OFF GRID POWER; various thoughts on...

[OlJarhead]

http://www.infinigi.com/renewable-energy-charge-controllers-c-2_37.html?page=6&sort=2a

this might save you a few bucks on the Xantrex

Thanks

If all goes well we will be making our solar power purchase within the next couple months   Gotta get a roof on and some walls done etc first though!

[Beavers]

Well finally got started on my off grid power system.  This going to be gradual build, starting with a battery bank being charged by an alternator, with solar panels added as we have the cash for them.  I figure we can still use the alternator down the road to charge the batteries on cloudy days.

I got a cheap Harbor Freight 6 1/2 horse motor, and ordered the mounting plates and direct drive coupler from the The Epicenter.

Buying the mounting plates from them saved a bunch of work.  They are well made, looks like they cut them with a plasma cutter, they bolted right up to the motor and alternator.  

So here is the meager start of my system...
The motor generator combo, and the Exeltech inverter I got from Considerations.  I removed the small gas tank, going to hook up a 6 gallon marine tank.  With the quick release fittings should make for easy fuel changes.  Also have to come up with some kind of enclosure to mount the setup in...something along the line of what Mt. Don built for his generator.





Close up of the couplers.  The direct drive really makes for a nice looking unit IMO...almost looks like store bought, not redneck engineered!    

[MountainDon]

That looks nice; rubber insert shaft coupler by the looks of it.   

I see the engine has a cast iron sleeve; that's good too.

[Solar Burrito]

Well finally got started on my off grid power system.  This going to be gradual build, starting with a battery bank being charged by an alternator, with solar panels added as we have the cash for them.  I figure we can still use the alternator down the road to charge the batteries on cloudy days.

I got a cheap Harbor Freight 6 1/2 horse motor, and ordered the mounting plates and direct drive coupler from the The Epicenter.

Buying the mounting plates from them saved a bunch of work.  They are well made, looks like they cut them with a plasma cutter, they bolted right up to the motor and alternator.  

So here is the meager start of my system...
The motor generator combo, and the Exeltech inverter I got from Considerations.  I removed the small gas tank, going to hook up a 6 gallon marine tank.  With the quick release fittings should make for easy fuel changes.  Also have to come up with some kind of enclosure to mount the setup in...something along the line of what Mt. Don built for his generator.

Great looking motor. Is this setup cheaper than a Champion 3500w generator for $299? Or is this more of a fun project by building it yourself?

[MountainDon]

I'll bet it cost a little less, depending on the alternator output and not counting the 6 gallon marine fuel tank.

The advantage being that for battery charging purposes (12 VDC) it puts out the required DC and has a built in regulator obviating the need for a 120 VAC to 12 VDC charger.    On the downside it only puts out 12 VDC.

Close?   

[Beavers]

I got the motor on sale for $150 from HF, and the alternator, mounting plates, and couplers were $150 minus shipping.  Not any cheaper, but like Don said it doesn't need a charger to charge batteries.  I'm hoping that I will be able to idle it down and use less than full throttle to charge the batteries to cut down on noise, and fuel use.

I actually have one of the Champion 3500w generators.  For just running power tools ect. on a jobsite the Champion would be the way to go.  With the motor/alternator you still need an inverter and a battery to make 120v power.  Once you factor in those it's much more expensive than the Champion.  If you are looking to charge batteries though, the alternator would be better as far as I can tell.

[diyfrank]

One thing to keep in mind, A car alternator puts out about half its rated current at an idle 600 rpm"s or so. The ratio from the crank to the alternator is about 3 to 1.
At 1800 RPM's you'll be at half power output. at 3600 RPM'S to reach full output.
Either gear that sucker up or burn a lot of fuel to reach maximum output.

I like the mount though, It has a clean look.
If you could separate the two and mount something in between to increase  the alt. speed.  

