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cb750 05-31-2021 05:19 PM

Boondocking - Batteries and Generator Plan
 
Hey folks,

I'm one month in to full-time rving. Campsites are great, but the only thing holding me back from boondocking is electric. I work remotely so I do need reliable electricity.

I just wanted to run my plan by some other rv'ers and see if I have any gaps.

I use about 125 amps a day - and that is a generous allocation. That is leaving my laptop, phone, and two wireless routers plugged in for 8 hours. Heating and refrigerator are on propane, I don't use hairdryers, microwave, or AC.

I therefore bought 2x AGM 190 Ah batteries. This gives me 190ah per day. The store I bought them from seriously recommended not running them down to 50%, so at 125amps a day I am under that limit.

I have a 2000w inverter.

I have a 6.5kw Onan generator that puts out 54 amps.

Question: Do I need solar panels? The shop I bought the battery from said I'll be running the generator for ten hours to recharge those batteries. Really? I thought it would be 4 hours at most (54 amps x 4 hours. Does that make sense or am I stupid?). They recommended purchasing solar cells, but unless I have 500+ watts of solar, what difference is it going to make to that 10 hour estimate?

Question: I found a good guide online for wiring the batteries to the inverter, but how do I include the generator in the circuit?

All input is appreciated! Thanks :thumb:

lockinload 05-31-2021 05:40 PM

You need a 2000 watt generator, it will run 6 hours on a gallon of gas, keep your bats topped off and supply you with all the amp hours you need...less AC. The Predators are good little units and very quiet.

Nwcid 05-31-2021 05:53 PM

There is a lot to unpack there.

You have 3 parts and a decent understanding so far.

Part 1: Use. You have identified that in a 24 hour period you use about 125 AH of power. How did you come up with that number? I am not saying you are right or wrong, just curious.

Part 2: Storage/reserve = batteries. You said you bought 2 AGM batteries of 190 AH. Are these 6 volt or 12 volt? If they are 12 volt then your 125 AH use is well under the 190 useable AH. If they are 6 volt, you might need more batteries.

Part 3: Recharging/refilling. There are many ways to accomplish this.

Your generator (sounds like one you already have) is 6500 watts which = 54 amps at 120 volts, not 12 volts. This is WAY more power than you need considering what you said you use. The best way to incorporate a generator into your system is by plugging the trailer into the generator with the shore line. Your onboard converter will charge your batteries. You do not say what unit you have, but most charge at 30-60 amps (of 12v). In theory, if you use 120 AH of your batteries, and you charge at 30 amps it would take 4 hours (4 x 30 = 120) to fully recharge. However that is theory since batteries do not charge at a constant rate. If your converter does not charge at a high enough rate for you then you could buy one with a higher output or get an inline inverter/charger that has a high output charger. My Magnum has a 125 amp charger. The other thing about using the generator plugged into the the RV is that you will be using the power from the generator to both charge your batteries and power you work equipment, just like on shoreline power.

Now for solar. Solar is nothing more than another way to charge your batteries. For every 100 watts of solar you get about 5 amps of charging at peak performance. Peak is typically considered to be around 6 hours a day, but it depends on where you are and the season.

At 125 AH/day you are using an average of amps, which seems a little on the low side to me, but it is possible. Obviously when you are working you are drawing more power than at night. If you add 500 watts of solar you would be charging at 25 amps (of 12 volt) during peak times. This would need 5 hours to refill the 125 AH you used (see above math). You would also need to account for how much power you are actively using. If you are drawing 10 amps during the day and making 25 amps, that only leaves 15 amps for charging. Now 125 AH used would take 8.3 hours to charge.

