Mastervolt Charge Mate Pro 90 Electronic Charge Relay

Mastervolt Charge Mate Pro 90 is a current-limited electronic charge relay with high efficiency and reverse current protection. It is designed for boaters who need a dedicated charging solution for a secondary battery, distributing charger or alternator current effectively between two banks such as a starter and service battery.

This relay connects both batteries during charging and isolates them when discharging, significantly reducing the risk of a flat starter battery. Unlike mechanical charge relays, the Charge Mate Pro limits charge current to the secondary battery so the primary (like a starter battery) charges with priority, automatically blocking return current even when the secondary battery has a higher voltage — an optional bypass switch enables emergency start. Browse more options in our battery chargers category.

Key Features

• 90 rating
• current-limited electronic relay
• reverse current protection
• priority charging for primary battery
• optional emergency bypass switch

Frequently Asked Questions

What does this relay protect against? A flat starter battery, by isolating banks during discharge and limiting current to the secondary battery.

Can this relay support an emergency start? Yes, via an optional bypass switch.

What batteries is this relay designed to manage? Two banks, such as a starter and a service battery, with the starter given charging priority.