Controlling Hydroelectric Systems Bob-O Schultze KG6MM I've been living on and with Microhydro for over ten years. I realize that I'm damn lucky to be among the fortunate few to have the natural resources to do it. I define Microhydro as the ability to generate 3 or more amps @12VDC or better per hour continuously and year-round. Less output than that falls into the "Nanohydro" category. Many homesites have Nanohydro capability and don't even realize it, but that's another article entirely. The 3 amp cutoff isn't arbitrary. Less than that you're usually better off with a permanent magnet type of hydroplant which uses none of the generator output to energize its field; hence, what you produce you get. Above 3 amps output, you're starting to fight the limits of residual magnetism and are probably better off with an alternator or induction motor system. At this point, I can visualize dyed-in-the-wool hydromanics everywhere unsheathing their pens, ready to do battle. Whoa! There are some very notable and good exceptions to the rule, but geez, ya gotta start somewhere! In my opinion and experience, the alternator gets the overall nod for Microhydro for most systems. It's flexible in both voltage and amperage output to cover a vast amount of situations, cheap and readily available to replace and, as a rule, the user or a local tech can do the job. Field or Load Control? Most Microhydro users have the ability to generate more juice than they use. Ain't it great? Well yes, but whaddya do with the extra? It boils down to either you dump the excess energy somewhere or don't produce it in the first place. Load Control All load controllers that I've seen work the same way. They sense a preset battery voltage level and turn on a transistor or a relay to use the power elsewhere, usually to a resistive load used to heat either air or water. The problem is that it takes a heap o'amps at 12VDC to heat any significant amount of air or water. If you got'em, fine. If you ain't, why bother? Besides that, you have to size your shunt load to be capable of handling your hydroplant's maximum output. If you nozzle down for summer flow as most folks do, and use the same shunt, your controller has to work overtime switching on and off. And if, God forbid, the controller or the shunt fails for whatever reason, (they're machines, ain't they?) the full, unregulated, output of the hydroplant mainlines directly into your already full batteries. Boil, boil, bubble, and trouble! Field Controller For my money, this is where it's at for 3 good reasons. 1-By reducing the load on the alternator when the batteries are full, it runs cooler and lasts longer. Yes, I've heard the argument that the fluctuation in RPM as the alternator loads and unloads is more conductive to wear on bearings, etc. than one run at a constant load, but I ain't going for it. Picture that same alternator in your Chevy going down the road, stopping for a red light, zooming down the freeway, naw, I ain't buying it. Cooler=longer life period. 2-If you have a good field controller, such as Electron Connection's Mark VI, it will Pulse Width Modulate the last 10-15% of charge. Yum, Yum said the batteries. The PWM feature plus ease of adjusting the voltage preset for summer to winter temperature conditions, equalizing, etc., is the real beauty of the Mark VI. 3-If your field controller should fail, (Alas, the common feature of machines, of whatever description, is that sooner or later the buggers break) the alternator output just quits. No fun, but it won't ruin your batteries or 12 VDC appliances, either. The Mark VI Why not use an ordinary automotive voltage regulator? Good question! In 99% of hydro situations it won't work and here's why. Nearly all 12VDC alternators are designed to provide between 50 and 100 amps depending on type, brand, application, etc. The old style Delcotron used in most Microhydro set-ups will produce 50-55 amps at 5000 RPM. Getting an alternator to spin that fast under no load is one thing, maintaining that speed under a 50 amp load is another! In a vehicle, it's no great shakes. If it needs a couple or three extra horsepower to do it, it just grabs 'em off the engine and no one even notices unless you happen to be at idle when you can hear the engine RPM pull down a hair. In this case, the automotive type voltage regulator just throws a couple of amps at the field, the alternator grabs what RPM it can get from the engine and honks on. In a hydro situation, on the other hand, you have a very limited (usually) amount of torque and RPM provided by the velocity and volume of water hitting your water wheel. If you attempt to load it past that limited amount, RPM falls and output drops dramatically. Since the automotive regulator only knows to pour the coals to the field and let the engine pick up the slack, it blows it. The Mark VI is a two-stage, all electronic, electronic device (no relays!). The first stage uses an adjustable, PWM to control the output amperage of the alternator. This allows you to adjust the load on the hydroplant's alternator to compensate for the limited torque/RPM situation. You can only get what the water is capable of giving you and no more. The second stage monitors system voltage and reduces the alternator's output should the voltage exceeds a preset, adjustable limit. Neat, huh? I've been using the Mark VI on my old "Water Watts" hydrocharger for well over a year now and I love it. No more buying gallons of distilled battery water by the 6-pack, no worry, set it and forget it. I've installed two other Mark VIs on Harris Hydro systems to the complete satisfaction of the owners and just recently put together and installed a 24 volt model that's riding herd on a set-up that's producing 35 amps! Can you imagine 35 amps at 24VDC, 24hrs a day year'round? Tough break, huh? Access The Mark VI Field Controller is available thru Electron Connection, Ltd. POB 442, Medford, OR 97501 ¥ 916-475-3179. Complete, tested Mk.VI is $155.ppd. Kits are available for the do-it-yourselfer from $15 to $105.ppd. 24 volt models slightly higher. See HP#2 for a complete description of the Mark VI including build your own instructions complete with schematic. Bob-O Schultze is the owner/operator of the Lil Otto Hydro Works, POB 8, Forks of Salmon, CA 96031 ¥ 916-462-4740.