I also telework and we mainly boondock, so we are rarely plugged in. I have 2 laptops along with dual monitors. Of course routers, phones and other daily stuff are often on. This puts me drawing between 20 and 25 amps while working. My solar system puts out about 50 amps at peak. This is enough to keep my batteries up and power our use. In spring/fall or cloudy (smokey in the PNW from fires) there is not usually enough sunlight to keep up. When this happens I typically run the generator, which powers the 125 amp charger, for an hour or so in the morning and an hour or so in the evening. My built in generator is not loud, but the sound of silence from solar is very nice. I hope this helps.

djc290 05-31-2021 06:04 PM

I agree with the comment about adding a portable 2000w quiet inverter gen. I carry one when boon docking, a WEN 2000, about $400, runs about 10-12 hrs on a gal of gas and keeps the batteries charged as well as supplies all common usage all day. I have a 40' DP with a 8K gen and solar, but find that running the little 2000w makes life easy.

astrnmrtom 05-31-2021 07:24 PM

Solar certainly helps. One common thing that people don't realize when charging lead acid batteries is as the charge level increases, the amount of amps the battery can accept goes down. That last 10 percent of charge takes the longest. I have a 100 amp charger, and in the morning when I fire up the generator I can watch it push over 75-80 amps into the batteries. After a little while it's dropped to 45 amps, then 35, etc. By the time the batteries are at 95% the charger is only putting in 5 amps so that last few amp hours of charge takes a while.

I've been full timing for almost a year with some boondocking with 600 watts of solar, a residential refrigerator and 470ah of AGM batteries. On good days the solar will charge me to 100%, but for the most part, I've settled into a routine of using the generator twice a day. In the morning I'll run it for about a hour to dump maximum amps into the batteries for the bulk charge, then let the solar top them off. I'll usually want to use the coffee pot and toaster oven for breakfast anyway, so why not put some amps into the batteries? I'll then run the generator before bed for a while to top the batteries off for the night, usually shutting it down at 10pm. My batteries will be around 75-83% by morning. Where this changes, is if you are using Lithium batteries as they'll accept their rated charge amps at a pretty constant rate without tapering off as the charge level rises.

My routine varies with the weather, time of the year, and local horizons. We watch some TV in the evenings, and if we want to conserve, we use tablets instead of our laptops. My laptop is a gaming laptop and can be a power hog, so I'll only use it when the generator is running when boondocking.

One thing about solar is; once it's installed, there's nothing to do, nothing to start, nothing to fuel, no oil to change, and it's silent. The down side is it relies on the sun and puts out zero after the sun goes down. Thick clouds can be an issue too.

Another very common mistake people make when calculating for solar is they do simple gross amps of load vs maximum amps of solar in. Even figuring out 5 hours of good sunlight, people forget that of whatever amps the panels are putting out, stuff running during the day strips some amps off the top leaving you with less net charging power going into charging the batteries. You can overbuild your solar system to compensate for shorter days, higher loads etc, or just use your generator for balancing it out.

There's been times I've considered adding more panels but I just can see where it would be worth the cost and effort. Supplementing with some generator time works very well. There have been a few campground we've stayed at that have very limited generator hours but even these haven't caused any problems unless the weather is bad, but even then we've gotten by without taxing the batteries.

Re: wiring the generator. If it's built in, it's already wired properly with a transfer switch and will charge your batteries when you run it. Solar will be hooked to the batteries direct, in parallel with the onboard charger. They should all play well together. Mine do.

No matter what you do, get a battery monitor. That's the only way to really know what's going in and what's going out. Another thing to note is even though your refrigerator runs on propane, it's controls take 12v. furnace blowers can draw 10 amps when running. Then there's propane leak detectors, and other small draws that you might not be aware of. Many modern electronic devices like TVs don't really turn off when you hit the off button, they go into a standby mode which draws a constant, albeit small load. All these little loads add up.

Without a battery monitor the only way to really know your battery's true state of charge is with a hydrometer, and if your batteries are sealed, you can't use one. You can get a ballpark idea by battery voltage but even that is only accurate if the batteries are disconnected from a load and left to rest a while.

Crasher 05-31-2021 07:48 PM

One more vote for the 2KW generator. It feeds a 40 amp smart charger and is independent of the solar or coach generator so it's never overloaded. I set if away from the coach so no noise. Only 1 gallon of gas for 8 hours of charge. My monitor tells me I am rarely below 65% charge.

PS56 05-31-2021 09:17 PM

Quote:

Originally Posted by cb750 (Post 5773389)
Hey folks,

I'm one month in to full-time rving. Campsites are great, but the only thing holding me back from boondocking is electric. I work remotely so I do need reliable electricity.

I just wanted to run my plan by some other rv'ers and see if I have any gaps.

