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Author Topic: Solar on the cheap?  (Read 10262 times)

hpcmbw

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Solar on the cheap?
« on: July 07, 2010, 12:36:13 AM »
This site has been incredibly helpful, so I'm hoping for a little more great help. I've got a 1997 Salem 30' 5th wheel boondocked near Lake Tahoe, Ca.  I stay there every weekend. I've got a pair of trojan 6v batteries in it. It's been there for a month, and the batteries seem to be getting weaker and weaker. I thought my cheapo solar battery maintainers (2 for $20) would charge during the week, but think they are useless. 

I run a little 800w generator for an hour or two each weekend with a battery charger, but that doesn't seem to get them close to full charge. The battery charger doesn't seem to work correctly, and I've read that the 800w genset won't put out enough juice for many battery chargers. The genset has a direct hookup to 12v that I've been using, but suspect that it's putting out to much electricity and might be overcharging the batteries, since there doesn't seem to be any controller. I've just been hooking up a set of motorcycle jumper cables between the genset and the batteries. My genset is a Honda ex800.

I'm on a real tight budget, so am looking at cheap options. I found this 60 watt setup at Costco for $300.00 (see link below). I don't really have $300, but I've got to do something. I might have to disconnect the batts each weekend and haul them 2 hours home to hook up to batt charger at home. Anyone know if this Costco setup is a reasonable cost effective solution, or just throwing good money after bad? Thanks again!


http://www.costco.com/Browse/Product.aspx?Prodid=11298029&search=solar&Mo=19&cm_re=1_en-_-Top_Left_Nav-_-Top_search&lang=en-US&Nr=P_CatalogName:BC&Sp=S&N=5000043&whse=BC&Dx=mode+matchallpartial&Ntk=Text_Search&Dr=P_CatalogName:BC&Ne=4000000&D=solar&Ntt=solar&No=3&Ntx=mode+matchallpartial&Nty=1&topnav=&s=1
1997 Salem 30' fifth wheel; 2000 F250 7.3 diesel; 1996 Four Wheel Truck Camper
Northern California

Tony_Alberta

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Re: Solar on the cheap?
« Reply #1 on: July 07, 2010, 01:55:39 AM »
Some number crunching is required.   What kind of watts are the solar maintainers?  If, for example, they are 8 watts each, that means you are putting in about 1 amp per sunlight hour.   (And if you get a cloudy week forget about it.  Solar cells work at 15% efficiency depending on the could.)

Those batteries can hold about 225 amp hours when new.   But this means that seven days of sunlight might give you, just guessing 60 amp hours of 12 VDC coming in.   But you might be drawing 80 amp hours every weekend you are there.   

It really helps to know how many amp hours are going in and how many amp hours aka watts are going out.   It also helps to have a volt meter to read the battery voltage.   

Running off of the 12 VDC ports off a genset might be only 10 amps.    What kind of battery charger did you mention that you have at home?   If only a 10 amps then it's not going to help much but 225 amp hours of capacity can charge at about 1/8 capacity or 30 amps.   So an ideal charger for those batteries would be about 30 amps.   But you'd have to run the generator for at least 12 hours to get a full charge.

The reason is that the first 70% of the charge in a lead acid battery can be at 1/8 the capacity.   But after that the amount of amps put in the battery goes down when you are using a smart charger.  And you should be using a smart charger as that will greatly increase the life of your batteries.

See http://www.batteryuniversity.com/ for lots of information about batteries.

Gary RV_Wizard

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Re: Solar on the cheap?
« Reply #2 on: July 07, 2010, 06:16:47 AM »
The short answer is...
(1)Those $20 solar panels are essentially worthless. Somewhere around 0.5-1.0 amps per hour of charging at high noon on a sunny day. Insignificant effect.
(2) Your EX800 provides 700w of continuous 120vac power. That's enough to run a 50A battery charger all day long, so you should be using your trailer's own charger rather than the wimpy 8A the generator puts out for DC. Let it run for several hours - 2 hours is nowhere near enough.
(3) The Costco solar unit is much better than what you have, but still only 4 amps of output. Whether it would be adequate depends on how much direct sunlight you get.
Gary
--------------
Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

seilerbird

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Re: Solar on the cheap?
« Reply #3 on: July 07, 2010, 07:39:59 AM »
Since you are looking for cheap it doesn't get any cheaper than hauling your batteries home.

DonTom

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Re: Solar on the cheap?
« Reply #4 on: July 07, 2010, 08:36:38 AM »
Quote
I'm on a real tight budget, so am looking at cheap options.

These are on sale NOW:

http://www.harborfreight.com/45-watt-solar-panel-kit-90599.html

The sale won't last long. This is the setup I use with a couple of extra panels.

