Posted 2005-05-22 3:58 PM (#25450) Subject: Power requirements for LQ?
Regular
Posts: 50 Location: Portland, OR
For those of you doing your own LQ conversions...
How are you calculating the power you'll need for your refrigerator and water heater?
I'm thinking in terms of battery usage when there's no power hook up.
Since these appliances are mostly on standby, not sure how to figure the power usage per hour. Anybody out there have suggestions/experience with this?
Posted 2005-05-22 10:10 PM (#25460 - in reply to #25450) Subject: RE: Power requirements for LQ?
Veteran
Posts: 216 Location: Chillicothe, Ohio
If you are using an lp water heater and fridge, the 12volt dc amp draw is pretty low. My water heater has only a pilot light and I dont use the electric starter, so there is no 12 volt draw. A typical propane fridge draws only a few milliamps when in operation, just enough to operate the control board. If it has electronic ignition, when it lights it will take a couple amps but only for a couple seconds until the pilot is on. Check out phrannie.org for a lot of information on this subject. We camped in wyoming for over a week, ran the water pump and water heater and fridge took 2-3 showers a day and kept the battery up with one 85 watt solar panel. Check them out. We also use the olympian propane wall heaters, they dont use any 12 volts either. No noisy generator!
Posted 2005-05-23 11:48 AM (#25489 - in reply to #25450) Subject: RE: Power requirements for LQ?
Elite Veteran
Posts: 634 Location: Tipton, IN
In answer to the question, I am with martyg, LP appliances pull very little amperage when on LP. Now if your asking about 110V appliances with no LP, then you have a problem. They don't run on batteries with a converter, at least not ones your truck could haul, they only run on 110V AC current.
Ok, first, this is jus an observation. I think it's great that people want to be DIY's, but putting a complete LQ in a trailer is pushing it folks. Unless you really know what your doing you can get into some tricky stuff. Especially when it comes to putting holes for vents in the side of your trailer where braces may be, running gas lines, plumbing, adding appropriate bracing for a/c and roof vents and all the other crap. Or then again, maybe I just don't have the drive you folks do to save the $$$. I can see adding an a/c to a trailer, or a portable fridge, and so forth and running a outside plug for an inside receptacle, but sometimes things are better left to professionals I think. I am in no way condemning anybody for trying to build there own piece of heaven, just really expressing my opinion and questioning just how many folks that undertake this really have the necessary skills to achieve it without it being a major blunder that ends up costing as much as you would have paid to have one installed in half the time and would come with some sort of guarantee and liability responsibility from a recognized manufacturer.
Posted 2005-05-23 12:21 PM (#25495 - in reply to #25450) Subject: RE: Power requirements for LQ?
Regular
Posts: 50 Location: Portland, OR
Thanks for the replies and info...
efaubert...Your concern about DIY LQ and info are appreciated. The reason I'm asking about the power requirements is that the company I'm looking at hiring to put in the solar system wants a detailed list of the expected power usage.
Being unfamiliar with RV type appliances I'm having trouble calculating this. Don't know how much power to budget for water heater and fridge (on standby or full operation) or even if it's practical to attempt to run these completely off the 12v (without LP). .
Also wondering if it's possible to do without gas. Most of the time a power hookup would be available but would also like short term operation without 'land line'. And...would a LQ without gas be a bad choice when it came to resale?
Posted 2005-05-23 1:01 PM (#25502 - in reply to #25450) Subject: RE: Power requirements for LQ?
Elite Veteran
Posts: 634 Location: Tipton, IN
Ahhh, solar power. Running a refer off a battery as well as/ or a hot water heater is not really likely to be achievable. The size battery you would need to sustain the useage on current would be substantial. Not to mention you have convert the 12V DC to 100V AC. The converter and battery pack for somethin like that will cost more than your truck and trailer. Now maybe solar power has something going that I don't know about or understand, but from a strictly electrical outlook it isn't feasible. If they need estimates for draw on full useage just look at the back of you refer or go to one like it in the RV store and see what the amp draw is listed as. Or better yet, to be safe, tell them you need ten amps at 110V constant draw. 10 amps of 110V would be more than sufficient to run your water heater, water pump and refer. If they can actually do something like that. As for resale, yes, no gas is harder to sell. You are then bound by the need for electricity for all appliances, or a solar panel the size of your truck bed, and a battery and converter that will fill up your stalls.
