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Old 03-28-2004, 08:55 AM   #11
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Wow…I stay up on Alternative energy info pretty seriously …I haven’t heard anything about the charge controller being outdated.

Kevin, the Solar Boost 2000E I have is an MPPT controller.

The one I’ve got is rated for 25-amp peak power, because that’s more than enough for my needs …that link you gave if for a controller rated at 60 amps …

My 25 Amp MPPT controller could handle 3 300-watt panels if I needed …that’s a lot of wattage Kevin.

My controller only cost 200.00 versus the one you’re looking at which costs 485.00.
If you’re going to run a 24-volt system you’ll need a controller that can handle that …the 485.00 one will …mine wont. But I can’t imagine why anyone living in a bus or RV would need a 24-volt system anyway.

Since you say you’re mostly going to be lighting your rig with LED & Propane lights …and are setting up the rig to be energy efficient. Stick with a more inexpensive charge controller, like the one I’ve got. You’ve got 25-amps of peak power input, plus it’s got the same 30% increased output ability the more expensive charge controller has.
The only real difference in the 2 controllers is one has a 25 amp peak power capacity and the other has 60 amps.

Just figure out what size panels (output amperage) you’ll be installing and buy the appropriate charge controller.

Michael
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Old 03-28-2004, 12:59 PM   #12
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Hi Kevin,

Given the capacity of the battery bank(s) you're suggesting what the heck are you going to charge that with? Unless you're in a specific region where you have an incredible amount of sunshine and lots of solar panels or are in an extremely windy area something other than sun and air is going to be needed to replenish capacity of that magnitude.

Three weeks is extreme unless you're really not using electricity for much of anything. Remember, the capacity of your batteries is approximately 35% (to 40% max) of rated amp-hours. If you use only 100 amp-hours a day (that's being pretty conservative) for three weeks you need 2100 amp-hours...that's means you should have 6300 amp-hours of capacity in your batteries (that's 18-pair of Trojan L-16's).

Or put the other way three pair of Trojan L-16 batteries (just using them as examples) will give you 1080 amp-hours of total capacity; about 378 amp-hours of useful capacity. For 21 days that's 18 amp-hours per day; that's so low it's not worth the money invested to get it (honestly!).

None of my comments are meant to be discouraging! But you must be realistic and look at the system as a whole. Don't get so stuck on one idea that you don't keep exploring others; there are lots of answers to the same questions. Just look at the number of products on the market! And, don't get caught up in the typical American 'bigger is better' mentality; often times bigger is just bigger. You can easily spend $100,000 on a massive stereo system; most of us would probably label that overkill. Plan a system to meet your needs, don't just go by (or buy) what you can afford.

If you can find (buy or get from the library) Nigel Calder's Boatowner's Mechanical & Electrical Manual you will learn much about what it takes to put a balanced and realistic system together. Offshore sailboats have dealt with these issues (particularly that of independence) for years and years and there are lots of solutions from the marine world that apply to being off-grid in a rolling home. Most U.S. RV's are designed to handle a weekend or a week away, or to travel from campground to campground. They're meant to be easily (read cheaply) constructed and very little of what's in the average RV is worth putting in a long-term, off-grid live-aboard rolling home.

You're researching and hopefully having fun planning; it doens't get any better than that!
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Old 03-28-2004, 02:39 PM   #13
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Amen Les….

Kevin, Here’s something REALLY important that I learned years ago about Alternative Energy for mobile applications.

You cant look at this from a ‘stick house’ ( semi-large non-movable home) point of view.
When you’ve got a House , you can do all sorts of fun & fantastic Alternative Energy stuff…you’ve got the room for huge banks of batteries that can store the power you’ll need for 3 weeks of non-optimal solar gain situations.
But, unless you want to give up most of your weight carrying capacity in your rig to a huge and extremely heavy bank of batteries…you just cant expect to do what you want here.

3 weeks is asking a lot.


Be realistic about this…look into getting a couple of decent sized Solar Panels, whose output will run a few things and put some juice back into your system. Keep your battery bank reasonably small …you really just don’t need a huge storage bank , even in a big rig.
Use a small energy efficient generator to charge the batteries during rainy periods …and the wind generator when applicable.
Lot’s of RV folks who spend most of their time Boondocking get by really well with one 300-watt panel ,3-4 batteries and a small generator…they’re able to live quite comfortably every day, watching their satellite TV , running all their lights etc.

