MultiPlus-II 2x120V 2. Description 2.1. 120/240V input and output, or 120V input and output (always 120V output when in inverter mode) The AC input can be supplied from a split-phase 120/240V source or a single-phase 120V source. When an AC source is available, the inverter/charger will feed through the AC to its output. The output will therefore mirror the AC input. The inverter/charger connects to the neutral and the preferred input line (L1). The power needed to charge the batteries will therefore be drawn from L1. The inverter/charger switches to inverter operation when no AC source is available. The inverter output is 120V single phase.
In invert mode, the inverter/charger connects both output lines (L1 and L2) together to provide 120VAC to loads on either line. Any 240V loads will therefore be supplied only when the inverter/charger is supplied by a split-phase AC source. This prevents heavy loads such as water heaters or 240V air conditioners from discharging the battery. 240V loads should be connected between L1 and L2 which could be either AC-out-1 or AC-out-2. There will be 240V between them when the unit is connected to a split-phase input and 0V otherwise (single-phase grid or inverter mode). The voltage L1-N and L2-N will be 120V regardless of single or split-phase input.
This can be better understood when looking at the power flow diagrams located in Power flow diagrams [37] . 2.2. Battery charger 2.2.1. Lead-acid batteries The microprocessor-driven adaptive battery management system can be adjusted for various types of batteries. The adaptive function automatically adapts the charging process to battery use. Adaptive 4-stage charge algorithm: bulk – absorption – float – storage The right amount of charge: variable absorption time In the event of slight battery discharge, absorption is kept short to prevent overcharging and excessive gas formation. After deep discharging, the absorption time is automatically extended in order to fully charge the battery.
Preventing damage due to excessive gassing: the BatterySafe mode If, in order to quickly charge a battery, a high charge current in combination with a high absorption voltage has been chosen, damage due to excessive gassing will be prevented by automatically limiting the rate of voltage increase once the gassing voltage has been reached. Less maintenance and aging when the battery is not in use: the Storage mode The Storage mode kicks in whenever the battery has not been subjected to discharge during 24 hours. In the Storage mode float voltage is reduced to 2.2V/cell (13.2V for 12V battery) to minimise gassing and corrosion of the positive plates.
Once a week the voltage is raised back to the absorption level to ‘equalize’ the battery. This feature prevents stratification of the electrolyte and sulphation, a major cause of early battery failure. Battery voltage sense: the correct charge voltage Voltage loss due to cable resistance can be compensated by using the voltage sense facility to measure voltage directly on the DC bus or on the battery terminals. Battery voltage and temperature compensation The temperature sensor serves to reduce charging voltage when battery temperature rises. This is particularly important for maintenance-free batteries, which could otherwise dry out by overcharging.
The temperature sensor is not supplied with 48V models. It can be ordered separately. Order number: ASS000001000 2.2.2. Second charge output for starter battery The 12V and 24V MultiPlus is equipped with a second charge output intended for maintenance charging of a starter battery. It uses a simple circuit with a current limiter and diode, allowing a continuous trickle charge (4A) from the main (domestic) battery to the starter battery. Due to the diode's 0.3 - 0.6 V drop, charging only occurs when the main battery is being actively charged or when the starter battery’s voltage is much lower. Page 3 Description