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Author Topic: Excessive Power Consumption  (Read 1287 times)

Lou Schneider

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Re: Excessive Power Consumption
« Reply #30 on: October 17, 2017, 07:33:19 PM »
Welcome to The RV Forum!


I have been reading and I am having a similar issue to many of you. Today my land host hit me up with a $155 bill for power as my 5th wheel is pulling around 545kWh per month. I could tell she really didn't want to do it either. She is too sweet. I though it right and fair that I pay for my power usage, but also weird that the power jumped so much. Last month our power bill was $45, and we used close to 200kWh. This is crazy to me.

$45 / 200 KwH is 22.5 cents per KwH.

$155/545 KwH is 28.4 cents per KwH.

So the rate per KwH from one month to the next looks reasonable, as long as you didn't use the full 200 KwH last month.  It's considerably higher than the national average, but that's California.  Your land host may also have tiered pricing, where the cost per KwH goes up as you use more per month.

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A little back story; I am new to all of this. I jumped in head first into full timing because my month rent increased to $3000/month. I have a 2016 Sandpiper 381RBOK. We bought the really nice package, but got bait and switched by camping world in Fresno, so we only have one AC, 3way fridge not residential, and while there is an outside kitchen, we keep the fridge in it off. I say all of this because I cannot figure out where all the power is going.

As noted elsewhere in this discussion, absorption cycle refrigerators are notorious power hogs.  They use electricity or propane to heat the refrigerant that makes their cooling cycle work.  Depending on the size of the fridge, they can use up to 600 watts.  If it's hot outside, they'll run on a continuous basis to keep the insides cold.  0.6 Kw x 24 hours = 14.4 KwH per day x 30 days = 432 KwH per month.  If it's on 2/3 of the time that's still 285 KwH per month.  That's a big chunk of your power usage.

You can save money by switching the refrigerator to gas, the disadvantage is you'll have to buy propane more often.  But there's a lot of energy in a gallon of propane, and the fridge will run for several weeks on a single 7-9 gallon propane tank.

As far as how much you'll save, there's 22 times more energy in a gallon of propane than there is in a KwH of electricity.  Since you're paying 28.4 cents per KwH, you'll save money as long as propane costs less than $5 per gallon.

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I am thinking it has to do with the length of cable between me and the home. Starting from a 20A outlet at my land host house, I have a (4/6) 50 foot 110 20A cable that feeds into a 20A/30A plug adapter, then into a 30A/50A pigtail, then into my 50 foot 50A shore cable to my rig. To sum that up, it's a total of 103 Feet, 50 feet each on 20A and 50a, and 2 adapters.

So I am thinking maybe its the resistance on the 20A cable? My rig doesn't know not to try to more that 20A. We know that we can't run the AC, but have popped the breaker (@ land host) with a microwave and 2x fantastic fans running.

Power (KwH) is Voltage x Current, so yes, you will lose some power along the cord.  It will be proportional to how much power you're using, with zero power loss when you're not drawing power and the most loss when you're using a lot of power.  But even at the worst case I doubt it's contributing more than about 5-10% to your power bill.

Of more importance is the voltage you're winding up with at the RV.  Things start getting dicey around 105 volts, if the voltage drops much below that you risk damaging your appliances.

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I recently bought a plug in kWh meter to try to be more accurate with my usage. I am thinking about solar, but none of my house outlets run off the battery, they require shore, so this will only off set the LED lighting. Ultimately I need a solution. $150/month is as much as my power bill from my bricks and sticks house. Your expert advise is always appreciated.

I'd forget about solar, the payback time for the amount of power you'll get from solar panels versus the cost of buying that same amount of electricity from the utility is somewhere around 10-20 years.   Solar is popular with RVers that boondock without electrical hookups because of the convenience and freedom from having to run a generator every day.  But it's not that useful when you're plugged into electricity.

Since you're not using the A/C, that eliminates it as a power draw.  RVs aren't well insulated, and the ceiling and almost all of their walls are exposed to the outside heat and sun, so it's quite possible to use as much power to heat and cool an RV as a larger, well insulated house.

