How to estimating Boondocking Power needs?

[SteveJ.]

Originally Posted by kdauto

I think your idea of trying it at home is the best and what I recommend to most folks to start with. No one uses power the same as the next.

If your battery is the original one I strongly suggest testing it or have it tested. Many of the original ones are toast after a few seasons. Check the water level if its FLA (flooded lead-acid). Best thing and cheapest is when that battery dies replace it with at least 2, either golf cart batteries (6V) in series or 2 12V in parallel. We went with deep cycle AGM for our use, plenty of threads on that in the solar forum.

A simple LED voltmeter will give you an idea of your current state of charge. No need to start big with all sorts of fancy monitors. If you're handy you can get one off Ebay and wire it in for well under 5$.

Next best is get an extra solar panel. The folding type are less efficient than a good monocristalline one but will help immensely.

As an example, we run a 32' 5th wheel with 3 batteries, 450W total of solar,a 5000W pure sine inverter and a cheap solar controller. Everything except A/C will run and for decent periods too. We run 2 CPAPs each night, watch TV with surround sound on several hours before bedtime,hot water showers etc.

Use logic and practice at home doing what you want, you'll get a quick handle on it. I kinda wish we'd find only boondocking spots up here but they're rarer than hen's teeth. I now loathe getting out cables, hoses and such AND having neighbours 10' away.

A note concerning the above post:

Portables do come in monocrystalline, mine are. Renogy and some China cheapo.

[NYJoe]

Thanks for the comments.

[stinespool]

The best thing I've done is add battery's.Had 2-6 volts in our old rig and added 2 more. 100 watt solar panel and that solved all our boon docking power issues. Our new to us rig has 4-6 volts and we added 175 watt solar panel. all we use the geni for is AC or microwave.

[rarebear.nm]

The answer is it depends.

There are too many differences in RV and our individual power usage (profiles) to consider one person's solution will work very well for you. If you want to just shotgun a solution that's one option. If you want something that works for you, you need some real data. Basically you need to collect real usage numbers how many watts every 12 volt device takes and a best estimate how many hours per day you use each device. Multiple the watts x hours to get watt-hours. Next total the watt-hours. Then convert to amphours by dividing the watt-hours by 12.4 or so (average voltage). This is based on Ohms Law (watts = voltage x amps or amps = watts/voltage). Now you have a realistic estimate how power you use in a 24 hours period. You do not have to measure over a full 24 hours period.

In order to get a good reading of watts used, you need to install a decent shunt based battery monitor. You can't get useable data with a voltmeter. There are several on the market as mentioned above and another is a Bogart Trimetric 203 RV monitor. If you are going to boondock you'll need this type of device sooner or later.

As others have said add to your battery capacity. Standard are 2 or 4 six volt golf cart type batteries. These will hold up much better than most deep cycle batteries. These are usually lead acid flooded batteries. On each basis figure at least $110/each. There are nicer solutions for more money.

Then you need to be able to recharge the batteries. In boondock mode that means either solar and/or an inverter generator. Many have and use both. There's an old myth that solar does not work on cloudy days. This may be true for low end systems. But is a BS statement about solar. I have not used a geni or shore power to recharge batteries for five years. Last week we were out with heavy clouds and rain all day and the solar recharged the batteries by about 1:00PM. I've seen 100% recharge on cloudy days with 1/4-1/2" of snow on the top. Not all solar systems are created equal.

There are great regions for solar and others are not as friendly. Without knowing where you want to camp and your power profile, it's difficult to recommend very much. Keep in mind its very rare to ever get the rated wattage from a solar panel. Those numbers are calculated in an idealized lab setup. You can use a portable solar setup, but you may wind up babysitting the panels for a few hours per day. That may or may not work for you. Otherwise panels get mounted on the roof. They can be flat or made to tilt for the sun angle. If flat try to add about 30% more capacity to offset the loss from angled panels. Panels are getting cheap. I see some for around $0.50 per watt.

