charged from the traction battery, by the charger in the inverter (silver coloured device on top of the engine). This is where the 50 Amp limit comes in.

The engine will start to recharge the traction battery from time to time.

The 12V battery is used to "start" or power the electronics. You can't start the car without it. The 200V battery is used to actually crank over the engine, but the inverter converts the 200VDC to three phase 550V and uses MG1 to "crank" the ICE, or internal combustion engine.

 

its not yet lion its Nimh battery cells

 

50 amps at 120 volts = 6000 watts.

 

there's two way to calculate that..

50 amps on the 12v side is only 600 watts

50 amps on the hybrid battery side 200v is more like 10,000 watts... but i assume you risk frying things like that.

 

Keep in mind the -battery-, that is, the traction battery, the 200VDC one, is only a 6.5 Amp-hr device. To get 50 Amps from it would be unproductive. So the HSD system usually gets that kind of current by generating it using MG1. I'm not saying you -can't- get 50 Amps from the traction battery, just that you can't for very long. And it's not good for it. It will heat up. Bad.

The 50 Amps I was talking about was at 12V, and that's about 600 watts. A modern aftermarket (Radio Shack for example) inverter running from the 12V system would be about 90% efficient, so you could rely on about 500W (allowing for losses in the cables and connections). Don't try this with a cigarette lighter connector. Use proper ring terminals and connect to the fuse box under the hood on the "boost terminal". Use an inline fuse, rated for 60 Amps or so as well.

-IF- you could find an inverter that can run on 200V DC (I don't know of one commercially available), then you could tap in to about 10 kW, but the engine would have to run (hard) continuously. That's about 15 HP out of the engine, so when I say "hard", I mean that would be your perception. The car could actually generate a lot more if the electronics could handle it.

Be aware, any of this can reduce the life of the cars' components significantly. Personally, I have an emergency generator for situations like the ice storm. I wouldn't try to use the car. It's just not designed for that. It could be, but it isn't.

 

The first link (priups) does tie into the 200 volt NiMh Traction battery. He found a commercial UPS that internally used a 200 volt battery and tied the Prius Traction battery to it and used it to supply about 10 kilowatts. This should only be attempted by someone familiar with high voltage circuits as you can get fried. The Prius, if kept in "Ready" mode, will periodically start the ICE and recharge the traction battery as required.

This will also happen when using energy from the little 12v battery. It is kept at about 14v by DC to DC converter from the Traction battery (when in Ready mode). The 12v charging system can supply about 100 amps (that's about a kilowatt), but blowing the supply fuse is not a good idea so fuse any attached equipment to limit drain to about 80 amps.

JeffD
EE Professor

 

Last season (pre-Prius) we had two three-day outages. Thanks to a number of earlier posts, I bought an AIMS 1000 Watt Pure Sine Wave inverter, a pair of #4 cables, a short cable, 150 Amp fuse and holder, and remote switch (Amazon/TheInverterStore).

In the recent ice storm, and the power had been out for a day, I installed the cables, fuse and inverter, connecting red to the positive battery connector and black to a convenient nearby bracket bolt. (I did not disconnect the battery--I am aware of the "arc-welding" capability of 12 volts, so taped exposed loose ends). Nothing needed drilling or notching, and the cable routing permits the inverter to be either on top or under the "floor" of the trunk area.

The 1000 Watts is adequate to power, via heavy extension cord, any one appliance or our oil/wood/solar radiant heating system, plus a computer or TV. It would not run our 220V water well pump (nor electric range). For the heating system the circulation pumps permit us to use our wood stove "on high" without overheating the heat exchanger therein and radiant heating. The oil burner also kicks in, but could be separately turned off. I monitored initial operation (with a ScanGaugeII) and noticed that the indicated battery voltage stayed pretty much the same, the ICE kicking in at two bars or so left on the MFD and off at three bars (although water temperature may also be a factor). The inverter and connections stayed merely warm to the touch.

So far Prius was out of garage. I have ordered an exhaust hose to let the Prius stay in out of the cold (single digit).

 

Just a couple of technical corrections:

• NHW11 - will handle 70-75 A @ 13 VDC for a solid 1 kW. I suspect the NHW20 will do the same but have yet to conduct a load test.
• NHW20 direct connect - I've only read of a 3 kW test.
• 7.5 A at 208 VDC -> 1.5 kW
• 15 A at 208 VDC -> 3 kW.

Bob Wilson

 

b2j2, I like to see you with a smaller than 150 outboard fuse. Better to melt that than some prius part.

Other than that, very fine business.