I'd switch your refrigerator from electricity (auto) to gas and see what that does to your power bill. Also make sure the electric element on your water heater is turned off and use the gas side instead.   I'll bet these two steps will shrink your electric bill a lot  in return for having to buy a little more propane.

If you got the Kill-A-Watt power monitor, since you're plugged into 20 amps you can plug the whole RV into it, then turn things on and off and see how much power they're using.  You'll have to be a little careful since the Kill-A-Watt is only rated for 15 amps but it should be OK for a test.
« Last Edit: October 17, 2017, 08:22:01 PM by Lou Schneider »

Ernie n Tara

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Re: Excessive Power Consumption
« Reply #31 on: October 18, 2017, 07:13:25 AM »
I'd suspect you are right. The Air Conditioner is likely getting low voltage due to drop in the long wires. An AC motor draws much higher current at low Voltage than normal. The rest of the bad news is that the AC may well be damaged as well. Measure the AC Voltage at the trailer with the AC running. If it's below about 105, then you've likely found the problem.

Ernie

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Re: Excessive Power Consumption
« Reply #32 on: October 18, 2017, 11:14:50 AM »
I'd suspect you are right. The Air Conditioner is likely getting low voltage due to drop in the long wires. An AC motor draws much higher current at low Voltage than normal. The rest of the bad news is that the AC may well be damaged as well. Measure the AC Voltage at the trailer with the AC running. If it's below about 105, then you've likely found the problem.

But Leave.Today said, "We know that we can't run the AC."  So I assume they haven't been running it at all, and much less enough to rack up that amount of electrical usage.

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Re: Excessive Power Consumption
« Reply #33 on: October 18, 2017, 11:53:59 PM »
I am thinking it has to do with the length of cable between me and the home. Starting from a 20A outlet at my land host house, I have a (4/6) 50 foot 110 20A cable that feeds into a 20A/30A plug adapter, then into a 30A/50A pigtail, then into my 50 foot 50A shore cable to my rig. To sum that up, it's a total of 103 Feet, 50 feet each on 20A and 50a, and 2 adapters.

So I am thinking maybe its the resistance on the 20A cable? My rig doesn't know not to try to more that 20A. We know that we can't run the AC, but have popped the breaker (@ land host) with a microwave and 2x fantastic fans running.

I really don't think it's the length of cable that's causing the problem.  We fulltime in a 40-foot motorhome that is on a 20-amp plug a lot, using something similar to your setup, but with 100 feet of 10 AWG extension cord, and haven't noticed any voltage drop issues.  If we don't, then you certainly shouldn't.

As for tripping the breaker, we almost never trip ours, even when using the microwave and assorted electronic devices.  And often with the refrigerator on electric, as well.  Is there any chance that your host has something else on the circuit that your RV is plugged into?  We were having breaker tripping issues, and found out that someone was plugging an engine heater into an outlet that was on the same circuit we were using, but located far away so you'd never expect it.   

What are you doing with your water heater?  Is it on electric or propane?  You can't run the microwave and water heater on electric at the same time--could that possibly be what made the breaker trip?

But back to your original question about the spike in electrical use, I've always measured our electricity when we're on a meter and it's quite consistent at about 15 kwh/day, or a little more, with no air conditioner or electric heat, but with absorption refrigerator and water heater on electric and occasional use of the washer/dryer (actually dryer--the electrical use of the washing machine is insignificant), and typical hair dryers, TVs, computers, etc. 

That puts me at about 450-500 kwh/month.  As I said above, my refrigerator is responsible for about 7 kwh/day.  If you have the same 4-door model, then you'd be using 210 kwh/month just for the refrigerator, but you said one month you used just 200 kwh total.  That seems low.  The 540 kwh seems kind of high, but it wouldn't be crazy high if it were my RV.

I think there's something else going on.  If your host does have something else plugged into that circuit, that would explain the breaker tripping and the relatively high usage, but I'm still concerned about your 200-kwh month. 

Get your kill-a-watt after it.  Those things are fun to play with.  Actually, you could leave the kill-a-watt plugged in for several days to see what you're using in total over an extended period of time.  Or leave it in for a month and see what it reads.  Which makes me think--how is your land host determining your electrical usage?  Is it separately metered?

