Electric Power from Prius

You are correct. An easy way to convince yourself this is correct is to go to either or each of those modes, and try to get the A/C to cool. The traction battery relays will still be open and the ICE will not run, so the A/C compressor will not run as it can't get high voltage. You will not get cold air.

So while you will not be in danger of discharging the traction battery, you will be in danger of discharging the 12V battery. Which will leave you stranded just as much. Well, not quite. It's easy to recover from a 12V battery discharge. Not so much if you could fully discharge the traction battery.

If you're going to use a 100W inverter on the acc. plug familiarize yourself as to where the fuse is and get yourself a spare or three. You will be operating close to the limit, and if the voltage at the inverter is slightly lowered due to contact resistance, it will draw more current. This could result in a blown fuse, usually after a while (fuse has to heat up before it will blow).

Most of these portable inverters are quite efficient. The worst I've seen is 80%, with most being around 90%. This is quite good. The ones I used to make myself ran at 60 Hz and were about 60% efficient. The current modern ones run around 100 kHz and pulse width modulate the output to give a 60 Hz square wave.

Be aware, the "sine wave" inverters will be less efficient, and will consume quite a bit more current.

 

Sounds like the original question has been well answered (and yes, if you want the engine to keep the traction battery charged as needed, the Prius must be in READY mode.)

For folks who need more power than the low-voltage circuit can provide, Richard Factor's site is well worth a visit. www.priups.com.

I recommend checking out his "portable power" solution in particular.

 

Efficiency is a funny term since it incorporates both the source and load. A straight resistive load doesn't really care what waveform provides power. However, motors and some laptop power supplies have inductive and capacitive loads that are sensitive to the waveform:
1) square
2) modified sine wave
3) sine wave

As a general rule, test loads with the inverter in a 'safe' mode before hitting the road. It is so much easier to deal with problems at home than 'on the road.'

GOOD LUCK!
Bob Wilson

 

<div class='quotetop'>QUOTE(crichman @ Aug 10 2007, 09:29 PM) [snapback]493835[/snapback]</div>

I've looked at his site, and it rambles around a bit. I haven't figured out where the "starting" point is, although it did provide some answers. Bob Wilson's site is probably better for my purposes. However, I was thinking setting something up specifically able to handle my gas furnace, which apparently has internal fuses limiting it to 11.7 amps max load at 115V AC. That would seem to imply I need to supply up to 1400 watts (peak, I assume), but Bob and others are saying don't go above 1KW, and that's before power losses in the inverter and cables. Would adding an external 12V battery in parallel before the inverter be a safe thing to do for the possible peak conditions? If the external battery has a slightly lower voltage, then I think the Prius system would effectively be charging that battery as well, unless I was able to isolate it somehow.

Also Bob's site has a diagram of fuses, apparently in the NWH11 model, showing 120A fuse for the battery, but it's limited by a 100A fuse closer to the traction battery. Why would they put a bigger fuse after a smaller fuse? Also, it appears there is more 12V amperage available on other fuses. Are these in use by important car functions, or could we tap in in two places to the 12V supply? (I don't have the 2003 electrical wiring diagram).

From http://hiwaay.net/~bzwilson/prius/priups.html:
<blockquote>HVC inverter B+ output goes to F11, F10 in "FUSIBLE LINK BLOCK NO. 1" - the total fuse protection sums up to 592.5 A. (pp. 50-51) Remember that fuses protect wiring, not specify the expected load which will be lower.
100 amp fusible link connect to F12, F13 - the total fuse protection for these circuits adds up to 262.5 A. (pp. 50-51)
120 amp fusible link protects the battery and probably the cable that runs from the engine compartment to the trunk. (pp. 50-51)
</blockquote>

 

Ultimately, I'm headed towards Richard's solution but I'm not there, yet. Richard's approach has the potential of +10kW of power and makes going with a heat pump a much more attractive solution.

I also want to use the same interface to support pre-charging the traction batteries to soften the warm-up fuel costs. I also want to test adding power to see if the Prius systems will use it.

Bob Wilson

 

Wth does anyone need 10 kW of power for when camping? Yeesh.

