Question on garden solar LED light

T Chap

I picked up a garden solar powered LED spot light today that is supposed to turn on at dark and claims 6 hours. A test shows this thing is very bright, a powerful LED for sure. I am using it for a project where I will remove the solar panel from the light and separate the two parts by a few feet. There is a small PCB behind the solar panel, I have not studied in too much detail but I would assume there is resistor in series to the LED, but not sure how much trouble it is to track it down. I'd like to both dim the LED and extend the hours, so would it be assumed that adding a series resistor in line to the LED by some value to get the brightness I want would simultaneously gain some time? Certainly there is circuitry for the light sensor and other parts, but I just wanted to make sure my thinking was correct on adding resistance to the LED would add some amount of longer life.

jmg

Measure the voltage across the battery and then across the LED & check the current flows for each (may need a 1-ohm series R and Voltage drop)
FWIR of such lights they use a single NiCad battery and thus a SMPS booster to power the White LED.

tonyp12

Open it up and take a picture of LED boost driver.
Replace the "settings resistor" that controls the constant current.
Here is an idea what part may be inside:
http://www.mouser.com/Semiconductors/Driver-ICs/LED-Lighting-Drivers/_/N-7zhqfZscv7?Ns=Pricing|0

T Chap

Thanks for the info. I found the datasheet for the SD4209. It is a dedicated garden solar part with programmable timer and the output changes over time, 5 hours full on, next 5 half. May be simpler to just diffuse the LED.

Sapphire

Can you post the link to the datasheet? I can't find that part SD4209 anywhere. Thanks.

T Chap

http://www.sewonsemi.com/upload/LED_product_line.pdf

Sorry I didn't put the right part

SD42609