RC charging station 100watt 12V

[ryanf55]

I'm Back!

6 months later, I did some research and remembered about this forum

Here is an update on the project, which is now quite different.


I just received a Sharp Nt-185-U1 185 watt panel for free, and I hope to create a roof rack mount for my car.

There are lots of things I need to do:
1) Safety: When I received the panel, the + and - wires were connected. Does this short the panel so it cannot create anything but heat? When I build the charge station, I need to make the wire leads longer. The panel puts out 40 volts, so I will have it travel into the car on 40 volts, with the charge controller inside the car. Any outside wires will be weatherproof. I also need to add the correct diodes for reverse current, and fuses to prevent bad short circuits.

2)My 10Ah battery works well for fpv flying all day, but is not nearly suitable for this panel. Neither is the car battery. I will need to find a larger capacity battery bank .185watt/12V= 15.4 amps, so 154 Ah battery bank would be sufficient. Not quite sure where I can find that much battery without spending all my money.

3) Find 200 watt charge controller, supports 40 volt input, steps down to 16V or so.

4) Mount panel to my roof rack. It needs to be easily removable, and possibly hinged. Best case is the solar panel can put on by 2 people, and with just a wrench. Front bar is hinged, and the panel can be angled up at around 45 degrees with ease.


I hope to complete this project around May.

[inetdog]

One caution: If you drive much, the added wind resistance from the panel on the rack may cost you as much energy in extra gas as you are gaining from the solar setup.

[ryanf55]

I was thinking of mounting the panel for when I go flying RC planes up in the mountains, and keep it removed normally. Does it impact the aerodynamics significantly even if it is mounted flat on the rack?

I also read some panels could fly off if mounted badly... This is some serious stuff!


One option is to not mount the panel off the roof, and keep it inside the car unless I am using it.

I would like to start shopping for charge controllers, but I should test to make sure the panel is working. I do have a multimeter now.
If there are any must not do's when soldering on a new connector for the solar panel, please let me know. Obviously I am going to disconnect the + and - when soldering. Is it safe to plug them back together when I am done, or do I just plug them in and let there be a spark?
Thanks.

[Sunking]

Look I am an RC pilot so I know exactly what you need. You do not need any solar period, just a battery you charge up at home and take with you. If a 12 volt 10 AH last you all day like you claim, then buy you a good 12 volt 20 to 50 AH deep cycle battery and a $20 AC charger. Charge the battery up the day before you go and you are set.

Want more power. Install you an Auxiliary battery in your car with a electronic Isolator, and let your vehicle alternator do the charging. Your vehicle alternator can generate more power in the hour drive to the site than a 180 watt panel can generate in a week. You can even buy a charger made to plug into your cigarette lighter power port to charge a battery.

Don't waste your money with foolish solar on this application. All you need is a good battery and a cheap home charger. It will outperform an expensive solar panel and charge controller with a cheap 12 volt 10 AH battery. Th ebatery is what you want to spend the money on. You should know that if you are and RC pilot.

Enjoy the hobby while you still can. NoBama and the FAA are going to pull the plug on Quads, FPV, and Drones and severely limit RC planes and copters. The goberment sees them as a severe national security threat.

FWIW a 180 wat tpanel at 40 volts requires a very expensive ($200) 20 amp MPPT charge controller, and a 180 watt panel minimum battery size at 12 volts is 120 AH. Just the battery and CC is going to cost you $350 to $400. You can still have the large 150 AH battery and AC charger for $200. Use your head for something other than a place to hang your cool hat on.

For $100 you can get a good 12 volt 50 AH battery, AC charger for the house, and car cigarette charger. The $300 you save wasting on solar can be used to buy a lot of Big Mac's, 6-Packs, and a Roll In The Sack. That is what the Cool and Smart guys do. Think about it. Or could buy another RC model if you are a funny kind of guy and don't like to play with girls.

[ryanf55]

Although you bring up some interesting points, I would still like to do the project.

For the solutions you mentioned I do in fact own some of the stuff. I have a 300 watt inverter that can either plug into a battery (xt-60), cigarette lighter on car, or alligator clips for 12V input. It outputs 2 AC ports,and 2 5V usb for phone/camera. It does work very well for charging small packs on the way to flying.

You are right it is convenient but the issue is idling my car. A quick google search pulled up cars waste .1 to .2 gallons per hour while idling. Considering each battery takes 1 hour to charge (1C charge rate), I spend a lot of time with the charger on, and my van hates being off when I do that. I have had to jump- start a few times from charging a 3s 5000mah.


Question: What do you mean by good ebattery? Are you talking about the 20-50 AH in the car, or lipo in the planes. I know someone mentioned not to buy used batteries as it's like buying a used toothbrush, but I cannot afford a new 20-50 AH agm. Do you mean to buy a normal flooded cell that could spill?

Also, I do not need more power than the solar. My charger is 5 amps max, and I use 4s batteries (5ampsx 16V= 80 watts). The panel will be able to handle charging plenty of batteries, and I can share power with others.

