Mastervolt Charge Mate Pro 40

Meet the Mastervolt Charge Mate Pro 40, Model 83304002 — an electronic charge coupling with a very low voltage drop that makes effective dual charging possible for all battery types, including Lithium Ion. The secondary battery current is limited to 40 A, delivering high system reliability by prioritising the main battery while keeping the two banks isolated when discharging. This unidirectional device blocks return current under all circumstances, preventing power dips in the onboard electrical network. Compatible with all chargers and alternators, it features LED monitoring for quick status checks and IP65 electronics housed in a corrosion‑resistant casing with aluminum heat sinks for durable marine‑grade performance and fast, easy installation.

The Charge Mate Pro enables smart distribution of charging current between two battery banks — such as a starter and a service battery — charging both during charging and keeping them isolated during discharge. This significantly reduces the risk of a flat starter battery. Compared with mechanical charge relays, it adds the advantage of limiting the charge current to the second battery, so the primary starter battery is charged with priority. Return current is automatically blocked even if the secondary battery voltage rises above the primary. An optional bypass switch provides emergency start functionality, if needed.

In marine applications, the Charge Mate Pro is ideal for supplying a service battery (for example, a bow thruster) while ensuring the service battery remains charged and the onboard electrical network stays stable. It’s a robust, purpose‑built solution for distributing charging power reliably and safely.

Technical specifications

• Model: 83304002
• Output current: 40 A to the secondary battery (maximum)
• Number of battery outlets: 2
• Input voltage range: 9–32 V
• Parallel configuration: Yes
• Battery voltage automatic detection: 12/24 V
• Remote switch functions: On, Off, Auto, Start Assist
• Switch on voltage: 13.5 V (12 V) / 27 V (24 V)
• Switch on delay: 5 seconds
• Switch off voltage: 12.75 V (12 V) / 25.5 V (24 V)
• Switch off delay: 2.5 seconds
• Relay type: Electronic MOSFETs with low voltage drop (max 0.2 V)
• Connection possibilities: 3 x fast-on connectors (switch, ground, status)
• Monitoring: LED status / warnings
• Protection class: IP65
• Temperature range (ambient): -40°C to 60°C
• Dimensions (HxWxD): 6.2 x 5.5 x 3.1 inches
• Weight: 1.9 lb
• Battery types: All types (Lithium Ion protection via multi‑purpose contact)
• Power consumption (switch open): < 1 mA at 12/24 V DC
• Additional note: Suitable for all chargers and alternators; bypass for emergency start available via optional switch