Question about solar panel voltage near the same voltage as the battery

[Sunking]

The plane was pretty skinny and clean yet somehow they installed a 3000mAh 4S battery, 20A ESC, video camera transmitter, gps, antenna, etc. I have a few friends that have FPV type planes and they have a lot of "gingerbread" hanging on it..

Yes the video was fake. Like yourself someone who is in the hobby can spot it real easy. As you noted a 4S 3000 mah battery is pretty darn large and was no where in site to be found.

[Sunking]

You ran your napkin numbers and then used that information to show how solar on a plane was pointless is what I'm pointing out. My numbers say it should take 50 - 70 watts to keep my plane in the air. I should know because I have a volt and amp sensor on the plane. Those numbers are with my 825 gram 4s4p ncr18650b battery with an all up weight of 2142 grams.

I had to use some numbers based on assumptions. You did not give details. Look I am not saying it will not work, just not like you think. You may very well put 100 wat of cells on the plane. But what you do not know is you will not get 100 watts. 50 to 60 at best if that much. That is only if you fly at solar noon on a bright crystal clear cool day. If you are flying, the battery is not charging.

You do not need any type of controller or regulator. The battery and ESC will do that for you. As long as the motor is running and you arer flying, you will not be charging the battery. You might extend your run time. As Sun Eagle and I pointed out the video you have is a fake. Look closely yourself. Where is the huge 4S 3000 mah battery. A 4S 3000 mah battery is for a large plane. I know I have a 3D Extreme Flight Extra 300 with a 60 inch wingspan and weighs just over 5 pounds and uses 4S 3000 mah battery. The Wing Plane in the video was a flying stick using from what I saw was a 2S 400 to 600 mah battery.

Good luck to you.

[scotty562]

With 32 solar cells (Vmpp~18.6V), running a 4S battery at 16 volts sounds good. Will all your electronics and the motor run at this voltage?
I see on the diagram that you posted that they have a switch mode supply to drop from 16V to 12V. If you can run the motor at 16V and maybe the control electronics at 12V it would be good.

There setup is a little different than mine will be, but 16v for everything won't be a problem. The voltage will be dropped down where necessary.

As a safety precaution to protect your battery and your plane I would have an electronic switch that would disconnect the solar panels if the voltage got too high and for the control electronics to shutdown or slow the motor if the battery voltage gets too low.

Yeah I agree a switch like they used would be a good idea.

With 32 solar cells you are looking at an optimum power output from the panels of ~110W. You are going to have a very tight energy budget if you need an average motor power of ~80W to stay in the air. 80W equates to ~72% of the optimum output from 32 cells. I would think that reducing the energy usage to 50%-60% of the optimum solar output would be a goal to aim for.
Simon

I may need to drop the weight of the plane down to get the wattage needed to stay in the air down. There is some weight to spare, but we'll see how it goes. Optimization will be stage 2 so to say. Safely getting off the ground is stage 1 .

[Sunking]

If I had made this statement I would be banned. If you had a full battery connected to the solar panels with little or no other load out in the sun under the charge rates we are talking about it would be minutes or tens of minutes, not a day or more before the battery would start smoking or worse.

You are showing your ignorance again. If you knew anything about the hobby, then you would know you can't leave the plane setting on the ground powered up you zzzzzzzzz. Try it some day. zzzzzzzzzzzzzzz I hope I hope you loose a finger or hand

[scotty562]

Fake? Really? There are lots of people that have done this. https://www.youtube.com/watch?v=seqlvgEnfo8 is another one.

Anyway, I thank you all for your knowledge. I know what I need to do now to get this project off the ground.

[Sunking]

Fake? Really? There are lots of people that have done this. https://www.youtube.com/watch?v=seqlvgEnfo8 is another one.

Anyway, I thank you all for your knowledge. I know what I need to do now to get this project off the ground.

You need to watch the video, it failed and crashed 4 times before he gave up.


Real simple what they claim, and the plane does not match. Find all that candy on the plane in the video starting with that brick of a 4S 3000 mah battery. That size battery would be heavier than the flying stick they claimed it to be.

Look closer at the cells they tacked onto the wing. Where are the tabs and wiring? It is not there.Now look at your second video where the guy crased 4 times. The tabs and wire are there before he shattered all the cells crashing.

[SunEagle]

Fake? Really? There are lots of people that have done this. https://www.youtube.com/watch?v=seqlvgEnfo8 is another one.

Anyway, I thank you all for your knowledge. I know what I need to do now to get this project off the ground.

The second video is more reality concerning an RC plane using solar cells.

You can see those cells have a "grid" and the plane's body do not have all of the stuff associated with FPV. The video with the yellow wing is fake. This video with the large glider is more believable.

The problem I see is getting the solar cells to "charge" a LiPo. Running a DC motor directly from the cells will work depending on the motor voltage rating and number of pv cells.

IMO two totally different applications and videos.

[Sunking]

You can see those cells have a "grid" and the plane's body do not have all of the stuff associated with FPV. The video with the yellow wing is fake. This video with the large glider is more believable.

Yes sir and it crashed four times. He never got it to work. I know who the guy is and a frequent member on RCG. Same one that used the Pb battery and states right on the video PB has no application on RC planes. It took LiPo batteries to make electric RC planes usefull and now dominates the hobby. I designed and built the solar charger at my club in TX and now working on one in Panama at a park.

