Charging battery from Generator

PartyOf Five wrote:
Get the fridge nice and cold on AC, then open it as little as possible. We find that draws very little propane

I precool all my food in the house before loading fridge, I pack ice cube bags in the freezer just in case. Very important that you remove any cardboard from packages before you load fridge. Cardboard acts as an insulator and holds heat longer. Also monitor your fridge with a thermometer. I like and follow your idea of keeping door closed as much as possible.

Frig is a two door standard RV refrigerator - Dometic. I assume it is an absorption type. Battery is a Group 27 12 volt Battery from Costco.

You needed to specify whether the fridge is an RV type, cooling on propane or using 110vac power from the house battery(s) through a converter. A 110vac fridge draws a lot of current because of it's compressor, etc. (run time may be only around four hours. If you are using a typical RV propane fridge and little other 12 volt items, you may get 3 days before lights go dim and battery is "dead". Battery capacity depends on the age, condition, and whether battery(s) have been kept charged, not overcharged, and electrolyte levels above the plates. Batteries may need replacing at around 10 year mark give or take.

Get the fridge nice and cold on AC, then open it as little as possible. We find that draws very little propane

If the fridge has a humidity control switch... turn it off.
If battery is a group 27 or larger and you do not use the furnace then three days should be doable.

I recommend a voltmeter to monitor the daily battery level.
Day 1: 12.6 to 12.4
Day 2: 12.5 to 12.3
Day 3: 12.4 to 12.1

If your voltage is dropping out of range you need to conserve even more. Or run the generator for an hour as you cook supper.

As others have said, there's not quite enough information to give an answer; it could be anywhere from half a day to half a week or more before you need to charge the battery, and anywhere from a few hours to a day or so to charge it from the generator (that depends largely on your converter).

Assuming you have an absorption fridge running on propane, the control electronics probably take somewhere around 12 Ah or so per day. If it has some sort of climate control system (to keep the door seals from freezing shut) that consumes a good bit more power and should be switched off if possible.

A residential fridge uses somewhere around 75-100 Ah per day as a very rough guide (but, of course, no propane).

Incandescent lights use maybe 1-2 Ah apiece per hour they're used, depending of course on the wattage of the bulb(s). LEDs use a lot less.

The furnace uses a good bit of power when it's running, and none when it is not.

The water pump uses a few amps, but runs so little that it's basically negligible.

The propane detector and carbon monoxide alarm and similar phantom loads might use a couple Ah per day, more or less.

A typical 12V battery used for RVs has about 40 to 50 Ah of usable capacity before it ought to be recharged. A pair of 6V golf cart batteries has a little over 100 Ah. Both of these are to around fifty percent charge.

I have two golf cart batteries in my motorhome. I can go about a week with just the fridge and a few lights etc. without too much trouble before they need charging. With moderate furnace usage overnight, it's closer to two or three days. A few hours of generator usage (thanks to a modern multistage converter) will bring the battery bank up to nearly a full charge. The last little bit takes a lot longer and at least for me is not worth worrying about on generator power.

Heater is the biggest draw on battery and many would argue that one day is about all you get from your single battery during the winter. Most Class C's come with one 12 volt battery (usually type 24) - you should consider adding a second 12 volt battery (about $70 at Costco) if your dry camping. Not sure how long it takes to recharge using your on-board generator but make sure start the vehicle engine before you try and start the generator ... will put all your batteries on-line to help start the generator and help prevent you from being stranded in the middle of no-where with dead batteries.

Your water pump will draw also as well as your gas safety alarms. I've gone 2 nights on just one battery without recharging. Have no idea if that's maximum.

Refer type? Absorbition or residental? Battery type?
Your question is like asking how far can I drive on a tank of gas with no information given.