battery question/solar recharge also

[burlesot]

I'm thinking through a couple of design ideas and thought I would pose a couple of questions here regarding batteries. I am also going to say that my dad tried to explain to me watts and amps and one of them can kill you and the other just makes you wet your pants, but I honestly cannot remember which is which.

If I plan on camping away from power sources, how do I figure out how 'long' I could run my teardrop (only using LED puck lights in the cabin for one hour average and the fantastic fan on high for 8 hours a night) using a deep cycle marine battery? I am imagining that we would usually be in one place no longer than two days. That would mean that the battery would trickle charge while driving and then the whole system would engage again.

I'm looking into an 85 Watt Solar panel to charge the battery during the day while we are out exploring, etc.

Does anyone out there use their solar panel to charge a second battery while driving? I know a lot of people use a trickle charge from the tow vehicle while they are driving. Is there any logic for using the solar panel to charge the main battery rather than the trickle charge? Could you have a second battery to 'store' the solar energy that is generated? I'm thinking about while you are driving down the road, the top of the trailer would almost always be exposed to the sun, this would be a great time to harvest the solar power, no?

Thanks in advance for you patience.

Todd

[eamarquardt]

In short, I think your plan is fine and viable. OK Tex? (an inside joke).

I'm thinking through a couple of design ideas and thought I would pose a couple of questions here regarding batteries. I am also going to say that my dad tried to explain to me watts watts is the product of amps and voltage (A times V) and amps is the amount of current or electrons flowing and one of them can kill amps are more important than voltage and if you have enough amps to kill you you, by the formula A times V, you have enough watts to kill you you and the other just makes you wet your pants, but I honestly cannot remember which is which.

I you wanna simple explanation voltage is like water pressure. Amperage is like water flow. Watts is the energy in the flow. Flow times pressure.

If I plan on camping away from power sources, how do I figure out how 'long' I could run my teardrop (only using LED puck lights in the cabin for one hour average and the fantastic fan on high for 8 hours a night) using a deep cycle marine battery? I am imagining that we would usually be in one place no longer than two days. That would mean that the battery would trickle charge while driving and then the whole system would engage again.

Your LED lights will draw minimum current. Your fantastic fan will draw a maximum of three amps or 24 amp hours during 8 hours (amps time hours). Figure 30 amp hours a day max for your lights and fan 9(this is probably several amp hours high). An 85 watt panel should produce (on an average) 4 or 5 amps perhaps 6 or 7 hours a day. Maybe more or less depending on the time of year, the weather, and where it's placed. This figure may be low. So your going to get pretty close each day put back into the battery to the same amount your drawing out of your battery. If you have a hundred amp/hour battery you can draw about 50 amp hours out if it and not damage it. So, IMHO, you'll do fine with an 85 watt solar panel and a battery rated for 100 amp/hours.

Charging your battery while driving is a good thing and it will be far more than a "trickle charge". I'd figure on 3 or 4 amp hours for each hour of driving and this is probably very conservative.


I'm looking into an 85 Watt Solar panel to charge the battery during the day while we are out exploring, etc.

Does anyone out there use their solar panel to charge a second battery while driving? I know a lot of people use a trickle charge from the tow vehicle while they are driving. Is there any logic for using the solar panel to charge the main battery rather than the trickle charge? Could you have a second battery to 'store' the solar energy that is generated? I'm thinking about while you are driving down the road, the top of the trailer would almost always be exposed to the sun, this would be a great time to harvest the solar power, no?

Thanks in advance for you patience.

Todd

[burlesot]

My head hurts trying to memorize the difference in watts and amps, but that's just because I'm a visual learner. I remember my dad teaching me this and then also telling me to 'never' pee on the electric fence. Well, you know what I did right? I peed on the fence. Whew! I learned pretty quickly what a connected current was and I also had a real life connection to the power supply! I really appreciate the solid response here. Thank you very much.

I found this video which kind of explained, visually, the difference between 12 volt and 120 volt http://youtu.be/4Q7s7QANevA

This video explained what you were talking about in terms of the water metaphor http://youtu.be/6Zxp8lSdn8M

Any thoughts on the solar charger during transit? Does it make sense to have a second battery that it charges? Is it possible to have 'two' batteries that charge during transport? Is this better than having the solar cell charge it? Or is it best to simply let the solar cell charge when you are stationary and don't plan on running the tow vehicle for a while?

I appreciate the response and the patience.

