  Run-length limited (RLL) codes are a well-studied class of constrained codes
having application in diverse areas such as optical and magnetic data recording
systems, DNA-based storage, and visible light communication. RLL codes have
also been proposed for the emerging area of simultaneous energy and information
transfer, where the receiver uses the received signal for decoding information
as well as for harvesting energy to run its circuitry. In this paper, we show
that RLL codes are not the best codes for simultaneous energy and information
transfer, in terms of the maximum number of codewords which avoid energy
outage, i.e., outage-constrained capacity. Specifically, we show that sliding
window constrained (SWC) codes and subblock energy constrained (SEC) codes have
significantly higher outage-constrained capacities than RLL codes.
