A battery monitor is designed to monitor the state of charge of a 12v/24v lead acid battery bank. It measures the current in and out of the battery, the remaining capacity of the battery bank and the time to full charge or discharge. This information can lead to more efficient use of the battery, which can in turn, enhance the life of the battery and reduce the risk of failure.
A multimeter makes life much easier when installing solar panels or other simple electrical equipment: It measures the instantaneous voltage and current present. Both models listed here measure all basic electrical functions. The 'Pro' model also features a back-lit display and a stand, and is designed for heavier use. For prices like these, you might as well add one to your order!