Question regards 12v solar panel charger

Question regards 12v solar panel charger

Purchased one of these from Aldi not realising the significance of the 'charger' bit. Was going to use it to power a project but seems internal circuitry is preventing this -thats what the question is about.

If I put a volt meter across the output it shows over 16v (overcast day) but as soon as I put a load on it the output drops to about 2v, I’m assuming this is either a 'trickle charge' or some sort of protection. Would I be right in either of these assumptions ? If I am right regards my assumption is there a way without actually opening the sealed unit to negate this behaviour (diodes to prevent feedback ?) or would I have to open the panel to bypass any internal circuitry. Simple answers/thoughts please as I’m far from being knowable regards electronics

Define overcast? Its a very common misconception that Solar Panels work on a cloudy day, depending on the amount of cloud cover output can fall to nothing.

What load did you connect? this will also drag down the voltage.

A 12 volt battery "trickle charges" at 13.7 - 13.8 volts so that shouldn't be the problem(assuming Lead Acid Batteries)

Hi,

12v solar panel charger

The charger is the main descriptive bit in the description, it is not a power supply, which is what you need. It is designed to charge a battery, which you can use as a power supply. Did it come with a user manual? How many watts is it rated at?

If I put a volt meter across the output it shows over 16v (overcast day) but as soon as I put a load on it the output drops to about 2v,

The 16V is the typical OPEN CIRCUIT voltage.

What size load did you use?

Bypassing the internals of the charge circuit will not make it a solar power supply, adding a rechargeable battery will.

Tom.. :)

full sun today & the panel delivered about 20v, which dropped to about 3v when a load was put on it - so nothing to do with cloudy days.

the panel specs are power rating 2.4 w voltage 17.5v current 138ma

Tom, i hadn't realised that a charger was different to a power supply - now i know different the load was a 'Buck Converter Step-Down Adjustable Converter Power Module Regulator LM2596'. I will be wanting to step down the voltage but as much as anything it was the first thing that came to hand to give the panel a load. are you saying i can connect a rechargeable battery and take power to the Buck Converter at the same time, think that would actually be useful

IGraham: the load was a 'Buck Converter Step-Down Adjustable Converter Power Module Regulator LM2596'.

The LM2596 has a no-load current of around 10mA, I think. That shouldn't bring the voltage down that much under sunny conditions.

lg, couka

Hi,

couka: The LM2596 has a no-load current of around 10mA, I think. That shouldn't bring the voltage down that much under sunny conditions.

lg, couka

It can if the PV cannot supply the surge current that the 2596 will probably need to start. Hence the need for a battery. 2.4W is not a lot of power. Tom... :)

OK, I'll have bit more experiment, think I've got a 12v rechargeable battery in the garage *shame i dont have a car i could just use it on that *

a last question, would a Lead Acid Rechargeable Alarm Battery 12V 1.2Ah be ok to use with a power rating 2.4 w voltage 17.5v current 138ma solar pannel

If the charger you have is compatible with 1.2Ah batteries, yes. What do you want to power with your setup?

lg, couka

An already working project, using a 6v solar cell to provide power to a 6v pond pump, the arduino switchers between the solar cell and a mains transformer supply depending upon the solar actually providing sufficient power. Its been working well until recently but it seems the solar cell i have might be failing as its no longer providing 6v it was.

So getting a 12v solar and using a Buck Converter Step-Down Adjustable Converter Power Module Regulator LM2596 seemed an idea that would extend sunlight strength operating coverage.

Introducing a battery into the setup should extend again the cover provided by the solar

well thats the plan anyway

Generally theres no benefit from using a 12V panel and stepping the voltage down to 6V over using a 6 V panel, unless the 12 V panel is a higher power rating, which means it will be physically bigger than the 6 V one. However directly powering anything using a solar panel without a battery usually doesnt work well. This is because Solar panels behave like current sources and most loads want a voltage source.

Is there a website for this product? If could be a bare solar panel, or have a built-in charge circuit for a 12V lead-acid battery.

Solar panels for 12V batteries will produce perhaps 20V open-circuit, 16V in cloudy conditions sounds right.

Solar panels do work in cloudy conditions but the output current will fall to 2 to 10% of nominal, which is a huge factor. If the panel doesn't have enough voltage overhead it will become useless in overcast conditions, but normally panels are designed to work in overcast conditions (with silicon a 36-cell panel is standard for 12V charging).

this is the solar charger hopefully will provide moore than the 6v pump will use and so charge the battery to provide for when its overcast

IGraham: hopefully will provide moore than the 6v pump will use and so charge the battery to provide for when its overcast

Well, that depends on the weather and on the power consumption and how often and long the pump runs.

lg, couka

couka: Well, that depends on the weather and on the power consumption and how often and long the pump runs.

lg, couka

true but not forgetting that the arduino will switch to a mains transformer supply if the solar/battery falls below 6v

Ah, forgot about that, yes.

I also wanted to add that you have to make sure to not over discharge the 12v battery. 10.8V should be the absolute minimum.

lg, couka