Edit: I think the sale is off already. They had a price of $159.99, which is the lowest I have seen them ask.

But they go on sale often. Don't pay more than the $179.99 sale price.

-Don-


« Last Edit: July 07, 2010, 08:42:15 AM by DonTom »
-Don-   AA6GA

2000 Fleetwood Tioga 24D, 7.4L

Eight motorcycles:
Original owner of:
1971 BMW R75/5
1984 Yamaha Venture
2002 Suzuki DR200SE
2013 Triumph Trophy SE
2016 Versys 650 LT
2016 Moto Guzzi Stelvio
2017 Zero DS ZF6.5
2017 Zero SR 13 w/pwr tank

hpcmbw

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Re: Solar on the cheap?
« Reply #5 on: July 07, 2010, 10:39:04 AM »
Thanks for the great input. I think I'll keep an eye out til the Harbor Freight solar panels go on sale and give them a try. I can't tell if the Harbor Freight kit includes a charge controller, but I assume it's not that good. I read on "Jerry and Cynthia's Road Trip" that I should use a three stage PWM, but those look pricey.

In response to the input and questions from others:
my 5th wheel has a Magnatec 6300 converter, which I'm told on this forum is not a good battery charger, so I've been bypassing it.

The charger I've been trying to use, but this charger may not be working correctly, is a Schumacher 10a/2a/50a engine start. The one I've got at home, that I will probably try using this weekend is a Schumacher 2/12/75amp engine start. It has a regular and deep cycle switch on it (both chargers are at least 15 years old I think.). The 2/12/75 is a model SE 1275a.  Whats a good 50a battery charger that's reasonably priced?

re: power use, I run the heater for 1-2 hours total, I run some interior lights (standard 12v incandescent, haven't picked up LED yet) for a couple hours, a radio (regular 12v car radio) for a couple hours, water pump for an hour or less of actual runtime, refrigerator I leave running on propane 24/7 even when I'm gone during the week, and a small 150 watt inverter plugged into a cig lighter power supply to charge cell phones at night. I realize that if I disconnect the batteries during the week, i'll eliminate vampire draws and the fridge draw, but am hoping to keep my fridge, so I always have cold food and, more importantly, cold beer!

The solar maintainers are probably the cheapest you can find, probably .5a like RV Roamer mentioned.

I'm not at the 5th wheel much during the day, so I run the genset when I'm home, which is only an hour or so in the am and again in the pm, before going to bed.

Lastly, I'll probably just take the batts home each weekend til I find the Harbor Freight solar panels on sale.

Thanks again for all the help!
1997 Salem 30' fifth wheel; 2000 F250 7.3 diesel; 1996 Four Wheel Truck Camper
Northern California

Jammer

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Re: Solar on the cheap?
« Reply #6 on: July 07, 2010, 12:04:36 PM »
Solar is expensive.  There's no two ways about it.

The problem with the Magnetek chargers is that they will tend to overcharge your battery if left connected to shore power for more than a few hours at a time.  You do not have this problem.

The Magnetek will charge the batteries faster than an automotive charger.

Use the Magnetek and run the generator for 4 hours, and you'll be close to fully charged, and won't have spent any money.
2004 Suburban 2500 4wd 8.1 / 2010 Airstream Classic 30' /
1997 K2500 regular cab long bed pickup / 1971 Cayo C-11

Gary RV_Wizard

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Re: Solar on the cheap?
« Reply #7 on: July 07, 2010, 08:26:36 PM »
Quote
Whats a good 50a battery charger that's reasonably priced?

There are none, unless you consider $500+ "reasonable". Here is one for $300+, but I never heard of the brand.

http://www.summitracing.com/parts/ODY-OMAX-50AS-3B/
Gary
--------------
Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

Tony_Alberta

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Re: Solar on the cheap?
« Reply #8 on: July 07, 2010, 11:24:31 PM »
I'm not an expert but I'm with Jammer on the Magnetek suggestion of using it only while on the generator.   I'd also suggest disconnecting the inverter if not using it.  It might be drawing more amps than you think while it's not doing anything.   

I also ensure I have a cig lighter charger for all my cell phones, Palm, etc.  The chargers are cheap on Ebay so I frequently charge them while driving on the highway even if I charged them yesterday.

DonTom

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Re: Solar on the cheap?
« Reply #9 on: July 07, 2010, 11:44:46 PM »
I can't tell if the Harbor Freight kit includes a charge controller, but I assume it's not that good.
It's a good (and included) charge controller. It works very well and has many outputs, even USB and 9 VDC. It stops all charging when the battery gets to 14.5 volts and automatically recharges at lower voltages, and never seems to overcharge (I assume it's PWM, but it doesn't say and I never put a scope on it because whatever it is, it works well for me). It has a digital display for your battery voltage that can be turned off and on with a little round push switch that is hard to notice. The rocker switch can turn the controller completely off to stop all charging. I never turn mine off. Mine has been installed for a year and a half. I rarely have to add any water to the batteries, which tells me it's not overcharging. During the day, it shows my battery voltage as 14.5VDC but I doubt the batteries (two T-105 six volters) is drawing much current then.

