Posted 2011-03-30 8:28 AM (#132357) Subject: mini fridges
Member
Posts: 9
I'm trying to get an idea of how feasible installing a mini fridge in my dressing room would be. How big of a battery bank would I have to have to run it? I do have a generator that I plan on using to recharge batteries as needed but would hate to have to start it up more than once a day, every couple of days would be even better.
Posted 2011-03-30 8:51 AM (#132358 - in reply to #132357) Subject: RE: mini fridges
Extreme Veteran
Posts: 342 Location: Ohio
Are you talking about a dorm size fridge that runs off of 110 AC only? If so, it'd take quite a battery bank to run one for more than a day. You would need an inverter as well. One time a day charging would not be enough if it was less than 5-6 hours, in my opinion. There is one of these in my LQ trailer, but we rarely use it because we rarely stay at places that offer shore power. If it wasn't already there, I wouldn't have it at all. We use coolers and it works well for us.
If you're talking about the camper fridge's, I would get one thats switchable between 12v dc and LP gas. Then run the fridge off LP instead of the 12v bank.
Posted 2011-03-30 11:01 AM (#132363 - in reply to #132357) Subject: RE: mini fridges
Member
Posts: 9
I meant the regular small ones you see in Walmart and such and I have an inverter setup already with a couple of deep cycle batteries. I don't want to put in an rv fridge because 1. cost and 2. I believe you have to cut vents for them and I have a steel trailer and don't want to put holes in the side.
It requires 90 watts. Say 100 to make it easy. You'll have to run it almost continuously. But it will cycle on & off depending on the outside temp and how often you open it. ... let's say then a constant 50 Watts per hour.
We'll want amps ... So 50 watts at 12 volts Amps = watt/volt = 50/12 = 4.2 amps.
Say 5.0 amps since the inverter has some ? loss and the inverter will run 100% of the time.
24 Hours x 5.0 amps = 120 amp/hours of battery power per day.
Can your batteries supply that much ?? With some margin of extra power...
...a suitable battery will weigh about 100 pounds (96 actual)
The larger problem is recharging the battery. A quick charge will degrade the battery. So a generator will have to run almost as long as the discharge time.(there is some technologies that will charge forklift batteries quickly but, they are more expensive than most RV'ers are willing to pay)
The other avenue is to have a battery that is used only say ... 25% of capacity. the battery is now 400 pounds and the charging rate is 50 amps for about 3 hours.
Posted 2011-04-02 11:54 AM (#132535 - in reply to #132357) Subject: RE: mini fridges
Veteran
Posts: 114 Location: Home of the WNFR at Christmas
When we built the latest LQ we have we went with 4.6 Cuft bar / dorm fridge do to design and ease of use.
I pretty much live in as hot a place as you can get, the desert SW and to keep the fridge cold it does not run anywhere near constantly. I keep it full of beer and they are nice and cold.
As for amp hours my 12v system into the Xantrex Inverter with just the fridge running 24/7/365 the yearly use of our fridge is 342 Kwh per mfg, so that equals out to 78Ah daily at 12v I actually see less draw when I actually measure it, you can get more efficient units, this not really an issue as I have a 1Kw ( 1000 ah) bank and extensive solar on the roof. With that said, I say look at the web, if you are going to buy from Walmart, they actually post efficiency ratings and find the best one for your needs bases upon usage and size.
You can draw down on these quite a bit harder / further than flooded cell batteries, but you will pay for it up front.
Even easier buy yourself a 12v 230 to 250 watt solar panel, ( www.sunelec.com has best prices under 3.00 a watt I buy the seconds they usually just have a scratch in the paint no solar issues) a PWM charge controller( no need for an MPPT in a tiny system) like a Xantrex c35, under $100.00 and forget about ever charging again. Enjoy cold food and beer !
Posted 2011-04-04 7:51 PM (#132606 - in reply to #132357) Subject: RE: mini fridges
Member
Posts: 16
Location: braham,mn
when looking at these battery charts; in the Amps/hour rating column does that number posted equal the total number of amps available for so many hours ? Like when it says "Amp Hours/20" and below it will say "100" this means you have 20 hours to burn up a total of 100 amps ?
Posted 2011-04-04 9:47 PM (#132611 - in reply to #132606) Subject: RE: mini fridges
Expert
Posts: 2958 Location: North Carolina
Originally written by 4-H Dad on 2011-04-04 7:51 PM
when looking at these battery charts; in the Amps/hour rating column does that number posted equal the total number of amps available for so many hours ? Like when it says "Amp Hours/20" and below it will say "100" this means you have 20 hours to burn up a total of 100 amps ?
Seems to me it shows the number of amps/hours discharged over 20 hours. If you look at the colunms at the right, it shows the amps delivered 8, 15, & 25 for number of minutes. Notice that the minutes are not linear. The battery can deliver more amps/minutes at a slow rate vs a fast rate
Posted 2011-04-11 1:08 AM (#132871 - in reply to #132357) Subject: RE: mini fridges
Member
Posts: 32 Location: TX
I installed a mini fridge in my Sundowner with a 1500 watt invertor and two new group 27 Optima Blue Top gel batteries. Took it on my first trip this past weekend. Got 36 hours use at first, recharged with a regular battery charger plugged into my generator. Every night the alarm went off in the middle of the night on the invertor, indicating too low voltage. Seemed like I could not get a full charge back on the batteries after charging all day long with the invertor off. I was disappointed in the results. I use my trailer to attend endurance rides and generators are required to be off at 10pm. Not sure I would go to the expense again, although the battery bank will be used for other things, such as lights and fans.
mini fridges
