Solar powered yard light with water damaged board......

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nottawhackjob
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Solar powered yard light with water damaged board......

I have some solar LED spotlights that are powered by 3 X 1.2V NiMH’s.

These spotlights sustained water ingress damage such that the “driver” or whatever the board is that feeds the solar charging aspect plus the LED input are kaput.

What would likely happen if the solar panel direct charges the 3 X 1.2V batts essentially bypassing the now kaput driver?

Are we talking frying the batts or will the solar panel just quit charging the batts once they reach full charge? I’m assuming the solar panel is not putting out 3.6V here as it only measures about 3” X 5”.

I’m also thinking if I block off let’s say 1/2 of the solar panel that that may adequately compensate for potential overcharging during a maximum 12 hours of sun.

Just shooting darts here.

Lumens is lumens. Lumens make money. So follow the money.

Edited by: nottawhackjob on 05/14/2018 - 13:16
Pablo de Llama
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You can’t block any part of the solar panel if you want it to work.

And solar panels are, to the best of my knowledge, made up of 0.5v solar cells connected in series, and each cell can be pretty small, so the size of the panel is not a good indicator of the output voltage.

Pictures would help. Wink

nottawhackjob
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If my multimeter is reading accurately it appears the panel is charging at 0.5V in full sun.

Assuming 12 hours of full sun at optimum season and panel angle would this direct charge rate realistically cook 3 X 1.2V NiMH’s without driver intervention?

I’ll cautiously surmise on average per year more likely a full charge rate of 0.5V/hour over 7- 8 hours max. I’m probably still generous here. And of course these lights would normally run from dusk till dawn if they could. The solar panel has AFIK the light sensor that shuts off the LED. I figure that without a driver the LED’s will now only run till their VF limit kicks in anyway so the batts may not get drained completely.

If I could get 6 hours average runtime from dusk I’d be happy.

Lumens is lumens. Lumens make money. So follow the money.

kuoh
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Have you tried charging the cells out of the unit and reinstalling it to confirm that the dawn / dusk functionality is still operational? Pictures of the board might help, but I think the circuitry most likely control the auto on/off of the LEDs. Some charging circuits are not much more than a few passive components feeding the batteries. They rely on using low capacity, but more durable cells, like 600mah AA rather than the 2000+ mah we typically use. It sounds like you might be considering connecting the solar panel directly to batteries and LEDs, which probably wouldn’t work, as the LEDs would be on constantly and drain away all the current from the panel leaving very little if any to charge the batteries.

KuoH

WalkIntoTheLight
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From my testing with solar garden lights, they don’t appear to have any charge-termination circuitry. They simply charge at about 100-200mA in full sun, and when the battery is full it just keeps on trickle-charging. Some batteries handle that better than others, and that’s probably why they use low-capacity cells in solar lights.

But if you’re only reading 0.5v from your solar panel in full sun, I don’t see how it could charge your batteries. That sounds like most of the solar cells in the panel are damaged.

You could charge the batteries separately, and install them fresh every evening, but that’s probably not the kind of effort you want to do. I think your best action is to buy new lights.

nottawhackjob
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Both you guys make too much sense. GradLOL

Oh and these China batts say they’re 1500mAh @150mA for 15 hours standard charge. I think that mAh is kinda high for “durability” but who knows. The batt carriers btw were trashed too.

Lumens is lumens. Lumens make money. So follow the money.

Lightbringer
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There’s no “driver”, at least not between solar cell and battery. All it is is a schottky diode (1N5817 or similar) to keep the battery from back-feeding the solar-cell. They’re low-current, but in full sun can put out an extra volt beyond the battery’s voltage.

The “driver” is just a boost driver to convert the 1.2V to LED voltage (QX5252, YX805, etc.), or just an on/off transistor to crowbar the LED across the 3.6V from multiple NiMHs/NiCds.

They’re simple as dirt to put together. You can even buy the boards pre-built on AX.

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Lightbringer
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nottawhackjob wrote:
If my multimeter is reading accurately it appears the panel is charging at 0.5V in full sun.

Ugh. So it’s one big cell (with its own booster) vs multiple small cells feeding the cell directly.

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nottawhackjob
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Schottky’s be cheap too. Heck at this price might come in handy in a SHTF event for solar panels without reverse protection.

https://m.fasttech.com/products/0/10013212/2226200-risym-ss14-chip-1n581...

Check this out. These drivers have Schottky’s already built in. Since I have a slew of garden solar lites I might experiment with these on the damaged units. What the heck.

https://m.fasttech.com/p/1105800

Lumens is lumens. Lumens make money. So follow the money.