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It's hurricane season in Florida again and I got to wondering if I could use my Prius 04 as an emergency generator using a power inverter. There is a 1500 W model available but it looks like it has to hook up directly to the battery. Is there a way to connect it to the terminal under the hood or do I have to access the battery in the back. Also, would this create problems I may not be aware of?
 

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Unfortunately, the 12v circuit runs off the tiny accessory battery, which can't provide 1500W. I had trouble getting a 500W supply to work reliably. (Yes, the 12v battery is recharged from the HV 'traction' battery, but apparently that recharge circuit is less-than-1500W.)

Right now I've got a 300W inverter, and it works fine. I'd like to build it into the center console, so that I have a 120V outlet poking out the back. (Right below the rear-seat cup holders.) And it looks like Toyota Japan's website (sorry, I lost the link, it's in another thread on here somewhere,) they have an accessory 100V inverter that comes out the center support below the dash. IIRC, it's only 150W, though.

Oh, and I've thought about experimenting with a larger accessory battery (or even a second, more powerful battery,) to run an inverter off, but I don't know of the HV to 12v charging circuit could provide enough power.
 

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I do know of this report, I think on a Classic Prius:
http://autos.groups.yahoo.com/group/Pri ... ssage/2584

Yeah, you'll want to connect directly to the 12v battery, and leave your car in READY in a well-ventilated area. I don't know off-hand the max that you can draw/use, though.
 

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Power inverters

ehurtley said:
...Right now I've got a 300W inverter, and it works fine. I'd like to build it into the center console, so that I have a 120V outlet poking out the back. (Right below the rear-seat cup holders.) ...quote]

Good for you! That is where I installed an outlet on my 2001 Prius. Both the console and outlet are gray and a good match. Please take good care while insulating the new wiring.

I use a 1000 watt continuous modified sine wave inverter, hardwired to the 12v battery, and with an additional 60 amp ANL style fuse for protection. Started with the 100 amp rating but later learned how much overload it takes to melt an ANL open!

I only use the 110 vac system with Prius in READY mode, of course. With vehicle stationary and ICE cycling, eventually the radiator fans are also cycling. But I have never put enough load to heat up the MGs nor inverters, which was an early concern. Their coolant loop has no fan.

DAS
 

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The DC/DC converter output is fused at 100A, but I have read specs that may not be official stating that its nominal output is 80A. Battery itself has a 150A fusable link.

So, 80A*12V=960W inverter input, output would be less. Also consider that the car itself will draw 12V current, especially in READY mode, such as the coolant pumps.
700W inverter should be safe.
 

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Re: Power inverters

tochatihu said:
...Their coolant loop has no fan.
Well, I can honestly say that I am no fan of the coolant loop! ;)
 

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DanMan32 said:
The DC/DC converter output is fused at 100A, but I have read specs that may not be official stating that its nominal output is 80A. Battery itself has a 150A fusable link.

So, 80A*12V=960W inverter input, output would be less. Also consider that the car itself will draw 12V current, especially in READY mode, such as the coolant pumps.
700W inverter should be safe.
Yes, I've heard that 80A number also, but the nominal voltage on the aux bus is 13.8V, allowing a continuous drain of 80A*13.8V=1104W. My Mini-Scanner generally shows around 1.5A*273V=410W being used by the car itself when READY but not moving. This allows 694W at the inverter input, which is 625W at the output (if 90% efficient).

I have plugged in a drip coffee maker (rated 650W) long enough to brew a pot of coffee with no problem. I believe the car could power this coffee maker forever (until it runs out of gas). You can draw more power from the car for short times (I have a 1750W inverter), but exceeding the approximate 700W level will cause the 12V auxiliary battery to discharge faster than the main battery can recharge it via the DC-DC converter, so large drains should not occur too often or for too long.

Specifically, if the 12V battery is fully charged and brand new, it is rated for 28 A-hr. If you want to run an 1400W appliance (e.g. circular saw), you need 1400W/90%=1556W at the inverter input. If the DC-DC converter can provide 625W, the battery must provide the remaining 931W=12V*78A, which it can do for 28A-hr/78A=22 min before going dead flat. However, after a few years of use your auxiliary battery has probably de-rated to 75% of its design rating (28A-hr*75%=21A-hr), and you don't want to drain it below 50% anyway (21A-hr*50%=10A-hr), so you should probably run that circular saw for no more than 10A-hr/78A=8 min at a time.

Similar calculations will show you how long you have to wait for the auxiliary battery to recharge before sawing another log.

Douglas (2002 Silver, Wisconsin)
 

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johnson487682 said:
Yes, I've heard that 80A number also, but the nominal voltage on the aux bus is 13.8V, allowing a continuous drain of 80A*13.8V=1104W. My Mini-Scanner generally shows around 1.5A*273V=410W being used by the car itself when READY but not moving. This allows 694W at the inverter input, which is 625W at the output (if 90% efficient).
Miniscanner? I need more information.
 