[Beavers]

I think its a 65 amp alternator.  I can't remember where I read it but, you aren't supposed to charge the batteries at too high of amps.  I'll have to dig back through all my info, but I think 30 amps or so was the most I would want to charge the batteries that I'm planning on getting.

I calculated that I should only have to run the motor a couple of hours a day to keep things charged up.  If I can run it a half throttle I hope it won't be too bad on gas.  It's definitely not a long term solution, but I think it should work for a couple of months until we can get some panels.

[MountainDon]

The maximum charge rate for a typical flooded cell deep cycle battery is usually given as C/8, where C = the battery capacity in amp-hours. If batteries are parallel connected C is the total amp-hour capacity of the battery bank.

So with a 210 amp=hour battery, that is 210/8 = 26.25 amps maximum for a sustained period.

I've also seen C/5 listed as okay for flooded batteries that are deeply discharged, and a rate of C/10 listed for batteries that are 85% or greater charged.

There are special rules for gel cells and some brands of AGM allow higher rates. Best to check with the battery manufacturer when in doubt.

[Beavers]

Thanks for the number Don, saved me from digging through all my bookmarks to find it. 

My calculated load for the house is 49.5 amp hours a day.  Keeping under C/8 and charging at 25 amps would only have to run the motor 2hrs a day.  I think I could live with that for the short term.

[Solar Burrito]

Hey guys, I have an battery related charging question i've been wondering for a while.

Right now I have a 75watt panel and Xantranx c40 charge controller charging a single Deep Cycle group 31 battery. The problem is we keep a Honda 4x4 quad on our property and the battery dies before we get back to use it.

Any way I can connect the much smaller ATV battery to the Group 31 deep cycle being charged from our solar setup?

I've never heard of dissimilar battery sizes being charged together but It would be really convient if I could! The ATV battery is $50!

[MountainDon]

How long does it take for the ATV battery to go dead? Many months or a shorter period?


Rather than try to hook the ATV battery into the existing PV system it might be easier to use a small PV panel just for the ATV battery. If the battery is fully charged, or close to full, a small panel should be able to retain them in full charge. We use 22 watts worth of panels to keep the RV batteries full over the winter.

[Solar Burrito]

It will go dead in 2 weeks. I have a crappy 1 watt panel but it's not meant for being outside so I don't want to leave it up there.

We obviously don't have AC power up there either, only our small PV system.

Can a small 12v battery be connected to a large 12v battery?

[MountainDon]

If it goes dead in two weeks I think the battery is "dead meat" already and there is no hope for it OR there is a "phantom" drain that is sucking the power. No battery, if in decent shape, should go dead that fast.

Have you tried disconnecting the battery from the ATV system?  (pull the neg or pos lead off the battery)  You could install a battery switch or an Andersen connector to make that easy. I have a disconnect switch in the RV "house" system because there is an unknown small load that sucks the house batteries down if left connected during prolonged absences.

[MountainDon]

I am not sure if there is any danger to one battery or the other if the ATV was to be connected to the PV system.   

[OlJarhead]

Hmmm...did you check www.rockymountainatvmc.com

I think I got a battery for our Yamaha for half that there...mine was doing the same thing so I replaced it -- no point in messing with it beyond that.

http://www.rockymountainatvmc.com/productDetail.do?navType=type&webTypeId=19&navTitle=Electrical&webCatId=20&keyword=BATTERY&prodFamilyId=8926

[Solar Burrito]

Thanks but it's still $50. Some are $100! That seems really high for an ATV battery! It's for a Honda Foreman 400 ES. The ES stands for electric Shift and it has 3 lights on it and a cigarette lighter so I suppose it uses lots of juice...

[OlJarhead]

http://sunelec.com/index.php?main_page=product_info&cPath=5&products_id=255
Found these and was wondering if they sounded like decent panels for the money?

I want to put together a system for as little as possible but that will be reliable (within reason)...basically I can't afford $10k in solar power and budgeted $2k but could go a little more.