As for a generator, if you do not need it for AC or the microwave, you easily get by with a 1,000 watt model. If you also want it to power AC or a microwave you'll need at least 2,000 watts and closer to 3,000 is better. Keep in mind IF you camp at higher elevations a geni losses about 3% of rated output per 1,000 increase in elevation above sea level. I live at 7,000 ft and may camp at 10,000 so I bought a 3,500 geni to get enough capacity at elevation. Honda's are great but costly but very quiet. I use a Champion 3500 with remote start, somewhat louder but lots less expensive.

A word about recharging from a geni, you can get back to about 94-97% fairly easily, but 100% takes a lots of run time. For best battery health they need to get back to 100% fairly often. Many solar systems are able to reach 100% on a daily basis if the system was designed well.

In short either use a guess or someone else's setup or get real data that you cab build the right system for you.

[SteveJ.]

Originally Posted by rarebear.nm

The answer is it depends.

There are too many differences in RV and our individual power usage (profiles) to consider one person's solution will work very well for you. If you want to just shotgun a solution that's one option. If you want something that works for you, you need some real data. Basically you need to collect real usage numbers how many watts every 12 volt device takes and a best estimate how many hours per day you use each device. Multiple the watts x hours to get watt-hours. Next total the watt-hours. Then convert to amphours by dividing the watt-hours by 12.4 or so (average voltage). This is based on Ohms Law (watts = voltage x amps or amps = watts/voltage). Now you have a realistic estimate how power you use in a 24 hours period. You do not have to measure over a full 24 hours period.

In order to get a good reading of watts used, you need to install a decent shunt based battery monitor. You can't get useable data with a voltmeter. There are several on the market as mentioned above and another is a Bogart Trimetric 203 RV monitor. If you are going to boondock you'll need this type of device sooner or later.

As others have said add to your battery capacity. Standard are 2 or 4 six volt golf cart type batteries. These will hold up much better than most deep cycle batteries. These are usually lead acid flooded batteries. On each basis figure at least $110/each. There are nicer solutions for more money.

Then you need to be able to recharge the batteries. In boondock mode that means either solar and/or an inverter generator. Many have and use both. There's an old myth that solar does not work on cloudy days. This may be true for low end systems. But is a BS statement about solar. I have not used a geni or shore power to recharge batteries for five years. Last week we were out with heavy clouds and rain all day and the solar recharged the batteries by about 1:00PM. I've seen 100% recharge on cloudy days with 1/4-1/2" of snow on the top. Not all solar systems are created equal.

There are great regions for solar and others are not as friendly. Without knowing where you want to camp and your power profile, it's difficult to recommend very much. Keep in mind its very rare to ever get the rated wattage from a solar panel. Those numbers are calculated in an idealized lab setup. You can use a portable solar setup, but you may wind up babysitting the panels for a few hours per day. That may or may not work for you. Otherwise panels get mounted on the roof. They can be flat or made to tilt for the sun angle. If flat try to add about 30% more capacity to offset the loss from angled panels. Panels are getting cheap. I see some for around $0.50 per watt.

As for a generator, if you do not need it for AC or the microwave, you easily get by with a 1,000 watt model. If you also want it to power AC or a microwave you'll need at least 2,000 watts and closer to 3,000 is better. Keep in mind IF you camp at higher elevations a geni losses about 3% of rated output per 1,000 increase in elevation above sea level. I live at 7,000 ft and may camp at 10,000 so I bought a 3,500 geni to get enough capacity at elevation. Honda's are great but costly but very quiet. I use a Champion 3500 with remote start, somewhat louder but lots less expensive.

A word about recharging from a geni, you can get back to about 94-97% fairly easily, but 100% takes a lots of run time. For best battery health they need to get back to 100% fairly often. Many solar systems are able to reach 100% on a daily basis if the system was designed well.

In short either use a guess or someone else's setup or get real data that you cab build the right system for you.

Lots of good easy to understand data there.

Let me chime in on portables as a four year user. Unless I'm dealing with moving shade in a somewhat heavily wooded setting, portables are pretty much set and forget unless you are in a situation where you need all the charge that you can possibly get(virtually never for me).

They do give you the option to park in the shade and put the panel(s) in the sunny part.

