The “E-Coder” is an excellent water meter register, manufactured by Neptune Technology Group, that features an all-digital LCD display activated and powered by an integral solar cell. The register as a whole does not contain a battery, and it is entirely powered by a combination of hydroelectric energy (water passing through the meter) and the solar cell.

Neptune Meter Equipped With E-Coder Register
In order to minimize power consumption, the E-Coder register only activates its LCD when exposed to sunlight or another compatible light source. When the LCD is activated, the display alternates between meter totalization and flow rate. When inactive, the LCD is simply blank. While the ECoder is being interrogated by a SCADA device (eg “EtherMeter”) or AMR endpoint (eg “R900″), the LCD will go blank until the interrogation is complete — usually no more than 1 or 2 seconds at a time.
Note that if a flashlight is to be used for activating the LCD, the beam should be pointed directly at the solar cell at close range (10 inches or less) and from directly above. The beam should be held steady until the 9-digit totalization is displayed. SCADAmetrics recommends a Xenon-based flashlight which emits a “white” light whose spectrum is similar to sunlight — and therefore produces better results when attempting to energize solar cells.
The Model 2000 “Super SabreLite” flashlight by Pelican is a Xenon-based lamp that is powered by three (3) C-Cell batteries and produces 33 lumens/12,000 candelas. The Pelican 2000 may be purchased from Grainger as Part No. 4JC10, or from another Pelican supplier. A set of new Duracell C-Cell batteries are recommended. (Batteries are not included with this flashlight.)
The ECoder’s glass cover should be kept as clean as possible, as any residue or debris will weaken the light that is intended for the solar cell. If the ECoder register is interrogated automatically at short polling intervals (for instance, the EtherMeter’s default meter polling interval is every 8 seconds) — then the LCD may cease to display the meter totalization and flow-rate, even when activated with direct sunlight or a bright flashlight. If this poses a problem for the user, then the EtherMeter polling interval should be increased to 20 or 30 seconds. (eg. SET SAMPn 30) On the other hand, the user can always rely upon the EtherMeter’s LCD display, since it echos the flow-rate and an exact duplicate of the totalization from the ECoder.
Ultimately, your experience may differ from ours, so let us know what you observe. You may also want to solicit advice from Neptune technical support and/or your local Neptune distributor.

Pelican 2000 "Super SabreLite"