Solar Power: Baby Steps Questions - Page 2 - Fiberglass RV


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Old 10-17-2014, 12:39 PM   #15
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Another possibility for a connector for solar that won't be mistaken for 120V (or allow mixing up polarity) is an automotive SAE/bullet connector. It is used on many portable solar panels, so you may already have cables matching them. I found spares, cords, and even flush mounts versions at Solar Seller.com. Scroll down near the bottom to "E" for the RV Roof Connector.

I used a "set" (item D) combined with #10 landscaping cable to make up a long extension cord for my portable panel.

Here is what the flush mount looks like installed:
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Old 10-21-2014, 06:08 PM   #16
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Thanks everyone for your thoughts. I went ahead and returned the 13W panel to Harbor Frieght for a refund.

There is so much information available on solar power it's overwhelming. I am a researcher by nature and I have studied a ton of the info out there.

It seems that in order to run my laptop while off the grid, I will need at least a 65W solar power source.

What's troubling me is that it seems absurdly inefficient and over-complicated to connect the laptop, with it's inline power converter (adapter block which turns AC into DC), to my 1100W inverter, which is connected to the in-house converter, which is connected to the battery, which is connected to the controller, which is connected to the solar panel. I mean, there just has to be a better way.

I like the sound of Mike Magee's hack (“hack” meant here in the most positive way :-). I might try something like that. I'd also like to make it so I can plug the laptop into a 3-prong receptacle coming out of the controller. But what seems like it would be even more efficient and elegant (if it's possible) would be to take an appropriate cable (say, 8 gauge) with a barrel plug that matches my Dell Inspiron N411z on one end, and somehow connect the other end directly to the output of the controller of the solar panels, if the controller is smart enough that you can set it to exactly what voltage and amperage you want to come out of it, while it provides thermal overcurrent protection somehow (like with a thermal circuit breaker). When you look at the laptop's power cord, you see that it has an inline adapter that turns the AC input power into 19.5V, 3.35A output. So I want a controller that will take the solar panel's energy and deliver it at precisely that power profile.

I'm currently studying this thread which is helping me learn about it all:
Using a solar regulator with a laptop power supply
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Old 10-21-2014, 11:44 PM   #17
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If you want to go directly to your Dell you need an " aircraft adaptor" this little gizmo will replace the 110 plug on your laptop with a dialed device that turns battery power into 19.5 volts. I bought one in a travel store when we lived on solar power on our sailboat. The only thing is, I'm not sure you can get one that will convert 12v to 19.5v. You may find it easier to find a less than 12v laptop. My Toshiba was 10v so easily adapted to life on solar. Most panels have a peak output of 18v during the sunniest part of the day. So you see the problem? Yes, solar makes power out of thin air, but you can only ask it to do what it can do.


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Old 10-22-2014, 08:36 AM   #18
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I'd charge the laptop off your battery. If you don't have a 12V "cigarette lighter" type outlet they are cheap and easy to install. Then you can select from the various accessories from Dell.
Dell Inspiron Laptops Inspiron 14z (N411z) Replacement Parts | Dell
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Old 10-22-2014, 09:16 AM   #19
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I agree with Roy. Use a solar panel to recharge your trailer's 12V battery, and power the laptop (and the rest of your stuff) from 12V receptacles. Another source for 12V laptop power supplies is Powerstream.
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Old 10-27-2014, 03:11 PM   #20
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That panel is too small to do much good. It certainly won't need a controller to prevent over charging. I'd hook it right up to the battery. Likewise the inverter.

Unless you have a battery monitor in which case you want it after the battery monitor so it can count the amps going in and out of the battery.

You could connect those two things right to your fuse panel also. There are lots of ways of doing it.

Are you a sailor Julie? What do you sail?
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Old 10-27-2014, 10:52 PM   #21
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I'd charge the laptop off your battery. If you don't have a 12V "cigarette lighter" type outlet they are cheap and easy to install. Then you can select from the various accessories from Dell.
Dell Inspiron Laptops Inspiron 14z (N411z) Replacement Parts | Dell
I do have 12V outlets, they just don't work. The one in the dash of my tow vehicle uses a 10a fuse and it keeps blowing whenever I put any load on it. I'm wondering if it is safe to change it to a 20a fuse? Anyone?
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Old 10-27-2014, 11:16 PM   #22
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That panel is too small to do much good. It certainly won't need a controller to prevent over charging. I'd hook it right up to the battery. Likewise the inverter.

