Higher power solar charge project.

[DucatiWiz]

So, I bought official Arlo solar chargers for the cameras on a large old Victorian mansion, where it was pretty impossible to run power and even more impractical to keep changing batteries. In the summer, all was pretty good, however in the winter, the small solar panels just didn't get enough sunlight and all the camera batteries died. 

So, I thought about a "simple" project to make a larger solar panel that would keep the cameras charged even in the winter. Good news is that I did it, it works brilliantly and it was pretty cheap and simple. Bad news for me (but good for you) is that it's only simple if you know how everything works. So here it is as concisely as possible to hopefully save you lots of time.

Logically you'd think that this was easy,  get a nice, large, efficient panel that keeps a car battery topped up, add a cheap step-down voltage module with a USB socket at 5v, plug in an outdoor charge cable and winner winner chicken dinner, right? Wrong!

You see, the Ultra has three modes:

1. It's on a 5v USB charge lead with mains power. On this mode, it's recording constantly so it can save the 10 seconds before an incident.

2. It's on battery. On this mode it stays in low power mode and records only when there is movement to save battery.

3. It's on solar charge mode, were it is basically in mode 2 above, but allows the battery to be simultaneously trickle-charged without going into constant record mode. It also stops drawing any power when the voltage drops below 6v (panel out of sunlight) to avoid battery power leaking back into the panel.

If you simply add a solar powered 5v USB socket, the camera will switch into constant record mode. Even with a pretty powerful solar panel, the battery will run out even faster than usual as the solar panel will provide less power than the camera uses!

When there is a cable connected, the camera knows to choose mode one or three because of two things:

1. The voltage going in; the solar panel produces 7.5v, (not 5v).

2. The solar panel cable is wired so that 2 pins are negative and one positive. On USB charge/mains mode, only one pin is negative and one positive.

 So to make this work, I needed to make sure that the camera stays in solar mode. Three items are needed for that, well 4 actually because I went for a double solar panel solution.

1. One or more weather-proof car battery solar panels. I got two of Amazon (10w each) for £20 each.

2. A very efficient voltage step-down module. Again I found one of Amazon, complete with screw connectors that was 97% efficient for just £8. This you can tune to provide a 7.5v output from a 12v panel.

3. The tricky bit, you need an Arlo Ultra cable that is wired for Solar charging, which means two pins negative and one positive. I don't have a cheap solution for that I'm afraid, but someone else may find one. I cut the cable off my Arlo solar panel (which wasn't good enough in the winter anyway) and used that. Interestingly, there is only one red (positive) and one black (negative) wire in the cable, but the negative one must be joined to two pins in the camera connector end.

That's it!, connect your one or more 12v solar panels in parallel to the input side of the step-down module. Tune the module for a 7.5v output (the one I got was just a screw to change it). Connect your solar-panel-wired cable to the camera and you have a nice powerful solar panel that only needs a few hours of daylight (not even sunlight) to keep your camera topped up at 100%.

Hope that's useful for someone else. If the forum allows me to post links to the parts I bought, I'll post them below.

[DucatiWiz]

Let's see if this works...

1. This is the solar panel I used.

SARONIC 10W 12V Car Battery Charger with plug-Battery Clip Module and Suction Cups Portable and Waterproof for Automotive, Motorcycle, Boat,Powersports, Marine, Snowmobile

2. This is the stepdown module.

Hakeeta dc converter module,DC-DC Buck Step Down Converter Adjustable Power Supply Module 6.5V-60V to 1.25-30V 10A

If you don't have a multi-meter to set the output voltage, you can get this module. It's not quite as efficient (92% rather than 97%) but it shows you the input/output voltages on the LCD.

KingBra 2 PCS LM2596s Buck Converter DC to DC Step-down Voltage Regulator Power Module 12V to 3.3V，12V to 5V，24V to 5V，24V to 12V，36V to 24V Voltage Stabilizer with LED Display

I'd recommend a small plastic weather-proof box to put the module in.

HTH

[DucatiWiz]

Interesting idea, not sure that it would be possible to fit one of those discreetly in my specific application, but curious to know what one you got and how you mounted it?

[DucatiWiz]

Thanks, but I don't think that having one of those on the side of the house would go down well. Also,  aside from the cost, even with a concentrator one small panel will never provide as much power as two much bigger ones... Just MHO. 

[DucatiWiz · Accepted solution]

Why? Honestly it's hard to take seriously the suggestion to use a solar concentrator for the above task. To work properly, it would need to be motorised and mounted somewhere near the camera and would only focus a bit more light onto a small panel that really won't in reality produce very much more power. Aside from the unsightly and impractical mounting of a concentrator on your building, there's the massively higher cost involved. It's much cheaper, more discreet, more efficient and far more practical to simply use a couple of bigger, more powerful panels that will work even without direct sunlight. It's an easy upgrade once you know what the correct voltage and wiring needs to be.

[DucatiWiz]

What's wrong with the original solution? The point isn't to heat anything or power a house, it's just to power a camera reliably even when there is no sun, which using a couple of cheap car battery panels does well. 

[Vego]

Hi,

Would your equipment list power 2 x Alro Pro 2 cameras?

Also does anyone have the pin outs for the connector?

Thanks!

[DucatiWiz]

On the image below:

1. For Solar Power mode, there is a 468k resistor connecting the third pin (indicated as "-*" in the image) to the negative pin.

+   =   +7.5v

-    =   negative

-*  =   negative with 468k resistance. (shows 7.1v on positive)

2. For charging mode.

+   =   +5v

-    =   negative

-*  =   not used

[DucatiWiz]

The short answer is yes, but there are many variables including how much sunlight the location gets, how often the camera detects movement and how far it is from the base unit etc.

As a VERY rough guide, the OEM solar panel seemed to keep my camera charged with approx 100 captures and 8 hours of direct sunlight per week. More captures and less hours of sunlight would result in the battery depleting.

The problem I had was that in the winter, the camera on the front of our building didn't ever get any direct sunlight, so just went flat.

The nice thing about this project is that if the OEM panel isn't keeping the camera charged, you can keep adding panels in parallel until it does. I'd start with one 12v car charging panel per camera and add one more (or even 2 more) if it's not enough. In my case, I started with two panels on one camera and it worked fine. It might work with just one (they are more powerful than the OEM ones) but now it's working I don't want to remove one panel just to try. 

HTH