Newby experiment going wrong

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Newby experiment going wrong

Postby melmik » Sun Mar 11, 2012 10:58 am

Hi, I'm just learning about solar. we have a 2kW system on our home, but I want to know more so I've patched together some cheap bits and pieces to play around and learn.

I got a cheap 10W 0.98A 12volt panel, a Solar CMP 12/24 12A regulator, an old portable cooler 12volt 0.28A fan and an old 12volt 7Ah/20Hr UPS battery.

The battery is still fine, charges up from a 240volt car battery charger and holds the charge.

I wired the battery to the regulator, and the load light comes on the regulator, plus 2 of the 3 red 'battery charge status' lights.

I then wired the panel to the regulator and placed it on the roof.

Then wired the fan to the regulator.

No change in lights.

Turn fan on and it works fine.

The battery status stays on 2 lights during the day, which I assumed was normal, and then depletes overnight to the point where the regulator shuts it down to save the battery from fully draining. All OK?

Possible problem: The regulator has a Charge light, which supposedly comes on when it is charging. The only way I can get it to light is by disconnecting the battery, and then it doesnt have eneough power to run the fan. The only way to run the fan is by connecting the battery into the regulator. the battery doesnt seem to charge from the panel - it is now down to one red charge light, plus the load light comes on as soon as the battery is connected to the reg.

I've probably stuffed up my sums due to my very basic understanding of Amps, Watts and Volts, but I thought it would work by the panel charging the battery enough to run the fan during the day and overnight, slowly depleting the battery until the panel came back online the next day.

I know this all sounds stupid, but I want to get an understanding of it all before spending more money on more solar gadgets like pumps, lights etc.

thanks for anyone who can help!
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Re: Newby experiment going wrong

Postby Sonnig » Sun Mar 11, 2012 11:40 am

Do you know more specs for your panel? The controller will need higher than 12V to operate correctly.

Make sure that the cables to the solar panel are a suitable gauge and not too long otherwise your voltage drop will be too high.

I'd be suspicious of the 10W panel and its ability to perform the task. I believe the controller's consumption is quite low but even with 10W in, the efficiency will mean a reduced output.
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Re: Newby experiment going wrong

Postby melmik » Sun Mar 11, 2012 12:11 pm

Thanks Sonnig. Cables are all same spec as those wired to panel. Longest run is 6m from panel to regulator. Jaycar panel specs are: ZM-9093 Specifications:

 • Maximum power: 10W
 • Rated voltage: 12V
 • Open circuit voltage: 21.5V
 • Short circuit current: 680mA
 • Dimensions: 396 x 289 x 23mm
 • Weight: 1.4kg
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Re: Newby experiment going wrong

Postby melmik » Sun Mar 11, 2012 12:24 pm

Just checked panel and it is rated at 0.59A, so less than i thought, but still double the fans rating. Maybe this is the problem. Sonnig is probably right, panel hasnt got the power to overcome the regulators needs and also trickle charge the battery.
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Re: Newby experiment going wrong

Postby melmik » Sun Mar 11, 2012 2:03 pm

Played around a bit more. Panel directly connected to fan works. Spins it very fast so probably overspeeding it, but proves panel has enough grunt to run fan. But if I disconnect battery from the reg nothing works suggesting that battery needs to be a part of the regulator circuit for everything to work, or that the reg circuitry is draining too much power for the fan to run or the battery to charge?

Maybe i need to add a panel, or find a less power hungry regulator. Am i on the right track?
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Re: Newby experiment going wrong

Postby Gordon-Loomberah » Sun Mar 11, 2012 3:02 pm

You've said the panel is rated at 0.59A, and if it is a 10W panel, then it is delivering its 10W (and only under ideal conditions) at ~17V. You are no doubt using a PWM regulator, so you are probably, at best, getting 7W from the panel (12/19V *.59A), when the panel is cool and face on to bright sunlight. More likely you are only getting 5W out of it, and given your regulator is a 12A unit, much of that may be taken up by the regulator electronics inefficiencies, leaving little available power for battery charging

You really do need a multimeter (and the knowledge of how to use it correctly ;) ) to see how much current is flowing where, and at what voltage.

Most of those regulators must have a battery connected, since if there is no battery connected, then the battery terminal voltage will be zero, which is well under the low voltage cut-off!

You can connect your fan to the battery directly, so you are just using the regulator for battery charging, and not load control, but you need to keep an eye on the voltage so as not to kill the battery.
Given how little power that panel produces,and the fact that you want to run the fan all day and all night, you could probably also connect it directly to the battery and forget about the regulator altogether. It is just using up power for no benefit with your current arrangement, which will result in a flat battery before too long, and may well ruin it.
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Re: Newby experiment going wrong

Postby melmik » Sun Mar 11, 2012 3:25 pm

Thanks Gordon, very much appreciated. So much to learn and so many conflicting info sites. But this seems to be one of the best as you guys are actually doing, not just talking.

I'm more of a learn by doing type person, than reading reams of info, but I think I need to go back to the basics of how electricity works and how to calculate my needs etc. Thats why i started very small with used bits and pieces.....less expensive when I make mistakes, but gets the process into my head.

Despite the mistakes it is fun to stick a panel on the roof and make something spin or glow at the other end.

Back to the books and drawing board!
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Re: Newby experiment going wrong

Postby Gordon-Loomberah » Sun Mar 11, 2012 3:40 pm

melmik wrote:Despite the mistakes it is fun to stick a panel on the roof and make something spin or glow at the other end.


Indeed it is :)

You might like to read through this thread: solar-wind-gear/topic1936.html which covers how much more you need to put into batteries than you can use to power loads. You don't have the inverter stage losses, but just charging batteries is not very efficient, especially at such low power levels as you are experimenting with.
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Re: Newby experiment going wrong

Postby jde » Fri Nov 23, 2012 4:41 am

Hi melmik,

Sorry for waking up an old thread, but did you have any success at solving this problem ?

I'm having the exact same problem (just with a bigger panel : effectively producing 55W during the day).

Before using this charge controller, I plugged the battery directly on the panel and it worked, but I was a little scared to damage something, so I installed this controller in between.

When I connected the controller, my battery (a 100Ah deep cycle battery) was charged (13.1V), 2 lights of the 3 battery status light up.
I have been using it for a week and I am now down to 12V and still the "Charge" light never lights up.
(I don't use the "Load" plug since it is not practical in my setup, the load is directly connected to the battery).

During the day, I measure 21V on the panel input, but absolutely no current flows from the controller to the battery...

So is it just a bad controller or is there something to make it work ?

Thanks !
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Re: Newby experiment going wrong

Postby Tracker » Fri Nov 23, 2012 6:07 am

.
By default, you are way below the fully charged voltage and thus, you simply MUST have current flowing to charge the battery..
Without knowing the CC, one would think that it's faulty..
jde wrote:I don't use the "Load" plug since it is not practical in my setup

I would have thought that the CC would work correctly, in charging the battery, without the load connected anywhere.. in particular.. :!:
What is special with the setup that makes use of the LOAD output impractical..?
jde wrote:Sorry for waking up an old thread,

'tis good to resurrect, as it shows that folk are searching, and it saves clogging with the same topic threads..
..
.
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