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Old 03-10-2012, 08:40 PM   #1
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Solar panel to keep battery charged?

O.K.

We just bought a little 17 ft. Kodiak K-160 Hybrid camper last month My wife and I camp off grid 99% of the time. We are not energy hogs, using minimal battery power. Just enough to run a a couple of lights for maybe 2 hours each day, water pump for 2 short showers each day...maybe10 more minutes for washing dishes, drinking water, etc. per day. We run the furnace fan maybe 60 minutes total...a bit to knock off the morning chill and late in the evening. A tiny bit of power to operate the controls for gas refridg. No TV, Radio, computer usage. Won't use the microwave or Air Conditioner. We are outside of the camper all day. Sleep warm in sleeping bags at night.

So...what watt. solar panel would we need to keep the battery charged with maybe 4 hours of good sunlight per day? We have rented before and used a solar panel provided. I have no idea about it's watts or amps. We never ran the battery down...camping 2 or 3 days at a time between driving a few hours(which helped charge the battery.)

Last fall we rented and didn't even have a solar panel. Camped 4 nights without ever discharging the battery. Our power usage was as described above.

I've read all the technical stuff. Like to keep it simple. Is there an easy answer or suggestion?

Bob
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Old 03-11-2012, 06:26 PM   #2
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You are going to need to know what your actual load is for calculations. It is important to fully charge batteries and to keep depth of discharge to no more than 50%

One alternative is use your vehicle alternator to charge the battery. You can get a lot of power into the battery in a short period of time. I have two 30A lines to the battery (used for other purposes) but jumper cables work well.
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Old 03-11-2012, 08:22 PM   #3
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Quote:
Is there an easy answer or suggestion?
There is always an easy answer, never a good answer.

It is never just about a panel, its about sizes, types, batteries, controllers, etc. 25 Years ago I had two panels and a couple of so-called deep cycle batteries. Was never a good experience, Now I know better.

Best advice is to make a real calculation of how many amps you'll use. That's the basis of any installation.

Van.
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Old 04-01-2012, 09:20 AM   #4
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Smile Amp usage

What I did to calculate my amp usage was to purchase a 12 volt, 5 amp meter and placed it between the power lead and the appliance to see how much power it cosumes. It is a little bit of work but it told me what I needed to know to calculate my usage. I have a 22 foot trailer and only dry camp. I then purchased a 45 watt pack of solar panels from Harbor Freight tools. It comes with a charger controller. Granted, for the $125 (on sale) to $175 they charge, it's not cheep but it's a start to your needs. I ended up installing 3 sets on my roof and installing a 10 amp charge controller. At full sunlight I get just below 8 amps. These panels do not have roof mounting brakets. I designed my own. If you want to see what I did send me a e-mail at dndcrzn@hotmail.com and title it "HF Solar Panels"
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Old 04-04-2012, 09:48 AM   #5
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You should try and calculate your usage and think about the future and you will have an idea on where to start. Then there is the question of how much room on your roof can you use? A 100 watt panel is approx. 20" x40" and will put out about 5 amps/hour. Some good reading to get you started would be Handy Bob and Jacks Site.
I bought my system from AM Solar.

Do it right the first time and good luck.

Kevin
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Old 04-04-2012, 10:51 AM   #6
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The above are right. You will have to find your base load (mine is about 1.7 amps times 24 hours is 40 amp/hours). Then add your estimated other uses. I use about 30 to 40 amp/hours during the night for lights and heater fan, water pump, etc. So I need at least 60 amp/hours of solar charging (half the base load is included in the night use figure. These numbers come straight from my Battery Minder display. You will get around 50% of the rated wattage from the panels when flat on a sunny day at noon. I can get 21-22 amps at peak for about 4 hours then 8 hours of something less (about 1.5 amps at first light before the sun is even up), I guesstimated around 170 amp/hours available on a 12 hour sunny day in the Mohave with flat down panels on the roof. My Batts will give about 140 amp/hours to the 50% mark so I have some overkill. But when it is cloudy and raining my available solar is down 90% at times so I have then ability to take advantage of any sun breaks. My only problem now is that my 3 stage solar charging system does not include the chassis batteries. Love not having to run the generator for hours each day.
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Old 04-05-2012, 08:35 AM   #7
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Thanks gentlemen,

You have provided the road map. I understand the process was just being typically lazy...haa ha.

As said above we use very, very little power. The panel we have used on a rental before was on a long cord. We just sat in on the ground and pointed it south then left for the day. Never got the battery below 50%.

I won't mount a panel on the roof...just do the portable thing. Next step is to buy a deep cycle battery as the one with the camper will not hold a charge.

Any recommendations on the best deep cycle that will provide power at minimum usage for the longest time? I was at the Sun N Fun airshow in Lakeland FL last week. Honda had some incredible deals on their generators. 50% off retail on a EU-3000. I was tempted but even with their whisper quiet engine....I want to avoid a generator.

We are headed to southern Utah for 3 weeks in late May. Should be lots of sunshine. I'll let you know how it goes.

Bob
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Old 04-05-2012, 02:08 PM   #8
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Quote:
Originally Posted by Happy Prospector View Post
You should try and calculate your usage and think about the future and you will have an idea on where to start. Then there is the question of how much room on your roof can you use? A 100 watt panel is approx. 20" x40" and will put out about 5 amps/hour. Some good reading to get you started would be Handy Bob and Jacks Site.
I bought my system from AM Solar.

