This is the nicest complete battery monitoring system I've found. It has both iPhone or Android apps (free download) and is completely compatible with the RV Whisper Monitor system. RV Whisper will acquire and store all the data from the PowerMon, and broadcast via WIFI to your phone or computer wherever you are.
PowerMon is a Bluetooth hi-tech device that can be used to monitor the state of charge of any battery and power flow in any electrical system. On top of the monitoring functions, PowerMon can act as a power controller, allowing for low voltage disconnect, high voltage disconnect, over-current disconnect, battery isolator, remote ON/OFF switch, timer switch, generator control, and solar system automation. With Bluetooth LE (Smart) connectivity there is no need for drilling and extra wiring in existing or new applications (RVs, boats, solar systems). Small form factor and ease of installation make PowerMon ideal for quickly adding smarts to any existing electrical system. Remotely monitoring DC circuit parameters has never been easier!
Voltage, current, power, energy, battery state of charge, and temperature are all measured and displayed in real-time using Thornwave Labs’ mobile application, PowerMon, which is offered for free on Google Play and Apple App Store. The device supports multiple configurations and measurement ranges that can be set up using the app, allowing it to accommodate a variety of circuits. Control of a mechanical or solid-state relay allows it to be used for low voltage disconnect, high voltage disconnect, over-current disconnect, a battery isolator for multiple battery systems, remote power control, or timers. This wireless, multi-function tool is truly a Swiss-army knife for DC electrical systems.
The device measures two voltages up to 75V with better than 0.5% accuracy. It contains an internal shunt making it able to measure current up to 60A without using any external parts. The current measurement can be calibrated to an accuracy better than 1%. If higher current has to be measured (as high as 10,000A), an external shunt can be added. Current shunts are readily available and can be customized for the specific current measurement range required. PowerMon supports a wide range of current shunts.