  Let $K$ be a simplicial complex, and let $\Delta_i^{up}(K)$ be the $i$-th up
normalized Laplacian of $K$. Horak and Jost showed that the largest eigenvalue
of $\Delta_i^{up}(K)$ is at most $i+2$, and characterized the equality case by
the orientable or non-orientable circuits. In this paper, by using the
balancedness of signed graphs, we show that $\Delta_i^{up}(K)$ has an
eigenvalue $i+2$ if and only if $K$ has an $(i+1)$-path connected component
$K'$ such that the $i$-th signed incidence graph $B_i(K')$ is balanced, which
implies Horak and Jost's characterization. We also characterize the
multiplicity of $i+2$ as an eigenvalue of $\Delta_i^{up}(K)$, which generalizes
the corresponding result in graph case. Finally we gave some classes of
infinitely many simplicial complexes $K$ with $\Delta_i^{up}(K)$ having an
eigenvalue $i+2$ by using wedge, Cartesian product and duplication of motifs.
