The Mastervolt Mac Plus is a DC-DC charger which is designed to provide quick and safe charge to the service battery, providing stabilised voltage to protect the battery and the equipment it powers.

Traditionally, a service battery is linked to the starter battery via a charge relay. The starter battery will be located near to the alternator and receives most of the charge current. However the service battery is usually further away. The long cables used to connect it up cause a voltage drop, leading to slower charging, which can result in failing appliances and premature failure of the battery.

Modern, fuel efficient engines are equipped with smart alternators, following regulations such as Euro 5 and Euro 6. Instead of a constant output, smart alternators provide a variable voltage; after a brief charging period, voltage is reduced and the charging stops. Furthermore, the energy produced by regenerative braking leads to voltage peaks. Service batteries coupled in the traditional way will receive hardly any charge and may be damaged by these peak voltages.

To solve these issues, Mastervolt offers the Mac Plus DC-DC chargers, which monitors the service battery and compensates the voltage loss. It is suitable for flooded, Gel, AGM and Li-Ion batteries (including LiFePO4), and even revives fully depleted batteries. There is no fan so operation of the charger is silent and these units can also be used in parallel to achieve higher charging capacities. The Mac Plus is also MasterBus compatible, so can be monitored and included in an intelligent automated system.

Specifications battery charger

Battery temperature sensor: yes, included

Battery voltage sensor: yes

General specifications

Status indicator : yes, 3-color LED

Output voltage: 10-15 V

Nominal output voltage : 12 V

Output voltage stabilisation: 2 % at extremes of tem­ps, load and input

Output voltage ripple (peak peak): max. 1 %

Max. output power: 725 W

Nominal output power: 675 W

Max. output current: 50 A

Output charge current (3-step mode): 50 A

Nominal input voltage: 12 V

Input voltage range: 10-16 V

Max. input current: 50 A

Galvanic isolation: no

Voltage limited: yes

Efficiency: > 95 % (at nom. input voltage, full load); peak 97 %

Parallel configuration: yes

Alarm contact: yes, through MasterBus

MasterBus powering: no

Engine run signal input: yes (active high/active low)

DIP switches: yes, for basic setup

Dimensions, hxwxd: 255 x 165 x 66 mm (10.0 x 6.5 x 2.6 inch)

Weight: 2 kg (4.4 lb)

Compliance: CE, E-Mark, SAE J1171 & ISO 8846 Ignition Protected

Technical specifications

No-load consumption: < 2 mA

Charge characteristic: 3-step+

Battery types: flooded, Gel, AGM, spiral, Lithium Ion, traction, user defined

3-Step charge option: yes (DIP switch settings)

DC consumption: < 5 mA

Connections: 3 x M8 terminal for cable diameters of 10-50 mm², (positive input, positive output, joint negative connection) 8-pole screw connection for cable diameters of 0.75-1.5 mm² (remote on/off, temperature sensor, voltage measurement

Temperature range (ambient temp.): -25 °C to 60 °C; derating > 40 °C (-13 °F to 140 °F)

Cooling: natural cooling

Protection degree: IP23

Protections: overload, over temperature, DC short circuit, reversed polarity (fuse)

MasterBus compatible: yes