A Regulator for All Sources & Seasons Dale Glaser At certain times of the year, many of us have more renewable energy power available than we actually need to keep our batteries charged. You may, for example, have enough solar power for winter use, but then have too much in the summer. Or you may use solar in the summer and add hydro power in the winter, but have more hydro power than you actually need since it's coming in 24 hours a day. So power needs can vary throughout the year. What do you do when you have more power than needed to charge your batteries? I know some folks who monitor their batteries and shut off the incoming power when necessary, and others who just keep adding water to their batteries (and seem to go through batteries quickly!). Many people now use voltage regulators to control their individual sources of power. But while automatic regulation is the best way to protect your battery investment, it may not always be economical, because if you have more than one energy source, you have to pay for multiple regulation So, what would the ideal regulator in an renewable energy system be like? Here's my own wish list. 1. It would need to be easy to install and calibrate. 2. It would need to be adjustable for different seasonal temperatures, types and ages of batteries. And again you should be able to do this easily. 3. It would be nice to have "one regulator fits all", one regulator that would work with all the power sources in your energy system, including additional sources you might add in the future. 4. It would be rugged, and dependable. 5. (And why not?) It would be a regulator that not only protects your batteries from overcharge, but also gives that extra power back for other uses, like heating water, pumping water, running fans or lights, etc. 6. How about a regulator which was reasonably priced for what you got. 7. And finally, it would be fairly "idiot- proof." I'm not implying anything about myself, mind you, it's just that sometimes I'm not paying quite as much attention as other times. I'd hate to lose my investment in a voltage regulator during one swift lack of attention. Well, lo and behold, there is a regulator around that meets these requirements! Its the Enermaxer Universal Voltage Regulator made by the Enermax Corporation. This regulator taper charges your battery and very efficiently diverts the extra power to another load such as a water heater element, lights, etc. And the EnerMaxer will regulate up to 50 amps of power. What's interesting is that the EnerMaxer is different than many regulators in that it doesn't connect BETWEEN a power source and your battery like most regulators, but connects right to the battery itself. Therefore it is "universal" in the sense that it can act as a single regulator for any number of power sources charging your battery. You donÕt need any other regulation on your renewable energy system besides the EnerMaxer. ItÕs Easy to Use You simply connect the regulator (via a fuse) to the battery, and connect the output to the desired diversion load . Then you use one of two methods (described shortly) to adjust the regulator to the desired float voltage for your batteries. What is the significance of the "float voltage" of a battery? For every lead acid battery there is an ideal float voltage which allows the maximum amount of power to be stored in the battery. This float voltage lightly gases the battery to prevent stratification of the acid and water, and prolongs the life of your battery by reducing the expansion and contraction of the plates which occurs during the charge cycle. A given battery's "ideal" float voltage will vary with temperature, battery age, antimony content, and electrolyte concentration of the battery when it was manufactured. The EnerMaxer takes all these variables into account when you calibrate the EnerMaxer regulator with the adjustment knob on the front of the regulator. Once you set the float voltage, the regulator will hold the battery to that voltage. If your power sources keep pumping power into the battery and try to drive the voltage higher than the adjusted float voltage, the regulator sends that extra power to the diversion load. On the other hand, as soon as you start using enough power to draw the battery voltage below the adjusted float voltage, the regulator stops diverting power. This changeover from power going into the batteries to power being sent to a diversion load is instantaneous and very smooth, because the regulator is electronically sampling and diverting power at a rate of 400 cycles per second. By holding precisely the right float voltage and gradually tapering off the charging amperage, your batteries are filled to their maximum charge capacity with minimum stress on the battery plates. Why is there stress on battery plates? Whenever a lead acid battery is charged and discharged the battery plates expand and contract slightly as they undergo chemical change. Over time this expansion and contraction causes active material to flake off the plates and build up on the bottom of the battery cells. Holding a steady float voltage greatly reduces this problem and extends battery life. The Calibration Process The float voltage adjustment is made with a knob on the front of the regulator. This knob has no "calibration" markings because the calibration adjustment you make will be unique to your battery, and its type, size, and age. Calibration is easily done in one of two ways. Both these methods assume you have a fully charged battery and your power sources are continuing to supply power to the battery. And for both methods, you start by turning the adjustment knob fully clockwise (the maximum float voltage adjust point). The first calibration method uses a voltmeter connected to the battery terminals. This method assumes you know what float voltage you want on your battery and is best used for new batteries where you can get the proper float voltage information from the battery dealer. You simply turn the adjustment knob on the regulator counterclockwise until the desired float voltage registers on the meter. Then mark the adjustment pointer position on the face plate. And you're calibrated! The second method involves letting the battery charge until it is gassing - gassing occurs when a battery has absorbed almost all the charge it can. At that point, the extra power starts breaking down water into hydrogen and oxygen gases. Turn the adjustment knob slowly counter-clockwise until the battery is barely gassing, make your calibration mark, and you are calibrated! There are a couple of situations where you might want to have more than one calibration adjustment mark on the regulator. One is to take account of seasonal temperature changes. This is because the internal resistance of a battery changes with temperature, and it takes a higher voltage to push power into the battery in the winter than in the summer. Therefore, some people have a "summer adjust point" (a lower float voltage setting) and a "winter adjust point" (a higher float voltage setting) to obtain maximum seasonal efficiency. Another adjustment might be made in order to give your batteries an Òequalizing chargeÓ to correct uneven cell voltages. An equalizing charge is a gentle controlled over-charge, usually at a voltage higher than the float voltage, which allows low cells of the battery to charge up. Once adjusted, the EnerMaxer will work automatically to optimize the charge going into your battery. The regulator will control any type or combination of battery charging source(s) - solar, hydro, wind, generator, etc. - within its 50 amp power handling capability, at either 12 or 24 volts. Use the Extra Power to Heat Water A very common use for the extra battery power you get from your EnerMaxer is to heat water. The water heater element in an electric water heater is easily replaced with a 12 Volt element (available from EnerMax or elsewhere). These elements come in different power ratings so you need to have some idea how much extra power you will be generating that will be used to heat water. Some "Idiot proofing" built in If you put a screwdriver across the output terminals of the EnerMax, it immediately shuts itself down, without damage. As soon as the short is removed, the regulator begins working again. Pretty nice. The regulator will, however, fail if you reverse the polarity of the input leads during installation. However, a numbered connection sequence diagram is provided in the ownerÕs manual. You shouldnÕt have a problem if you follow the diagram. Cost At $249 the EnerMaxer is certainly isn't the least expensive regulator on the market today. But it may be a bargain when you consider the longer battery life you'll get because of the smoothly tapered float charge. And because of its 50 Ampere capability and multiple charging source regulation, you will probably need only this one regulator for your entire system. About the author: Dale Glaser is an renewable energy user and enthusiast who lives in the back country of Mendocino County in California. He was one of the original principles of the Burkhardt Turbines Residential Hydroelectric business, and has been tinkering with applying electronics to 12 Volt energy systems for years. He currently works as a reporter for an alternative paper in Mendocino County, and has written extensively in his paper on renewable energy, and alternative sanitation. He occasionally helps people install 12 Volt energy systems. Enermax can be reached at POB 1436, Ukiah, CA 95482, or call 707-462- 7604.