Hi @Erlingns95 -
As noted on the T200 product page:
Note that nominal operation at 12-16 V is recommended for the best balance of thrust and efficiency , though operation at up to 20 V is allowable. Exceeding 20 V is not within the rating and not recommended, please see here for more information.
You could use the higher voltage with your ROV, but you will need to limit the max and min throttle values to avoid damaging the thrusters, which would manifest as cracked stators leading to corrosion.