Remote solar cell to charge a solar garden light.

Thread Starter

Northerner78

Joined May 27, 2019
7
I have 4 hanging solar plant holders. The solar cells can't be moved since they're attached to the lamps. They rarely ever get enough light to work properly, but when they do they're great. My idea was to wire in an additional solar cell and mount it to the roof of my porch. Like a remote solar panel. Is this a feasible idea? Any help would be appreciated.
This is the light I have.↓

b97a1054-f437-454a-8e62-aa6fd9a76cfe_1.3b2eed2017ee323eb4fc10614b71f282.jpeg
 

MisterBill2

Joined Jan 23, 2018
3,878
That should work quite well, although the expense may be bothersome. If you can get hold of some of those lights that have failed batteries they will be the cheap source of solar cells. The hard part will be the wires, since they are quite thin and will be fairly long. Also, keeping the polarity right may be a challenge. Probably you would need to disconnect the internal cell on each of those planters, and most likely there will be a challenge in connecting to those very skinny wires. But you will only need to disconnect one side from the internal solar cell. The physical part of the project is what will be the hard part.
 

wayneh

Joined Sep 9, 2010
16,102
Ok, so the battery is1.2v 2300mah. I found a cell that is 6v 250ma. Would that work?
Probably not. Most solar cell devices I've looked at have a solar cell that delivers about 2X the battery voltage.

Also, the voltage booster that converts battery voltage to one high enough to light the LED, will not likely tolerate the higher voltage and something will get cooked, possibly the LED.

The problem could be an aging battery but in my experience the solar panels just aren't big enough in these things. Adding a remote one should be fine but as noted, the mechanical issue will be the bigger challenge.
 

Thread Starter

Northerner78

Joined May 27, 2019
7
I have a feeling that wiring won't be to bad. I found a cell 1.5v 300ma. Would this be better?
 

MisterBill2

Joined Jan 23, 2018
3,878
Ok, so the battery is1.2v 2300mah. I found a cell that is 6v 250ma. Would that work?
If the solar cell can deliver that 250 mA current with the light that arrives in your area during an average day, then yes, it should work with a bit of margin as well. There might possibly be some need for a charge controller, but probably not. And it might possibly be that you could charge multiple cells in series.
 

oz93666

Joined Sep 7, 2010
669
Very apparent from the size of the solar cells in your picture this is not a serious item ...

The cells are too small ... the battery is too small to be any good ....

You need to define what you want to achieve ...how long a lighting time , what is the light for ??
Then you can move forward ,perhaps remote solar panels and remote storage battery.

The implication from this product is the light will shine on the plant and help it grow , it won't have any significant effect , even if you boost it.
 

MisterBill2

Joined Jan 23, 2018
3,878
Probably not. Most solar cell devices I've looked at have a solar cell that delivers about 2X the battery voltage.

Also, the voltage booster that converts battery voltage to one high enough to light the LED, will not likely tolerate the higher voltage and something will get cooked, possibly the LED.

The problem could be an aging battery but in my experience the solar panels just aren't big enough in these things. Adding a remote one should be fine but as noted, the mechanical issue will be the bigger challenge.
The fact is that the part of the circuit that lights the LEDs is not producing much power when it is dark and the LEDs are lighted. Very few solar cells produce power when they are not in sunlight or equivalent. And when it is dark then power will come from the battery about 1.2 volts, possibly up to 1.4 volts, never more.
 

Thread Starter

Northerner78

Joined May 27, 2019
7
Very apparent from the size of the solar cells in your picture this is not a serious item ...

The cells are too small ... the battery is too small to be any good ....

You need to define what you want to achieve ...how long a lighting time , what is the light for ??
Then you can move forward ,perhaps remote solar panels and remote storage battery.

The implication from this product is the light will shine on the plant and help it grow , it won't have any significant effect , even if you boost it.
It's certainly not to make the plant grow. It's simply for esthetics only.
 

MisterBill2

Joined Jan 23, 2018
3,878
Very apparent from the size of the solar cells in your picture this is not a serious item ...

The cells are too small ... the battery is too small to be any good ....

You need to define what you want to achieve ...how long a lighting time , what is the light for ??
Then you can move forward ,perhaps remote solar panels and remote storage battery.

The implication from this product is the light will shine on the plant and help it grow , it won't have any significant effect , even if you boost it.
No, these are strictly for looks. And the solar charged LED lights do look nice in the inky darkness found in some localities. I have never seen any claim that they are other than decorations.
 

Audioguru

Joined Dec 20, 2007
11,251
All my solar garden lights use a 2V solar panel. Each 0.5V cell in the solar panel is seen and each panel has 4 cells. The current output of the solar panel is chosen to not overcharge the Ni-MH battery.
 

Thread Starter

Northerner78

Joined May 27, 2019
7
Thought I would write an update. I went ahead and purchased 1.2v 230ma 2300mah solar cells. I managed the tiny little wires and added a cell to the parallel circuit. It works! After only getting partial sun for part of the day, it was shining bright. Now just to do the same to the other 3. Thanks everyone for helping me out.
 

Audioguru

Joined Dec 20, 2007
11,251
The 1.2V 2300mAh battery in your solar light sounds like an Energizer AA Ni-MH cell. It barely charges from only 1.2V, the charger voltage is usually 2V with current limiting. My solar light comes with a Chinese Ni-CAD AA battery of 1.2V 250mAh and over-charges all day from a 2V solar panel. The Diode in series with it (to prevent the battery from discharging into the solar panel in the dark) reduces the voltage charging the battery cell to 1.7V and the small size of the solar panel provides current limiting.
 

Thread Starter

Northerner78

Joined May 27, 2019
7
Energizer is correct. Tonight will be the real test. I affixed the remote panel to the roof of my porch.
 

MisterBill2

Joined Jan 23, 2018
3,878
The hard part of the project was those tiny wires, and it sounds like you handled that well. Thanks for the update and progress report. We all can learn from that part.
 
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