Be sure to read the reviews on the HFT webpage I provided.

-Don-SSF, CA






« Last Edit: July 07, 2010, 11:48:40 PM by DonTom »
-Don-   AA6GA

2000 Fleetwood Tioga 24D, 7.4L

Eight motorcycles:
Original owner of:
1971 BMW R75/5
1984 Yamaha Venture
2002 Suzuki DR200SE
2013 Triumph Trophy SE
2016 Versys 650 LT
2016 Moto Guzzi Stelvio
2017 Zero DS ZF6.5
2017 Zero SR 13 w/pwr tank

DonTom

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Re: Solar on the cheap?
« Reply #10 on: July 07, 2010, 11:54:59 PM »
I think the Solar Panels ARE on sale NOW.

See:

http://www.harborfreight.com/catalogsearch/result/?category=&q=solar+panel

If interested, at the $159.99 (the lowest price ever):

BUY NOW!And I mean this very second on line, if the price is still $159.99 when you check.


-Don-
-Don-   AA6GA

2000 Fleetwood Tioga 24D, 7.4L

Eight motorcycles:
Original owner of:
1971 BMW R75/5
1984 Yamaha Venture
2002 Suzuki DR200SE
2013 Triumph Trophy SE
2016 Versys 650 LT
2016 Moto Guzzi Stelvio
2017 Zero DS ZF6.5
2017 Zero SR 13 w/pwr tank

hpcmbw

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Re: Solar on the cheap?
« Reply #11 on: July 08, 2010, 12:37:40 AM »
Thanks DonTom - I tried to buy online via Harbor Freight, where it shows $159, , but when I hit the "buy" button, the price went up. So I printed off the page with the $159 price, went to Harbor Freight in the next town and they honored the $159 price! Got the box in my truck, ready to take up to the trailer this weekend and install. Any extra parts I should bring to install on my 5th wheel trailer that you can think of?

Do you leave the panels hooked to the controller and the controller hooked to your batteries full time? The instruction manual says "don't leave connected to a battery unattended" (one of the few times I've read the manual).  I'm hoping to hook this up and leave it connected to the batteries (2 x Trojan 105 6 volters also) when I leave on Sunday and hopefully come back to fully charged batteries the following friday. It sounds like this is what you've done, so I'm very hopeful this will work out for me. I"ll keep an eye on the water level in the batteries every couple of weeks to see if I'm getting overcharged.  Thanks!
1997 Salem 30' fifth wheel; 2000 F250 7.3 diesel; 1996 Four Wheel Truck Camper
Northern California

Mexray

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Re: Solar on the cheap?
« Reply #12 on: July 08, 2010, 02:04:12 AM »
I think their specs call for a max output of 3 amps - I bought one of these setups for the roof of our TC a few years ago...

I bought a separate charge controller that would indicate the current in amps from the panels, and could be switched to also show the voltage...

I don't think I ever saw over 2.5 amps from those panels - they aren't the most efficient types...

You'll definitely need a charge controller if you're going to keep the panels hooked to your batteries all the time - even 2.5 - 3 amps will overcharge your two batteries over time - one week won't harm em' as you mentioned, but if you store your rig and leave the panels on line you'll need a charge controller - you can probably get a 5-7 amp rated controller for not too much money...you'll need to cut the voltage back as the batteries become fully charged, and the controller will take care of that if set up correctly...

Ray
Ray & Pat near Lodi, CA...

DonTom

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Re: Solar on the cheap?
« Reply #13 on: July 08, 2010, 05:32:54 PM »
I think their specs call for a max output of 3 amps - I bought one of these setups for the roof of our TC a few years ago...

I bought a separate charge controller that would indicate the current in amps from the panels, and could be switched to also show the voltage...

I don't think I ever saw over 2.5 amps from those panels -
2.5 amps into what load? There are many variables after the controller. The current your batteries draw will vary depending on their state of charge and type of controller. If your batteries are well charged, they won't draw much current. Besides that, aren't all solar panels somewhat over-rated and only tested under absolute perfect conditions to get their specs?

BTW, I just use a 1156 lamp direct from the solar panel to test them and decide how well they work by the brightness of the lamp. Works well for comparison purposes if the sunlight and temperature is the same during the test. Solar panels like light, but not too much heat.