Finally, the difference in cost between your proposal and adding a solar panel is barely existent. I already have the panel, a charge controller is $20 to $30. If I just kept it in the car than I can save $10 in mounting screws and stuff. The only real cost is the large agm battery.edit: Maybe not... I am realizing the cheap charge controllers are not able to step down the voltage efficiently.


As for your last comment: I get out and fly as much as possible. I am not concerned about any rulings on FPV. I see very little chance in it being outlawed. Any regulations will most likely not be enforced, and I am perfectly happy flying under 400 feet my whole flight. That's where all the fun is!

Lastly, I am 18, so I can't buy much of the fun stuff.. legally

[ryanf55]

That is not the kind of studying Russ is referring too. Non of what you say adds up or makes sense. If your device requires 72 watts to operate, a 12 volt 10 AH battery with a 100 watt panel is not going to work. Well unless you only want to run the device for 30 minutes a day and destroy your battery in a short time.

Secondly there is no way you can make a panel for less than you can buy one for. Better tap the brakes and do a few months of studying an dget a good grasp of the physics. Otherwise you are in for a very expensive lesson of failure.

Oh yea:
Working on the physics right now. Test coming this wednesday on electric charge, coulombs law, gauss's law, electric fields of disks, rings, spheres, and flux.


MTTP chargers are so expensive, and it looks like there is no way around using one. I unsuccessfully tried to find a 40 volt to 12V 200watt buck regulator. If anyone knows of a cheap source of MTTP charge controllers for my application, please post, otherwise I will return the panel.

[ryanf55]

Found a source of large 12V batteries, for free. My old boss has some extra, I just need to ask him if he has any.


After some more research, I realize there is no way to use my panel unless I get an MPPT. While looking for MTTP chargers, I see the MTTP's are more fancy, with digital readouts of current and stuff. I do not need any of that, so maybe I can find one without all the features, at a more affordable price.

If there is another charge controller option to step down the 40V to 12V with a lower price, please let me know.

Here is the best one I have found so far: 200 watt, 20 amp, 40 watt max OCV

http://www.eco-worthy.com/catalog/mppt-solar-charge-controller-free-shipping-p-182.html

[Sunking]

If there is another charge controller option to step down the 40V to 12V with a lower price, please let me know.

MPPT is your only option. The cheap ones are not MPPT. A good 15 amp MPPT is going to be in the neighborhood of $200.

[SunEagle]

Found a source of large 12V batteries, for free. My old boss has some extra, I just need to ask him if he has any.


After some more research, I realize there is no way to use my panel unless I get an MPPT. While looking for MTTP chargers, I see the MTTP's are more fancy, with digital readouts of current and stuff. I do not need any of that, so maybe I can find one without all the features, at a more affordable price.

If there is another charge controller option to step down the 40V to 12V with a lower price, please let me know.

Here is the best one I have found so far: 200 watt, 20 amp, 40 watt max OCV
http://www.eco-worthy.com/catalog/mp...ing-p-182.html

One of the lower cost MPPT chargers (without any bells and whistles and limited voltage programs) would the the Tracer 2215RN for under $150.

[ryanf55]

got a 12V 22Ah to add to my battery bank.

Question (extended):

Since car inverters charge the batteries way faster than my solar panel could, than couldn't I simply use my car battery as the battery bank? I do not need extended capacity(ah) as I usually charge during daylight when it would be replenished.

[Sunking]

got a 12V 22Ah to add to my battery bank.

Question (extended):

Since car inverters charge the batteries way faster than my solar panel could, than couldn't I simply use my car battery as the battery bank? I do not need extended capacity as I usually charge during daylight when it would be replenished.

Yes but it is a bad idea. Your vehicle battery is a SLI battery made for starting lighting and ignition. In other words designed to provide very high currents in small burst, and then be recharged quickly. They are not designed to cycle, and if forced into cycle service will destroy it in short order.

A better solution is to use an auxiliary battery with an Electronic Battery Isolator. It uses your vehicle alternator to charge it, but does not effect your vehicle SLI battery.

[ryanf55]

Hi guys.

I finally got a job so I will have some $ to spend on this solar system, but I still can't break the bank with batteries. I have 30Ah of the needed 150Ah 12V battery bank.

Where would I be able to find used AGM batteries? So far I have had no response from local wheelchair repair places.
Any other places I could try?

Thanks.

[SunEagle]

Hi guys.

I finally got a job so I will have some $ to spend on this solar system, but I still can't break the bank with batteries. I have 30Ah of the needed 150Ah 12V battery bank.

Where would I be able to find used AGM batteries? So far I have had no response from local wheelchair repair places.
Any other places I could try?

Thanks.

Unless you can get those used batteries for free don't bother with them. Chances are they are at their end of life will not last long.

You have now been introduced to the extreme cost of a solar/battery system. It is the batteries. High cost up front and short life. Where ever you find a set of batteries, DO NOT wire more than 2 in parallel. Better to wire 2 - 6 volt batteries in series. I have 2 x 6v 232 Ah Deep cycle FLA batteries in my RV. They cost about $130 each which gets you a lot more power for less money than using 2 x 12volt 100Ah AGM batteries.