Even if you’re looking at this from an ‘Expandability’ point of view…remember you’ve only got so much room in any sized rig to expand.
You don’t want to go overboard …and have a rig that’s too heavy to move around much. That defeats the whole purpose of having a house on wheels.


Kevin it’s hard sometimes …I understand completely what you’re trying to do here. Millie & I’ve been living with and around so-called Alternative Energy for a LOT of years. I Love the stuff.
But, sometimes what works well in a stick house situation doesn’t really cross over to what works best in a Bus or RV.
Our ‘Homes’ are reasonably energy efficient already…their small compact homes that use a very small amount of electrical power to run themselves…compared to even a tiny stick house.
You just don’t need a giant and expensive alternative energy system here…to live off the grid well.

There's a few other good books on this sort of thing...
RVers' Guide to Solar Battery Charging by Noel & Barbara Kirkby
RV Electrical Systems by Moeller

And a REALLY GREAT book called 'Sailing the Farm' by Ken Neumeyer...he's got some Very good info and projects for building small solar water heaters , ovens & solar water purifiers.
He lives on a small sailboat...so all the projects are small enough to fit into a Bus or van.
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Old 03-28-2004, 09:09 PM   #14
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Hi Kevin,

Let me take another slant on this...

There's almost no way I can think of that you could have 3 weeks worth of battery capacity on board; not and need it. Odd paradox really; you could have 3 weeks worth of battery power if you didn't really use it but then if you didn't really use it you wouldn't need the capacity. You can see why I said in the beginning that the best way to build a system was to decrese the demand on it; the less power you need (that comes from your choices of equipment) the less you have to store.

Think of the batteries more like a bank account; you've got to have (say) $30K a year to live on but (for most of us) it's not realistic to have that much in the bank all at once for the whole year. Rather, most of us rely on periodic pay checks to replenish our account then we're good for a couple more weeks (or whatever).

So if you plan a system that will allow it to be recharged quickly and easily you won't get into the problem of having to try and get an unreasonable amount of power back into the battery bank all at once.

Here's the balance process I go through when designing a boat's onboard system.

First item...how much power do you need? I know you said you didn't know yet but that's an important homework assignment and the basis for all your decisions. It's like I'm selling trucks and you come in and tell me you need a truck to tow with; if I ask you what load you want to pull and you don't know it makes it awfully difficult to make a decision. You certainly don't need a diesel dually to tow a 2,000# utility trailer but an import 4-banger is going to have a heck of a time with a 32' 5th wheel. You need to do a 'power consumption worksheet' (I've seen several on the Internet) which basically asks you what items you'll run and for how long (and how often). A lot of them have average power usage (make sure it's for AC or 12VDC as appropriate) on them so it's easy to compute the required amp-hours. As an example, a 10-watt 12VDC light takes about an amp to run; if that light stays on for 5 hours in the evening then you've used 5 amp-hours. A computer with a 250-watt power supply (on AC power) could be sucking down about 2 amps but run through an inverter with 80% efficiency will need 26 amps on the 12-volt side; a couple hours of that and you've used up 52 amp-hours.

Second question...how long are you willing to run your generator at any one time to recharge the batteries? In other words...if you have to charge your batteries with a generator (and you may have to depending on weather) you might as well get the batteries topped off within your maximum allowable run time. This is a strictly personal thing; some folks would rather run the generator every day but for just an hour or two. Others would rather run every third day for a longer period. The decision here will help you decide just how big the charging source (alternator, battery charger, etc) will have to be.

Given the limitations you've imposed by your choice for question #2 and the amount of power you've computed is needed from question #1 you can now start to sort out the battery capacity you'll need and the size of the charging source required to recharge them.

And, you can start to juggle the impact of solar and wind; there are many charts and tables out there (Soused Moose most likely has good sources on those) that will give you efficiency factors for different areas of the country for sun exposure and wind speeds, etc.

Personally, I'd build a system that you could live with that depended solely on recharging the batteries from the bus running down the road or the generator; then anything you get from sun and wind would just extend the period when the generator wouldn't be needed. If you happen to hit a period of bad weather or if you find some wonderful secluded spot by an emerald lake that didn't get much sun (right where the bus is parked) due to the towering pines and you were pretty protected from the wind then you wouldn't be all messed up on your battery capacity.

