Can someone help me out with an issue with ssmall solar charger?

[Dozerboy]

I started using solar panels to charge various 12v things at work. On this one I just have a panel hooked directly to a 12v battery for GPS grade control system. It doesn't seem to really charge it very well.



I did a little reading in saw something about at night time the solar panel can actually pull power out of the battery. A diode to prevent that if the paneldoesn'thave one. I really couldn't get a straight answer if the panel has one already or not.



I don't really want to add a controller, because this thing sits outside and it's either gonna get stolen or damaged by the weather.



So I guess my questions are. Does this panel have a dioded? If not, where do I add 1 and how big of diode do I need to have?



Here is a link to the panel I have.

https://www.northerntool.com/products/nature-power-7-5-watt-amorphous-solar-trickle-battery-charger-model-42075-5205961

 

[2004LB7]

Solar cells are themselves like a diode. So it's difficult to get voltage to flow backwards through the panel. But it does happen and the current is very small. Most of the time blocking diodes are used when panels are connected in parallel as the voltage difference between shaded and exposed panels can be large

If you do want to stop it at a small hit to your output of the panel then install a schottky diode in series. Those small panels that come with clips or directly attach to the battery likely don't have any blocking diodes in them. If your panel has a block over the wire connection then that's where it would be. If the wires are soldered directly to the panel then no diode.

On larger panels where they are designed to be connected in series they will install bypass diodes attached to the output lines so if one panel is shaded then the current from the others can skip over the panel not producing current. That would be a parallel diode.

 

[2004LB7]

I just looked at the link you posted for your panel. It already has a blocking diode. Maybe the battery has a self discharge that causes the panel to not really keep up. Or the internal resistance is too high for the panel to push and meaningful current into the battery. A larger panels may be needed

 

[Trimox]

I started using solar panels to charge various 12v things at work. On this one I just have a panel hooked directly to a 12v battery for GPS grade control system. It doesn't seem to really charge it very well.



I did a little reading in saw something about at night time the solar panel can actually pull power out of the battery. A diode to prevent that if the paneldoesn'thave one. I really couldn't get a straight answer if the panel has one already or not.



I don't really want to add a controller, because this thing sits outside and it's either gonna get stolen or damaged by the weather.



So I guess my questions are. Does this panel have a dioded? If not, where do I add 1 and how big of diode do I need to have?



Here is a link to the panel I have.

https://www.northerntool.com/products/nature-power-7-5-watt-amorphous-solar-trickle-battery-charger-model-42075-5205961

From that link it state it will charge a .4 amps. I don't know how much power you equipment draws but lets just say 1amp (a very small draw), You are using 60% more power than you are charging. Depending on how much the equipment runs during daylight hours you may not even see a charge to the battery. You might need a larger panel.

 

[malibu795]

In for learning

 

[Dozerboy]

I just looked at the link you posted for your panel. It already has a blocking diode. Maybe the battery has a self discharge that causes the panel to not really keep up. Or the internal resistance is too high for the panel to push and meaningful current into the battery. A larger panels may be needed

Not sure how I missed that... It might be a bad battery then. Thank you

 

[Dozerboy]

From that link it state it will charge a .4 amps. I don't know how much power you equipment draws but lets just say 1amp (a very small draw), You are using 60% more power than you are charging. Depending on how much the equipment runs during daylight hours you may not even see a charge to the battery. You might need a larger panel.

Ya I just winged the panel size, because I couldn't find much data on it. I probably should look into it more.