-Don- Reno, NV
« Last Edit: July 08, 2010, 09:10:35 PM by DonTom »
-Don-   AA6GA

2000 Fleetwood Tioga 24D, 7.4L

Eight motorcycles:
Original owner of:
1971 BMW R75/5
1984 Yamaha Venture
2002 Suzuki DR200SE
2013 Triumph Trophy SE
2016 Versys 650 LT
2016 Moto Guzzi Stelvio
2017 Zero DS ZF6.5
2017 Zero SR 13 w/pwr tank

DonTom

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Re: Solar on the cheap?
« Reply #14 on: July 08, 2010, 05:38:50 PM »
Thanks DonTom - I tried to buy online via Harbor Freight, where it shows $159, , but when I hit the "buy" button, the price went up. So I printed off the page with the $159 price, went to Harbor Freight in the next town and they honored the $159 price! Got the box in my truck, ready to take up to the trailer this weekend and install. Any extra parts I should bring to install on my 5th wheel trailer that you can think of?

Do you leave the panels hooked to the controller and the controller hooked to your batteries full time? The instruction manual says "don't leave connected to a battery unattended" (one of the few times I've read the manual).  I'm hoping to hook this up and leave it connected to the batteries (2 x Trojan 105 6 volters also) when I leave on Sunday and hopefully come back to fully charged batteries the following friday. It sounds like this is what you've done, so I'm very hopeful this will work out for me. I"ll keep an eye on the water level in the batteries every couple of weeks to see if I'm getting overcharged.  Thanks!
Mine is on full time. I would be surprised if the manual doesn't also tell you to wear safety goggles, as many of the HFT manuals do for items that should have nothing to do with such. They shut down at 14.5 VDC anyway. The only other thing you will need are to solar brackets to mount them and the sealant stuff to deal with the holes.
-Don- Reno, NV
-Don-   AA6GA

2000 Fleetwood Tioga 24D, 7.4L

Eight motorcycles:
Original owner of:
1971 BMW R75/5
1984 Yamaha Venture
2002 Suzuki DR200SE
2013 Triumph Trophy SE
2016 Versys 650 LT
2016 Moto Guzzi Stelvio
2017 Zero DS ZF6.5
2017 Zero SR 13 w/pwr tank

DonTom

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Re: Solar on the cheap?
« Reply #15 on: July 08, 2010, 08:58:26 PM »
Do you leave the panels hooked to the controller and the controller hooked to your batteries full time?
Now that I have some more time, I will tell you more. I have the output of the controller DIRECT to the house batteries so they continue to charge regardless of disconnect switch being on or off. The controller is in full control at all times. The controller can be turned off, but I have found no reason to turn it off  other than during installation.

For the solar mounts, I use one Unirac item number 90009 on each panel. Each set has four brackets. So you will need to buy three 900009's for your HFT set up.

For the sealant (seal bottom as well as top of brackets-doesn't have to be too neat, nobody can see but you) I used Dicor Lap Sealant.

If you want to use some extra screws on the brackets like I did, there's a nut and bolt from HFT that fits in the kit, item number 31852. But mounting hardware for the solar panel side come with the brackets. No screws come for the roof, because they don't know what you're mounting to.

On RV roof, try to find a metal strip (using a hand metal scanner, or whatever they are called)  to screw into, in case your roof is as soft as mine. Mine was like screwing into cardboard, only screw that would hold well is the one screwed into the metal. However, when the sealant dries (even though it's a sealant and not an adhesive) it holds very well. I tried to move one with no mounting screws and I could NOT pull it off with reasonable force.

Screws to mount to the RV roof should be fairly large (but must fit the holes in the brackets) and be fairly long. IIRC, I used screws that were 1 and a half inches long that would fit in the bracket. And that's what worked best for mine after some experimentation. Your roof might be different. If you're  lucky, it will be a roof where you won't even have to find the metal strips going across the RV roof.

Dicor Lap sealant (get the tool to hold the sealant too):

http://www.dyersonline.com/Products/Dicor-White-Self-Leveling-Lap-Sealant__31527.aspx?utm_medium=shoppingengine&utm_source=googlebase

I am assuming here your roof is EPDM rubber as mine is. If not, ask somebody else <g>.

Brackets:

http://www.civicsolar.com/product/unirac-990009-0?qty=1

Extra bolts that will fit into solar panel rims to mount brackets to solar panels:

http://www.harborfreight.com/125-piece-stove-bolt-assortment-31852.html

Note:

The bolts are tricky to install in the panels, but no force at all is required. They will fit, but you will have to get them exactly right, even the ones that come with the brackets. You might first think they don't fit, but just keep playing with them until they fall right in. I used thread locker and washers as needed too.