 

<div class='quotetop'>QUOTE(richard schumacher @ Aug 23 2007, 09:48 PM) [snapback]501356[/snapback]</div>

The 10 kW is for whole house power during a power outage.

Bob Wilson

 

<div class='quotetop'>QUOTE(richard schumacher @ Aug 23 2007, 10:48 PM) [snapback]501356[/snapback]</div>

Hey, the 60" plasma TV, the dishwasher, the convection oven . . . ya know, that stuff all adds up.

I mean look at this guy:

[attachmentid=10870]

He had a battery pack as big as the Prius just to power the sound system
[attachmentid=10871]

So ya need a few extra watts in the Great Outdoors.

 

If you power requirements are minimal (less than 7 amps at 120 VAC), I invite you to look at my inverter project "Prius as Back-up Power" at http://www.box.net/shared/9dc62z6acc

 

<div class='quotetop'>QUOTE(Solar_Powered @ Aug 24 2007, 06:09 PM) [snapback]501790[/snapback]</div>

Not bad but you need to measure the actual voltage under load. I think you'll find you can easily handle a full 1 kW, resistive load. My NHW11 03 Prius provides a full 1 kW before going into voltage limited, power mode:

http://home.hiwaay.net/~bzwilson/prius/priups.html

My inverter has a 1.2 kW surge, which limits the current draw. If the inverter can draw more than 100A, the fusable link is at risk, IMHO not a good thing for emergency power. Some folks recommend using a high current, 75-80A, circuit breaker. You can find them at RV supply companies.

I have thought about using one of those huge capacitors that the boom-box folks use. But it remains speculation. Using pig-tail junction boxes with in-rush limiting thermistors has solved my load management problem.

Good job!

Bob Wilson

 

I don't think the AIMS 1250 can draw more then 100 amps can it?

 

Just saw your document for the fitrst time, solar powered. Very nice job.

The cheapest source I know for ANL fuses and holders are the ebay auctions. They often include 'no-name' brands, but I suppose that since we are being conservative on fusing the probability of killing the Prius' main fuse remains low.

 

<div class='quotetop'>QUOTE(Danny Hamilton @ Aug 10 2007, 01:00 PM) [snapback]493606[/snapback]</div>

You are correct. You need READY mode to be able to engage the traction battery; a shift position other than neutral to be able to charge it.

 

<div class='quotetop'>QUOTE(bwilson4web @ Aug 8 2007, 08:11 AM) [snapback]492311[/snapback]</div>

In ready mode, the 12V bus is powered by the vehicle's DC-DC converter, not by an inverter. The two inverters power the electric motors in the transaxle, and rectify current back to the boost converter. They have nothing to do with the 12V bus.

Since "power control unit" didn't catch on, Toyota has taken to calling the unit that houses the inverters, the boost converter, and the DC-DC converter an "inverter assembly." This error leads to much confusion, and it's always worthwhile to take the time and untangle that error.

 

<div class='quotetop'>QUOTE(tochatihu @ Nov 18 2007, 07:07 PM) [snapback]541351[/snapback]</div>

I agree. This puts it all together logically with real products, no jumping around from page to page, wondering if one page is describing the same setup as the previous page, etc.

Unfortunately I don't think the 12V bus will be able to handle the inrush current on my furnace, although that has a variable speed motor. Perhaps I can set that to a low-speed (which is what it starts on anyway...obviously I need to take some real measurements and not speculate) or limit myself to a space heater. I'm not too worried about the fridge, my standalone freezer has lower requirements, and I can transfer frozen objects to the fridge to keep that cool in an extended outage. So I think the system described would fit my situation, and be quiet and portable for those camping trips should I actually want to bring entertainment electronics along... :blink:

 

<div class='quotetop'>QUOTE(nerfer @ Nov 20 2007, 02:25 PM) [snapback]542111[/snapback]</div>

Electric blankets on fall and spring camping trips are very, very nice. A flood lamp solves the after dark "where is that . . ." problem. In the summer, a fan can make the nights more enjoyable. In the south, a six-pack and bug zapper are great entertainment.

Bob Wilson