Unless you have a battery monitor in which case you want it after the battery monitor so it can count the amps going in and out of the battery.

You could connect those two things right to your fuse panel also. There are lots of ways of doing it.

Are you a sailor Julie? What do you sail?
I used to live in FL, and had a Hobie 16 which I sailed mostly at New Smyrna Beach, FL. Those were the days!
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Old 10-27-2014, 11:19 PM   #23
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Quote:
Originally Posted by bluesail20 View Post
I do have 12V outlets, they just don't work. The one in the dash of my tow vehicle uses a 10a fuse and it keeps blowing whenever I put any load on it. I'm wondering if it is safe to change it to a 20a fuse? Anyone?

It would depend on the wire size. Put electricity through a wire and it heats up. Larger wire can carry more current . Fuses are sized to protect the wire. There is a margin of error. Perhaps a 15 Amo fuse would work in your case. Much depends on the size of the wire attached to your cigarette lighter.



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Old 12-28-2014, 08:52 PM   #24
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You can get 12 volt laptop adapters from PWR+ on Amazon for about $22; these work great. I recommend 30-amp Anderson Power Poles for all your 12 volt connections, they require some basic soldering and assembly skills. I recommend plenty of solar, in the form of efficient polycrystalline or monocrystalline panels - not the amorphous ones. They've gotten relatively affordable. I would get 50-75 or more watts if you are going to bother. Another solution is to upgrade your vehicle starting battery to a very good one capable of some deep cycle usage, like the Sears Platinum AGM, made by Odyssey/Enersys, and run things from that, letting your alternator do the charging whenever you drive. A cigarette outlet in a vehicle is limited to 10 amps I think; if you are blowing the fuse you are likely exceeding that- and that's a lot of power! Go with cheap LED replacement bulbs, they are now excellent. Like other posters, I recommend a basic energy audit and thinking a bit like a minimalist.
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Old 12-29-2014, 09:25 AM   #25
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Quote:
Originally Posted by bluesail20 View Post
I do have 12V outlets, they just don't work. The one in the dash of my tow vehicle uses a 10a fuse and it keeps blowing whenever I put any load on it. I'm wondering if it is safe to change it to a 20a fuse? Anyone?
The typical 12V outlet in most vehicles (and trailers) is only good for around 10 amps, so going to a larger fuse probably won't help, and, if the wire size isn't large enough for the extra current, dangerous.

If you are sure the load you are putting on the outlet is less than 10 amps, check for a loose connection in the outlet. Remember, if you are plugging an inverter into the receptacle, the 12V side draws 10 times the current on the 120V side, so it doesn't take much of a 120V load to blow the fuse.
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Old 12-29-2014, 10:52 AM   #26
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If a 12V outlet would blow a fuse to run a laptop directly, then it most likely would still blow a fuse to run the inverter with laptop attached to it.

Charging the laptop battery off the panel directly is not efficient use of the panel, and what if you want to run the laptop for 2-3 hours at night? No solar recharge takes place without sun.

It makes the most sense to charge the trailer battery with the panel, so you never run out of power for any device (laptop, lights, fan, and everything). Is it somewhat inefficient to convert to 120V AC and then back to 12V DC? Yes, but it's easy, simple, and not so inefficient as to run down your Casita's battery prematurely. You should have all the power you need, and it's coming into the solar panel for free. But if it really bugs you, just run heavy wires from the battery power (from fuse box) for a new 12V outlet in the trailer; tadaa, no more inverter.
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Old 12-31-2014, 02:16 PM   #27
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Hey Julie,
Full disclosure – We are a solar manufacturing company that specializes in RV, marine, mobile and off grid applications. I am not here to promote but to help you find the best solution to your questions regarding solar. Please don’t hesitate to call us and discuss your personal situation.

