Things that Work! Home Power tests the Ample Power Company's Energy Monitor Testing conducted by Bob-O Schultze-KG6MM copyright1990 by Robert Schultze It's an old saw in baseball that "you can't tell the players without a scorecard." In battery based Renewable Energy systems, it's just as hard to tell at a glance whatcha got under them battery caps without a Amp- Hour meter. Ample Power's new Energy Monitor not only gives you a running numerical total of the Ampere-Hours into and out of the battery, but throws in a highly accurate digital voltmeter and ammeter to boot. The Energy Monitor Ample Power's Energy Monitor (or EMON) is basically a microcomputer instrumentation system which provides all the essential information required to manage your RE system's battery bank. It consists of a heavy duty shunt and the Display and Processing Unit (DPU) which processes the measured data and shows the information on a large (1/2"), well backlit, LCD display. The DPU has two switches on its 4.75" X 4.75" flush mounted front panel. One of the switches turns the backlighting on or off (a watt saved is a watt earned), and the other toggles between Volts, Amps, and Ampere-Hours. The Ampere-Hour function records up to 1,999 A-hr, and with a full scale voltmeter reading of 32 volts and a full scale ampere reading of 400 Amps, the EMON is equally at home in either 12 or 24 VDC systems. Packaging and Documentation The EMON arrived in fine shape shipped via UPS Brown at this location packaged in an oversized box with plenty of insulating material. The docs were thorough and complete with hook-up diagrams and enough well- written information to satisfy both the average user and all you techies out there. Test Environment We installed the EMON in a Home Power test system consisting of 8 Kyocera K-51 PVs, a Heliotrope CC-60B charge controller, Trace 2012 SB inverter, and 440 Ampere-Hours of reconditioned Nicad pocket-plate batteries. Additional charging was provided using a 3.5 kW. gasoline generator. All EMON measurements were compared against two Fluke 87 DMMs. Installation The Energy Monitor is designed to be flush mounted. Since I had a handy uninsulated wall within reasonable proximity of the battery bank, I followed the instructions, cut out a 4" square hole, ran the hook-up wires thru the hole, made the connections, and set it in. If I had it to do over again, I'd buy some extra wire and mount the EMON in the living room. It's a very good looking unit. The Energy Monitor is connected to the world via five wires. One to the negative distribution side of the provided shunt, two to the "+" side of the battery (sensing and backlight power), and two to the shunt itself. A word about this shunt... I'm very leery of putting anything between a battery terminal and an inverter. A fairly small amount of resistance in inverter cables can mean the difference between an inverter starting a high starting surge appliance or not. The folks at Ample Power recognize this and provide a gonzo 400 Ampere, 50 mV. bruiser of a shunt made by Empro and rated at 0.25% accuracy. I'm impressed. The manual recommends twisting the two shunt sensing wires together to reduce transients on the lines and where radio transmitting is happening or where the wires pass in proximity to large fluorescent lighting, shielded, twisted sense wires are required. Being a Ham Radio kinda guy with a house full of fluorescent lighting, I went for the shielding. Ample Power sells this shielded wire for $.50 per ft., or you can find 30 feet of Part #278-777 for $7.95 at your local Radio Shack. INSERT SCHEMATIC Operation User operation is simple. The switch on the left turns the backlight on or off. So much for that. When the right hand switch is in the down position, the display shows Ampere Hours. A negative number shows cumulative discharge from the battery and a positive one indicates recharging past the zero point. When the EMON senses a battery voltage of 14.2 V in a lead-acid system or 15.5 V in a Nicad systems, it resets the Ampere Hour function to zero after the charging cycle ends. With the switch in the up position, the display shows either volts or amps. Toggling the switch back down then up again displays the other function. The Ammeter shows net current flow to or from the battery. For example, if your PV array was putting out 12 Amps and your usage load was 8 Amps, the meter would read "4", indicating that 4 Amps were flowing into the batteries. Performance The test data shown by the chart was taken over a 5 hour period one evening. Typical energy uses were for lighting, TV, VCR, and a big Macintosh computer. The variances between the Ampere-hour discharge figure recorded by the EMON and the 2 Fluke 87s were so small that they don't even count in Home Power systems. Voltage and current measurements varied by ñ0.25%. Close 'Nuff! INSERT CHART Cost Ample Power Company's Energy Monitor costs $299.00. It comes complete with its own gonzo heavy-duty 400 Ampere low insertion loss shunt and a good set of instructions. Order #2020 for lead-acid or #2020N for nicad battery systems. Conclusions The Energy Monitor is a highly accurate instrument for measuring your battery's state of charge. It features the best shunt used on any ampere- hour meter in the Home Power market today. It's a voltmeter and an ammeter into the bargain. I like it. I like it alot. It's a "Thing that Works!". Access Author, Bob-O Schultze, Electron Connection, POB 442, Medford, OR 97501 ù 916-475-3401. Maker: Ample Power Company, 1150 N.W. 52nd Ave., Seattle, WA 98107 ù 800-541-7789 or 206-789-5758.