A better way to power LEDs is to employ a power supply unit with dedicated LED driver circuits providing outputs to suit the LED series configuration. As a side note, putting LED lamps in the series configuration ensures equal brightness to each of the LEDs. While each lamp may consist of the same LED components from the same production lot, there will still be slight differences in the forward voltage. Putting them in series with a power supply unit gives users the same current for each LED, and thus the same brightness level.