How to convert DC to AC on 2006 Prius

Your connection is OK and a benefit of that is that you are connecting near the Prius inverter output.

900W continuous is about the most that you can expect. When the Prius is READY the inverter will be drawing ~70A at 14V to produce 900W AC power, taking into account efficiency loss. And of course the car needs ~30A of current or so to keep its systems running.

The DC/DC fusible link is rated at 120A while the MAIN fuse at the 12V battery is 100A. Before your current draw gets to that level you will probably find that the voltage on the 12V bus starts to sag.

Regarding cable size, that is dependent upon the current flow and the length of the cable.
American Wire Gauge table and AWG Electrical Current Load Limits with skin depth frequencies

I would use at least AWG 4 size or a bigger size, when powering the 900W space heater. I would also suggest you keep the wire length carrying the 12VDC to the 110VAC inverter as short as possible, say 6 feet or less.

 

I have a 1.1 KWcontinous, 3KW peak invertor permenantly installed in the trunk. It is connected to the battery with 4 AWG wire. The plus goes directly to the battery, and the minus goes to the chasis directly. I also have a flooded battery, not a AGM battery, so it can provide higher surge currents to the inverter. (I knew there was a good reason to put in the cheap $35 battery, rather than the expensive AGM battery!)
This past weekend we had a serious storm here, and lost power for 32 hours. I back fed my house from the invertor. I was able to run my furnace once. Then the White Rogers controller in it gave a polarity error. I am trying to find out exactly what that means, since the invertor has more then ample output to run the furnace. It also ran my 27 cu' side by side refridgerator, with one caveat. When the invertor turns on, the fridge starts and runs, but when the fridge cycles, it kills the invertor, which resets and restarts and then the fridge runs. This is caused by the inrush current being too high. When the invertor powers up, the inrush current is lower, since the voltage does not come up to full output instantly, so the inrush is reduced. The fridge works as long as the other loads are light < 100 watts. I was able to use my lights, watch tv, and go online with this system, but you have to use careful power management. I'll be in good shape with this system for the next power outage, once I find out how to fix the furnace issue. I used about 3 gallons of gas leaving the Prius on for this time. (Actually it was on for about 24 hours.) Also, a nice thing to do is come up with a way to reduce the inrush current to the fridge, so the power does not collapse.

 

To do this we have to at least isolate the house from outside wires by tuning off the main circuit breaker I suppose?

I wonder if adding a transformer between the inverter and the house would help with the current surge problem and also maybe run at a lower voltage say 100 as opposed to 120?

 

Yes, you must turn off the main breaker, and yes a slight stepdown might help.

 

You can use SMART5000XFMRXL - SmartPro 5kVA Line Interactive Sine Wave UPS, Extended-run & SNMPWEBCARD options, 3U Rack/Tower, USB, Serial, EPO, 208+120V UPS. it has an anderson plug on the back for external battery. Just hook that up to the Prius's HV battery pack.

 

I wouldn't drop the AC voltage, I would increase it. A lower voltage will cause the load to draw higher current and most loads to run hotter. Most loads will react poorly to lower voltage (electronics). Only incandescent bulbs would react the way you want. We don't use those anymore do we?

 

+1 on hooking directly to the HV battery for large loads. The normal continuous recharge rate from the engine is about 15A @ 250V = 3750W, whereas the max continuous rate on the 12V system is about 1500W. There is also the efficiency issue: a 12V inverter involves having power inverted three times (MG1 -> inverter -> battery -> inverter -> 12V -> inverter), whereas the direct connection removes the costly step-down to and step up from 12V. I can't remember who did PriUPS, but that has a good description, especially sourcing a second hand 208V inverter.

 

Cool thread. But may I suggest a cheaper alternative for heating at least.
They sell these LP Gas heaters (Kozy World etc) that run great off a 20 lb LP gas bottle and can heat up a house really nice and very cheaply. The stoves are around $ 125 and a bottle of LP is $45. That will last almost 4 days on that one bottle. And then to recharge the bottle is $15.
I have lots of relatives up north who use them. Especially NH which is terrible in the Winter electric wise.
Good Luck!

 

Also, any electric space heater with nichrome construction and 208V/240V rating can be hooked directly to the HV battery -- no inverter needed.

 

You could also look at another TrippLite model, SU5000RT4U, which has a 240v option. I need backup to run a water well pump.

 

I looked into the one I posted and the battery is 48V system so it won't work with the Prius. The one you posted is based on 192v so it will work with the Prius's system.

 

Right for motors too. Running them at too low a voltage makes them draw more current, which can cause them to overheat.

Also, another post mentioned backfeeding a house with the main breaker off. This might work, but is "not recommended" because it's not idiot proof (if you forget, or connect/disconnect in the wrong order, you can backfeed power out to the utility or feed utility power to your generator/inverter when the utility power comes on - possibly even with no protection from the breakers in your panel depending on exactly where you tie in). Also, some inverters expect the neutral to be floating (not connected to ground), but by tying directly to your home's electrical panel, the panel will tie these together for you. The correct way to feed power to your home's wiring is with a transfer switch (either whole house model, or individual circuit model). Note that transfer switches may not switch neutral, so even with a transfer switch the inverter's neutral may end up tied to ground through the main panel.

 

Great thread! But why is it dead since 2011? I am sure there is new information about this stuff out there.

I just finished installing a 30 Amp (at 240V) transfer switch in my house. It has 10 circuits (2 30A, 2 20A and 6 15A). Instead of trying to wire my Prius up for 1000 Watts I purchased a small pure sine wave inverter generator which is rated at 2000 watts peak and has no problems with 1700 watt heat gun I tested it with. It is quiet, fuel efficient and is more powerful than the 12V Prius solution. I bought it used for $350, but even new they are under $500. A 3500 watt inverter generator from Harbor Freight is $600. I am not sure it is worth bothering with Prius solutions, cool as they may be, in light of this new crop of inverter generators. These generators run at low rpm with no load and only spin up when the load increases. They have a pure sine wave inverter on the output and electronics are happy with the power they generate. They are neighborr friendly as they just hum instead of screaming. The Harbor Freight one in particular is super quiet.

Having said all that I would love to harness the HV battery in the Prius to serve as an emergency power supply for the house. However inverters that take 200+V inputs are expensive.

 

When I installed the Prolong Charger harness to my hybrid battery I also installed a #6 wiring harness to the hybrid battery contacts in hopes of harvesting the 200+ volts on the battery pack and hook a Inverter to it but 200 volt input Inverters are very rare and expensive.
I followed the thread on here years ago about someone who found a 200 volt input and had it hooked to his prius but it was expensive.
And very large.