I use about 125 amps a day - and that is a generous allocation. That is leaving my laptop, phone, and two wireless routers plugged in for 8 hours. Heating and refrigerator are on propane, I don't use hairdryers, microwave, or AC.

I therefore bought 2x AGM 190 Ah batteries. This gives me 190ah per day. The store I bought them from seriously recommended not running them down to 50%, so at 125amps a day I am under that limit.

I have a 2000w inverter.

I have a 6.5kw Onan generator that puts out 54 amps.

Question: Do I need solar panels? The shop I bought the battery from said I'll be running the generator for ten hours to recharge those batteries. Really? I thought it would be 4 hours at most (54 amps x 4 hours. Does that make sense or am I stupid?). They recommended purchasing solar cells, but unless I have 500+ watts of solar, what difference is it going to make to that 10 hour estimate?

Question: I found a good guide online for wiring the batteries to the inverter, but how do I include the generator in the circuit?

All input is appreciated! Thanks :thumb:

When you get into boondocking you are going down the rabbit hole and need to learn a great deal.

You work remotely and I wouldn't risk my job by not being prepared.

For full timing and working remotely I would have gone with a different set up.
Some things to consider and research.

Solar panels with controller - yes - consider being able to raise them toward the sun. Understand the relationship as to latitude and time of year. Solar panels have come down greatly in price. You don't have to go full solar or full generator, they work together.

Batteries - Lithium

Inverter - close to batteries, proper size wires, on/off switch

PS - heating overnight - fan on/off uses energy and you may not want to run the generator at that time.

TV and/or Sat'l TV?

Biljol 05-31-2021 09:27 PM

My opinion on solar......you can buy a lost of gas for one panel.

Santan solar has 250 watt panels for 40 right now but for 40$ you can get 20 days of more power from a 2000 watt genny.

You of course would also need to by the charge controller and wire and ........

If you want to go green and not have a genny running get the solar but bang for the buck I think a small genny has it beat.

Bonus the small genny can run a ac unit with a soft start.

paul65k 05-31-2021 09:41 PM

Quote:

Originally Posted by Biljol (Post 5773708)
My opinion on solar......you can buy a lost of gas for one panel.

Santan solar has 250 watt panels for 40 right now but for 40$ you can get 20 days of more power from a 2000 watt genny.

You of course would also need to by the charge controller and wire and ........

If you want to go green and not have a genny running get the solar but bang for the buck I think a small genny has it beat.

Bonus the small genny can run a ac unit with a soft start.

While all these points are accurate what I believe needs to be taken into account is the charge characteristics of using the generator to charge LA batteries......those 20 hours are really more like 30 - 35 to get them to 100% ;)

The other great thing about using solar to charge RV batteries is that is is completely passive.....no reason to start, monitor and eventually stop....not to mention the "Are they charged yet" factor ;)

Nwcid 05-31-2021 09:47 PM

Quote:

Originally Posted by Biljol (Post 5773708)
My opinion on solar......you can buy a lost of gas for one panel.

Santan solar has 250 watt panels for 40 right now but for 40$ you can get 20 days of more power from a 2000 watt genny.

You of course would also need to by the charge controller and wire and ........

If you want to go green and not have a genny running get the solar but bang for the buck I think a small genny has it beat.

Bonus the small genny can run a ac unit with a soft start.

For the foreseeable future a generator will be the most cost effective. Even if if you only have 1-2 batteries you are trying to maintain and basically run the daily stuff off of a small generator.

For me the quiet and the "let it do its own thing" are invaluable to me. I never have to think about do I have enough charge or did I leave the lights on etc. I forgot to switch my fridge from AC to gas and while my batteries did get a good work out my solar mostly kept up with it. I park at home and I do not have to run cords, I just unhook.

Sure "green" is nice, but I do it for me and the way I want to travel/boondock.

Biljol 05-31-2021 10:44 PM

Quote:

Originally Posted by paul65k (Post 5773717)
While all these points are accurate what I believe needs to be taken into account is the charge characteristics of using the generator to charge LA batteries......those 20 hours are really more like 30 - 35 to get them to 100% ;)

The other great thing about using solar to charge RV batteries is that is is completely passive.....no reason to start, monitor and eventually stop....not to mention the "Are they charged yet" factor ;)


I would not be using LA one of the first things I would change on any coach. So the switch to lithium would get you charged in a 2-3 hours.

