Can I charge the house battery with a generator in an hour

No.

I second No, but define slow charge. All batteries' charge time is dependent upon:

a) depth of discharge
b) charge amps

“ figure I can run the generator for an hour and charge the marine battery.“

Your wet cell battery will not fully charge in an hour and don’t get fooled by a reading two seconds after you disconnect the charger after an hour. Two hundred bucks of solar gets you very little. Real solar would be the answer.

No again and one battery, no matter how big it is won't power your furnace which is a juice hog. Fridge and HWH yes, Furnace added, no and don't plan on using anything other than lights either

I run 2 Group 31's and I still run my genny every eveinng for a couple hours on econo mode (inverter) and it never tops off the batteries. I might get to 80% charge, thats it.

I understand your reluctance to run the Onan. It's a 3600 rpm screamer = noise.

The fridge and water heater both use 12V from your battery even when running on gas. The fridge uses it for the electronics, and the water heater for the ignitor. Your going to need alot more charge time that one hour!

I agree, the short answer is no. It will take longer than an hour, probably quite a bit longer.

How long it takes depends partly on your converter. If you have the original circa 1988 converter, it probably is a single stage unit and takes somewhere between half a day and a day to come close to fully charging the house battery (though you could get some useful charge in a few hours). Replacing it with e.g. a PD 9200 series converter would help a lot; you could get somewhat near a full charge in a couple or few hours. If you have space, replacing the single marine/RV battery with e.g. a pair of 6V golf cart batteries would increase your usable battery capacity quite a bit and reduce the total amount of generator runtime required.

As a general rule, the last little bit of battery charging takes a lot longer than the first portion. Going from, say, 50% charge to 80% charge is generally a lot quicker than going from 80% to 95%. Even under ideal conditions it's not really practical to charge a lead-acid battery from 50% to 100% or close to that in an hour (for the sorts of batteries generally used in RVs, at least.)

The generator probably uses closer to half a gallon of gas an hour when lightly loaded, by the way.

If you have a good battery combiner setup, you could also use the main engine to charge the battery, and there's at least a reasonable chance it could be quicker as the alternator output voltage is higher than the converter output voltage, and hence the charge amps would be higher. To really know what's going on in any of these situations you'd have to measure the voltage and battery charge current, or have some fancier meter like a Trimetric that measures them and does some figuring for you to suss out the state of charge.

Agree with the others. You might consider buying a second 12 volt battery - cost about $60. If you have enough space two six volt batteries is another alternative.

Hi,

Another NO.

You might be able to use 16.5 volts to charge with the "right" equipment But even then the charge acceptance rate is limited by the chemical reaction. For example, at 85% state of charge the battery can accept only 15 amps--anything more than that merely causes the cells to gas (bubble) excessively.

I'll also say "NO" to a $200 solar charging system. There won't be much money left for the actual solar panel wattage after you purchase a charge controller, wiring, brackets, and other hardware items.

X2 on the convert part. Your converter may only go to 13.6 volts and possibly only see 13.5 or 13.4 at the battery. When the battery is fully charged and the converter goes into float it will sit at 13.2.

There is a big difference in that and an upgraded model that does 14.4 or even 14.8.

I have helped several people in our travels with dead batteries. One guys batteries were so dead and his converter was only able to put out 13.6 v I told him it will take a couple days. After several hours the specific gravity started to rise but he told me my hydrometer was broke and it couldn't possibly take that long. He also said he had been making cakes and stuff with his inverter and four old gc2.

even if you could, it wouldn't be very good for the battery. Let's say you let the battery run down to 50% SOC. To go from 50-85% SOC in an hour would mean charging at about a C/2 rate, a vey high charge rate. getting from 85%-100% is almost impossible to do with most any charger in a hour. that last 10% or so takes a long time since it is voltage limited and hence current limited. So you be at 85-90% the next day, same discharge would get you down to 40% SOC...... to get back to 90% SOC would again mean a C/2 or higher initial charge rate.

so, IMHO the solution is either (A) expect a 3hr or longer charge cycle or (b) add a second battery or best (a) and (b). along with a PD Iota or similar high amp charger.