Have fun! BTW, I am not expert on this stuff, but I got the job done, thanks to some help here in this forum, that I am now trying to pass on.

BTW, I now have a total of five panels for the house batteries and one 5 watt panel for the chassis battery. I use a solar controller (probably not necessary, but I use one anyway) for the chassis battery too, this one:
http://www.harborfreight.com/7-amp-solar-charge-regulator-96728.html

I never turn that one off either. And all my batteries are at full charge at all times when left sitting, as it is now. Fast starting and very little start up load on the alternator.

-Don- Reno, NV
« Last Edit: July 09, 2010, 01:38:06 AM by DonTom »
-Don-   AA6GA

2000 Fleetwood Tioga 24D, 7.4L

Eight motorcycles:
Original owner of:
1971 BMW R75/5
1984 Yamaha Venture
2002 Suzuki DR200SE
2013 Triumph Trophy SE
2016 Versys 650 LT
2016 Moto Guzzi Stelvio
2017 Zero DS ZF6.5
2017 Zero SR 13 w/pwr tank

obelix67

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Re: Solar on the cheap?
« Reply #16 on: July 08, 2010, 09:20:39 PM »
Don why use the unirac ?
Why not use a tracking mount ?
A Scot en Suisse, 2 daughters, 2 sons, 2 great pyrenean dogs Cali & Azlan,
2008 Hayabusa,

DonTom

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Re: Solar on the cheap?
« Reply #17 on: July 08, 2010, 09:31:18 PM »
You'll definitely need a charge controller
A decent charge controller is included with those HFT panels. Has outputs for  USB charging, 3, volt, 6 volt, 9 volt as well as a few12 volt outlets built in, along with a voltmeter built in. Solar and battery wiring is from terminals in the rear. The little round button turns off and on the voltmeter.

It can be taken apart in a way that the bottom of it can be the top. I have mine mounted on the RV ceiling, right under the air conditioner. Mounted to it by it's feet screws, but now not upside down. Those over  seven feet tall, must be careful inside my RV. They can hit their  heads on it!

Oh, I have a picture of the included HFT controller here:

The reason my battery is only at 12.1 volts, this was when it was first installed before it had a chance to charge up the house battery and this picture was taken at night:



-Don-


« Last Edit: July 08, 2010, 10:02:19 PM by DonTom »
-Don-   AA6GA

2000 Fleetwood Tioga 24D, 7.4L

Eight motorcycles:
Original owner of:
1971 BMW R75/5
1984 Yamaha Venture
2002 Suzuki DR200SE
2013 Triumph Trophy SE
2016 Versys 650 LT
2016 Moto Guzzi Stelvio
2017 Zero DS ZF6.5
2017 Zero SR 13 w/pwr tank

DonTom

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Re: Solar on the cheap?
« Reply #18 on: July 08, 2010, 09:58:54 PM »
Don why use the unirac ?
Why not use a tracking mount ?
IIRC, a much more efficient mounting came came with the deal, but I did want to deal with such.

What I did  works well enough for my needs and is a lot easier to deal with. In fact, for my needs, (just to keep all batteries charged during storage) this is an over kill. I have never ran down a house battery when boon docked yet. I always get a charge one way or the other every day, usually from driving. If I stayed boondocked for long periods of time, I would then try to be a lot more efficient. But between driving, RV parks with A/C and the generator (with converter) and storage, all my batteries (includes chassis battery) always has a full charge that will last us at least for any time boondocked during a trip.

Others might have more needs for more panels as well as tracking the sun. I have no need. During storage, my house batteries are always at 14.5 volts during the day and are well charged for any night use. My chassis battery stays around 13.8 VDC during the day. Don't need for any better than that.

-Don- Reno, NV
-Don-   AA6GA

2000 Fleetwood Tioga 24D, 7.4L

Eight motorcycles:
Original owner of:
1971 BMW R75/5
1984 Yamaha Venture
2002 Suzuki DR200SE
2013 Triumph Trophy SE
2016 Versys 650 LT
2016 Moto Guzzi Stelvio
2017 Zero DS ZF6.5
2017 Zero SR 13 w/pwr tank

hpcmbw

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Re: Solar on the cheap?
« Reply #19 on: July 09, 2010, 12:25:04 AM »
Thanks Don. My 5th wheel is boondocked for the summer, so I won't be moving it at all. I'll probably just set the panels in place for the time being, and not permanently mount them, but the info you provided re: mounting will be invaluable if/when I permanently mount them. I'll weight them down or do some sort of temp attachment.

The package did not include wires to wire the panels to the charge controller. Any idea what size/gauge wire to use? I wouldn't think it would need to be very heavy gauge wire, since I doubt there is a lot of electricity going thru the wire, but I wonder if I need a heavier gauge wire so i don't lose alot of power between the panels and the controller. I'll probably have about a 15' run from the panels on the roof to the controller which I'll probably place in the battery compartment (large compartment in the 5th wheel overhang, under the bed).

