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05-17-2013, 11:55 AM
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#1
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Junior Member
Name: Ken
Trailer: Scamp
Pennsylvania
Posts: 20
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Hybrid Car as Generator
It's starting to warm up here, and I've been reading all the suggestions about having A/C in the summer. Okay, my 1991 Scamp 16' has an air conditioner. But most state parks here don't have electric hookups, and I'd hate to carry a generator for noise, weight, and bulk.
But wait... I'm towing this with a Prius! It makes an amazing power supply - super efficient (only running when the 220v batteries need refilling) and super quiet. The Scamp A/C seems to draw about 600W when the compressor runs, and 100w with the fan - peak is high but short.
http://www.aprs.org/FD-Prius-Power.html
And they tested it with an electric heater. Lots of detail at:
Prius - UPS Project
I'd like to clamp a 1000W inverter on my Scamp battery terminals, and run an extension cord inside for the A/C. I believe this will draw current from the Prius battery and the Scamp battery simultaneously. I've got the charge line and ground of the 7 way connector wired to my Prius 12V battery. The URL above says the Prius can deliver 100A @ 12V, so I imagine I can get 50 Amps from this line, and let the remainder of what the Prius decides to supply go into the battery as it would anyway.
Is this about to blow anything up? Do I need to connect it directly to the battery? Is this a bad plan overall?
Also: when I can't have the Prius there at all, what will happen if I run the A/C briefly (just to cool it down) off the Deep Cycle battery alone? I've read suggestions to not completely discharge it. What happens if I do?
Thanks!
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05-17-2013, 12:28 PM
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#2
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Senior Member
Name: Dave W
Trailer: Trillium 4500 - 1976, 1978, 1979, 1300 - 1977, and a 1973
Alberta
Posts: 6,926
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Ken,
You may be able to get 100A from the Prius, but your 7 way connector will not carry that much current. You should either run #2 wires to your trailer, or put an inverter in your Prius and run an extension cord from that to your trailer.
The battery in your scamp would have a maximum of 130 A hrs, it may be half of that. You should not use more then half of that. so 65 A hrs, (or 40 A hrs). At 600W, that would be a minimum of 50 A. So you should be good for about an hour, (or half an hr) of air.
Potential problems:
Starting current on AC is at least double running current, so you require at least a 1500W inverter.
Inverters are not 100% efficient, so it will draw on the order of 10% more then it supplies.
Your battery may not want to supply 50A for an hour. I would monitor the temperature of the battery.
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05-17-2013, 12:47 PM
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#3
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Junior Member
Name: Ken
Trailer: Scamp
Pennsylvania
Posts: 20
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An hour of A/C should be plenty for cooling the place down. Thanks for confirming my hope there.
I'll put the inverter at the Prius end instead of the camper end, and run the extension cord from there. Makes sense.
Thanks!
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05-17-2013, 01:07 PM
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#4
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Senior Member
Trailer: No Trailer Yet
Posts: 5,112
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I'd suspect that your problems will come from starting the AC on the inverter. You will need a big inverter and may need true sine vs modified sine output. (More $$$). I would also fuse the input from the Prius' DC-DC converter so that you don't accidentally blow that out, as they are very expensive. The Prius 12 volt battery is small, so you might want to add an additional battery next to it, or connect the Scamp battery with very large cables, as has been suggested.
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05-17-2013, 01:27 PM
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#5
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Senior Member
Name: Jack
Trailer: '98 BURRO 17WB
Delaware
Posts: 2,548
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30k$ generator for "emergency" HVAC? Heart be still!
jack
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05-17-2013, 01:37 PM
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#6
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Senior Member
Trailer: No Trailer Yet
Posts: 5,112
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Quote:
Originally Posted by rabbit
30k$ generator for "emergency" HVAC? Heart be still!
jack
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Be nice Jack. You know that you are a tinkerer at heart.
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05-17-2013, 02:03 PM
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#7
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Senior Member
Name: Francesca Knowles
Trailer: '78 Trillium 4500
Jefferson County, Washington State, U.S.A.
Posts: 4,669
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Are the Prius batteries recharged in this scenario by the gas engine, and if so, how does this differ from any other tug-to-trailer power transfer????
Francesca
__________________
............... ..................
Propane Facts vs. Fiction:. Click here
Tow Limit Calculator: Click here
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05-17-2013, 02:12 PM
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#8
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Senior Member
Name: Jon
Trailer: Escape 21C
New York
Posts: 2,387
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I've been impressed by the fuel cell developed by Chevy. According to their engineers that attended the New York State Fair a couple of years ago, it was the size of a breadbox & developed 100KW. Now, if you could get it to run on propane, and get the cost under what they were paying ($1,000,000.00 each) that would power your AC and then some!
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05-17-2013, 04:30 PM
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#9
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Senior Member
Name: Dave W
Trailer: Trillium 4500 - 1976, 1978, 1979, 1300 - 1977, and a 1973
Alberta
Posts: 6,926
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Quote:
Originally Posted by Jon Vermilye
I've been impressed by the fuel cell developed by Chevy. According to their engineers that attended the New York State Fair a couple of years ago, it was the size of a breadbox & developed 100KW. Now, if you could get it to run on propane, and get the cost under what they were paying ($1,000,000.00 each) that would power your AC and then some!
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Enough for ~100hp. No more heavy batteries in hybrids. $1,000,000? what is it made of?
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05-17-2013, 04:47 PM
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#10
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Senior Member
Name: Jon
Trailer: Escape 21C
New York
Posts: 2,387
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I don't know, but it is impressive. Biggest problem (other than the cost) is that it requires hydrogen to operate - both finding the stuff & storing it in the vehicle are problems. Still, an incredible amount of power in a small package. I'm sure the carbon in propane would poison the cell & I'm not sure I want a hydrogen based fuel system for a trailer!