First off – I’m happy to see you returned the 13 watt solar panel. That panel was made with amorphous solar cells, their life span is roughly 5 to 7 years for the most part. Since those were in a solid structure it likely would have lasted longer. They are also the least efficient solar cell out there. Most quality solar panels will have a 25 year power output warranty. Look for ‘lass A’.

Those smaller solar panels are great for battery maintaining when you park your RV but not for producing a decent charge to replace the energy you’ve used. You would likely need at least 120 Watts of Portable solar power when using that laptop for 8 hours a day and your other smaller draws. However, this is assuming that you will be using this mainly in the summer when the days are longer and you have good lighting – no shades and not many clouds. If you were to be in an area that is fairly cloudy you would need a larger solar system for your needs.

How I estimate your solar needs. You gave me some great information regarding how and what you were using electrically. Your laptop is rated at 65 watts – this is the maximum wattage draw that your laptop will allow and unless you’re using it for large amounts of computer processing - you won’t see 65 watts all the time – likely 20% less for the majority of your usage.

65 Watts at 12 volts is 5.41 amperes or a draw of 5.41 amps an hour. 8 hours a day and you could have a potential max of 43 amps for the day – this is potential but generally unlikely. I’d estimate your computer usage to about 30 to 35 amps a day (still considered high). This is just the laptop with no other external electrical equipment (monitor, hard drive, etc.).

An 80 watt Portable solar panel from Zamp is configured for 12 volt battery charging, it will deliver 4.6 amps of power per hour under optimal sunlight. 80 Watts is about 36 ampere a day for 8 hours of full sun. Again if you have partial sun or might experience partial sun, take this into account when configuring solar. For your specific needs I would recommend a 120 watt Portable Solar Charging System.


Your other usage sounds very light. Typically single battery small RV users are around 15 to 20 amps a day. You’re likely at about 10 to 15. Add that to your 30 to 35 amps a day for the computer and you’ll be at about 45-50 (almost half of battery capacity). A 120 Watt Portable solar system will deliver 6.84 ampere or about 54 amps a day (8 hrs). This should cut it for the most part.

A little bit about batteries. Generally RVers are poor caretakers of batteries. Batteries last much longer if you can keep them topped off when stored and only use 30 to 50% of capacity before you recharge them. This mean on your 115 amp hour batter you should only use between 35 and 57 amps out of your battery before you recharge it. If you follow my recommendations on how to use your battery expect to keep it for 6 to 8 years instead of the 2 to 3 that’s typical. This relates to solar by making sure you have the right amount of solar to recharge your batteries from daily use. Having a solar system that’s about 20% larger than your daily use is an ideal situation to be in.


ANSWERS TO YOUR QUESTIONS:
We recommend that you connect solar directly to the battery to ensure you have the proper wire size, tight connections and quality. Don’t connect solar directly to the battery as it is not a 12 volt battery and thus won’t charge correctly.

For that 13 watt panel you wouldn’t need a solar charge controller on your 115 amp battery. Larger solar panels I would recommend a PWM solar charge controller (smart charger).

Inverters should be connected directly to the battery with the recommended size and length wire. DC (direct current/Battery Power) doesn’t travel well over small wires or longer lengths. Always use the recommended wire length and size for your specific inverter – better yet get an inverter that comes with the wire.

Your inverter will draw a small additional amount of power from just being turned on. Likely 1.1% of the total wattage. 1100 watts at 1.1% is 12 watts or about an amp an hour. It won’t draw the full 1100 watts unless you have more devices powered from it. You can run up to 1100 watts. Turn it off when not using it. Better yet you can get a DC to DC converter for your laptop. I would only get a converter from the manufacture. This can be directly connected to the battery various ways – likely a cigarette lighter adapter. This removes the inverter and works just as well.

Another important factor is making sure you have a pure sine wave inverter. The other cheaper models are modified sine wave. Expect to have about a 1/3 life expectancy decrease on your battery when charging from a modified sine wave inverter consistently. Pure sine wave is the same power source you will find when plugging into a socket in a house or building. It’s considered clean and won’t put added stress on your devices. Pure sine for all sensitive electronics.

You can reach us via email or by phone – just go over to Welcome to Zamp Solar. Power to Explore. if you need to. We’re more than happy to help as you can see form this long post.
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