Solar RC Battery Recharge station.

[BobW55]

Hello all.

Bob I so enjoy your videos.
Since you all are doing solar in real world I figured you would be best to ask this question to.

I am getting a 6'X10' enclose trailer with a V nose.  This is to transport and store my RC airplane gear.
I would like to build a solar powered recharge station for the batteries the planes use.  Although currently doing so from the car battery at the field, you are usually limited to recharging about 2 of them before having to start the car, or risk needing a jump start. 
Totaling up all my batteries, I have about 50 Ah of possible draw from a storage battery.  This is figuring if every battery I have was at Zero which will never happen.

Equipment I am looking at:
1 300 Watt 24 volt panel (about the largest I could fit on top).  OR
1 200 Watt 24 volt panel. (or duel 100 watt panels in parallel.
MPPT Charge controller 40 watts or larger.
2X 6 volt 250AH golf cart batteries  (not sure the brand friend is helping me out here)

Other than a few LED lights, and a 6" roof vent (running durring the day only) I only need high power to recharge the batteries.
With a 250 AH battery take out 25% capacity, I would need to recharge back into the Storage batteries about 63 amps.  Not sure If I would ever discharge that far but it is possible.  
It takes about 1 hour 20 minutes to recharge one 6AH lipo battery.  and it could be an hour or more before I recharge another one, all my other batteries are smaller.
Now the trailer will be parked where it will receive what ever sun there is all day with the panels flat.  And it would be days before I go out to the flying field again.

On another forum, I am being told this will never work, that I would never be able to recharge to golf cart batteries back up to full, they would sulfate and die an early death.
Many of you on here are living with minimal solar setups.  Am I throwing my money away or would this work.
There is another guy at the field he uses 4 golf cart batteries, but he plugs into AC at home to recharge them.  Id rather just let the sun do it.

Bob

 

[John61CT]

The best battery value by far is Duracell (actually Deka/East Penn) FLA deep cycle golf cart batteries, 2x6V, around $200 per 200+AH pair from BatteriesPlus or Sam's Club.

 

[John61CT]

You don't need much storage if you start with a 100% Full bank, and then are charging your little batts from "free excess" solar controller output, without other loads consuming at the same time.

Keeping the big lead bank full is key to them lasting a long time, completely different from your RC batts.

 

[John61CT]

What charger are you planning to use? DC-DC I hope?

If you haven't bought it already, I recommend iCharger's 4010-Duo, lots of flexibility.

 

[BobW55]

I use a Hitec X2 AC/DC DC/DC Charger.
Hook it direct to my car battery at the field. While it works great, not the best for the car battery. We have had several cases where someone needed a jump start by days end.
Yes I could just use a golf cart battery bank and use my AC battery charger at home, but that entails hauling the big charger out, grabbing an extension cord, and having to leave the trailer wide open. I know I could wire in a socket or something on the side of the trailer.
My better half calls it my mobile man cave!!!
I am lazy, other than maybe once a month (esp in winter) I would rather have a stand alone system.
I only fly maybe once twice a week. plenty of down time for the solar to do it's job.
IF IT WILL WORK

 

[BobW55]

John,
I have not gotten the batteries yet. I have a friend that works at a custom golf cart shop. He said he would hook me up when the time comes.
Don't want to invest in everything if it will never work.
I have a MAC Tools 60 Amp charger (the kind on wheels) that can easily handle topping off the storage batteries now and then. It is a PITA to drag out and hook up.

 

[John61CT]

So more than one full day to restore 65AH of draw?

300W is plenty, in great sunny weather 200W is enough.

And when too cloudy, put it on the mains charger overnight.

But no need for solar at all if you can make the mains charging easier for yourself.

The key is the bigger battery bank, actually designed for deep cycling.

 

[BobW55]

I figured with 250AH of batteries 2x6volt golf cart style.
Id have more than enough for when I use it. It is the putting back part I am worried about.
My math (which is often wrong) say's that a 300 watt panel @ 24 volts into a MPPT controller into the batteries should do it.
I do understand that durring the winter, I may have to drag out the beast and do it the hard way.