Do it right the first time and good luck.

Kevin
Thank you,

Moving along like a blind man describing an elephant.....I read Handy Bob and Jack's site. So...here is what I am thinking.

1. A Trogan SCS 200 12V. battery..............................around $200.00
2. A Solarland 100 watt solar panel............................around $400.00
3. A Morningstar Tristar 45 amp charge controller...........around $140.00
4. 10 feet of #6 battery cable....................................around $35.00
5. 5 feet of #4 battery cable....................................around $40.00
* plus a bit of miscellaneous hardware................................$15.00

Total........ $830.00

I know that I can buy a Solar panel complete kit for a couple hundred less
than making up my own. However I am choosing products recommended
in the above mentioned articles. I want good stuff that will work and last a while.

I do not want to roof mount the panel, rather keep it portable, having used such a system when renting in the past and it worked well. Once again we will use very, very little power. Lights for maybe and hour a day. Water pump maybe 1 hour per day and furnace 1 hour per day...a bit of the morning and a bit late in the evening.

So being a novice....will I have any difficulty making up my own solar kit? And are the items listed...panel, charge controller and wiring plus hardware all that I will need/

I am not as stupid as I may sound...but I have never liked messing with electricity and as a result am now just learning the very basics.

Ohh. And also the articles referenced above said that one needs a charger controller that will allow you to set the voltage up to around 15 volts to fully charge the Trojan battery. The author uses the Morningstar controller mentioned. Does it have a manual setting rather than an automatic cut off around 13.5 volts like many controllers? I couldn't tell when reading Morningstar's data.

Thank you for your wisdom and patience.

Bob
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Old 04-05-2012, 02:41 PM   #9
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The tristar controler has dip switches that you use to select the voltage you want.
The onwer's manual is located here:
http://www.morningstarcorp.com/en/su...nual.04.EN.pdf

You can select 14.4, 14.6, 14.8, 15.0 volts using the dip switches, or select custom values using a PC and the software available from Morningstar.
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Old 04-07-2012, 03:34 PM   #10
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Hey Bob,
I don't know a lot about generators. I do know the "Inverter" style give cleaner power and everything being plugged into it seems to run better. If you are looking for something cheap and easy, Harbor Freight has a 900 watt generator that runs on 2 cycle gas, not very loud and works well. Many auto parts stores carry the same little generator but with a 10 amp battery charger built into it. I have one. I Like it. I'm not a HF fan, but being in my 60s, I don't need the best as when I was younger. The 45 watt solar kit HF has comes with a free standing brkt for the panles, charge controller and a few 12V compact floressesnt lights. Costco has a 60 watt version of the same kit. Buying a single solar panle is way cooler but a lot more expensive.
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Old 04-07-2012, 09:38 PM   #11
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One note on generators, spent 4 nights in Death Valley last month with the loudest portable generator I ever heard 2 sites away. It was so bad we could not sit outside and talk over it. He ran it for hours each morning and evening during legal times but. . .
I was going to move but he left first. 2K Honda's are almost silent but most others can heard unless placed well behind some sort of sound barrier. I not saying it should be pristine quiet but when you cannot talk over the noise when 30 yards away.
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Old 04-08-2012, 03:13 PM   #12
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Thanks Folks...

...for the great responses. Looks like we will stick with the original thoughts except now I believe we will convert to 2 Trojan 6 volt batteries. That will cost more up front but I believe that it will give us all the power needed given our "camping" habits.

The generator is highly unlikely as the only time I can imagine using one is to run the air conditioner. We chose isolation where the only sound is silence. Given the seasons that we like to travel and location geography....it would be rare that we would need air conditioning.

If we wanted all the comforts of home...we would just stay home.

I appreciate your helping a novice.

Bob
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Old 04-08-2012, 10:25 PM   #13
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Why not mount a panel or two on the roof and be done with it? No set up or tear down, less chance of breaking it, always charging even when you are moving...

I installed two 195 panels on my rig. TriStar 45 (I could use the inexpensive non MPPT model as I had low voltage panels), Trimetric meter to keep track of the whole process. Spent about $1500 including very professional install where I participated and learned a ton. Works flawlessly.

Replacing that rig with a larger fiver. Will put 735 watts in three panels. Bought them for $0.90/watt on close out. I'll put an inverter on this rig.
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Old 04-08-2012, 10:33 PM   #14
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Accidentally hit send before I finished. Meant to add that the OP parts list looks good. The real key is to keep the distance between the charge controller and the batteries very short and use large gauge wire. The voltage drop in smaller wire will kill the charging process. I think the voltage for the Trojans is 14.8 but check the specs. If your wire size is too small you won't get 14.8 to the batteries and they will not fully charge. Period.

Very short means a couple of feet of large wire. Think #2/0 at least, not #4. I would mount the charge controller on the batteries maybe and use the temperature sensor you get with the Tristar. The run from the panels isn't quite as critical but for small panels you will want to get every watt you can to the cc so size that right too. I'll use #4 in my fixed panel rig but that might not be practical due to inflexibility for your portable setup.

Depending on your flexibility and rooftop real estate you might can find a larger panel for less than $400 and really charge some batteries!
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