BTW most solar geeks would say lithium and solar goes hand in hand, your fighting a loosing battle with LA and solar too many charge cycles.

Biljol 05-31-2021 10:50 PM

Quote:

Originally Posted by Nwcid (Post 5773720)
For the foreseeable future a generator will be the most cost effective. Even if if you only have 1-2 batteries you are trying to maintain and basically run the daily stuff off of a small generator.

For me the quiet and the "let it do its own thing" are invaluable to me. I never have to think about do I have enough charge or did I leave the lights on etc. I forgot to switch my fridge from AC to gas and while my batteries did get a good work out my solar mostly kept up with it. I park at home and I do not have to run cords, I just unhook.

Sure "green" is nice, but I do it for me and the way I want to travel/boondock.


So what’s your plan if it’s cloudy for a week at a time and the solar has 10% output?

Do you just let it do it’s own thing or are you still monitoring the charge “in case” you need to plug in or run the genny.

Don’t get me wrong solar is great for a lot of people but I will never believe that “hey I put solar on so I don’t need to monitor the charge level any more” too many things can go wrong between no sun, bad connection, charge controller goes out, ect.

mr.tommy 06-01-2021 04:39 AM

Quote:

Originally Posted by djc290 (Post 5773448)
I agree with the comment about adding a portable 2000w quiet inverter gen. I carry one when boon docking, a WEN 2000, about $400, runs about 10-12 hrs on a gal of gas and keeps the batteries charged as well as supplies all common usage all day. I have a 40' DP with a 8K gen and solar, but find that running the little 2000w makes life easy.

If you could please, I'd like some clarification on how you hook up and use your WEN 2000
1) Your 50amp like us, so do you just use a dog bone adapter to plug your 50amp cord into that steps down to a 120V plug and plug right into the WEN 2000

2) If above is true, once hooked up and Gen is running, what can you/do you run in the coach

3) How many amps does the WEN 2000 bring into the coach

4) I see that the WEN 2000 has some parallel ports, a ground outlet and others. Do you use any of these other ports and if so how

5) Is the onboard inverter a Pure Sine

Just trying to understand the real daily application of how you use it and what can you power with it

A LITTLE BACK GROUND:
We spend summers in the Northeast and live off 15amps by plugging into a 15amp garage outlet that's available to us. We use a dog bone to step down and use and extension cord. It's totally enough energy because we don't need to run AC and we just manage our power. Once in awhile we'll forget and turn a couple of to many things on at the same time and pop a breaker but then we just go and reset it. By being plugged in, our batteries are always being charged like they normally would be, our propane/electric fridge is always running on electric, we watch TV/Netflix every night etc etc. I mean it's amazing how much we can run off 15amps.

But I have been looking for a back up system (other than solar) to produce power to the coach either to produce more power than 15amps when really off grid, or in an emergency—like last winter when ALL power was out in Texas. I would normally use my onboard Onan 5500 onboard genny but looking for alternatives. I like what I'm hearing about the WEN 2000.

Mark_K5LXP 06-01-2021 07:33 AM

I don't think the power requirement is out of line for what he's trying to do. 125Ah over an 10 hour period amounts to 150 watts, which I could easily see being soaked up by a PC, monitor, networking, a few other gadgets and some lights over the span of a work day. Maybe there's some economy to be gained there by optimizing the system with different lower power hardware but I don't think it'd get a lot lower than that.

You could throw a bunch of money at this in the form of overkill solar and a huge bank of lithiums. It would probably work fine. But it would also easily be more than a handful of thousands of dollars. That's up to cb750, he can do whatever he can afford.

I don't count on solar any further than I can throw it. I take what I get but generally the genset gets run every other day or so no matter what. It comes down to economy vs utility. Given that this is "work" and presumably there is no option for "later", I would lean towards a larger battery bank and a genset, because it only takes a cloudy day or two to make you run the genset anyway. Solar is great when you can live dynamically to adjust your usage but to create a solar system reliable enough for my daily livelihood is an expensive proposition. There's probably a compromise between solar capacity vs genset only but only cb750 can make that call.

Mark B.
Albuquerque, NM


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