hi,
You could settle for 7 in series if you have a problem, add a suitable series resistor.
E

 

hi,
You could settle for 7 in series if you have a problem, add a suitable series resistor.
E

I agree. The LED strings will be more reliable at seven versus eight LEDs.

 

The "typical" forward voltage for those white LEDs is 3.2V at 20mA or 3.0V at 10mA. They are binned according to forward voltage, at 20mA the lowest bin voltage is 2.8V to 3.0V and the highest bin voltage is 3.8V to 4.0V.
Since the measured voltage is much lower then the LEDs must be extremely dim at a very low current or they are cheap fakes.

 

What audioguru said...

Design the specs, not what you measure. I can almost guarantee that using 2.7V as the Vf, that.several of your strips will blow out.

Personally I’d use 7 LEDs in series or two strings of 4-5 LEDs in series wired subsequemtslky in parallel.