I need 2 of these 18Vmp panels, 4 Trojan L16RE-B 6v batteries, not sure what kind of inverter but my corrected watt hours per week is 6347 as calculated right now.  Also need a charge controller for the panels.

Since those panels list at $348 that's $696 in panels
Those batteries run about $330 -- so that's $1320 (ouch -- I think I might take Don's approach -- heck, 12vdc deep cycle RV/Marine batters aren't that expensive.  In fact I could get Optimas and save $400 at least and they've got to be decent...maybe I'm thinking wrong?)

http://store.solar-electric.com/xaxwmp60amps.html
I'm still learning (have a long way to go) but this appears to be what I would need for a controller?  I know I could go cheaper but I thought I read the MPPT's were the way to go???

That's $529

http://store.solar-electric.com/xatr15wa12vo.html
$760 for this inverter which has the charger plug in for the generator.

OK so if I went this route then the cost looks like:

$3305 for a 400 watt system with 1500 watt inverter and MPPT controller as well as 4 good batteries.

Hmm...also I have a 3000 watt generator that peaks at 4000 watts and will use that as a back up for the batteries as well as running saws and such (for construction at the cabin).

Thoughts?  Am I choosing the wrong components?  Did I miss something?  Could I reduce costs by going with 6v golf cart batteries?  Is the contoller/inverter combination incorrect?

It's kinda fun mind you, doing this.  I'm using Don's spreadsheet and trying to figure out what kind of power we will need at the cabin since all we've done to date is camp out in the trailer with ONE battery (except one time I had 3 becuase it was very cold) and the main thing that used the battery was heat which we've solved by buying the wood stove   And better insulation.

Anyway, thanks in advance.

http://sunelec.com/index.php?main_page=615_watt_off_grid_system

This system is very close to the one I priced out -- but has what might be better batteries, 3 panels and all the other goodies I hadn't added.

Thoughts?

[MountainDon]

Well, the panels ARE made in the USA, nice to see. It's okay being blemished. No UL approval could be a problem if there were an electrical inspection.

Other thoughts in no particular order:

What is the shipping on the batteries going to be?  They have a marginally higher rating than the Sam's Club batteries but cost more to begin with, plus shipping.

Xantrex states the amperage draw on that inverter is a max of 77 amps at rated power. Allowing 25% for a surge that means a 100 amp input breaker to the inverter is large enough. They are selling a 250 disconnect, which appears to be a breaker. You need a breaker, or fuse, in the inverter feed, but not one 2.5 times the calculated likely maximum current.  Way too much breaker for the inverter. At least I'm assuming that the 250 amp disconnect/breaker is meant for the feed from batteries to inverter.

Their package offers no discounts over buying each item picemeal from them.

Another assumption is that they mean the panels are to be connected in series. I say that as the charge controllers I am familiar with all want/need an input voltage that is greater than the battery bank it is going to charge. A 24 V battery is usually powered by 48 volts input from panels. So that fits with the 20 amp breaker being used at the combiner as a disconnect/breaker.

IF the panels are in series, and if your system is not going to be inspected, you can likely come up with a substitute box and disconnect for less than 79 + 15 = $94 as with the panels in series you really have nothing to combine. Parallel panels would be different.

I'm confused why they include two 60 amp breakers. Xantrex recommends 50 amp for the charge controller output breaker. You only need one breaker in the positive line if you have the system properly grounded. 

I can tell you where you can get the C40 for $104 instead of $145

Anyhow that's some thoughts about their "kit"

[OlJarhead]

Thanks Don,

I asked mostly becuase I wanted to get some thoughts on their package vs. the one I put together with your help.  I was curious why they did some things and at the time hadn't looked closely at the batteries which I then discovered were golf cart batteries too -- interesting.

Anyway, I was also curios about the voltage and wanted to see if the package we came up with compared.

I see that with your assistance my package has more thought into it (thanks to your spreadsheet too) and price wise is very competitive   I like that.