I like the idea of sun and wind power too but I don't want to be restricted on my choice of sites to park in and I certainly don't want to have to choose some stark wide open place just because it has the sun and wind I need. I'd rather park where I want and deal with recharging the batteries with the generator if necessary.

Shoot, keep the system simple and easy to recharge and get a Honda EU2000 'suitcase' generator. Haul that thing about 50' from the rig and plug in the shorepower cable to run the battery charger...you'll never hear it running! For that matter, you can buy two...they'll parallel themselves and you'll have 4,000 watts to play with and two portable gensets to use where you need them. All for under $2500 (for both).

Hope some of this is helping!
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Old 03-28-2004, 10:38 PM   #15
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Hi Kevin,

Well, I just lost all of a rather long post I was preparing for you; clicked on the wrong button at the wrong time.

In short (since I can't type that much again!), the 1350Ah of capacity is correct; you'll have about 475 Ah of usable power. This I would consider a good 4 to 5 day system.

The flip side is you'll need an AC charger capable of about 270 amps if you want decent (like 5 hour) charge times. This is the batteries' 20% charge rate; which it can't sustain. When the battery gets about 85% charged it needs to drop to a 10% charge rate to avoid damage.

You can see then that solar panels that will put out enough to keep a 20 amp chage controller at max capacity would take about 33 hours to charge our 50% discharged battery. That's assuming a full 20 amps of output for the whole time with no load on the battery.

I understand that most consider 5 hours/day of max panel output to be a good working number. Given that we'll get perhaps 100 amp-hours per day out of a 20 amp system. That's enough to keep a conservative system going and would keep already charged batteries from getting depleted very much. But if the power from the solar panels isn't available and the battery bank of the size you suggest did go down it would take quite a bit to recharge it; in fact, there's a good chance that you'd never get the batteries charged (off the solar system) unless you have another bank to switch to. Your load on the system is likely to take everything a 20-amp solar system can put in.

Also, to charge a 1350AH bank when running down the road in the bus you should have an alternator on the main engine capable of at least 350 amps and 400 amps would be better. These numbers take into account the losses typically experienced with heat and rpm variations.

Don't forget when running systems capable of up to 400 amps you need to incorporate some serious wire.
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Old 03-28-2004, 11:16 PM   #16
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Hi Again!

Geez; I feel like the Grinch here

You can not run an A/C unit on a battery bank; it's got to be shorepower or a genset. Even the Mach 3 is pulling around 10 amps; that's on the AC side. Running through an inverter with 80% effciciency you're going to be pulling 140 amps! That's going to totally wipe out your battery bank in about 2 hours. The math doesn't work, right? Well, there's this little deal called Peukert's Law; in essence it says the higher percentage the load on a battery the faster (exponentially) it loses power. Battery amp-hours are rated at a 20-hour discharge rate so in the case of out 1350Ah battery that's 67 amps for 20 hours; if you more than double the discharge rate you'll get close to 4 times less the time. And remember, we should only pull about 465 to 500 amp-hours out of this battery to keep it healthy.

I don't know about the jacuzzi pump; there are some efficient pumps around but it's going to take some research. I know the houseboats on Lake Shasta have hot tubs on them that are heated with propane heaters and have 12-volt circulating pumps so that may work out ok.

None of us are living in the bus when we start our conversions so we all have to 'project' what we think things are going to be like. For power you just need to think about what things you'll want to be using; like how long you think you might have a reading light on, how long you'd have the bathroom light on, how many lights do you need running at any one time. It's just an estimate to get you going. Then figure if you have any heavy 12-volt loads; like a refrigerator and inverter loads.

Watts is watts; a 250-watt computer (not counting its monitor) takes 250-watts on AC or DC (running direct to DC will avoid the 15% to 20% loss of the inverter). So on 12VDC that computer's going to consume 20 amps (plus the monitor); two hours use is going to 'cost' you 40 amp-hours of your battery power.

You can do everything you want...as long as you run that generator. Most of the rest of the stuff you're talking about running is going to be difficult and expensive to run on a 12-volt system. You can buy a lot of fuel for that generator for what it's going to cost you to set up a viable 12-volt system for the loads you're talking about. And some stuff like the A/C isn't viable at all without the genset.

