NASA Battery Monitors
The NASA BM-1 and BM-Compact are designed to monitor performance of 12v lead acid battery systems with capabilities up to 600Ah. They are supplied complete with a precision 100A shunt and a prefabricated cable assembly to enable simple DIY installation.
They monitor battery voltage, the current into and out of the battery, the total Ahr since it was last fully charged, and predicts the time to achieve full charge (during charging) or the time to full discharge (during discharging). A visual indication of the state of the battery charge is always available, and an alarm is used as an alert when the battery voltage falls to a preset level.
The BM-1 has a industry standard 110mm x 110mm display and the BM-Compact has a 124 x 62mm x 23mm display.