Leave.Today

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Re: Excessive Power Consumption
« Reply #34 on: October 19, 2017, 06:34:05 PM »
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You can save money by switching the refrigerator to gas, the disadvantage is you'll have to buy propane more often.  But there's a lot of energy in a gallon of propane, and the fridge will run for several weeks on a single 7-9 gallon propane tank.

As far as how much you'll save, there's 22 times more energy in a gallon of propane than there is in a KwH of electricity.  Since you're paying 28.4 cents per KwH, you'll save money as long as propane costs less than $5 per gallon.

At this point I have put my 3-way fridge on gas only. I am going to measure how much gas use per day with it, and what my energy draw is. My plug kWh meter arrived so this is going to help. I wish this was the type of thing listed in an RV's online specs.

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I'd forget about solar, the payback time for the amount of power you'll get from solar panels versus the cost of buying that same amount of electricity from the utility is somewhere around 10-20 years.   Solar is popular with RVers that boondock without electrical hookups because of the convenience and freedom from having to run a generator every day.  But it's not that useful when you're plugged into electricity.

I am more looking for off setting costs not investing in the means to offset costs 10 years from now. though if the solar system could transfer from one vehicle to the next, then they might still be worth it.

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What are you doing with your water heater?  Is it on electric or propane?  You can't run the microwave and water heater on electric at the same time--could that possibly be what made the breaker trip?
The water heater is still a bit of a mystery to me. It is a propane water heater but once, when we first got our 5th wheel we left the lights on killing the battery completely. We were not able to turn on much of anything including the fridge, water heater, and heater (gas) until I got a charge on them even when I initially plugged the coach into power. This could all be coincidence and unfamiliarity though.

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hat puts me at about 450-500 kwh/month.  As I said above, my refrigerator is responsible for about 7 kwh/day.  If you have the same 4-door model, then you'd be using 210 kwh/month just for the refrigerator, but you said one month you used just 200 kwh total.  That seems low.  The 540 kwh seems kind of high, but it wouldn't be crazy high if it were my RV.

I am seeing a lot of the same numbers so... guess I may have to get used to this. I still love my lifestyle so...
A man and wife coping with insatiable wanderlust, youngest child/teen Luna, and Lucifer a.k.a. Lumpy a.k.a the best dog around.

"Surely" 2016 Sandpiper 381 RBOK ( A 40' 5th Wheel)
"Laverne" 2006 Ford F-350 6.0 Crewcab (1 ton)

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Re: Excessive Power Consumption
« Reply #35 on: October 20, 2017, 08:54:37 PM »
At this point I have put my 3-way fridge on gas only. I am going to measure how much gas use per day with it, and what my energy draw is.

How are you going to measure what only your refrigerator uses?  Since your water heater also uses propane, how will you separate them out?


I am more looking for off setting costs not investing in the means to offset costs 10 years from now. though if the solar system could transfer from one vehicle to the next, then they might still be worth it.

You can transfer the solar stuff to another RV.  I'm a big fan of solar, but would never recommend it as a way to try to offset electrical costs in an RV that's hooked up to shore power.  You'll see people claim that they slash their electric bills by using solar, but the numbers just don't add up, and they will invariably forget to mention they switched their refrigerator and water heater to propane.


The water heater is still a bit of a mystery to me. It is a propane water heater but once, when we first got our 5th wheel we left the lights on killing the battery completely. We were not able to turn on much of anything including the fridge, water heater, and heater (gas) until I got a charge on them even when I initially plugged the coach into power. This could all be coincidence and unfamiliarity though.

I don't know anything about propane-only water heaters, but I do know that the control systems on both gas furnaces and absorption refrigerators run on 12 volts, so neither of those will run if the battery is completely dead.


I am seeing a lot of the same numbers so... guess I may have to get used to this. I still love my lifestyle so...

Do you know how your land host is calculating how many kilowatt hours you're using?  Now that you've said your water heater is propane only, your 540 kwh in a month does sound relatively high (if you're not using air conditioning or electric heat), and your 200 kwh the month before sounds low if you have a 4-door absorption refrigerator.

If you're not controlling the climate, there shouldn't be such a big difference between consecutive months.  Is there a separate meter for just your RV?

 

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