Big conversions buses where they want maximum comfort and livability set up for almost all AC electric operation and run the generator (or main engine) much of the time. Somewhere you're going to have to find a balance between 'need' and 'want'.
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Old 03-29-2004, 10:22 AM   #17
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you're putting a jacuzzi in this thing?? How big is it? Is it well insulated?
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Old 03-29-2004, 12:53 PM   #18
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Old 03-29-2004, 01:12 PM   #19
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Kevin, Les is a smart guy and he’s right on the money …when he mentions that it probably would be smarter to rely on the Generator & the alternator as your primary charging sources when you’re away from ‘Shore power’…and anything you get from your solar & wind setup is just added ‘frosting on the cake’.
I agree with him totally on this.

Solar power is fantastic stuff; I wouldn’t even consider having a rolling home that wasn’t equipped with solar modules …but it does have its limitations. The same applies to wind generators.

On our last bus “Home” ,I installed a couple of Uni-Solar modules and had a pretty decent bank of storage battery’s. We didn’t have a generator …just the solar panels for off the grid living.

So, one day we unplugged from shore power and moved the bus down to the ‘Fishing Hole’ in Homer. We wanted to be there for the Silver Salmon run …so I could fish everyday and Millie would can it up to store it for winter food.
We were there for a couple of weeks and I was thrilled that the panels were outputting enough power to run our little 12-volt TV and our lights for a few hours everyday…I thought, Wow, this cool.
But what I hadn’t taken into account was we had reached a point of diminishing returns…each day more and more juice was taken out of the battery bank and even with almost 20 hours of Sunlight the panels couldn’t keep up.
Eventually the bank was empty …and the only power we were getting was direct from the modules, which wasn’t that much.
It certainly wasn’t enough to be comfortable.

And, Even if we had picked up some bigger wattage panels and had a larger battery bank …eventually we would have still reached a point of diminishing returns. That just the way it is …given weather situations and our limited roof areas that dictate how many panels we can get up there and how much battery weight we can carry…etc.etc.etc.

For me ‘comfort’ is really important. I don’t ever buy an RV or convert a Bus or van to just camp out in for a couple of weeks.
They’re always our Fulltime Home…. and I don’t want to do without the same conveniences and comfort that a ‘stick house’ has.

Kevin it’s not so much an issue of what you’re looking at cant be done…it’s more an issue of, is it truly efficient in the long run …and how much ‘comfort’ are you willing to give up.
I truly understand what you’re trying to do here …But even though It might sound and look really cool on ‘paper’ … after you live without the comforts of home for a while …you get sick of doing without.
All you’re doing is ‘Campin out’ …and that ‘gets old’ after a couple of years.

I’m talking from COMPLETE experience here.
Starting in the 70’s I lived out of a backpack and hitchhiked all over this country and many others for a LOT of years…I’ve lived in communes and all sorts of places where the electrical power was coming from solar panels…and nothing else.
Millie & I lived in lots of places with no Electricity other than Solar.
Basically out of 45 years of living on this planet …I did without the civilized amenities for over 22 years …
It’s fun & cool to live that way …but it sucks after awhile.

The REALITY of living off the grid completely, unless you’re a millionaire who can afford a massive solar array and an equally massive bank of storage batteries is doing ‘without’.
You’re endlessly running around nervously watching your battery capacity …shutting off the TV in the middle of something you really wanted to see …and all sorts of other non-fun things.
Trust me …the allure of a lifestyle like this wears off pretty quickly.

That’s not to say a person can’t have a really good Alternative energy system on their Rig …they just need to recognize its limitations…and be realistic about it.
And even though there’s new stuff coming out every year that makes the dream of living completely off the grid, more & more reachable …it still has its limitations.
The sun doesn’t always cooperate …once you start living with solar modules you’ll find out that many months of the year have less than optimal solar gain. You really need to take into account those bad times more seriously than the optimal situations when you’re looking at installing a system. Those are the times you really need the power.


