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How much electricity does a converter burn through?


BrianT

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How much electricity does a converter burn through?

 

I know no one can give me an exact answer but I'll tell you what got me to thinking about it...

 

I'm parked at a park where we have to pay for the electricity seperately from the park rent. Not unusual for long term people.

 

Month before last, it was COLD out. We had temps down in the single digits and even a few nights as low as 13 below zero (F). During that time, we ran our electric heater nearly non-stop. I think it's 1600 watts. I was expecting the electric bill to be high. It was right around $100.

 

So after the meter was read, I made a concious decision to cut the electric heat and just heat with propane thinking that it should drop the electric bill dramatically. The weather warmed up pretty nicely and even the furnace wasn't running much at all. I was surprised to find that our bill this month was $60. OUCH!!

 

So what is it that's eating up that much electricity? I have a small chest freezer that is supposed to use about $3/mo. Even if it's $5/mo, that leaves a lot of electricity to be accounted for. I am using both the water heater and the refrigerator on electric and I have known for quite some time that the refrigerator is really not that efficient on electric. Interestingly, the water heater was turned off for about a week over that last month because we were traveling a bit away from the rv and turned it off. Hmmm.

 

So that leaves the converter. I have wondered just how much electricity one of these converters goes through in a month's time. Our lights are mostly automotive type and on a few hours at night. The control boards are 12 volt. The furnace fan, when that is running would draw a pretty good amount of electricity, but that's not been running much.

 

I don't know. I kinda of suspect that I have an energy hog somewhere. Might be the refrigerator. I might be able to kick that over to propane for a month just to see. But I don't have a good handle on what a converter typically does when it's operating normaly. Figured maybe some of you might have been down this road before.

 

Kinda makes me wonder if a few panels and a few golf cart batteries would do a decent job of running the 12 volt end of things at a reasonable cost. But I could be exagerating how much the thing is pulling.

 

I'd be interested if some of you have done some quantifying on your own energy usage and what you might have found, just generally speaking.

 

Thanks!

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The converter isn't likely to be that much of a cost as remember that it is a 10/1 step down so 1a of 120V power will supply roughly 10a of 12V power. The only power your converter will be supplying is whatever 12V power you are using, mostly the lights and a little bit for the controls of the refrigerator, water heater, and also the power for the furnace including it's blower. That blower probably draws no more than 5 - 10a of 12v power or 1a or less from the 120v supply to the converter.

 

The water heater is probably the largest 120v load as it probably draws about 10a when heating, possibly a bit more. I can't remember what it is fused for. The refrigerator heating element is usually fused for 5a and typically draws 3a or less. Of course, the refrigerator may operate more hours than the water heater so no doubt that they both play some part. But the cost really doesn't tell the story as you need to look at what you are paying per Kw hour. Watts are amps times volts, or 10a at 120V for 1 hour is equal to 1200 watt hours, and 1.2 Kwh. Since prices of electric power vary widely and some parks charge more to customers than they pay for the power, you really need to know what you pay per Kwh.

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Newt, I don't have a Kill A Watt. I should pick one up. Just outta curiosity, how would you go about hooking up the rv fridge or water heater? It's sounding as though one of those might be a pretty good sized energy hog. The converter would be easy. The freezer would be easy. Not sure about the microwave but wasn't too concerned about that one as it doesn't get used much.

 

Kirk, thanks for the general thoughts on the various electrical users. That was pretty much what I was looking for and you did a nice job of laying it out simply. I appreciate that. :-)

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You guys might be right. I might have overestimated the amount of electricity the electric heater was using on full blast and underestimated what a "normal" electric bill is like.

 

I still think I'll pick up a Kill A Watt at some point, just to see what I can see using it.

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I use a short, 18 inch extension cord on the plug side of my Kill-A-Watt if the socket is a bit out of the way, makes it easier to read.

 

If you have a device that doesn't have a plug (fridge should, converter may) you can just make up a pig-tail by whacking the end off an old cord.

 

 

Converter power use varies as was said, some based on your usage but also based on how efficient the converter is, an antique MagneTek may burn through several times the power a new smart converter does.

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How many killowatt hours are you using each month. It is not the cost as they could be charging you .25 a kwh one month and less the next. Need to figure usage and not price. If you use 1000 kw a month that is $250.00 where as if they charged you .12 kwh then the bill would be 120.00.

 

Do you pay it to the power company where the rate is stable or the park where it can be whatever whenever.

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Newt, I don't have a Kill A Watt. I should pick one up. Just outta curiosity, how would you go about hooking up the rv fridge or water heater?...........

 

 

I still think I'll pick up a Kill A Watt at some point, just to see what I can see using it.

I have one and they can be very educational and fun, but for most of us that is about all they do as the majority don't really manage power use but just live with it. I bought one of the cheaper ones from Amazon, but they actually come with quite a range in capability. It can be pretty surprising what you learn even for those of us who are in theory, electrically educated. :huh: One that turned out to be significantly more than I anticipated was our dehumidifier.

 

As to the way to use one, most of the RV's 120v appliances have a power cord connected to a standard house outlet box where they plug in. The catch is that if you don't get one of the Kill-a-watt versions which have a memory, you will then need to be able to see the display before you unplug it. I do as Stanley suggested and use a short extension cord to the outlet, connect the device to the end of that cord and the load to that. That way it allows you to check it fairly easily. I wish now that I had been smart enough to get one with the battery backup.

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Brian, to your direct question: "How much electricity does a converter burn through?"

 

Well other then normal inefficiency heat losses (in converting 120 VAC to 12/14 VDC) , the energy it consumes is whatever 12/14 VDC loads require (vent fans, water pump, furnace, lights etc) PLUS keeping the batteries charged. Those 12 VDC loads aren't all that much as the water pump or vent fans don't run often, lights (unless all are still incandescent??) although YES a furnace may draw 5 to 8 amps when operating. MY QUESTION WOULD BE IS THERE A BATTERY PROBLEM (such as a short or dead cell etc) which requires a lot of Converter power????????????? What shape are your batteries in???

 

I don't know the KWH the park charges, but figures in the $50 to $100 range don't seem so far out of bounds. It appears using a resistance electric heater (3.41 BTU per Watt), plus the fridge and water heater operating on electricity is your biggest cost other then what the converter is drawing. IE I don't envision the converter as the problem, simply the fact the fridge and electric heat and water heater are using so much.

 

Anytime you go through a conversion (AC to DC or DC to AC) you do waste energy in the form of heat (other then in winter its actually put to use lol), so anytime you can operate a device and NOT loose the conversion inefficiencies you have gained.

 

I think the bottom line is the comparison between LP Gas operation cost versus electricity cost (fridge, heating, water heater). That requires some calculation and is, of course, based on LP gas and Electricity costs in your location.

 

You might want to take a look at insulation and heat loss reduction the RV,,,,,,,,,,get a handle on electricity cost and LP Gas,,,,,,,,,,,,make sure the batteries are okay and NOT drawing excess converter power,,,,,,,,,,,as posted get a KWH meter.

 

Best I have to offer not being there nor knowing your electric and LP Gas cost.

 

John T

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1 Gallon of Propane = 27 kWh (Kilowatt Hours) of electricity. So simply take the price you are paying per kWh and multiply it by 27 to compare the costs of electrical to propane. This simple check does not take appliance efficiency into account but it is handy for coming up with quick estimate between the two.

Later,

J

 

PS I have seen Kirk and others point this out in the past.

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