Why do you Need a Battery Monitor and What is it?

If you have a battery system, a battery monitor can be one of the most practical and easy improvements you can make. In this article, we will examine what a battery monitor is and how it can help you get the most out of your battery system.

What is a Battery Monitor?

While battery monitors are often thought of as fuel gauges for batteries, they do much more than that. They gather and provide valuable information about the battery, such as voltage, remaining capacity, anticipated remaining runtime, current consumption, cycles, and more.

How does a Battery Monitor Work?

There are two types of battery monitoring: shunt-based and voltage-based. The simplest type, voltage-based monitoring, is typically included as standard equipment in mobile power applications. This kind of monitor measures the battery’s current voltage and uses it to infer the battery’s state of charge. However, voltage-based monitors are not very precise due to the real-time voltage fluctuations caused by external factors.

Shunt-based monitoring is significantly more accurate because it measures the actual energy going into and out of the battery. To use this type of monitoring, a shunt must be added to the negative side of the battery terminal, which measures both the current draw and the real-time voltage of the battery system. This information is then used by the battery monitor to calculate the charge level, power usage, predicted remaining runtime, and other useful data about your battery system.

BMS (Battery Management System) vs Battery Monitor

A built-in battery management system (BMS) on lithium batteries helps to optimize their performance and prevent them from being used in unsafe circumstances. The BMS controls the individual batteries in the system, not the system as a whole.

The primary job of the BMS is to prevent overcharging and over-discharging, which can harm batteries and reduce their lifespan. It also determines the battery’s remaining charge, monitors the battery’s temperature, checks for loose connections and internal shorts, and balances the charge over all of the battery’s cells.

While much of the data that a battery monitor gathers is also collected by a BMS, the BMS uses this data to improve the functionality and state of each battery separately rather than displaying it to the user.

Why is a Battery Monitor Necessary?

A battery monitor provides valuable information about your battery system’s state, which can help you optimize its performance. For instance, lead-acid batteries experience a significant voltage reduction as you use them. Without a battery monitor, you won’t know when your batteries are running low until the BMS turns them off when they are completely dead. In contrast, lithium batteries do not suffer a considerable voltage decrease throughout the draining process, so a battery monitor is still necessary to know how much energy is still in the batteries or how much charge they have.

Improving Your Battery Care

Battery monitors provide more than just a display of your system’s charge level. They also give you historical and real-time data on voltage, power usage, temperature, and other factors that can help you improve your battery usage and charging. For example, you can use the data from your battery monitor to choose the appropriate time to switch your RV’s fridge from battery to propane power.

The Best Battery Monitor: EJ Battery Monitor Series

The EJ battery monitor series provides additional functionality and reliability, making it the best choice on the market. It measures and tracks the battery voltage, current, amp-hours used, and charge level, and estimates the remaining runtime using this data. Additionally, Bluetooth is integrated into the BM21 BM16 BM19 and Smartshunt, making it easy to monitor all of your real-time and historical system information.