So, I second the idea of getting a good little generator like the Honda EU2000i (Got one, LOVE it)…and if it were me, I’d get rid of that big gas-hogging noisy generator you’ve got right away and use that space for a decent sized battery bank.
That big generator must weigh a Hell of a lot…I imagine you could put at least 6 decent batteries in that compartment and still be below the weight of that generator.
The batteries you choose are up to you. There’s a lot of info out there on what battery is best and all that…but lots of folks are perfectly happy using deep-cycle batteries in their systems.

Then figure out what type of Solar panels and charge controller you want and need.
Personally I always stick with Uni-Solar Amorphous modules…they’re made up of a continuous layer of silicon versus a mono or poly-crystalline panel, which is made of a bunch of solar cells wired up together.
Amorphous panels produce power even when partially shaded …so you don’t need to be out there in direct sunlight to make them work. There also less effected by hot temperatures.
The only problem with amorphous panels is they are not available in wattages much higher than 64 watts. So you’d need at least 2 of them to even bother.
Then do all the things Les said…figure out your real electrical needs and design your whole system around that.


………………………………………… …………………………………………

Kevin, As far as Wind speed & Solar Gain charts go…
There’s plenty of websites out there that have charts on regional wind speed and solar gain data. But you have to be really careful how you read & interpret them …because they’re really designed to help with’ site specific’ planning.

What that means is …say a person buys a piece of property outside of Eugene Oregon. They decide to ‘power’ their new home using Alternative means. So they go to the local Solar Panel & such dealer and ask what can they use and what they can expect.
The dealer will put out his/her charts and tell them…well, you don’t get enough wind around your property to make installing a wind generator worth the effort or price …and to power your home year round using solar you’ll need …etc. etc.

That’s the ‘right’ way to go about designing and installing an alternative energy system in a home…. but a Bus or RV has a different set of working parameters attached to them.
They MOVE.

If a person is converting a rig to actually travel, instead of remaining parked in one spot for most of the year …you’re going to be exposed to many different areas that have completely different weather and solar gain conditions than the last spot you visited.

I.O.…a wind generator might be useless in Eugene, but once you drive over to the coast you’ll get plenty of situations where your wind generator is exposed to conditions that make it work.

I guess my point is …these charts are very useful if you want to check out the angle you’ll need to position your panels at a particular time of year for best solar gain… or to find out what you can expect the wind will be doing in August while you’re camped out in the Rockies…but they should never be used to figure out if a particular piece of Alternative Energy equipment is worth installing on your rig.

Kevin, there’s a lot of great information in books and on the ‘web’ about Alternative energy…but You have to be really careful about this sort of thing …there’s tons of folks out there (Not Here, but on other sites) who are going to tell you ‘it can’t be done ‘ or ‘it’s cost ineffective’…etc. etc. etc.
Don’t listen to them …they don’t know what the hell they’re talking about.
They installed a simple solar panel setup on their RV last year and now think they’re expects on Alternative energy…who can tell you a wind generator or composting toilet cant work in a rolling home.
Which of course is totally Bogus…and coming from abject ignorance on the subject.

I’m not trying to tell you what to do Kevin …I hope you don’t think so. I’m a bit sick today, so my writing style might seem a bit on the obnoxious side, but its not meant to be.
Just keep pluggin’ away until you figure out what’s best for you…I think it’s a cool thing you’re trying to aspire to.

Here’s a pic of a person who got really serious about alternative energy and has a system that can handle just about any load he wants to put on it. But imagine how much time it takes him to stow that system just so he can drive.

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Old 03-29-2004, 01:21 PM   #20
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Just a thought: Have you considered using engine coolant to heat the water for your jacuzzi. This is by far the best method for heating water if you're gonna be driving around. If you dont put it to good use, the excess engine heat is just vented to the atmosphere and wasted.

If it's insulated well enough, (or the holding tanks are insulated well enough) you could have hot water for several days. If you were to heat the holding tank water to something well above what you need for the jacuzzi, you could run both hot and cold water at the same time into the tub to make the desired temperature, just like the shower at home.

I have to keep half the water in my jacuzzi in separate holding tanks to keep if from sloshing out of the tub.

Don't worry about the excess weight of the water, or the lack of baffles in your holding tanks. I have 400 gallons of water, and the exces weight is really not an issue. Sure acceleration and braking take a big longer, but it's not that noticable. I can't feel the water surge back and forth. Thats one thing i was worried about when i put the project together.
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