  A certain class of neutrino mass models predicts long-lived particles whose
electric charge is four or three times larger than that of protons. Such
particles, if they are light enough, may be produced at the LHC and detected.
We investigate the possibility of observing those long-lived multi-charged
particles with the MoEDAL detector, which is sensitive to long-lived particles
with low velocities ($\beta$) and a large electric charge ($Z$) with $\Theta
\equiv \beta/Z \lesssim 0.15$. We demonstrate that multi-charged scalar
particles with a large $Z$ give three-fold advantage for MoEDAL; reduction of
$\Theta$ due to strong interactions with the detector, and enhancement of the
photon-fusion process, which not only increases the production cross-section
but also lowers the average production velocity, reducing $\Theta$ further. To
demonstrate the performance of MoEDAL on multi-charged long-lived particles,
two concrete neutrino mass models are studied. In the first model, the new
physics sector is non-coloured and contains long-lived particles with electric
charges 2, 3 and 4. The second model has a coloured new physics sector, which
possesses long-lived particles with electric charges 4/3, 7/3 and 10/3. We
explore the parameter space of these models and identify the regions that can
be probed with MoEDAL at the end of Run-3 and the High-Luminosity LHC.