Todd

[eamarquardt]

:)

My head hurts trying to memorize the difference in watts and amps, but that's just because I'm a visual learner. I remember my dad teaching me this and then also telling me to 'never' pee on the electric fence. Well, you know what I did right? I peed on the fence. Whew! I learned pretty quickly what a connected current was and I also had a real life connection to the power supply! I really appreciate the solid response here. Thank you very much.

I found this video which kind of explained, visually, the difference between 12 volt and 120 volt http://youtu.be/4Q7s7QANevA

This video explained what you were talking about in terms of the water metaphor http://youtu.be/6Zxp8lSdn8M

I think you'll get it now.

Any thoughts on the solar charger during transit? Does it make sense to have a second battery that it charges? Is it possible to have 'two' batteries that charge during transport? Is this better than having the solar cell charge it? Or is it best to simply let the solar cell charge when you are stationary and don't plan on running the tow vehicle for a while? If you wanna use the solar power while driving the panels will have to be mounted on the roof of your car or trailer. Having them more or less permanently mounted will limit your ability to place them in the sun when you are camping in a shaded spot to keep your trailer cooler than if it were in full sun. Charging two batteries (or three or more) while you are driving is certainly a viable option. When the batteries are not being charged it's "good form" to disconnect them from each other (an 1-2-Both switch can do this easily) as they will tend to discharge one another. Not sure how long it takes for this to be a factor but what the heck, do it right. Your car's alternator is more than capable of charging several batteries as you drive. This electricity is not free (as in reduced gas mileage) but I doubt that you'll have a noticeable decrease in gas mileage. I use my tow vehicle to charge while driving and switch to solar when parked and a/c power is not available.

Cheers, Gus


I appreciate the response and the patience.

Todd

[GuitarPhotog]

The challenge to operating a PV (photovoltaic) array while driving is mounting it so it doesn't want to flap at highway speeds.

I am planning to have my PV array mounted on a portable, tiltable stand that I can put out in the sun while I'm in camp. The TV charges the teardrop battery when I'm driving, but I want to park my (dark brown) teardrop in the shade whenever possible, so mounting the array on the top of the tear isn't practical.

I run my teardrop on a 65 Ah deep cycle battery and am able to stay unplugged for 3 days using my LED lights normally and running the fan all day and night. I can stay unplugged for 5 days if I'm "battery frugal" and use only the low intensity lights and run the fan on low at night only.

In retrospect, I should have chosen a larger capacity battery. But the purchase price for a premium 100 Ah, AGM, deep cycle battery was too high for my budget when I was renovating my tear.

<Chas>

[jstrubberg]

If you're moving every two days or so, you can charge that battery with a trickle from your TV a lot more successfully than you can from a solar panel.

[bdosborn]

If you're moving every two days or so, you can charge that battery with a trickle from your TV a lot more successfully than you can from a solar panel.

Huh? Where did that come from? Don't tell my batteries that the solar panels have fully charged them by noon on every day we've camped. I might have to start running the truck to charge them.

Bruce

[bdosborn]

85 watts would do a fine job of charging the battery with the loads you've described, no connection to the TV would be required. 85 watts is the same size I had on the teardrop. I made a tilting mount for the panel but the it worked so well I never had to tilt it, I just left it flat. The battery was always charged before noon. Just don't count on the panel charging your battery when driving at night.





Bruce

[eamarquardt]

Hi,

As usual you and I are again on the same page. This time on solar charging and charging while driving.

Week before last my #2 son and I were in Denver-Golden looking for a place to live when he starts Mines in August. We were only a few miles from the shooting as it took place. I had actually considered going to the movies to kill some time but even if we had I'd have been in the sack before the shooting. Found a great basement apartment a mile from school and .8 miles from the Coors brewery. When I told #1 son I didn't think the proximity to the brewery was a good thing he agreed. He said it was a GREAT thing. I worry about those boys.

I'm sure the #2 son's mother and I will be visiting him a few times. Perhaps traveling by car and camping along the way. We'll have to try and hook up.

Cheers,

Eric "Gus" Marquardt

[bdosborn]

Found a great basement apartment a mile from school and .8 miles from the Coors brewery. When I told #1 son I didn't think the proximity to the brewery was a good thing he agreed. He said it was a GREAT thing. I worry about those boys.

We hired a couple of new grads from Mines (great school BTW) and they've treated me to "Coors Lab". We used to call it the "short tour" as you could skip the tour and go right to the tasting room for three free beers. However, the really good beer is at the Golden City Brewery, the second biggest brewery in Golden. Let me know when you're in town and I'll treat you to a GCB beer.

golden city brewery

Bruce

[DragonFire]

Sorry to break up the beer party, but I've been kicking around the solar idea too. Currently I have 4 LED lights that feed off my battery. I also have an option of using my water pump for my sink...but that drains the battery very quickly. So I never use it, except to disinfect the system when home.

