solar shed lights - charger question

In order to make the (new) shed at the end of the garden somewhat more usable, I wanted some sort of lighting. Eventually it will have power run to it properly, but for now I have gone with a solar lighting kit, specifically this one. It consists of:

1) a solar panel with these specs:
Size: 364mm x 164mm x 17mm
Peak output: power 5w
Peak voltage: 18v
Open circuit voltage: 21.6v

2) a battery (12V, 12Ah, Valve Regulated Lead Acid)

3) a 12V charge controller (Landstar LS1024B, with a maximum PV input voltage of 50V and a nominal charge current of 10A)

4) 12V LED lights

I have attached some photos of the current setup. The light output by the LEDs is impressive and lights up the shed really nicely.

When the sun came out today (but behind a massive cloud) and the PV voltage went > 13.6V, it started charging, although only with about 0.1A.

So I think this will work well in the summer months with plenty of sun, but I think in the more overcast months, at best it'll trickle charge and maintain the battery, rather than charging it.

I have power run down to the shed most weekends during the day anyways for various power tools and am thinking I'll keep topping up the battery off the mains over the colder months.

I would like the charger to be wired in permanently so that I just need to connect the power supply to 240V, rather than having to hook it up to the battery or disconnect the solar panel every time I need it.

I am a completely noob as far as all this goes so was wondering whether anybody would be able to help me with these questions:

1) Seeing that there is a battery charge controller built in to the solar panel controller anyways I'm guessing I could just get a 12V DC bench power supply such as this one and hook this up instead of the solar panel, into the solar panel inputs on the solar panel controller. Set it to 12V and a few amps and it should charge the battery through the solar charge controller?

2) I don't want to physically disconnect the solar panel input to put the 12V power supply in its place every time I need to charge from the mains. I assume there is some type of switch or relay I could use to switch between the two, a little bit like this?
What would that be called?


Again I'm really sorry if this is all really basic. Any help greatly appreciated.

Thank you

Martin

I've got something similar wired up on a bigger scale (2x 40w panels, 3 car batteries).

I just use a car battery trickle charger for charging it, direct to the battery. I don't need to disconnect anything, I fitted a 12v car cigarette lighter into the workbench for and put the same plug in my trickle charger (because this is how I use it for cars too). I then just run an extension cable out to it and plug it in.

I don't think the solar panels put out 12v which is why you need the controller - when I checked mine in the summer I was getting something like 80v.

In the summer it's fine but in the winter with the short days and lack of bright sunlight it goes flat and I have to charge it every couple of weeks. However, I have 100w of lights attached I use for about an hour an evening so that's the real problem.

You don't need a charge controller with such a small solar panel. You will never overcharge the battery with such a small panel. Connecting 12 volt supply via the charge controller won't work. 12 volts is not enough to charge a 12v lead acid battery, you need around 13.5v.

Thank you both for your replies.

Jakg said:

I just use a car battery trickle charger for charging it, direct to the battery.

Click to expand...

I don't have one, but it may be time to get one anyway. A quick google search threw up a number of results but a lot of the 12V car chargers don't seem to mention VRLA batteries in particular. Do I need to get a battery charger specifically for VRLA batteries or should any "good" car battery charger do?

winston1 said:

You don't need a charge controller with such a small solar panel. You will never overcharge the battery with such a small panel. Connecting 12 volt supply via the charge controller won't work. 12 volts is not enough to charge a 12v lead acid battery, you need around 13.5v.

Click to expand...

The charge controller came as part of the bundle so I thought I could just as well use it. Plus it shows load and battery status as an extra bonus. Thanks for clarifying re 12V. The power supply I was looking at can produce between 5 - 15V DC. So let me rephrase my original question. If I don't go down the route of the battery charger hooked up directly to the battery but instead were to hook a 15V DC supply up to the "PV in connection" on the solar charge controller (which is rated for up to 50V), how would I go about isolating the supply coming from the solar panel? Is there any type of switch would have four connections coming in (+ and - from PV and + and - from power supply), but only one output (+ and - to the solar charge controller) that would either switch +/- from PV to solar charge controller or +/- from power supply to solar charge controller?

Put a diode in series with the output of the solar panel (it could well have one built in) and another one in series with the output of your power supply.