[n2zon]

How long do you plan to camp dry at a time? A week? Two? That makes a real difference. For a week, 2 large 12V AGM batteries with a couple of generator hours plus solar *just* got us through a week with a few cloudy days last year. Three lead acid batteries got us through a week fairly reliably, but with more generator hours. Propane fridge, minimal lighting, pumped about 65 gallons of water, no furnace or other 12V use except infrequent inverter use (less than an hour a day) for phone an computer charging.

[SteveJ.]

Originally Posted by n2zon

How long do you plan to camp dry at a time? A week? Two? That makes a real difference. For a week, 2 large 12V AGM batteries with a couple of generator hours plus solar *just* got us through a week with a few cloudy days last year. Three lead acid batteries got us through a week fairly reliably, but with more generator hours. Propane fridge, minimal lighting, pumped about 65 gallons of water, no furnace or other 12V use except infrequent inverter use (less than an hour a day) for phone an computer charging.

It all depends on what you use and what can be put back in. I'm good with no solar for 2-4 nights on one flooded group 29 battery. My daily average is 15-25 amp hours. The upper end of that range would be running the Fantastic Fan and/or furnace for a bit.

I/we camp in a class b van that is somewhat optimized for boondocking.

[kdauto]

Originally Posted by SteveJ.

Lots of good easy to understand data there.

Let me chime in on portables as a four year user. Unless I'm dealing with moving shade in a somewhat heavily wooded setting, portables are pretty much set and forget unless you are in a situation where you need all the charge that you can possibly get(virtually never for me).

They do give you the option to park in the shade and put the panel(s) in the sunny part.

I think the babysitting issue with portables is that you don't want to leave that there while you wander off to explore,exercise or whatnot. Pretty easy to steal or get knocked over in strong winds vs roof mounts.

[ByeTheWay]

600 watts of solar is a good starting place, unless you have a residential fridge. If your running your gen more than you like add some more panels. You will need a battery monitor with a shunt. Some like to buy the monitor first. That just wasn't my style.

[SteveJ.]

Originally Posted by kdauto

I think the babysitting issue with portables is that you don't want to leave that there while you wander off to explore,exercise or whatnot. Pretty easy to steal or get knocked over in strong winds vs roof mounts.

Good points. When gone from the site(which is pretty much every day) I will tuck the panels by some protection or lay them down flat. I have had them blown over, thankfully no rocks or other protrusions were where they landed.

As far as theft, I'm out for about 4+ months per year, mostly out west, and have not had an issue. I do attempt to have them deployed in an inconspicuous manner though not always or even usually possible. I do have a cheap chain and lock to prevent casual theft. If someone really wants them they will get them. For a couple hundred bucks I can replace them easily if they do grow legs.

For my style of camping, ease of "install", and light electrical demand, I'll stick with portable. Everyone's needs and wants do vary.

[rarebear.nm]

As I frequently say, good solar installs are customized to the owner's needs and usage.

We are on the road moving many days and need to get back to full recharge while on the road. Thus roof top panels is our best solution.

[SteveJ.]

Originally Posted by rarebear.nm

As I frequently say, good solar installs are customized to the owner's needs and usage.

We are on the road moving many days and need to get back to full recharge while on the road. Thus roof top panels is our best solution.

Yup.

[Mr_D]

My rig is very power hungry. Home Jenn Air refer/freezer. Sat TV receiver and 2 wireless Joey's, 3 TV's, AquaHot for heat although I only run the elec elements when on shore power, only a few standard lights left. 400 watts solar (not enough, but that is the option it came with). Anyway I ran the gen for about 4 hrs a day. Used about 30 gallons of diesel in 2 weeks but that included hot water and heat. Temps were only in the mid 60's in the day and near freezing at night in Quartzsite earlier this year. If I was going to boondock much I would look into more panels and higher efficiency units since mine are from 2008.

[astrocamper]

To get back to opening post. I would start with a decent battery system plus a Victron Energy BMV 712 to monitor your batteries system state of charge and the flow of amps into or out of the batteries.

You will then know your power draw of your devices and can conserve your battery charge by limiting usage or add options to charge your batteries such as solar or generator.