I also have 3 12 volt plugs for cell phone charging, etc. I avoid using those too, since I can only trickle charge the battery when home.

The tear was set up to charge while driving..with the previous owner's TV. My truck is not wired to charge. I assume I need to go to U-Haul to have that changed over, then have the plug wired back to the old plug-in and replace the fuse.

So...if I get a new deep cycle battery (my current one is not that fancy..but works for now..) and get the correct equipment for solar, I can use all my current electrical and perhaps add a few features. I talked to a few campers at the IRG, including the guy from Kansas with the Rocket teardrop (not to be confused with the Rocketear) who had a Coleman panel attached to his custom made roof vent. It sounds like I could even take a small TV and video player and watch movies if I wanted to..(although I don't do so at home, and so far I have never been awake enough by the time I get back to the tear to do so...)

It would be nice to be able to charge the cell/camera/etc from the tear, use the water pump for dishes, and run the lights without having to worry about battery failure. I would actually like to use my little electric coffee pot and tea pot and run it off the battery. The longest I have stayed out so far is 5 days, but I have a longer trip coming up.

Please give me some tips on what I need, so I can get the proper equipment and get set up for next spring. The idea of solar charging is very interesting to me. I live in Sacramento where we have plenty of sun for a large portion of the year, so I think it might work very well for me.

[nevadatear]

BB, I have a flexible solar panel, controller. I put it on the roof when there is sun. Even without it, we can watch two or three DVDs (rainy days/nights), charge my cell phone daily, run the led reading lights and galley light for washing dishes, and have not run out of battery on a trip yet. Longest out was last year for dam gathering, it was 8 days. I used the solar maybe twice. Before we got the new battery, we ran out after 3 days. Oh, and when it is cold we use the heated mattress pad too. I can show you at wolf.

[jeffmutch]

Let's not under-estimate the power of our wonderful sun! As long as the math is done and the equipment is right, You'll never have to think about battery power again!

I have a single 95 Ah batter in my TTT and charge it with a custom made solar array on the tonneau cover of my TV. (producing right around 85 watts in the summer) I run fans as long as I want to at night, LED lights whenever I feel like it, and charge my phone, ipod, laptop, speakers, and sometimes my power tool's batteries without going below my 50% safe operating level. Next day, Its back to 100% by noon easily.

An american company called Uni-solar used to make flexible peel & stick panels before going out of business, though you can still find plenty on ebay. I always thought they'd be perfect for a teardrop's roof. They don't require drilling or any hardware to mount, they're nearly breakproof, and theftproof. Only catch is they only work in the sun. So be prepared for a toasty tear if it's left out to charge all day.

Dragonfire, I live in Folsom and I'd be happy to help you with your setup if you'd like it. PM me if you're interested. There's also a great guy in Winters that does custom work I can hook you up with.

[bdosborn]

An american company called Uni-solar used to make flexible peel & stick panels before going out of business, though you can still find plenty on ebay. I always thought they'd be perfect for a teardrop's roof. They don't require drilling or any hardware to mount, they're nearly breakproof, and theftproof. Only catch is they only work in the sun. So be prepared for a toasty tear if it's left out to charge all day..

They're also 112" long and be careful about the warranty as I don't think there is one anymore. That's the problem with thin film; half the efficiency and usually way more expensive per watt than silicon panels in the sizes that work with a teardrop. My favorite PV panel is a silicon folding type. I made a 60 watt panel from two 30 watt panels from eBay. Solves the mounting problem and lets you park the tear in the shade. Even though we have 220 watts of solar on the roof if the trailer, most of our battery charging is done by a portable panel as we're usually in the shade. Its also easy to track the sun with a portable panel for maximum harvest, just aim it right at the sun every time you happen to walk by.

DIY Folding Panel. I can get almost 30 amp-hrs a sunny day out of this one when tracking .



The only draw back is it might grow legs and walk away if you leave it unattended....

BTW, the government enacted tariffs on Chinese PV panels so most of the good deals from 6-9 months ago are gone.

Bruce

[jeffmutch]

Ah, Bruce is right about the warranty being void. Especially if you do what I did and cut them in thirds to fit onto my truck! They work just as well once you solder a few of the ends to themselves.

And yes, they are less efficient and take up more space. I suppose they have their place but might not be for teardrops... oh well.