It can and has been done. First thing that has to be done is use Thin Film printed substrate as the skin of the airframe. Second trick is use SLOW FLY inrunner motors and props like Solar Helios. Real easy to do if you have the big bucks and engineers to pull it off. There is only one commercial use known and it has not been used much at all. Military Communications or Rescue operations flying at extremely high altitudes. You use solr to gain altitude and charge communications battery during the day, then orbit the area or theater and glide at night. Repeat next day. We are talking 100,000 feet where the panel efficiency and insolation is off the charts.

There are even some solar RC gliders out there. So it can be done.

[Sunking]

FWIW if you use only 28 cells, no worries about any overcharging a 4S LiPo. Additionally forget Arduino as it is antiquated. A Teensy 3.1 or 3.2 is what you want to use. Much more powerful and does not use antiquated interrupt timers. A Teensy 3.1 is the size of a dime and lighter than a dime. You get 12 bit analog accuracy running 6 times as fast with 6 times the memory for a fraction of the price. I use them to make a 3-axis PC USB joystick into a RC PPM Transmitter. Once you use a Joystick, you will never go back to two thumbsticks. You cannot buy them, you have to design and make them yourself. You can find my design on both RCG and Watt Flyer. Not to shabby for someone out of date huh?

[karrak]

Interesting video. I was impressed with the ability that it can run that long and that far using the solar cells to keep the battery charged but I have some questions on what I saw and what was presented in the details at the end.

The prop on the plane was a folding type yet the details showed a fix type. Also I am not convince the motor shown on the working model was the same as shown at the end of the video.

The plane was pretty skinny and clean yet somehow they installed a 3000mAh 4S battery, 20A ESC, video camera transmitter, gps, antenna, etc. I have a few friends that have FPV type planes and they have a lot of "gingerbread" hanging on it.

The solar cells were "blank" (without any grid to collect the electrons) so I am not sure how they worked.

So I am not sure exactly what was used for the FPV video run.

If it is a hoax it is a pretty elaborate one, they have gone to a lot of trouble.

I think you will get a view of the battery here https://youtu.be/KHV-RjvTb1c?t=48
As for the cells




There is some technical information on these here, http://pveducation.org/pvcdrom/manuf...g/rear-contact
Simon

Off grid 24V system, 6x190W Solar Panels, 32x90ah Winston LiFeYPO4 batteries installed April 2013
BMS - Homemade Battery logger github.com/simat/BatteryMonitor
Latronics 4kW Inverter, homemade MPPT controller

[SunEagle]

If it is a hoax it is a pretty elaborate one, they have gone to a lot of trouble.

I think you will get a view of the battery here https://youtu.be/KHV-RjvTb1c?t=48
As for the cells




There is some technical information on these here, http://pveducation.org/pvcdrom/manuf...g/rear-contact
Simon

Off grid 24V system, 6x190W Solar Panels, 32x90ah Winston LiFeYPO4 batteries installed April 2013
BMS - Homemade Battery logger github.com/simat/BatteryMonitor
Latronics 4kW Inverter, homemade MPPT controller

I stand corrected.

That video shows the battery hanging from the bottom near the front. I also saw the FPV antenna hanging below on the left wing tip. So it is possible they built that RC wing to fly FPV.

Also I was not familiar with the rear contact solar cells. They also look to be a possible product used on that wing.

So I will hang my head and agree that the video is not a hoax as I first stated.

The problem I still see is that without feedback (visual or telemetry) on the battery voltage and having a way to disconnect it from the solar cells, that LiPo can be overcharge and fail.

Whoever builds one of these solar RC wings needs to take care on having the safeguards built in to protect the battery.

Final statement on that RC wing. Unfortunately due to FAA regulations in the US, you are not allowed to fly a plane out of sight of the "pilot", above 400ft or over any populated areas.

Those regulations make it very hard to fly FPV legally with or without using solar cells.

[jflorey2]

Final statement on that RC wing. Unfortunately due to FAA regulations in the US, you are not allowed to fly a plane out of sight of the "pilot", above 400ft or over any populated areas. Those regulations make it very hard to fly FPV legally with or without using solar cells.

Those regulations are getting waived more and more often as drones demonstrate reliable navigation and collision avoidance. We do BVLOS testing here quite often; we have drones running courses several miles long.

[Sunking]

Those regulations are getting waived more and more often as drones demonstrate reliable navigation and collision avoidance. We do BVLOS testing here quite often; we have drones running courses several miles long.

Perhaps you should tell that to the FAA and AMA. They did not get that memo. Recreational use requires to stay below 400 feet and line-of-site only.

Commercial Drones require a FAA airman's license.

Commercial Regs FAA part 107. Stil 400 feet limit
Recreational Drones fly under AMA Rules outlined here. 400 feet altitude limit, and Line of site.

Rules are getting stricter, not looser. A Drone can easily be converted into a weapon. Just imagine mount a RPG, sit and wait for that limo to head your way. Pop up and fire, roll over in your bed miles away and go back to sleep. If you use cash and buy your parts here and there, almost impossible to trace. How about a football or baseball game anyone. Better yet an outdoor concert. 10 pounds of SEMTEX is easy to get and makes a nice BANG for the buck.

Bottom line commercial or recreational must stay under 400 feet. Only exception is a commercial Drone in order to clear a structure.

[SunEagle]

Those regulations are getting waived more and more often as drones demonstrate reliable navigation and collision avoidance. We do BVLOS testing here quite often; we have drones running courses several miles long.

I agree that the FAA is allowing more uses for UAV's but those are for commercial and industrial applications. Not for hobbyists which must still abide by the AMA visual line of site and elevation rules.

You also have to get a certification from the FAA to fly a UAV which at least has been simplified from requiring a full pilot's license to just being tested by an FAA person.