Electrical questions before boondocking dress rehearsal

[StreaminGeo]

This Thursday we are going on our initial dry camping outing. We’ll be in a state park with no hookups (or even water — pit toilets only) for seven nights. There will be two of us in a 2005 25-foot Safari. I think we’re going to be okay on water and plumbing, and weather shouldn’t be too much of an issue, but I want to be sure I cover the electrical aspect of the experience. Our rig is already equipped with two solar panels and a Heliotrope HPV-22B panel mounted on the wall over the dinette. But although our trailer came with the paperwork for just about every item and system I have nothing on this. Is it as intuitive and easy as most other systems on the trailer? Do I just flick the switch to “dry camping” on a sunny day and the system does the rest? What figures should I look for on the voltage display on the panel?
In addition to the solar system we will also have a Honda Eu2000i generator. We’re not going to be going crazy with the electricity, but I want to keep the batteries charged (I have two 12 volt Interstate Deep Cycle Marine/RV batteries). I understand that I should run the generator for two hours in the morning and two hours in the afternoon to keep my batteries fully charged. Is that correct? Can I run anything else electrical (except AC and microwave), like laptops, water pump for showers, fans, etc. while the generator is hooked up to the trailer?
Is there anything else I need to know?
Thanks!

[alano]

When connected to your generator, you should be able to use any of your AC appliances except A/C. When your not connected to your generator, you should also be able to use any of your DC appliances and even your AC appliances if you have an inverter provided you keep an eye on the state of discharge of the battery.

To keep your battery healthy, you should not run them down more than 50%. Here's a chart that gives you an idea of the battery state of charge based on open-circuit voltage. Be aware that open-circuit voltage is only measured when there is no load on the battery for at least an hour.

There's no hard and fast rule for generator usage. I don't use much electricity in the morning so after the sun has had a chance to recharge my system I'll check my batteries at dusk and see if I need to top them off. Only then will I run the generator until they are topped off.

The one thing that I would highly suggest if you plan on doing a lot of dry camping is to invest in a battery monitor. These devices measure the current into and out of the battery and will tell you at a moments glance the state of charge of your batteries. In my opinion these are essential to using and maintaining your batteries. Take a look at the Trimetric monitor. Happy camping!

[StreaminGeo]

Thanks for the reply, alano. I’ll definitely be looking at that Trimetric monitor.
So I’m correct in my assumption that if I turn the Heliotrope setting to “dry camp” the system will take care of the rest and charge the batteries as much as the sunlight cooperates (and then top off with the generator as necessary)?
Thanks again!

[alano]

I'm not familiar with the Heliotrope HPV-22B but I found info about how to use the "Dry camping" switch at this site. It appears that when you select the "Dry camping" switch, you're allowing the Heliotrope to charge the batteries to 14.6 V rather than 13.2 V. The higher voltage will ensure your batteries will be fully charged with sufficient sunlight, etc.

If you have any doubts the folks at AM Solar should be able to get you a copy of the user manual for this controller.

Since it looks like this controller is no longer supported and the charging profile is antiquated, you might consider upgrading to something like a BlueSky MPPT controller. They have an optional remote (IPN Pro remote) that also features a quality battery monitor.

[StreaminGeo]

Thanks for the great information!

[McDave]

We do a lot of dry camping or boondocking in our 23' Flying Cloud. We have a 160 watts of solar cells. Assuming the solar cells fully recharge the batteries during the day, we have plenty of power to keep the lights going at night until we go to bed, use the water pump as needed, run the exhaust fan over the stove, watch a movie using the inverter, and run the various systems like the refrigerator and furnace that are mainly propane but do require some electricity. Sometimes on overcast days, the solar doesn't fully recharge the batteries, and I give them a little boost with the generator. Sometimes if we want to cook something in the microwave, I'll turn on the generator. But I only use the generator as needed, which for us is once every few days, depending on the weather.

[AWCHIEF]

Last week I spent 5 days dry camping in the Keys. It was very cloudy and overcast a couple of days. My 100watt Renogy suitcase was able to bring the batteries to full charge on the sunny days. It was basically useless on the cloudy days. I was frugal with my DC usage. One LED light on at a time, voltage to fridge and Fantastic fan to try to move some air. No inverter, radio or Television used. I have decided the next purchase is going to be a generator. Fun part is going to be where to safely carry it and extra gas. Might get the propane conversion kit.

[gecko]

Alamo's advice for the Blue Sky controller and remote is an excellent one. Not only does it protect your battery by adjusting proper charge rates, it actually draws more voltage from your panels, effectively boosting your solar. Finally, it will let you know exactly how much of your "battery bank" has been used during the night. As mentioned, you don't want your AGM batteries to ever go below 50% of capacity--that will prolong their life. The Blue Sky also gives you battery status in terms of how many amp hours from full, and this is another excellent guide. It tells you what charge is coming into itself from the panels, and what charge it is currently sending to your batteries. Finally, it tells you both the current battery voltage and whether the system is net minus or plus in charging at that moment. This is very helpful to learn which appliances are using what power--just watch the display, and turn your lights on and off, or unplug your computer charger, etc.

Your refrigerator, even on propane, will be pulling a small amount of amps--times 24 hours! So will your inverter (that converts your dc battery current to AC to run those devices that won't work on DC. And believe it or not, your hard wired propane detector, too.

We just spent two weeks boondocking in a National Park close to the Gulf of Mexico. We NEVER use a generator. When we had four consecutive days of storm or dark overcast, we went down about 80 amp hours--that's as low as it went. Of course, on the second day of gloom, we became more conservative in our electric use by turning off the inverter and our weather station, for example, but full blast on all cabin lights, stereo, subwoofer, both fantastic vents, charging cell phones, etc. With our Blue Sky, we know that our cooktop vent fan draws a fair amount of power, so we just use the more efficient Fantastic vent fan, instead. Sunny days are a whole different story--no electrical conservation necessary for those nights!

We got rid if our two original 12v batteries when the coach was new and replaced with 4 6v AGM Lifelines instead. The 6v are supposed to be more durable for lots of use. The four batteries (two pair each wired together as 12v) doubled our battery bank to 440 amp hours, so at 50%, we have a usable 220. This is most likely twice what you have. And as mentioned, in our worst case scenario, we've only used about one third of our alotted 50%-plenty of margin left. I would only be concerned if we were camping in winter (Lower sun angle generates less light and therefore power in fixed roof panels, plus shorter days and more chance of consecutive gloom.)

Your panels are the next place to look. We have a modest 260 on our roof, which was enough to top off those 80 amp hours deficit in part of the first sunny day with a moderate first day of spring sun angle. Many people are running 400--that will cover even more heavy usage, like running the TV all day!

I hope you'll never have to use your generator! What are those two panels on your roof? Consider adding the Blue Sky so you can self educate on your appliance consumption and you will hopefully have unlimited clean, quiet energy--and not have to lug around the generator, either!

[DonRich7878]

Projected Battery Amp/Hour AH values for 24 hours of dry camping, showing estimated battery discharge rates. Typical stock AS dual 12 Volt system will provide around 100 AH or approximately 2-3 night’s worth of 12 VDC device power. If you add the use of 120 VAC devices, your batteries will be fully discharged in less than 12 hours. If it’s a cloudy day, your Generator will need to run 4-8 hours per day to maintain batteries. Your results may vary..