 

Congradulations to both you and John for trying this, I think it is very significant that you first of all used a pure sine wave inverter. Also you obviously monitored different loads and noted operation with the scan guage and monitored inverter temps. I think you have pretty well proved that Prius can serve as a temporary emergency AC source. All the theoretical math concerning Wattage, Amperes etc is all very interesting but you have actually done it without harm to Prius. That's all that counts. Any future posts on this would be very much appreciated. andy

 

Thanks. The 150A fuse would handle the claimed surge wattage (2000). Note: a couple of specs on Amazon are (or were) wrong--the surge is not 3000W, and shipping weight is not 19 lbs. Should be 2000W and 6.4 lb. There is some internal fusing in the inverter, but I have not opened it up to see.

Besides, isn't an electronic device supposed to blow first to protect the fuse?

 

The fuse is to protect the wiring or in this case, the 100A fusible link. If the Prius 100A fusible link blows during a power outage, you'll be without Prius and power.

My NHW11 testing indicates the inverter voltage falls off first:

• 13.94 V., 1.1 A. with inverter OFF
• 13.94 V., 1.7 A. with inverter ON and no load
• 13.83 V., 50.3 A. heater on lowest setting (~ 700 W)
• 13.75 V., 71-74 A. heater on medium setting (~ 1 kW)
• 11.48 V., 89-90 A. heater on high setting (~ 1 kW)

​

Because tests can fail, the best time to check the limits is when the power is good and repair services available. Also, RV shops often carry a range of high current, 12 VDC circuit breakers. Resetting a circuit breaker in an emergency is easier than putting in the last fuse.

Bob Wilson

 

Bob:

Thanks. My Bentley book indicates a "120A fusible link block" (F15) at the battery. I'm connected to the battery before that, but the current might (mostly) be coming from the HVB through F15.

I'll look for an 80 to 100A dc over current breaker, also a polarized plug so I can disconnect the inverter. A solar store has a 90A breaker for $42.53 with threaded connectors that would replace the 150A fusible link I put in (terminals to be protected). This can also work as a switch.

The ScanGaugeII showed voltage at 14.1 or so, but that is not at the inverter, which I assume your voltages are. I'll run some similar tests.

 

Anyone know for sure what the 12V fusible link value is for a 2006?

If it's 100A I'd go with the Aims 1000W, if it's 120A I'd be tempted to go to a 1200W inverter. In either case I'd use a breaker to protect the link, it'd just be nice to get as much AC out of it as possible.

 

Seems to me that an interesting, though not trivial pastime would be to build an imitation power unit that pretended to be the motor, fix the frequency at 50 Hz (60 for you people over there ) and use the output from the inverter to feed whatever you liked. With a Hymotion 6 kWh conversion it would feed my house for 6 or 7 hours or so. It would give a three phase supply that could with a bit more (not trivial) electronics, be grid connected.

What voltage is the inverter output on the car?
Presumably it uses either IGBTs or reams of MosFETs, not sure what shape it would be but it could be made a sinusoid I am sure.

The three phase switch to divert the power from the motor to the house would be a costly, bulky item but I don't really see any show stoppers in the idea.

Why? I hear you shout. Because it's green

I am actually involved in Smart Grid and have done half of this with my electric scooter.

I bought this
Zhejiang Xingyu Industry & Trade Co., Ltd.
and fitted a zigbee inside it then built a charge point.
When the scooter gets within 2 meters of the charge point the charge point interogates the scooter to see if it is valid, bills paid, not stolen or whatever, if all is well it turns the power on to the socket and asks the scooter if it is charging, if it is then it monitors that and gives the utility the option to turn on and off the charge depending on availability of spare capacity on the grid. The next stage is to prove it with a car and then complete it by allowing hte car to feed the grid. At the moment I am undecided whether to buy a prius to do it or to go with a pure electric car.

Interesting times

 

amisslexi:

Note that Bob's Prius is a 2003, while we have later models (covered by my Bentley book). You and I should look at the fuse blocks to verify labeled ratings (I couldn't find my dental mirror).

Depending upon "package" there are two different 12 volt battery capacities-I'm pretty sure that I have the smaller, but understand that the larger will fit with a tweak to a bracket. Since the power is actually coming from the other side of the fuse block, battery size should not be critical.

(I am using "full sine wave" out of concern for various motors and electronics.)

Hooking into the HVB looks good using a refurbished "UPS" outputting pure sine wave 120/240 at 10 +/-kW which would handle water well and even some electric range usage, unfortunately at about ten times the $ cost. (per an earlier post in this thread)