Somewhat subjective battery question...UPDATE

[ripperoo]

As the subject says, I have a subjective battery question. I know there won't be a definitive answer here, but looking for your gut feel.

I'm going camping this weekend, and then again next weekend, at the same campground. Since I know the owners of the campground, they're going to let me leave my camper in a parking lot for the week so I won't have to tow it the 75 miles back home, and then 75 miles back the next weekend. There will not be electric to plug into for the week.

So, the question. Do you think my batteries will last the week running only the refrigerator? I'm hoping to leave whatever food and drinks inside. More importantly, I'd like to arrive the second weekend with the fridge cold, so I can avoid the 1/2 day or so it would take to re-cool it. I've never boondocked with it yet, so I don't have any history on battery longevity.

Details:

-I'll be leaving it at the campground unplugged from Monday afternoon until the following Saturday morning, at which time I'll be able to place on new site and plug in.

-The batteries will be fully charged when left. They are group 24, standard 12v deep cycle RV batteries.

-The batteries are about 3 years old, always maintained, i.e., water kept up. Except they were run down to dead once last year; forgot to disconnect them once for 3 weeks while in storage. I take them out at season end, and keep them on a Battery Tender in my garage.

-Outside temps will be between 80 and 90 degrees. Inside could hit 100 degrees. Don't remember if the lot is shaded or sunny.

-Plan on turning off all breakers except the fridge.

So what do you think? Might they last the 5 days or so?

Thanks for your thoughts,

Mark

[ripperoo]

Well, I got to the camper Friday afternoon, a little leary of what I might find. To my surprise, the fridge was at 34 degrees, the batteries were still at 2/3 according to the wall indicator, and it never changed over to the full LP tank. The one it was using was half full. So, all in all, there wasn't much of a drain on the LP or batteries for the week. Temps outside were probably around 80 during the day, 60-70 overnight.

It was so nice not having to pull all the food and drinks out last Monday, load up a cooler to take home, only to load up a cooler again and bring it all back Friday.

Thanks all for your thoughts and advice. Experiment was a success!

[ripperoo]

Well I'm home now. Decided to go with it and see what happens. I pulled the LP detector and radio fuses. LOL. When I did, a little red light came on next to each fuse, I guess to tell you which one is blown. Now I'm wondering if the lights will draw as much juice as the items I disabled. Guess I'll find out Friday. Fortunately, this week is supposed to be milder than I originaly thougth, with overnight lows in the lower 60s.

[opnspaces]

Well today is Saturday so I know it's too late for this weekend. But if the owners are really friends I would see if they will turn on the fridge Friday morning so it's cold when you get there.

[EldIr]

biohazard wrote:

otherwise a larger solar system would definitely help.

That would confuse the hell out of the astrophysicists tho...

[gmw_photos]

Some refrigerators have a heater coil in the door gaskets to keep frost at a minimum there. Mine does. Some refrigerators allow you turn that feature off, to eliminate that draw, such as when boondocked. Mine does not have that feature, and there is no way I can run it for a week on just the battery.
I bought a small solar panel to help keep the battery topped off.

[Rolling_Condo]

smkettner wrote:
Yes on LP you should make it. 120v breakers on or off is not relevant.
You might save a small amount of power by pulling the 12v fuses to the radio and propane detector.
Either way I think you will be fine.

Of course if you had 80w of solar....

Do pull the fuses for any extra parasitic loads. I would feel comfortable doing so in my trailer.

[ripperoo]

biohazard wrote:
maybe one of these will buy you a couple of days,
15 watt battery tender
otherwise a larger solar system would definitely help.

Yep, that would probably do the trick. Unfortunately I waited too long to pose the question on here. Damn my procrastination. Lol. I actually have to solar "units" which came off 2 new Volkswagens years ago. They're about 12" x 16". Back then, not sure if they still do, they would ship their cars with these small solar panels hung on a window, plugged into the OBDC port. They were to keep the batteries charged while the cars were shipped and stored until hitting the dealerships. I don't know waht their output is; can't be much. But I wonder if they'd be enough to bridge the gap.

[ripperoo]

KD4UPL wrote:
You never stated how many batteries you have so everyone is guessing. Do you have 2 or 4 or more?
If 2 I think you should be fine. More than two no problem at all. A solar panel would really help in this situation.

Oh crap, so sorry. I thought I did. I have 2.

[biohazard]

maybe one of these will buy you a couple of days,
15 watt battery tender
otherwise a larger solar system would definitely help.

[EldIr]

If you pull all the 12v fuses except the fridge, it should be no problem. Remember, nobody is going to be opening the fridge a dozen times a day. It will cycle less often than when you're camping. Unless, that is, if it's going to also be much hotter in the trailer due to not running a/c.

The thermal mass suggestion is a good one.

[KD4UPL]

You never stated how many batteries you have so everyone is guessing. Do you have 2 or 4 or more?
If 2 I think you should be fine. More than two no problem at all. A solar panel would really help in this situation.

[TheGriswolds]

I think it would work. I picked up one of those wireless temp moniters at Wal Mart for under 10 bucks and it works great, but the ice cube trick sounds even cheaper.

[hmknightnc]

The thermal mass comment is a good one. Don't know about your TT but my FW wouldn't make on 2 GP24s starting out fully charged and if it did the batteries would down below 11.0 volts. My parastic draw including running refer on gas is about 20AH per day. My twin 6volts would make it 5 days but likely approaching 50% charged at point (assumming I turned the solar off, with solar it could do this forever)

[SprinklerMan]

Think of thermal mass , Freeze a bunch of 2 liter bottles of water , fill both the refrigerator and freezer with them in adition to what food you are leaving . This will help greatly in keeping things cold .