Any ideas re: the correct gauge wire?

Thx!
1997 Salem 30' fifth wheel; 2000 F250 7.3 diesel; 1996 Four Wheel Truck Camper
Northern California

DonTom

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Re: Solar on the cheap?
« Reply #20 on: July 09, 2010, 01:13:11 AM »
Any idea what size/gauge wire to use? I wouldn't think it would need to be very heavy gauge wire, since I doubt there is a lot of electricity going thru the wire, but I wonder if I need a heavier gauge wire so i don't lose alot of power between the panels and the controller. I'll probably have about a 15' run from the panels on the roof to the controller which I'll probably place in the battery compartment (large compartment in the 5th wheel overhang, under the bed). Any ideas re: the correct gauge wire?
It's about four amps max under best of possible conditions after all three panels are wired in parallel.

See the chart (in the link below)  and use five amps at 15 feet and get 16 gauge for your answer:

http://www.engineeringtoolbox.com/amps-wire-gauge-d_730.html


-Don- Reno, NV
-Don-   AA6GA

2000 Fleetwood Tioga 24D, 7.4L

Eight motorcycles:
Original owner of:
1971 BMW R75/5
1984 Yamaha Venture
2002 Suzuki DR200SE
2013 Triumph Trophy SE
2016 Versys 650 LT
2016 Moto Guzzi Stelvio
2017 Zero DS ZF6.5
2017 Zero SR 13 w/pwr tank

hpcmbw

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Re: Solar on the cheap?
« Reply #21 on: July 14, 2010, 10:36:06 AM »
I hooked up the solar panels last Sunday. When i hooked them up, my Trojan 6v battery set was reading 11.6 v. By the end of the day, the battery set was reading 12.1 volts, so I'm hoping this is going to work out well. I'll see what the batts are reading when I get up there this weekend.

Thanks for all the advice!
1997 Salem 30' fifth wheel; 2000 F250 7.3 diesel; 1996 Four Wheel Truck Camper
Northern California

DonTom

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Re: Solar on the cheap?
« Reply #22 on: July 15, 2010, 12:16:55 AM »
I hooked up the solar panels last Sunday. When i hooked them up, my Trojan 6v battery set was reading 11.6 v. By the end of the day, the battery set was reading 12.1 volts, so I'm hoping this is going to work out well. I'll see what the batts are reading when I get up there this weekend.

Thanks for all the advice!
It sounds like they are working fine, but I am wondering if you have your disconnect switch on disconnect with the solar controller output bypassing that switch, as you should. 11.6 VDC just seems low when there's nothing connected. But perhaps you're just starting with a well discharged battery.

After a few sunny days I would expect during the day for your battery voltage to be right at 14.5 VDC (exactly where the solar controller stops charging) and around 12.7 during each night.

-Don- SSF, CA

-Don-   AA6GA

2000 Fleetwood Tioga 24D, 7.4L

Eight motorcycles:
Original owner of:
1971 BMW R75/5
1984 Yamaha Venture
2002 Suzuki DR200SE
2013 Triumph Trophy SE
2016 Versys 650 LT
2016 Moto Guzzi Stelvio
2017 Zero DS ZF6.5
2017 Zero SR 13 w/pwr tank

hpcmbw

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Re: Solar on the cheap?
« Reply #23 on: July 15, 2010, 10:07:48 AM »
My battery was at 11.6 before I hooked up the solar, hence the need for the solar. When you refer to the disconnect switch, are your referring to the little button that turns off the display or something else? I only recall having two switches, the display on/off little button and the "on/off" rocker switch.

Don, I found that if I had the rocker switch to "off" the charger didn't send any juice to the batteries. I have the on/off rocker switch on "on" and the display button pushed so that I don't have a display showing. Is there a third switch I'm missing?

I've run a set of wires directly from the solar charger controller neg and pos battery outputs on the back of the controller, to the pos and neg battery posts.

Can you clarify what disconnect switch you are referring to?

Trailer is in a partially sunny spot at Donner Lake, gets full sun maybe 4 hours/day, and partial sun the rest of the day. It's been hot and clear up there the last week, so there should be plenty of solar power.

I'll be at the trailer tomorrow (fri) nite, and am hoping to find my batteries at full charge and the beers in the fridge nice and cold!

1997 Salem 30' fifth wheel; 2000 F250 7.3 diesel; 1996 Four Wheel Truck Camper
Northern California

DonTom

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Re: Solar on the cheap?
« Reply #24 on: July 15, 2010, 05:17:58 PM »
I only recall having two switches, the display on/off little button and the "on/off" rocker switch.

