Xantrex XW-MPPT60-150 Owner's Manual - Charge Controlling

Introduction

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Charge Controlling

The XW SCC can regulate PV array current at 12, 24, 36, 48 or 60 volts DC for 

charging batteries. It produces up to 3500 watts and 60 amps of charging current 

for all battery voltages except 60 volts.

The XW SCC controls how the batteries are charged by the DC source (the PV 

array). It can be configured to use a two-stage (“No Float”) or three-stage 

charging process to maintain battery voltage at bulk or float levels.

When charging, the XW SCC regulates the battery voltage and the output current 

based on the amount of DC power available from the PV array and the state of 

charge of the battery.

The XW SCC is able to charge a lower nominal-voltage battery from a higher-

nominal voltage array. For example, the XW SCC can charge a 12-volt battery 

from a 36-volt array. This gives flexibility to installers to use longer wiring runs 

without compromising efficiency on a higher-voltage array.

The XW SCC is not able to charge a higher-voltage battery from a lower-voltage 

array.

Three-Stage Battery Charging

The three-stage charging process results in more efficient charging compared to 

on-off relay type or constant voltage solid-state regulators. The final float stage 

reduces battery gassing, minimizes electrolyte loss, and ensures complete battery 

recharging. Battery voltage and current vary during the three-stage charging 

process as shown in Figure 1-4 on page 1–5.

Bulk Stage

During the bulk stage, the XW SCC sets its voltage limit to the bulk voltage 

setting. If the batteries are discharged, the XW SCC operates in constant current 

mode, delivering its maximum current to the batteries. When the battery voltage 

reaches the Float voltage setting, the controller will transition to the absorption 

stage.

Figure 1-3 PV Charge Controller