Light circuit for an art project

[KJ6EAD]

Unfortunately, the Vf of typical 470nm blue LEDs is a little too high to get away with series strings of three considering that the battery is at 10.5V at the end of it's discharge. The best solution if it can be done is to start with a much higher supply voltage either by using a boost converter or putting 3 batteries in series so you have a minimum around 30V. That allows you to construct strings of 8 LEDs.

 

[Harald Kapp]

I assumed the batteries are regularly charged so 11-12 V are available. If however, the battery is drained, you're right.

The best solution would be a "switch mode led driver" (Google this) which would maximize efficiency and minimize the risk of damaging the LEDs.

Harald