Chevy built 100 Equinox SUVs that combined the fuel cell & Nickel Hydride batteries in 2008, but I haven't seem much about the technology lately.
It would make an interesting tow vehicle if the range could be improved. With a 120V tap for the trailer it could supply all the energy needed for everything.
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05-17-2013, 06:57 PM
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#11
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Senior Member
Name: Leonard
Trailer: not yet
California
Posts: 151
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Thomas G, don't you tow with a Hybrid? Are you the one that has a battery hookup from the tug to the trailer, tapping into the big battery bank? Or is that someone else?
Just curious, if it is you, did you use a DC/DC converter to lower the voltage before passing it back to the trailer, or did you do the conversion there?
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05-17-2013, 07:31 PM
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#12
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Senior Member
Trailer: No Trailer Yet
Posts: 5,112
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Quote:
Originally Posted by LeonardS
Thomas G, don't you tow with a Hybrid? Are you the one that has a battery hookup from the tug to the trailer, tapping into the big battery bank? Or is that someone else?
Just curious, if it is you, did you use a DC/DC converter to lower the voltage before passing it back to the trailer, or did you do the conversion there?
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Hybrids use a dc-dc converter in place of a 12volt alternator. So I simply tapped off the 12 volt battery. The dc-dc converter provides about 110 amps at 12 volts in the Escape. I've seen installations where the traction battery is tapped with a 330 volt to 120 volt dc-ac converter to provide much more power. This allows you to use the full power of the generator - about 15,000 watts.
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05-17-2013, 08:40 PM
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#13
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Senior Member
Trailer: Boler (B1700RGH) 1979
Posts: 5,002
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Quote:
Originally Posted by Thomas G.
I've seen installations where the traction battery is tapped with a 330 volt to 120 volt dc-ac converter to provide much more power.
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For high power demand (such as for an air conditioner), this makes vastly more sense to me than converting 220 V DC to 12 V DC, and then converting again to 120 V AC... and running about a hundred amps at the 12 V DC stage while pushing the limits of the car's DC-DC converter. This assumes, of course, that one can find an inverter that will run on that input voltage.
Quote:
Originally Posted by Thomas G.
This allows you to use the full power of the generator - about 15,000 watts.
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The inverter would still be a limiting factor, of course, and 3600 watts might be a sensible size (fully powering a 30 amp RV shore power connection) - no need to handle the whole 15 kW MG1 output.
__________________
1979 Boler B1700RGH, pulled by 2004 Toyota Sienna LE 2WD
Information is good. Lack of information is not so good, but misinformation is much worse. Check facts, and apply common sense liberally.
STATUS: No longer active in forum.
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05-18-2013, 06:50 AM
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#14
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Senior Member
Trailer: No Trailer Yet
Posts: 5,112
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Quote:
Originally Posted by Brian B-P
.............
The inverter would still be a limiting factor, of course, and 3600 watts might be a sensible size (fully powering a 30 amp RV shore power connection) - no need to handle the whole 15 kW MG1 output.
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Right. The conversion I read about was a salvaged industrial inverter. I can't imagine the cost, or even the source of a new one.
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05-22-2013, 09:29 PM
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#15
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Junior Member
Name: Ken
Trailer: Scamp
Pennsylvania
Posts: 20
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Okay, so I tried it and it failed. It fails on startup of the AC motor. I was all set to send it back when I looked again at the specs: 2400 watts peak.
So... Is there some other problem? The alligator clips don't have a lot of surface connection when they are clipped to the battery leads. Could that be limiting the current? Is the inverter bad?
If its the inverter, what is the best brick and mortar store to visit to try different inverters until I find one that works?
For reference, here is what I had on hand:
http://www.amazon.com/gp/aw/d/B007SL...m_ss2?pi=SY125
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05-23-2013, 06:31 AM
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#16
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Senior Member
Trailer: No Trailer Yet
Posts: 5,112
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Quote:
Originally Posted by Thomas G.
I'd suspect that your problems will come from starting the AC on the inverter. You will need a big inverter and may need true sine vs modified sine output. (More $$$). I would also fuse the input from the Prius' DC-DC converter so that you don't accidentally blow that out, as they are very expensive. The Prius 12 volt battery is small, so you might want to add an additional battery next to it, or connect the Scamp battery with very large cables, as has been suggested.
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Quote:
Originally Posted by Ken in Philly
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Reference my earlier post repeated here, above. The problem could be that the Prius battery is too small, the cables too small or not making good contact, the inverter surge capacity is bogus, or that the surge current of the AC unit is more than you realize.
Also, this inverter is a modified sine wave, not a true sine, which may also be working against you. You may find some help from the owner's of this site: http://www.donrowe.com/inverters/inverter_faq.html
Do you know how to make some measurements to quantify the start up surge current?
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09-07-2018, 12:11 PM
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#17
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Senior Member
Name: kevin
Trailer: 13' Scamp
Colorado
Posts: 172
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no worky
Probably doesn't startup because of voltage drops from wiring etc. But even if you get it to start it will not actually function well. The Prius has a small charger to keep the 12V battery charged while the main battery has a much more capable converter to push energy into and out of the traction battery. So Prius is really good at charging the 12V battery from the (traction battery) if you have too many lights on and the battery needs charging, but will provide no where near enough power for AC.
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09-07-2018, 03:59 PM
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#18
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member
Name: J
Isle of Wight
Posts: 536
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Turn the A/C on in the Prius and run a hose back to the Scamp.....
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