So final questions:
I was looking at the Renogy panel
https://www.renogy.com/renogy-300-watt-24-volt-monocrystalline-solar-panel/

1) Where is the best place to buy so you know you are getting the real deal and not a knock off?
2) What brand charge controller that has a display not just LEDs? Woild rather not have to wire in separate meters.

I know you all just love us newbies.

 

[John61CT]

Just not from China.

I like Victron, 75/15 SmartSolar

Specific batts listed above, make sure FLA not sealed

 

[BobW55]

I have seen that controller. It has good reviews, but I want something with a display.

 

[John61CT]

It displays more than you'd ever want to know, right on your smartphone.

Including history log data, pretty charts. . .

 

[tx2sturgis]

Yes it works fine. 

I charge my 4, 4500 mah drone flight batteries (and drone RC controller and ipad, plus a laptop and smartphone) almost exclusively from my solar panels regularly. I have never run the main supply bank low...it barely dips when charging 2 flight batteries simultaneously and/or several in sequence, as long as I have good sunlight.

My primary system in my truck camper/sleeper is 200 watts of solar, flat mounted. 

PWM controller.

110ah AGM. 

300w sine wave inverter when needed.


My backup system in the trailer that also powers my ham radios:

100 watt portable solar

PWM controller

200w sine wave inverter

Large Deep Cycle flooded marine battery.

Plus a small portable pack for charging laptop and running wifi unit.

And there are two generators, one primary, one backup. I have occasionally used the generators to charge multiple flight batteries simultaneously in late evening as the sun is dropping, just so I wont dip too far into the main battery bank at about the time I will be losing solar input.


And just to toss a wrench at the monkey, you can charge those flight batteries with a small inverter generator if your chargers will plug into 120v AC.

Of course, generators make noise, and that might be an issue at your RC meets.

One more consideration: If this vehicle is parked for long periods under a canopy, a tree, carport, garage, etc, you might not see full recovery after a full days use, meaning your battery bank will slowly, and quietly, get depleted. You will need to park it where it can receive solar for most of each day.

 

[BobW55]

Fortunately Trailer will be parked in full sun when not in use.
I rarely fly my batteries below 20% left when I land. I figure worse case, I charged everyone I own off of the storage battery (very unlikely)
we are talking 53 AH if they were all at zero before I started.

Just trying to decide between 1 300 Watt panel or 2 150 watt panels. I know I want 24 volt panels, not much but a slight edge over 12 volt.

Never thought about tossing a 2meter rig in there too.

 

[B and C]

If there is any chance of a partial shade on a panel, 2-150 watters in parallel would be better.

 

[tx2sturgis]

Never thought about tossing a 2meter rig in there too.

Ok...here is the 'rub'....

MPPT controllers are huge RF noiseboxes, so that is why I use tel-comm rated PWM. Yes, I loose a bit of power production, but my radios can actually hear signals.

If you are a ham, this is a consideration.

Snap on ferrite chokes can help, as well as physical separation between your controller + connecting cables and wires, and the 2m antenna.

 

[BobW55]

Not all that worried about running ham equipment off the set up.
Just bought a new Transit connect Wagon, haven't even put my 2/440 rig back in it.
Would think an all metal trailer would make enough of a Faraday cage to keep out the noise.

I had found 2 Mono 150 watt 24 volt panels at a great price, now I can not find the link again.

 

[jonyjoe303]

just make sure the controller can handle the 2 panels hooked up in series, the 24 volt panels are actually 36 volt, and the 12 volt panels are actually 21 volt panels.
Some controllers max out at 45 volt solar input, others go as high as 150 volt solar input.

You get about 1 amp charge power for every 20 watt solar. On my 240 watt solar panel and 20 amp ecoworthy mppt I average about 12 amps charge power on lead acid when the sun is overhead.

 

[BobW55]

Going to parallel them, and use a MPPT controller.
300 Watts is about as big as I can fit on the roof of the trailer.
2 smaller panels are just easier to handle than 1 big one, spreads the weight out a bit too.
I just hope Diane does not sneak out there and paint "Mobile Man Cave" on the side..

 

[tx2sturgis]

I just hope Diane does not sneak out there and paint "Mobile Man Cave" on the side..

Or on mine either....

 

[BobW55]

Is there a section on WHO/Where to buy from on this forum?