This dehumidifier from Hydrosorbent comes with an inbuilt recharge indicator. The indicator is initially orange in color, but it really turns by itself clear when it needs a reactivation. These dehumidifiers can also be quieter than their refrigerant counterparts considering the fact that they do not rely on a compressor. https://dstdehumidifiers.co.uk/case-studies/desiccant-dehumidifiers-in-cold-stores/