Don, I found that if I had the rocker switch to "off" the charger didn't send any juice to the batteries. I have the on/off rocker switch on "on" and the display button pushed so that I don't have a display showing. Is there a third switch I'm missing?

I've run a set of wires directly from the solar charger controller neg and pos battery outputs on the back of the controller, to the pos and neg battery posts.

Can you clarify what disconnect switch you are referring to?
Is your trailer battery disconnected from everything else except for the solar controller? You will get better charging that way because there will be no parasitic loads on the battery to drop down the solar charging voltage.

Most RV's (not sure about trailers) have a switch to turn off all 12 volt stuff while in storage. And I mean all the way off, just as if there's nothing connected to the battery. Many individual items draw a little current even when off. The disconnect switch turns all that stuff completely off, just as if the battery is disconnected from it all.

But if your battery voltage is 14.5VDC during the day and around 12.7VDC at night, just don't worry about any of this. Then just leave everything as is.

Yes, always keep the solar controller on (rocker switch) at all times, except for when connecting it up or disconnecting.  I keep the voltmeter (small round button) off unless I am checking the voltage, but it should not  make much of a difference if left on.

-Don- SSF, CA




 
-Don-   AA6GA

2000 Fleetwood Tioga 24D, 7.4L

Eight motorcycles:
Original owner of:
1971 BMW R75/5
1984 Yamaha Venture
2002 Suzuki DR200SE
2013 Triumph Trophy SE
2016 Versys 650 LT
2016 Moto Guzzi Stelvio
2017 Zero DS ZF6.5
2017 Zero SR 13 w/pwr tank

DonTom

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Re: Solar on the cheap?
« Reply #25 on: July 15, 2010, 05:26:13 PM »
I'll be at the trailer tomorrow (fri) nite, and am hoping to find my batteries at full charge and the beers in the fridge nice and cold!
Oh, I didn't realize that you wanted to leave the fridge on. Even if it runs on mainly propane, it needs to draw some 12 volt current while on. Your voltages may not be as high, especially during the night, but it should still work fine. The solar will still  help a lot.

Let me know what your day time and late night time voltages are. It might be a few tenths lower than I mentioned in my previous post, which will still be fine.

-Don-

-Don-   AA6GA

2000 Fleetwood Tioga 24D, 7.4L

Eight motorcycles:
Original owner of:
1971 BMW R75/5
1984 Yamaha Venture
2002 Suzuki DR200SE
2013 Triumph Trophy SE
2016 Versys 650 LT
2016 Moto Guzzi Stelvio
2017 Zero DS ZF6.5
2017 Zero SR 13 w/pwr tank

hpcmbw

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Re: Solar on the cheap?
« Reply #26 on: July 07, 2011, 12:33:34 AM »
I'm resurrecting my old post with some questions re: battery charging. As I recall, last summer the solar kept the batteries about 12.6v after a day of charging, and down to about 12.1v in the morning, before the sun hit the solar panels. Everything worked (except for some fridge problems) and I don't think I ever had to use the generator last summer. I was able to run fridge, use lights, radio and run heater and water pump without ever running out of electricity. When the batteries got down to 12.1 or 12.2 in the evening, I'd run some jumper cables from the two 6v batteries to a backup 12v RV battery for peace of mind.

I hooked up the RV to shore power in an RV park for the winter, but now I'm back to boondocking for the summer.  During the winter, I removed the two 6v batteries, took them home, fully charged them, then put on a trickle charger. The trickle charger was a small one for motorcycles, and never turned "green" (meaning fully charged).

Now I've put the batteries back in the RV and have the 45w solar panels hooked up. I run the fridge all week, but otherwise turn everything else on the trailer off from mon to friday. Saturday I show up and stay in the rv for the weekend.

Now for my question - after a full week of solar charge, the batteries were at about 12.6v when I arrived Fri night. By sat morning (after running heater for an hour), the batteries were at 12.1v, which quickly went up to about 12.5 v once the sun came up and hit the solar panels. I don't think the batteries ever get to 13v, let alone the 14.5v that Don had mentioned in an earlier response (not this summer or last summer).  The volt readings are all off the charge controller that came with the harbor freight solar panels. I haven't checked with a multimeter to verify the charge controller reading.

I purchased the batteries early last summer from a shady battery shop near a bunch of auto dismantlers. Of course, I was told they were brand new, overstocks, but I think I only paid about $125.00 for both trojan 6v batteries, so who knows the true story.  Then I let them get pretty discharged the first couple of weeks before I got the solar panels. Maybe my batteries aren't holding a charge?

