Charging battery from Generator

You could do what we do and go a week or better. We run run the gen 2 hours morning and evening to get breakfast, shower and what ever, charging phones and anything needed. In the evening cook dinner, run an electric heater to keep us warm, and keep things charged, and cold. Then at bed time the charge level will hold the night with the furnace set to a level to just keep us warm enough to pottie, warm blankets. Now we do have two batteries but never start to run the charge level down. Three days at less than 12 hours gen time, 6 gallons max of fuel a $20 bill and there is no worry. Now I do see you are north so cold might be a problem and need a little more heat so you might want to run gen late in the evening and as early in the morning as possible, thats is what I do hunting in colder times.

LEN

We used to do a lot of dry camping in our 1990 Winnebago Warrior. Now we mostly use campgrounds. I found that a single house battery (ours was under the hood and so limited in size) could not get us through a weekend if we had to run the furnace. So, I added a second battery in one of the underneath storage bays. Now we can go all weekend without trouble.

Steve

lthrneck689 wrote:
I'm brand spanking new to RV'ng, but have been a boater for many years, spending a lot of time on the hook or a mooring. Conservation is key. It was always the fridge that sucked up battery power. An additional house battery will do great if you have the space, but you always have to use diligence when dry camping. Luxury items such as ice cream may suffer when conserving power, but most food that requires refrigeration does very well if you utilize power conservatively. Of course, a cooler filled with ice will keep that beer cold!

Did the boats have absorption fridges that used propane (or some other fuel), or were they purely electric? I would generally expect that they're not using the same refrigeration technology.

Propane RV fridges do not use a lot of battery power. Mine uses around half an amp when it's cooling and less than that when it's not cooling. It's on the low side, admittedly, as it doesn't have any fans etc. operating as some models do. The secret, if you want to call it that, to the low power usage is that the actual cooling unit is powered by the propane burner, not by battery power, so the electrical usage is only for the controls.

Some RVs do have residential-style refrigerators with electrically powered compressors, and those naturally use a whole lot more battery power.

I'm brand spanking new to RV'ng, but have been a boater for many years, spending a lot of time on the hook or a mooring. Conservation is key. It was always the fridge that sucked up battery power. An additional house battery will do great if you have the space, but you always have to use diligence when dry camping. Luxury items such as ice cream may suffer when conserving power, but most food that requires refrigeration does very well if you utilize power conservatively. Of course, a cooler filled with ice will keep that beer cold!

Running the RV generator to recharge or keep house battery charged depends somewhat on the design of your converter charger. Recent designs may have fast charge rate capability built in. Older designs had quite slow charge rates to protect battery from over-charging while rig is on shore power or when generator is powering the converter charger. You can check the state of charge in your house battery with a simple voltmeter when generator is shut down and engine is not running. You should get a reading of over 12.6 volts with fridge, etc. drawing current with fully charged battery and 13.6 volts with RV generator running, and around 14 volts with truck engine running and RV generator shut down.

What an honest assessment?

I think you have got about a snowball's chance.
Yes, if it the right number Dometic, it might not be too bad.
You don't know how much you will use the water pump, and unless go to bed and get up with the sun and even with LED in all the lights, there is not a real good chance that you will make three days on a single Grp 27 conventional. That size jar is typically 90Ah (Ampere-Hours), and you get to use only the top half without damaging the battery.

Are you aware that recovering a conventional battery from 90 to 100% State of charge will take ~4 hours unless you want to risk all you DC equipment with a higher charge voltage, Then you can make it 3 hours. But, you can get from 80% to 90% in an hour it you have the right stuff in place.

My best bet?
Make a plan. Run you generator either 2 hours every day or 4 hours every other day. Or, just watch the voltmeter. When it gets close to 12.2, start the APU(genset). That way, the house bank is never that far gone, but you also don't get to count on it being 100%.

Matt

nbking wrote:
I plan on a three day trip where I will not have hook ups. I will conserve power because I do not use the TV/DVD, seldom use the lights. The only draw on the new 12 volt battery will be the refrigerator.

I am guessing it is NOT a true "deep cycle" battery. True deep cycle batteries hold more power (because it can be released slower). While they do make true deep cycle batteries that are not easy to find, which is why so many people use 2 deep cycle 6V golf cart batteries. (Easy to find and reasonably priced.)

nbking wrote:
How much time do I need to run the generator to fully charge the battery?

This depends more on the converter/charger you have.

nbking wrote:
Any advise on maintaining the battery fully charged?

After camping, use a battery maintainer on a cheap, mechanical lamp timer and only charge for a couple hours per day.

nbking wrote:
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.

Run the fridge on propane and 12V use is almost nothing.

Recharge time depends on the converter. What make and model is it?


If it is a wfco recharge time may be 7 to 8 hours to get to 95% state of charge, and 3 to 4 hours to 85% state of charge.

Run time with only the fridge staying above 50% state of charge may be 36 hours.

If you plan to boondock on a regular basis consider adding a solar charging system.

On our boondocking trips, we ran the generator a bit during the day for the A/C and charging the batteries, then an hour or so towards eve to cool off (or you could warm up) camper before bed.

The batteries get a bit of charge and you are more comfortable with the temp you want for sleeping ;)

I used a long heavy 30amp extension cord to put the generator back in the woods to not disturb our neighbors or our camping experience.

Turn the fridge to "Gas only" so it doesn't draw on your generator when you run it.

Hope this helps :)