Very small solar setup

[HarmonicaBruce]

My idea is to have a small solar panel attached (duck tape) to the inside of the back window, with a little battery built in behind the panel above the rear window.

Here's the solar panel, it's 12" by 5", 5 watt, $23.99.

Here's the battery, it's 2ah, 5.75" x 3.5" x .75", $22.95.

Here's the voltmeter, and here's the cigarette lighter socket. ($8.80 and $2.75).  

Also a fuse holder ($2.41).

I figure it could be used to charge electronics without using the van's battery.  Total cost = $60.90.  The nice thing is it would be completely out of the way.  What do you think, is it so small as to be useless?  I'm thinking it's cheap, and a way to get started in solar.
  

 

[Optimistic Paranoid]

Do a google search on solar panels behind glass.  Depending on window thickness, iron content of the glass, and other factors, you will lose as much as 50% of your output.

Regards
John

 

[highdesertranger]

bruce, bob Dickerson on another thread is giving away 15 watt panels. I got 15 amp/hr batts for about 30 bucks. like these http://www.batterymart.com/p-12v-14ah-sealed-lead-acid-battery.html . much better deal imo. I just shopped around. however with a 15 watt panel you will need a controller. I think the question here is what are you planning to do with this. highdesertranger

 

[TucsonAZ]

I think there are many flaws in that plan, you would be better off using the vehicle battery for the charging and solar to keep that topped off.

http://www.amazon.com/RENOGY®-Solar-Panel-Starter-Monocrystalline/dp/B00E7NDMC4/ref=sr_1_15?ie=UTF8&qid=1425184346&sr=8-15&keywords=20+solar+kit

That's double the money but I'm certain you can find that kit for much closer to $100 and mounted to your roof it would be a MUCH better use of resources.

 

[skyl4rk]

I have a simple system to charge a smartphone and an led light, both of which have their own internal batteries.

A 10 a-h battery with a fuse, tied to a male cigarette lighter connector.
http://www.batterymart.com/p-12v-10ah-sealed-lead-acid-battery.html

A 1.5W solar panel with some sort of controller, maybe just a diode, with a male cigarette lighter plug. Harbor freight special
http://www.harborfreight.com/15-watt-solar-battery-charger-68692.html

A three way cigarette lighter splitter where all three of the outlets are connected, plugged into the car cigarette lighter outlet.

Most battery charging is done by running the car.  The three-way cigarette lighter splitter is connected to the car electric system by plugging it in to a socket that turns on and off with the ignition.  The battery and solar panel are plugged in to the three-way, connecting them and energizing the third plug.  When the car is turned off, the battery is disconnected from the car system, so the battery power can be used without affecting the car starter battery (note some cigarette lighter plugs may be hard wired to the battery and not shut off with the ignition).

Both the smartphone and led light have cigarette lighter plugs.  I usually unplug them when not needed so as not to drain the battery over long periods of time.

The 1.5W solar panel is there to keep the battery trickle charged.  I throw it in the back window shelf and forget about it.  I doubt that it would recharge the battery in a day, it would probably take a week or more to get it back up to charged voltage levels with just the solar panel.  A 10W panel with a small charge controller would be more appropriate, but I just used stuff (junk) that I had in the garage.  

The battery would probably charge the smartphone twice before needing a new charge (more or less).  The led light lasts for a long time between charging and I don't think it takes much power to recharge it.  http://www.harborfreight.com/rechargeable-led-work-light-with-magnetic-base-94668.html

 

[skyl4rk]

It is actually a little different than described above, but connected the same way. I got a little confused between how I built my trailer system and car system.

 

[skyl4rk]

 

[skyl4rk]

Here is the trailer system.  There is an old car battery in the battery box, if it dies or proves to be inadequate, I can easily replace it with a marine deep discharge battery.  The battery has a fuse between it and the cigarette lighter outlets.  There is no connection to the car electrical system, but it could be done.  The solar panel is wired to a male cigarette lighter plug, which is plugged in to the highest outlet on the battery box.  There is no solar controller, just a diode between the 10W panel and the battery.  I probably will get a charge controller, larger solar panel mounted permanently on the roof and a deep discharge battery eventually.  The heater is 120V, not running on the battery.

At the moment this works because my electrical loads are very small, just a smartphone and led light.

 

[MK7]

This is a better buy, IMO: http://www.harborfreight.com/12-volt-jump-start-and-power-supply-38391.html

This can be had for $39 (w/coupon right now) and sometimes $35. There's a 17-18 AH SLA 12v battery inside. My first one lasted almost 10 years, not taken care of well and when it died, I found a 17 AH SLA inside. It has a ciggy socket to recharge your phone, etc. I've used it to power electric jacks, lifting up 4000 lb. cars often (usually to rotate 4 tires), car vacuum cleaner, inflate tires from 5psi to 35psi, 12v impact wrench, etc. There's a utility light and volt meter. Comes with AC plug to recharge itself and ciggy plug to charge while you're driving. And you can jumpstart your van with it. Completely, contained unit with a rugged case.

