Hi,

I'm a complete newbie trying to gain a better understanding of electronics - I thought opening up a garden solar light to repair it would be a good start.

I've read many forum posts and watched a few videos to try and understand the theory behind how these cheap generic items work. the item I am working on uses the XY8108 IC. As I understand it, the chip is prone to fail, and the on/off switch can become corroded. I had a few parts laying around so I changed the switch as the existing one was a little rusty.

The panel itself is showing 1.2v on my MM - I left it on a window sill today and the battery reads 1.3v.

When I cover the PV the light comes on for a few seconds, then each time I expose and cover the PV the led lights up, then flickers and gradually fades out. Now the battery is reading 0.7v.

Would this indicate that the battery is not holding the charge - or could something be draining the battery when it is activated?

Any pointers would be appreciated.

Thanks.

 

When I cover the PV the light comes on for a few seconds, then each time I expose and cover the PV the led lights up, then flickers and gradually fades out. Now the battery is reading 0.7v.

Would this indicate that the battery is not holding the charge - or could something be draining the battery when it is activated?

Yes.

Either of those is possible. No way to know which based on the information provided. You would need to isolate things to determine which is which. A couple of ways would be to remove the battery and power the device with an external supply while monitoring the current draw. Another would be to insert a current meter between the battery and the rest of the device and do the same.

 

If you can make a temporary connection to monitor the battery voltage with a digital meter and see what it changes to when the LED is switched on, that can tell you about the battery. It might not be receiving a charge, or it may not be holding a charge.

 

If you can make a temporary connection to monitor the battery voltage with a digital meter and see what it changes to when the LED is switched on, that can tell you about the battery. It might not be receiving a charge, or it may not be holding a charge.

How will this tell me if the battery is not holding charge OR if something is draining the battery? The PV seems to be charging the battery.

When we say measure the drain - can i do that with a regular DMM?

 

it's the battery --or-- the controller pins (extreamly fragile and corroding) --or-- PV connection (you dont want to apply force to the wires/-attachment points)

the next vid composer claims that 10nF in parallel with LED a bit adds to luminosity of the output (& tolerates 3v supply voltage)

some WP article https://dzrmo.wordpress.com/2012/05/29/garden-light/
--also--
i measured the PV-"battery" and it gives out up to about 10 to 12 mA (not more) at direct sun light
+ the PV to PV characteristics are quite varying (either due manufacturing/QM policy or the ohmic contact quality to PV terminals ??)

 

If the battery voltage drops rapidly when a load current is drawn, then for whatever reason, the battery isnot delivering it's charge to the load. That voltage drop is common in both under-charged batteries and in failed batteries.