Posted 2005-05-23 1:33 PM (#25508 - in reply to #25450) Subject: RE: Power requirements for LQ?
Regular
Posts: 50 Location: Portland, OR
efaubert - Thanks for your info/input.
The fridge can be run on 12v so would not need 110. The info I've found says it uses 60 watts...so for 1 day's operation, would it be calculated 60x24? Or, does a fridge draw less when on standby? If so, what is a 'rule of thumb' for calculating standby power usage for an appliance like this (or water heater)?
Posted 2005-05-23 1:55 PM (#25510 - in reply to #25450) Subject: RE: Power requirements for LQ?
Elite Veteran
Posts: 634 Location: Tipton, IN
Congrats on finding a 12V refrigerator, and may I ask where you found it so I will know for future reference. As for the 60watts deal, that would require 5 amps. Being that wattage is converted to amps as such: amps divided by voltage = amps. So 60 watts divided by 12V should equal 5 amps. And that would most likely be 5 amps constant, not hourly I would think.
Posted 2005-05-23 3:43 PM (#25517 - in reply to #25450) Subject: RE: Power requirements for LQ?
Elite Veteran
Posts: 634 Location: Tipton, IN
Theres variables we don't know here. Such as the batteries this solar thingy will be charging. If this company does that for a living they should be asking you for nothing more than how many amps of 12V DC you need continuously. Which according to the page you sent me to is 3.7 amps for the fridge. They, being your solar supplier, should take the total number of amps you need, the size of the batteries, and so forth to determine how much of a solar panel system you need to drive the system worry free. If they can't figure it out then I'd check some other companies first to be on the safe side.
Posted 2005-05-23 6:37 PM (#25539 - in reply to #25450) Subject: RE: Power requirements for LQ?
Expert
Posts: 2689
Originally written by karenb on 2005-05-22 3:58 PM
For those of you doing your own LQ conversions...
How are you calculating the power you'll need for your refrigerator and water heater?
I'm thinking in terms of battery usage when there's no power hook up.
Since these appliances are mostly on standby, not sure how to figure the power usage per hour. Anybody out there have suggestions/experience with this?
Thanks!
K
You could figure a "duty cycle" and do some arithmetic with that. e.g. a fridge that is ON 5% of the time would consume ON AVERAGE 0.05 times it's running wattage, same with the water heater (IF you decide on an electric one, I wouldn't), same with whatever else and add 'em up. Then fake an efficiency factor for batteries, inverters, etc. and you can probably get a good idea of how long you can go between re-charges or how big your battery bank needs to be.
Posted 2005-05-23 6:56 PM (#25542 - in reply to #25450) Subject: RE: Power requirements for LQ?
Expert
Posts: 2689
I guess I should have read through the other replies.
For the fridge case stated, yes it will take 5 amps WHEN RUNNING and essentially NONE when not running (-:
The interesting thing from the storage battery point of view is that it might be running only a small percentage of the time. I've no idea if 5% is reasonable, but if it is then the power system that needs to keep up with it would need to be able to supply an AVERAGE equal to 0.05 * 5 = 0.25 amps.
Even I know that the sun doesn't shine (in the same place) 24 hours a day, so you (your solar contractor) would have to figure another factor for the sun's availability, awww say 8 hours a day for the convenience of the arithmetic. So multiply the above 0.25 by 24/8 = 3 to get 0.75 as the needed battery replenishment rate, then get a solar charger and battery efficiency factor for THOSE losses - - and on and on.
Well, there's an APPROACH for you.
I think I'd ask the solar dudes how many watts they could get and what it would cost to cover the roof (about 310 sq ft.) of my trailer, because that is probably the upper limit, then I'd go and buy a generator.
{but I'm cheeep}
Power requirements for LQ?