Still learning a LOT/TON and am excited becuase we may be starting our buys REAL soon  

I plan to stick with what we came up with actually and was going to ask about running the panels in series for a 12 vdc system and I think you just answered that!  Series to 24vdc to charge the 12vdc battery bank for the cabin right?

One other thing, I'm considering trying to run a 24vdc feed to the well pump (but I need to check the pump out first) if it's actually 24vdc rather then 12vdc and the panels will be closer to it if I put them where I plan, but the batteries further away (I need to do a drawing) -- what are you thoughts about that?

By the way, this is an amazing resource and at times I just smile becuase I know I'm going to learn something!

[MountainDon]

The inverter Sun spec'd is meant to run on 24 VDC.  That's why the 24 v battery system.

The panels in parallel would not be able to charge the 24 V system. At least using equipment I am familiar with, that would not work. I have not used the Xantrex or looked heavily into their specs and operation. BUT the ones I am familiar with require a higher voltage INTO the charge controller than the battery pack voltage. This is partly because the panels may not be putting out much voltage on a cloudy day... not enough to push the current into the batteries. So with a 24 VDC system you need more than 24 VDC output from the panels to be able to have sufficient power to charge the batteries on cloudy, low voltage panel output days. Those panels singly put out a max of something like 18 VDC.

I'm being wishy-washy, waffling, on that answer because I doubt that Xantrex has any magic power boost built into the charge controller but I don't know for sure.

OTOH, with a 12 VDC battery system the panels would be okay in parallel, but the cables etc need to be bigger, and that inverter would not work.


Re: the pump. Yes, you need to verify it's voltage and current requirements, or volts and watts.   Add a nice diagram with distances between components.

[considerations]

I might be wearing out my Honda eu1000i.  It seems that for the last few days that when the charger on the Prosine 2.0 inverter is enabled, it just keeps cycling back and forth every 10-15 seconds from standby to charging.  Nothing's changed recently.  When the inverter cycles to the charge mode, the generator "lugs" for a second, recovers, and the charge phase on the inverter cycles back into standby mode. 

It's like the gen isn't responding with enough power soon enough to keep the inverter in charge mode. 

I'm careful about the maintanence on the gen, change the oil once a month, add some every 5 days, etc. 

I'm a little worried about all that cycling....all I need is for the inverter to go boots up as well..        

Tomorrow is Monday and I'll be making some calls to see what sort of tech support I can drum up.   

[MountainDon]

Have you tried using the generator to power some regular AC loads, like a power tool or toaster?

[considerations]

"Have you tried using the generator to power some regular AC loads, like a power tool or toaster?"

Yes, the power from the gen is still going into the inverter and then into the house and still running the whole house and the electric fence, I just have the charging mode on the inverter turned off. 

I think that rules out the possibility that the quality of the sine wave being produced by the gen is inadequate, or I don't think I'd be able to run the house on the gen through the inverter. 

If I turn on the charge mode, the inverter switches to charge for 7 to 10 seconds, the engine lugs down, then the inverter switches back to standby, and the gen revs back up to normal, then the inverter switches to charge mode and the aforementioned repeats until I turn the charge mode off.

I tried shutting off the house to eliminate all AC loads and then turning on the gen and the inverter's charge mode...no dice.

I get the gen serviced each summer....but there have been 4 summers and there are a lot of hours on it.  I wonder what the life expectancy is.   Having a "spare" so I could take one offline as servicing is needed is a goal. 

I have a 5500 watt B&S gen but it won't run the house through the inverter, I'm pretty sure its the type of sine wave it produces.
 
Anyway, the PV panels are keeping the battery bank charge in good shape, and I just shut down every nonessential electrical item at night.  As the days lengthen and the sun shines more, and I get another job (always helpful), I'll be able to explore the issue further. 

In the meantime I think I need to figure out how to hook the big gen directly to the house in case the Honda goes completely gunnybags. 

[pagan]

considerations,

Your Honda generator is 1000 watts? Did the Prosine charge controller work fine with the Honda prior to these events?