How long should a battery last?

pianotuna said: "12.3 volts is 50% If it is a marine battery that's already pushing it too low."

I'm thinking 12.3 is about 70%, and not an issue, until getting closer to 12.0, which will shorten life of battery.

This thread reminds me of a friend who bought an EV and wanted to take a road trip. In theory they should be able to drive a couple hundred miles before charging so not much of a road trip. To make it worse they wanted to travel in the winter months. The batteries are less efficient in the cold and battery power is needed to heat the interior of the car. So no road trips in that car.

They had great intentions. First they thought they would save on operating costs. We live in an area where electric rates are way, way over the national average so that is not going to happen. Next they thought they were helping to keep pollution down and doing their part to reduce global warming. That electric power did not come free. It comes from a power plant burning natural gas or an older plant burning oil.

Sometimes there just isn't a good fix after buying the wrong thing.

swimmer_spe wrote:

ewarnerusa wrote:

swimmer_spe wrote:
...They don't install absorption fridges anymore.

That's what I've gathered from the forums. Followed by grumpy scoffs from boondockers! LOL You mentioned that you're in a one-off boondock situation so not worth investing in any more gear. So you can fire up your tow vehicle and plug in the trailer via 7-pin to get some juice into the battery. Without upgrades to that wire path, it will not provide a whole lot of current for charging. But it is equipment you already have.

How long should I run it for if the battery goes down below 12V?

I do boondock with others, but they have a generator. That generator is not mine, and is not available for this one off time. I do plan to get a generator, but not likely for this trip.

12.3 volts is 50% If it is a marine battery that's already pushing it too low.

It would be pretty hard to say how long--but assuming an 80 amp-hour group 24, discharged to 12.3 (40 amp hours down), about 2 hours with #4 jumper cables.

The computer that controls charging "listens" to the starter battery. That tapers the voltage so that not much charging is done. A dc to DC charger would solve that. My dc to DC does about 17 amps at idle. It is rated for 20 amps.

Charging by idling the tow vehicle would be my last choice.

If the tow vehicle is diesel, make sure it is on high idle.

My first choice for a "one off" trip would be to use auxiliary battery to supplement the group 24.

Have fun on the trip.

Frozen water jugs won’t keep frozen food, frozen if the weather is warm enough to need it. IE ice.
Trying to run the whole camper, even sparingly, unless you’re “hyper watting “ lol, for 3 days is real close to impossible.
Running the fridge at all, or furnace or anything else you might have that sucks some power will be a non starter.
But you can use your car to charge the battery, with jumper cables, a couple times pretty easy.

Gjac wrote:
For two days I would just freeze ice jugs and put several in the freezer section and several in the refer section. You start with fully charged batteries frozen jugs, and cold food, while driving you are powering your refer from the alternator. Once the ice jugs melts after several days use the ones in the freezer section. If you use your battery power just for water pump and a few lights you should be fine for several days. When it comes time to replace the battery, replace it with 2 GC batteries wired in series and you will last a week and still be at 50% plus SOC, with your electric refer off.

I love that idea! Realistically, it is just me using it, so not much in it and as I am not a kid, it won't get opened and closed constantly.

ewarnerusa wrote:

swimmer_spe wrote:
...They don't install absorption fridges anymore.

That's what I've gathered from the forums. Followed by grumpy scoffs from boondockers! LOL You mentioned that you're in a one-off boondock situation so not worth investing in any more gear. So you can fire up your tow vehicle and plug in the trailer via 7-pin to get some juice into the battery. Without upgrades to that wire path, it will not provide a whole lot of current for charging. But it is equipment you already have.

How long should I run it for if the battery goes down below 12V?

I do boondock with others, but they have a generator. That generator is not mine, and is not available for this one off time. I do plan to get a generator, but not likely for this trip.

A group 24 battery really is absolute minimum that a builder will put in just to provide the minimum required.

swimmer_spe wrote:

MNtundraRet wrote:
That's about right. You should not be running an electric fridge on that battery. The battery will be shot before the end of the year.

We have no choice as it is a 12v/120v fridge. I typically do not use it on 12v except for while driving.

Your fridge is 12v ONLY. It doesn't run on 120v AC power. I don't know of any such thing as a 12v/120v AC RV fridge. The only RV fridge close to that, are the much smaller 3-way fridges
And many RV manufacturers offer a 2-way propane/electric fridge as an option.

For two days I would just freeze ice jugs and put several in the freezer section and several in the refer section. You start with fully charged batteries frozen jugs, and cold food, while driving you are powering your refer from the alternator. Once the ice jugs melts after several days use the ones in the freezer section. If you use your battery power just for water pump and a few lights you should be fine for several days. When it comes time to replace the battery, replace it with 2 GC batteries wired in series and you will last a week and still be at 50% plus SOC, with your electric refer off.

swimmer_spe wrote:
They don't install absorption fridges anymore.

Who is "they"? There are plenty of makers who install 3 way, absorption refrigerators. You bought the wrong unit for any boondocking. You need to camp with hook ups always.

In fact the situation is even worse than that. It seems you have a fairly large compressor refrigerator and a puny battery. Totally depleting the battery in 24 hours means even an overnight stay at a rest stop or Walmart while traveling is going to be a strain and shorten the life of your battery. You better also hope that when camping with hookups, the power never goes out for more than a brief time.

How much cold food and drink do you need for a weekend trip without electricity? Use an ice chest or get everything cold before your boondocking and then turn off the refrigerator.