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I bought a solar panel and a regulator to trickle charge the 12v car battery that runs an electric poultry fence for my chickens. The fence uses so little juice that a fully charged battery will last for about 3 weeks. Ideally the intention was to use the solar panel so that I would never have to disconnect the battery to charge it in my garage, or if that was not possible, to extend the time between charges as much as possible.

So, I bought a 5 watt solar panel, and a regulator. All perfectly simple to connect, pretty pictures and everything. The problem is that my electrical knowledge is zero, including how batteries charge and discharge. So when trying to read the manual, I might as well be reading Japanese. And since the regulator was made in China, the bloke who write the instructions might as well have been writing Japanese, as they're completely incomprehensible.

So, to the question. I can see that there is a charge going from the panel to the battery. It's not much, about 5 amps I think, but that's not really the point - for now I'm happy enough that it is working. The problem is that the voltage meter which relays the state of the battery doesn't seem to be working as I would expect. This morning at 8.00, it read 7.5v, so roughly half charged. By 9.30 the sun was out and it was all looking groovy - voltage was up to 7.8 and climbing. I just went out and checked it again, and it's down to 7.5 again.

I would have expected the voltage to rise during the day, and fall at night. Or if the panel is not man enough to charge the battery, then I would expect the voltage to be static or dropping more slowly during the day. But it seems a little all over the place.

As I say, I know absolutely dick about this stuff, so any comments or education would be really appreciated. Basically I need to know if what it is doing is normal, or if I have a duff unit.

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In case it's any help, here is the manual section regarding the various LCD monitors - there is no option to change anything, you can only monitor what is going on:

IMG_0881.JPG

IMG_0880.JPG

So my mode 1 shows the 7.5 volts as mentioned above, the current battery voltage.

Mode 2 shows 0.00 - my assumption is that this means that all the juice from the panel is going directly into the battery, and none of it is being used to power the fence itself. This assumption may very well be wrong. It is the result of me trying to understand Japanese.

Mode 3 shows 5-7A, which to me demonstrates that the thing is actually charging.

So on that basis, I don't quite get the fluctuation in the battery voltage.

post-7727-0-01326500-1444646650_thumb.jpg

post-7727-0-41208000-1444646652_thumb.jpg

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amperage x voltage= wattage or wattage divided by voltage = amperage

So if you are getting a reading saying it producing 3-7 amps your panel must be producing 36- 84 watts

The output voltage from the panel required to charge a 12v battery would normally be 13-14 volts

Sounds like you have something wrong or knackered as you say the panel is 5 watt

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Hmm, I don't think anything is knackered - after I wrote the initial post I checked again when the sun was shining and we were getting more like 21A, which I assumed to be amps, but maybe not. Either way, the manual shows 18A so what I was getting in bright sunshine was in line with that.

The battery charged quite well through the day, rising to 9.5v, and then tailed off again this evening back to about 7.5v. So I think it is working ok. Maybe I'll just treat it like a woman and understand that I have no hope of ever understanding it.

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Hmm, I don't think anything is knackered - after I wrote the initial post I checked again when the sun was shining and we were getting more like 21A, which I assumed to be amps, but maybe not. Either way, the manual shows 18A so what I was getting in bright sunshine was in line with that.

The battery charged quite well through the day, rising to 9.5v, and then tailed off again this evening back to about 7.5v. So I think it is working ok. Maybe I'll just treat it like a woman and understand that I have no hope of ever understanding it.

No - something is very wrong.

What is the physical size of the panel? - a 5w panel will be about 20-30 cm square. A 5w panel will only be able to output about 0.5A. Even in the sunniest weather...

Also a 12V lead acid battery with anything under about 10v across the terminals is knackered.

If I had to guess I'd suggest that you've got the battery connected to the regulator solar input and the solar panel where the battery should be. That might mean you've destroyed the panel, but you might be okay.

As an aside, you don't need a regulator with a very low output panel (such as yours) and a car battery - it would be sufficient to just connect all the +ves together and all the -ves together. Now you've got a regulator you might as well use it, but if it breaks it isn't worth replacing (IMO).

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Yep. Get a volt meter and measure the battery. If in good condition and fully charged you are looking for 12.6V or above. 12.0V is pretty much flat and as Dgul says, below 10V, pretty much done for. A knackered battery will take a bit of charge and perhaps see the voltage rise after charging but it won't hold that charge for very long.

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Can't help thinking I've posted something above that is not correct, because I am quite sure the battery is definitely not knackered - I've been using it for months and have had to trickle charge it once every three weeks or so. If it helps, the battery was not fully charged when I connected the solar panel, in fact I would say it was about 2/3 disharged based on when I last charged it (I was hoping that the panel would charge it fully, hence not needing to disconnect it again).

