generator charging 12V batteries

[funpro]

Going dry camping in two weeks. If I run my generator an hour in the morning and an hour in the late afternoon will that be enough to keep my batteries charged up.

Two optima 12V batteries. Frig. on gas, heater on gas, hot water on gas. Known battery uses - pump, lights, mandatory whatevers.

[bpounds]

We boondock a lot, so we use the genset a lot. Here are some things I've learned.

Plug your regular shore cord into the genset. Let your onboard converter do the charging. The 12VDC outlet on a genset is just about worthless.

Run your generator at least a couple of times a day, and start on the very first day. Don't let the batteries get down before you try to bring them back up. It is easier to keep them topped up, than it is to recharge from a low state.

Splitting your charge time to morning and evening, or even 3 times a day if you feel like it, allows the batteries to rest between charges, and they will take on charge better than if you try to run once a day for longer.

Make sure your fridge is on propane. No sense using what AC your genset is putting out to run the fridge. Likewise, and even more important, make sure your water heater is on propane only. We never bother using AC on our WH, so the switch is permanently in the off position.

Combine your charging time with other power consuming things, like using the pump to take showers. You'll get a better shower because the pump will run better on the high voltage your converter is putting out, and that is just that much more juice that won't be sucked out of your battery. Same with washing dishes. And if you like to watch movies, a good time for that is while the genset is running.

Small things matter. Like when you first park on your site, leave your truck running and the umbilical connected to the trailer while you operate your landing gear and your put out your slides. Those use major 12VDC juice. No sense losing that juice in the first 5 minutes of your trip. Those motors will thank you too.

All living area lights should be LED. Makes a huge difference in power consumption.

[Parrothead_Mike]

When we used to camp in the infield of Michigan International Speedway for about 4 days I used my little Honda 2000 only about 45 minutes to 1 hour per day and my battery never went below one notch on the panel.

[laknox]

funpro wrote:
Thanks for all your advice. We will be out for 10 days, but don't plan on a lot of battery use. Mostly the occasional use of the pump, and lights in the evening.

Don't forget that there's still parasitic draw from the stereo and gas detectors. Also, fridge and water heater draw power. A good solar setup would be an excellent choice, IMO. It's charging all day long. I know that my el cheapo 45w solar charger from Harbor Freight gives me at least 1 extra day on our annual boondocker and we are fairly heavy users. Yes, we could change our usage profile (use water from the extra water jugs instead of the pump, use battery lights, etc.), but why? That's why we have the FW! 🙂 A 100w panel with a =good= charge controller and a couple good 6v batteries, and you'd be set. Generator use would be minimal.

Lyle

[funpro]

Thanks for all your advice. We will be out for 10 days, but don't plan on a lot of battery use. Mostly the occasional use of the pump, and lights in the evening.

[kopy_kat]

I have two solar panels with a smart controller-this system keeps the charging going all day long-but I do end up using the genie now and again which also brings up the charge.
Have fun!
Larry

[Gearitis]

If no inverter involved, your are fine. Just get outside and have fun. You are camping for Gosh Sakes, if you run out of electricity, then so what? You will probably have a campfire. Go camping and don't worry about the small stuff. If you are taking kiddo's, then spend time with them and not the generator or the batteries. All will be fine.

[valhalla360]

You should be fine for a weekend. Just don't try and use the 12 volt outlet on the generator. It doesn't put out much. Plug in as if you are at a campground.

Realistically, you will only get up to 80-90% of full charge with 2 hrs per day but that's OK.

Assuming it's a pull start generator, your worst case scenario is a dead battery in the morning that you charge back up.

If this is something you are going to do regularly, you should look into your usage more and make sure you aren't being hard on the batteries but for a one off weekend, you should be fine if you keep your usage limited.

[pianotuna]

since optima are a sealed battery it is important to get them to 100% state of charge as often as humanly possible.

Generator charging is not economic to do this, even with agm batteries.

email optima and find out the maximum safe charging voltage.

[AZ_T_T]

No problem!! You shouldn't be using a lot of battery this time of year.

[Crazy_Ray]

You can NOT CHARGE btry in two hours PERIOD. JMO

[NMDriver]

I do not think two hours/day will recharge batteries that are under heavy use, however...I am no 12V guru, (there are several on the tech forum) and, that being said, I will assume you are not using the furnace (it is summer time) and since daylight is lasting until 20:30 or so you will not need much lighting, and your pump does not run constantly, so with those assumptions I believe you will be ok for several days.

You might mention where and for how long you plan on being off the grid.

[KD4UPL]

Depends on the size of the batteries, how much you draw out of them, how large your charger is, how good your charger is, what kind of condition your batteries are in, etc.

[Me_Again]

Are you going to charge via a 40 or 50amp converter? Is the converter a three stage unit that raises charge voltage to 14.5 to 14.8 Volts? Propane furnace will be a big draw. Chris