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gagendel said:
Miniscanner? I need more information.
This is a device designed and built by Graham Davies to view operating data from the OBDII port on the 2001-2003 Prius. See

http://home.earthlink.net/~graham1/Priu ... canner.htm

and, quoting johnson487682,

"My Mini-Scanner generally shows around 1.5A*273V=410W being used by the car itself when READY but not moving. "

I am uncertain whether those watts should actually be deducted from those available at (the nominal) 12volts. All I can say for sure is that with the largest sustained load I have put on the 110 vac inverter (a 900 watt toaster), the system voltage was not pulled down and thus the 12 volt battery was not being discharged.

DAS and Tochatihu, 12 vdc, 273 vdc, 110 vac
 

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410W yields about 30A. That's quite a bit without anything turned on, but then you always have the inverter coolant pump running.
 

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tochatihu said:
I am uncertain whether those watts should actually be deducted from those available at (the nominal) 12volts.
I agree. I can't prove that all that power is being used by the auxiliary bus. It is quite possible (as I think DanMan32 is pointing out) that some of that power is being used directly from the main (273V) bus. However, it is an indicator of the maximum power being consumed by the car's systems, telling us we have at least 625W to play with our inverters.

Ideally, I would like to insert an ammeter at the 13.8 V output of the DC-DC converter, so I could see exactly how much current it is actually providing at any time. This would allow me to better manage the inverter's load.

Douglas (2002 Silver, Wisconsin, USA)
 

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Power Inverters for Hurricane Season

You can get lots of power (5+KW) from the Prius if you take it off the HV battery. I decided this would be fun to try and created a web site dedicated to the proposition. There's some useful technical data on the HV battery charge/discharge characteristics there as well.

Richard

http://www.PriUPS.com
 

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All the talk about 1000W makes me wonder, I plugged a 500W (max) inverter in to the dash socket, and blew the fuse without anything even plugged in to the inverter!

I guess I'll have to wire my mod directly to the battery, rather than the existing outlet circuits.
 

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Re: BIG inverters

RichardF: Very interesting work on PriUPS. During load testing of this setup, I suggest you monitor the temperature of the inverter coolant loop (there it is again), because the heat generated in the Prius inverters and electric motors goes there. A stationary vehicle won't cool that for you.

With my 110 vac inverter on the 12 volt system, the biggest sustained load has been a 500 watt rice cooker for 1/2 hr. This caused no heating issues, but you are potentially asking for 10x more power.

Ehurtley: My inverter is hard wired to the 12 v battery as you suggest, but through a separate fuse. I do not wish to accidently pop (expensive) Toyota fuses, nor disable vehicle function because of not carrying spares. I started with 100 amp ANL fuse, but after learning how much overload they take to melt, I moved down to 60 amp. So far so good.

DAS
 

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500/12=41A, way too high for the 15A fuse guarding the power outlet.
Even when you aren't actually using that wattage, the inverters are typically switching supplies, which can have a brief initial high current draw as it charges its capacitors. The surge may be brief, but obviously high and long enough to blow the fuse in your case.
 

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Re: BIG inverters

During load testing of this setup, I suggest you monitor the temperature of the inverter coolant loop (there it is again), because the heat generated in the Prius inverters and electric motors goes there. A stationary vehicle won't cool that for you. With my 110 vac inverter on the 12 volt system, the biggest sustained load has been a 500 watt rice cooker for 1/2 hr. This caused no heating issues, but you are potentially asking for 10x more power.
In my setup I take the entire load from the battery itself, which is recharged by the motor-generator. The only current taken from the inverter is the normal vehicle load - computers, etc. The motor cooling fan does cycle under the higher loads.

Richard
 

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So Hobbit, the solution to your problem in Hurricane season is get to your closest Home Depot on a sale day and grab a cheap generator. Only problem with this simple solution is that you will have the only cold beer in the neighborhood, so better yet, bring all your neighbors with you. My Florida friends did this during the xmas season when any offer would hack it. Don't give up totally on the Prius however, you can get it to power your electric razor. "No problemo"
 

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Re: BIG inverters

RichardF said:
In my setup I take the entire load from the battery itself, which is recharged by the motor-generator. The only current taken from the inverter is the normal vehicle load - computers, etc. The motor cooling fan does cycle under the higher loads.

Richard
I suggest that such large power draw on the battery will cause the ICE to soon start, and pass its juice through MG through inverter and then to the HV battery. All of this generates heat; ICE-heat is indeed dispached through the fans you mention, the HV batt has its own fan, but that from the inverter and MG exits through the other coolant loop. The one without an electic fan.

A thermocouple would be the simplest way to watch that temperature in the 2004+ prius. In the 2001-2003 Prius, a Graham Davies miniscanner is an aternative.

If this large power draw does perchance overheat the MG/inverter/coolant, likely your system will shut down. I hope that you do not continue drawing upon the HV battery then, because it would be expensive to replace.

DAS
 
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