I guess I'll try turning off the fridge and disconnecting everything from the batteries except the solar chargers this Sunday, and see if maybe there is a significant parasitic load. I'll see if next week the batteries at above 13v.

Should my batteries get up to 14.5v during the week? How low is "low" for discharge? I don't think I've seen below 12.1v since I've been boondocking this summer.  The solar charge controller is wired directly to the + on one 6v batt and - on the other (with the other + and - connected to make it 12v).

Sorry for the long rant. I really appreciate all the help I've gotten so far.

1997 Salem 30' fifth wheel; 2000 F250 7.3 diesel; 1996 Four Wheel Truck Camper
Northern California

Gary RV_Wizard

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Re: Solar on the cheap?
« Reply #27 on: July 07, 2011, 08:10:34 AM »
The expected voltage has to be viewed in the context of whatever charging may be taking place and the load (amp draw) at the time.You may see 14+ when the battery is actively being charged by the solar panel, but 13.3-13.6 is the resting voltage for a fully charged battery with little or no load. That same battery would probably show 12.6v under a moderate-to-heavy load but would soon drop down if the load lasted very long.  The fridge circuit board does not draw much power at all, so I would expect the battery to still show more than 12.6v once the solar charger is inactive. Maybe not 13v, but probably somewhere between 12.6 and 13.0.

Have you checked the water in the battery cells and replenished as needed? Use distilled water.

I'm surprised your trickle charger was not able to get the batteries into the green zone after an extended period of charging. Makes me suspicious. On the other hand, if your batteries aren't getting any lower than 12.1v after a night's usage, I would not be too concerned. 12.1v with a light load is about 50% charge.
Gary
--------------
Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

Tony_Alberta

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Re: Solar on the cheap?
« Reply #28 on: July 07, 2011, 05:09:33 PM »
Note that the gauge of wire running from the solar panels to the charge controller and on to the batteries can make a big difference if they are sized too small for the length of the run.

hpcmbw

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Re: Solar on the cheap?
« Reply #29 on: July 10, 2011, 10:27:57 AM »
I got to the rv after dark on Sat nite and the batt voltage read 12.6. The solar chargers (15w x 3 harbor freight solar panels with HF charge controller) had been hooked up all week. I get partial sun most of the day, full sun probably 2 hours per day. Only thing left on was the fridge.

That night I ran 12v light for an hour, water pump for 10 minutes, phone charger in cigarrette lighter outlet overnight, and fridge. At 7 am next morning, I ran heater for 15 minutes and checkd batteries- batt voltage was 12.2. I ran heater for another 30 minutes and plugged in 175w inverter to charge laptop and battery read 12.0 (solar panels in partial sun by now).

The voltage seems a little low to me. I checked battery water and it was good. The solar panels are hooked up with the wire that came with them - bigger then speaker wire, but not much bigger. The wire run from solar to charge controller is about 12 feet. The charger controller to battery wire is same as other wire (came with the kit), probably 3' run. The charge wires are connected to the batteries with alligator clips.

I'm planning on turning off fridge when I leave today, disconnecting all power from batteries, then see what charge I've got next weekend when I come back up.

Any addtl ideas or input appreciated!
1997 Salem 30' fifth wheel; 2000 F250 7.3 diesel; 1996 Four Wheel Truck Camper
Northern California

hpcmbw

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Re: Solar on the cheap?
« Reply #30 on: July 18, 2011, 10:14:16 AM »
Well, I guess my batteries aren't up to snuff. I turned off the fridge and disconnected all hot wires between battery and RV. I left the 45W solar panels hooked up for a week of sunshine. I checked last night in partial sun, about 6:00 pm, and the charge controller was only showing 12.8v. I checked the water level in the batteries last week and it was good. I guess my batts won't charge beyond about 12.8v. Fortunately, my weekend usage seems to be light enough that I haven't run out of power yet. Maybe when I pull the batteries for the winter I'll have them hooked up to one of those desulfiting battery chargers and see if that will bring them back.


Thanks for all the help.
1997 Salem 30' fifth wheel; 2000 F250 7.3 diesel; 1996 Four Wheel Truck Camper
Northern California

Tony_Alberta

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Re: Solar on the cheap?
« Reply #31 on: July 18, 2011, 04:37:58 PM »
You should do an energy budget.  Figure out how much each of your devices, including inverter and laptop charger, consume while running and how long each run for.    Note that an inverter consumes some milliamps even when nothing is plugged in and it's turned on.

Now figure out how much energy you calculate is coming in via the solar panels.   You will need to know the length of time you get reasonable strength of sunlight for your latitude.  Also realizing that cloudy days mean about 15% of the energy.   You should also calculate the angle of the solar panels to the sun.   You may be getting as little as 50% efficiency given that they will never be directly pointing to the sun.

 

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