I'm also certain the connections are all right way around. The regulator has very clear pictures showing +/- for both the panel and the battery, and even if I were cretinous enough to have got that wrong, the regulator allegedly has protection in it to prevent erroneous connections from damaging either the panel or the battery.

In addition, I have a tester to check how much electricity the fence is getting from the battery, and it is at 90%. Out of interest, during the day today, the V monitor went up to 9.6V. I know that was charging the battery, because the electric fence requires an energiser which has a status light on it. That status light was showing the battery running low this morning, but not by late afternoon. Then this evening after dark, the V monitor dropped off again to 7.6 or so and the energiser status light went back to running low.

Btw dgul is correct, the panel is 40cm x 34cm and is 4.8 watts.

I am only assuming that the A stands for amps - the bloody manual is about as much use as a chocolate teapot and doesn't do anything as helpful as point out what that figure actually is. But the picture clearly shows the panel putting out 18.0A, whatever the hell that is, so 5-7 in lower light and 21 in full sunshine sounds in line with the manufacturers expectations to me?

Sorry for all the long and possibly useless info, but I don't know shit form shinola on this stuff so can only tell you what I know / can deduce...

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Just FYI, here is the regulator:

http://www.topraysolar.com/product_details.aspx?pid=6&id=201

And here's the panel:

http://www.maplin.co.uk/p/solar-powered-12v-48w-battery-charger-n30cx

Just for laughs, I saw this review on the panel. Damn near wet myself:

★★★★★5 out of 5 stars.
clive9346
· 11 months ago

i now have this item installed in the defunct sunroof of my mitsu pajero after suffering dead batteries . it is wired via a switch direct onto the terminals of the battery. problem solved

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A 5W panel is not even going to put out 1 amp (assuming I am remembering correctly and the output voltage is around 18V or so). Also, you're not going to get anything like 5W out of it at this lattitude at this time of year. There isn't enough sunlight. You need about 13V or above to charge a 12V battery. I strongly suggest that you buy a volt meter and check the battery. I think the battery is FUBAR. If by some chance it isn't, we can proceed further with diagnosis.

Edit - It might be that the Chinese have confused A with V and the 18 of whatever it is you are getting is the panel voltage.

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Well something is very wrong here. The battery at about 1/3 charge should be about 11.5 to 12v. And the only way you're going to get 21A out of the setup is if you're short-circuiting the output (and both the battery and the wires would be getting warm).

The As will be amps, and the Vs volts - it is increasingly looking like the unit might be faulty. According to the product description it shouldn't be allowing any energy to get to the load if the battery is at less than 10.4v, and the amp readings are crazy.

OK. If you want to see which bits are working...

  1. tomorrow in the sun try connecting the solar panel directly to the 12v input of the fence module - if it lights up as working then the solar panel is fine
  2. Connect the battery directly to the fence module - again, if it lights up the battery is fine.

Frankly, if the solar panel and the battery are fine I'd just connect them all together - panel and fence module +ves to the battery +ve, same for -ves. This will work just fine. A 5w input for 10 hours a day (not this time of year!) wouldn't get anywhere near overcharging the battery (which is why you'd need a charge regulator if you had a 100w solar panel) and the fence module shouldn't allow discharge below 10.4v destroying the battery (which is why you'd need a charge regulator if you were feeding a 12v lamp, say).

Frankly, you're right on the edge anyway - a 5w panel is just about going to keep the battery from self-discharging, especially this time of year - you might need to top up the battery every now and then come mid-winter.

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Thanks for the help guys, really appreciate your input, especially working blind from my crap descriptions. I'll get hold of a volt meter and check the battery and update the thread when I have an answer. Ref dgul's suggestions:

1. Unfortunately I'm not going to be able to do this because the fence energiser has a hole and pin type connection.

2. This was how the setup has been for several months, hence me saying I "know" the battery is ok - or at least it was, until I connected everything together. So I'll do that again today and check it is still working.

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1. Unfortunately I'm not going to be able to do this because the fence energiser has a hole and pin type connection.

But you were able to connect it to the battery..! The maplin PV module has croc clips option so just connect the fence energiser battery connectors (that you'd normally attach to the battery) to the solar panel crocodile clips - red to red, black to black. Don't include the actual battery! (not a problem if you do, just that you won't find out if the panel is okay). Try not to let the black connection touch the red connection. It would be okay if you let it touch momentarily, but best if you avoid it. Also okay if you touch it yourself. You don't have to do it for long - just enough to get the load (the fence unit) to light up the 'on' led.

[you just need a 12v 'load', so it would be okay to just use any 12v thing that doesn't take much power and you've got lying around - a spare car bulb would do - connect one croc clip to the metal shroud of the base and one to the little blob in the middle of the bottom of the base (sorry if this language is too simplistic - trying to cover all bases) - the bulb should glow, but don't expect full on bright as you've not got enough power. Don't use a headlight bulb as it might not even glow with 5w. If you get any kind of glow then the panel is okay]

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Oh, I see - yep, sorry, I'll add another star to my divvy badge :P

Right, so the solar panel appears fine - it can power the energiser and put a small (about 40-50%) charge into the fence. The battery is also able to power the fence directly, albeit currently only at about 40-50% as well. So for now, I've hooked the fence energiser up using the mains attachment and put it on my charger. Later on I'll pop out and get a volt meter and see what it's putting out.

