Energy Monitor/Controller II


English Language Messages

The EMON II is designed to completely monitor one or two battery banks. It provides the resolution and accuracy necessary to eliminate battery discharge problems and its selectable alarms will keep you informed of overcharges before they become dangerous. Solar and wind generator control with load disconnect make the EMON II the most sophisticated energy controller in existence. With English language messages like 7/8 FULL, even electrical novices are battery experts with the EMON II.

Three Versions: H1, H1A, H2

The Energy Monitor II is made in three versions. The H1 and H1A monitor a single house bank and a starter bank. The H1 has an auxiliary shunt for low side current measurement, while the H1A can be used with an optional Alternator Current Sensor and shunt to measure current in the positive lead. The H2 unit is applicable to systems with two house banks.


The H1 measures voltage, current and temperature for the house bank, voltage for a starter bank, and has an optional auxiliary input for charge current or alternator current (H1/H1A). The auxiliary shunt can be used in the negative lead of solar panels and wind generators to measure their current and accumulate the Amp-hours returned by those charge sources. The H1A accepts the signal from an Alternator Current Sensor and displays alternator Amps.

Solar and Next Step Control

The H1 provides an output signal that is used to control a solar panel disconnect relay, and to lock the Next Step Regulator into the absorption mode until the batteries are full. To control a solar panel, an optional EM-RELAY is required. This assembly is a Form-C relay capable of 30 Amps. Since it is a Form-C contact, the solar panels can be diverted to an alternate load when not charging the batteries. Relay actuation is based on programmable setpoints.

Generator and Load Disconnect

The H1 and H1A also has an output signal that can be used as generator start/stop, or as a load disconnect signal. Actuation is based on programmable setpoints. The signal is programmable to operate the generator at specific capacities, for instance "on" at 50% capacity and "off" at 90% capacity. The signal can also be used as a load disconnect output by programming the on and off capacities as desired. An optional Load Disconnect Relay is required to disconnect loads.

Remote SAR References

In addition, the H1 and H1A provide remote charge references to interface to the Smart Alternator Regulator. By using the references, batteries can be charged perfectly since the EMON II knows battery state-of-charge, voltage, current and temperature.

H2 Model

The H2 measures voltage, current and temperature for two house banks. It does not have the solar panel control, or remote charge references.


Both the H1 and H2 compute Amp-hours consumed and remaining, percent state of charge, and display state of charge as a fractional value, i.e. 7/8 FULL.


The EMON II contains alarms for two banks covering high and low battery voltage, high temperature, full charge, and both 50 and 80% depth of discharge. Alarms can be individually enabled or disabled. Alarm setpoints are programmable and all programmed data is saved in non-volatile memory in the event of power failure.

Non-Volatile Memory

The EMON II also protects your time spent setting up the instrument. All programmed data is protected in non-volatile memory ... you don't have to reprogram just because the unit was inadvertently turned off.

Universal 12/24V Operation

Either 12 or 24 Volts may be supplied as power to the EMON II, and the measurement channels can be a mixture of the two. Full scale voltage is 39.99 Volts with resolution of 0.01 Volts.

Current Measurements

Full scale battery current is $ \pm $399.9 Amps with a displayed resolution of 0.1 Amps. Battery current is measured with 13 bit precision (including sign). Auxiliary current is measured in the charge direction only, (positive), with full scale of 200 Amps and a resolution of 0.05 Amps.

Temperature Measurements

Battery temperature is measured to accurately calculate Amp-hours remaining using Peukert's equation. Temperature compensation is also used for controlling solar panels as well as the SAR and Next Step Regulators, when interfaced.

$\bullet$ Temperature Sensing for Two Battery Banks with Display in Fahrenheit or Centigrade.

Laptop Computer Interface

Computer interface hardware is standard inside the EMON II and optional software is available that allows full screen displays of electrical system parameters. Data may also be logged to the disk.

Computer software is user friendly, using a menu hierarchy. Panels of information may be named, saved on exit, and read at startup. View any named panel quickly. Disk logs are done in an analogous fashion.

Ergonomic, Watertight Packaging

The Energy Monitor II is packaged in a hardened and watertight housing. Signals exit the chassis via a waterproof cable and terminate on a free standing terminal block.

Keypad Calibration:

While not normally necessary, all measurement channels can be calibrated in the program mode. At least a 4-1/2 digit multimeter is required.

Dimensions and Mounting:

The EMON II front panel is 5.5 inches, (139.7 mm), wide by 4.5 inches, (114.3 mm), high. Allow 4.5 inches, (114.3 mm), depth to permit cable access. Unit requires a rectangular cutout of 5 inches, (127 mm), wide by 4 inches, (101.6 mm), high.

Ordering Information:

Energy Monitor II, H1 #EMONII-H1
Energy Monitor II, H1A #EMONII-H1A
Energy Monitor II, H2 #EMONII-H2
Auxilary Shunt #1011
Control Relay, 12V #EM-RELAY-12
Control Relay, 24V #EM-RELAY-24
Alternator Current Sensor, 12V #ALTCS-12
Alternator Current Sensor, 24V #ALTCS-24
PC Software, H1 #EMONII-PCH1
PC Software, H2 #EMONII-PCH2

Ample Power products are manufactured by Ample Technology, 2442 NW Market St., #43, Seattle, WA 98107 - USA