You can hook up your solar panel to it.

My question is, how does this little 17AH SLA battery, able to jumpstart a car? I've jumpstarted my completely dead Corvette, Trans Am, Mustangs, MR2, RAV4....all from leaving some accessory on for weeks. Half of the time, it was during the winter, as I recall. When the battery's in this state, I'd connect this jumper pack on for about 3-5 minutes and it cranks right up on the first try. Can't remember what my cars' CCA calls for, but most of them are high powered V8's, so not low. There's a circuit board inside this pack, so I wonder if if it's loading up some capacitor with enough amps in order to start cars.

 

[AuricTech]

For your proposed application, I would think something along the lines of this Anker 8W PV panel* and this Anker 5200mAh battery would be more suitable, as you wouldn't need to worry about overcharging the battery.  My suggested system would also provide native USB charging for your electronics.  With the Anker PV panel, you could get additional USB battery packs as backup.

Your proposed system would provide about 600mA of 12V current to a 2Ah battery, which is a charge rate of over 25%.  That's rather high for a sealed lead-acid battery; as such, you run the risk of overcharging the battery.

*As is my usual custom when I link to Amazon, I generated the links from our host's Amazon search function, so as to steer revenue his way.

 

[RogueRV2]

It might produce as much as 3 watts on the roof, but mounted like that it would not produce much. 1-2 watts? That would be good enough to run a couple of solar yard lights, or charge a cell phone, or run a small portable radio for a several hours.

 

[RogueRV2]

BTW, as a fellow HAM, if you do not already have a handheld, check out those Boafeng UV5R radios. Program it using Chirp. With 4 watts and a good antenna, it will open most repeaters. It is a good handheld for the price, $37 at Radiooddity.com, or elsewhere. Also look at their Anytone or Wouxun mobiles. $300 dual bander, 50 watts, cross band repeat, and the new one, I'm looking at is a quad band, 10, 6, 2 meter and 70cm.... $300!!!

 

[skyl4rk]

For your proposed application, I would think something along the lines of this Anker 8W PV panel* and this Anker 5200mAh battery would be more suitable...

I think that a folding solar panel system like this is the best solution for charging a smartphone, although I might go for a higher wattage system, maybe 15W.  This gives you enough power to provide a charge to a smartphone in cloudy conditions or when the panel is not properly facing the sun. 

I would like a folding panel of about 10" x 36" to hang it from a backpack, put it on bicycle panniers, tie it to a roof rack, put it on the back seat shelf of a car, or hang it on the wall. 15W is about 1 amp and that should charge a tablet and it might be enough to charge a laptop over few days.

 

[MikeRuth]

10 Watts is about the absolute minimum to run a cell phone charger at 5.25Volts.

 

[RVTravel]

http://www.amazon.com/ALLPOWERS-Charging-Technology-Blackberry-Bluetooth/dp/B00G6C5NR6

14 watt panel that some seem to like.

 

[Canine]

I posted today in the electrics forum about the folding solar 20 watt idea. I see a few replies here which may support the concept, it's price that's killing me. Nearly $200 for the 14 watt folding panel and I could buy 2 Walmart marine batteries for that... If I wired in, rats, I forget which it is, but get double the storage at 12 volts then maybe with minimum draw I could last up to 2 weeks, then recharge off the alternator. Thoughts??

 

[jimindenver]

Dusty, How about this.
http://www.ebay.com/itm/nw-18V-20W-...659?pt=LH_DefaultDomain_0&hash=item5d570bad9b

 

[jimindenver]

This might be just big enough to make a difference.

http://www.ebay.com/itm/18V-50W-sem...137?pt=LH_DefaultDomain_0&hash=item27d397ac31

 

[Canine]

Thanks all. Did find an alternative much cheaper to my original post:

X-DRAGON High Efficency 20W Solar Panel Charger with iSolar™ Technology for iPhone, ipad, iPods, Samsung, Android Smartphones and More(iSolar Technology, Foldable, Portable)
by X-DRAGON
149 customer reviews
Currently $69.99

Maybe that will work, that's less than a single marine battery.

That and the first link just above from EBay seem to be the right price. I gather not many people bother with solar charging of small electronics. If someday I can find some kind of panel for the roof that may be the best bet. Losing up to 50 percent of the already meager wattage through the glass windshield is not good.

Ok, I will likely just wait then until I can jury rig or find a really small true glass panel for the roof. I certainly appreciate the responses and forum folks looking up alternatives to my online musings.

 

[jimindenver]

With the first I listed I'd get four suction cups so you could stick it to the inside or the outside of the windshield.