Also, I called the shop and told them that the regulator was showing a 21 amp input from the solar panel yesterday, and they immediately agreed with you guys that this is just not possible - therefore faulty unit. So that needs replacing at least (I took a picture this morning showing 5-6A again in relatively low sunlight, so the thing is clearly screwed).

So hopefully the battery will come up good when I test it later, in which case I just need a replacement unit. But I also think now the panel is probably not man enough for the job, so I'll probably keep an eye out for a bigger one.

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From what you say, it appears that your battery can only produce as much power as a 5W solar panel in weak sunshine. It's flat as a pancake and probably about as much use to you.

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From what you say, it appears that your battery can only produce as much power as a 5W solar panel in weak sunshine. It's flat as a pancake and probably about as much use to you.

Nope, just hooked the multimeter up to it and it's giving pretty much dead on 12v.

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Just to update a bit more, I just spoke to the store to arrange the return of the regulator, and they agreed with you guys that it doesn't need one anyway, and to connect it direct to the battery.

So now we have a panel that we know works, and a battery which is not completely shagged. So I will charge the battery up fully and then stick it back out there with the panel attached and see if it lasts any longer between charges.

Thanks again for your help, and apologies for the painful progress :)

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So I understand that's definitely below par, but not completely fried, no?

Correct. If it was on a car, the starter would turn slowly. Possibly just enough to start it. Suggest that after you charge the battery, wait a day and measure the voltage (not immediately after charging, the voltage willl be artificially high). 12.6V and above = v. good. >12.4V = pretty good. 12.2 or less and it aint going to last much longer.

Being at a partial charge is very destructive for lead acid batteries and the deeper the discharge and the greater the time spent there, the worse the damage. If you end up having to replace it, get a 'leisure battery'. They are desgned for deep discharge and stand up to it well whereas a car battery is designed for high starting output above all else.

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Just to update a bit more, I just spoke to the store to arrange the return of the regulator, and they agreed with you guys that it doesn't need one anyway, and to connect it direct to the battery.

So now we have a panel that we know works, and a battery which is not completely shagged. So I will charge the battery up fully and then stick it back out there with the panel attached and see if it lasts any longer between charges.

Thanks again for your help, and apologies for the painful progress :)

Excellent.

Also remember that we're rapidly approaching sunlight-minimum for the year - you might find that the panel isn't up to it for nov-dec-jan, but does add worthwhile days between charges during summer - perhaps it would be an okay compromise to do whatever manual charging is required over winter, and get the benefits of the solar charging during summer.

If you do get a larger panel then I'd say you're okay for up to about 20w connected directly to the battery, but I'd want a charge controller if the panel was capable of more output

(more detail - I'd be content to connect a larger panel directly this time of year, but I'd want to do something to prevent overcharging come spring. Some people have larger panels optimised for winter, then angle them so they don't capture so much sunlight during summer. Anyway, all that is a bit overkill for you - you should be good for over a month between charges with just a battery already?)

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Brilliant, thanks guys!

And best of all is that I now have a spanky new multimeter. I intend to multimete my way around every electrical device I encounter for a few days, just to make it worth the investment :)

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In case it's any help, here is the manual section regarding the various LCD monitors - there is no option to change anything, you can only monitor what is going on:

attachicon.gifIMG_0881.JPG

attachicon.gifIMG_0880.JPG

So my mode 1 shows the 7.5 volts as mentioned above, the current battery voltage.

Mode 2 shows 0.00 - my assumption is that this means that all the juice from the panel is going directly into the battery, and none of it is being used to power the fence itself. This assumption may very well be wrong. It is the result of me trying to understand Japanese.

Mode 3 shows 5-7A, which to me demonstrates that the thing is actually charging.

So on that basis, I don't quite get the fluctuation in the battery voltage.

battery voltage output gets lower as it gets colder.

if you want constant output from your battery, then I suggest you put a great big capacitor across the terminals(before the invertor bit), and if the regulator has components you can change, change the zener diode- just remember that these work the wrong way round- put the cathode(the bit with the mark), at the +ve battery end.

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Just FYI, here is the regulator:

http://www.topraysolar.com/product_details.aspx?pid=6&id=201

And here's the panel:

http://www.maplin.co.uk/p/solar-powered-12v-48w-battery-charger-n30cx

Just for laughs, I saw this review on the panel. Damn near wet myself:

12v 4.8w panel.

so at full whack you should only be getting about 350ma charge, not 5A

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