Things that Work! Home Power test the Heliotrope CC-60 PWM Battery Charge Controller Up to now charge controllers have been basically voltage sensing switches. Well, Heliotrope has a new approach to battery state of charge control. Their new CC-60 is a real STATE OF CHARGE controller-far more than just a voltage regulator. The CC series of controllers are very well made and can handle up to 120 Amps in either 12 or 24 VDC systems. This PWM (Pulse Width Modulation) controller is an all solid state, series type unit applicable in PV systems. Control Theory Heliotrope's PWM controllers use power MOS FET transistors in series between the power source and the batteries. These FETs control the amount of current delivered to the system by rapidly switching on and off the connection between the power source and the batteries. The controller's logic considers battery voltage and BATTERY TEMPERATURE. Once the user has selected the appropriate state of charge (SOC) voltage for his batteries, no further human attention is needed. The control automatically maintains the battery's state of charge, even compensating for the temperature of the batteries. The Heliotrope CC series of charge controllers are totally transistorized and DO NOT employ relays or other failure prone electromechanical parts. They are field selectable for either 12 or 24 VDC operation. The Heliotrope controls are protected against reverse polarity, shorts during wiring, and overtemperature. Shipping Container & Documentation The CC-60 arrived via UPS in fine shape. The documentation on the unit is rudimentary and reflects the "just out" nature of this charge controller. Heliotrope assured me that a new, illustrated installation and operations manual is in the works. Physical Examination The CC-60 is housed in a heavy gray metal box that is 8.25 inches tall by 11.25 inches wide by 3.75 inches deep. There are five status indicator LEDs (Charging, Charged, Overtemp, and Low Battery Voltage) on the control's front face. The Heliotrope controllers use Shottky blocking diodes, and between 2 and 4 monster FETs (Field Effect Transistors), all heatsunk to a large metal bar within the controller. A hole is included for the optional fan. This fan extends the current handling capabilities of the controller by helping dissipate the heat caused by high current operation. The fan is thermostatically activated, only when needed, by the controller's logic. All wiring is accomplished from a slot on the bottom the controller. There are 4 very heavy 250 CFM lugs to connect the power source and the battery. These lugs easily make a durable, low loss, mechanical connection on wire or cable larger than "0000" gauge. We like these godzilla connectors. Their huge size and ease of use make difficult connections on heavy cables a snap! Battery voltage can be sensed via the main power wires or via dedicated separate wires directly to the battery. Using dedicated sense wiring assures that the battery's voltage is accurately measured and neglects the voltage losses caused by the high current flow in the power wiring to the battery. Connections are also included for the battery temperature sensor. This sensor is epoxied to the case of a battery and compensates the SOC voltage -3 milliVolts per cell per degree Centigrade. Temperature compensation means that when the batteries are cold, this controller is smart enough to realize the situation and raise the SOC voltage of the batteries. This feature is very good for folks with batteries in unheated areas during the winter. For example, this controller will automatically raise the SOC voltage in a 12 VDC system by about 0.45 VDC between a battery at 78¡F. and one at 34¡F. The "Low Voltage" alarm is user programmable to either 10.5 or 11. VDC in 12 VDC systems and 21. or 22. VDC in 24 VDC systems. One nice feature is an on board electronic switch to drive a user supplied 12 VDC buzzer when the battery voltage drops to the "Low Voltage" setpoint. Installation & Test System We installed the CC-60 between a 200 Watt PV array (Å16 VDC @ Å13 A.) and a pair of Trojan L-16W batteries (12 VDC 2 350 A.-H.). The unit is programmable via a DIP switch to state of charge (SOC) voltages between 13.5 and 15 VDC in 0.1 Volt increments. The very same control will also work in 24 VDC systems with a flick of the DIP switch. In 24 VDC systems the state of charge voltage points are from 27 to 30 VDC in 0.2 increments. We selected a SOC voltage of 14.4 VDC for our test system. Once it was wired up we sat back and watched it do its stuff. Control Performance When the system's batteries reached the state of charge set point we selected, the PWM controller began to rapidly switch the array on and off. The voltage set point was roughly maintained regardless of solar insolation and system electrical usage. When the voltage set point is reached the "Charging" LED goes out and the "Charged" LED lights up. While the controller was regulating we switched some loads on. The controller sensed the loads and the energy flowing from the PV panels was increased to compensate for the added electrical consumption. When the loads were removed from the system, the controller once again reduced the array's current to the batteries. The Heliotrope CC regulators are not voltage regulators per se. They are Battery State of Charge Regulators. Something newÉ As such, it took us a while to understand how they work. We were expecting a voltage regulator, what we got was far more. A small electronic computer with only one mission in life- your battery's well being. The CC controllers will maintain system voltage within about 0.2 VDC in 12 VDC systems. The CC-60 responded to changes in system voltage rather slowly- just like the batteries. The transition from heavy regulation to no regulation took our CC-60 about 7 seconds. Those looking for a voltage control that respond rapidly to large transients are advised to look elsewhere. These units are not voltage regulators, but Battery State of Charge controllers. We've had our CC-60 on line for about 6 weeks now and have experienced no problems with the unit. It does its job flawlessly, with absolutely no user participation. Whenever our batteries are full- it keeps them there and maintains the system's voltage at acceptable levels for all our equipment. Cost The basic CC-60 costs $165. and will handle 45 Amps. The addition of the optional fan for $36 will extend the CC-60's current limit to 60 Amps. There is also a 120 Amp version that employs 4 FETs and a fan, call Heliotrope for pricing. Heliotrope also offers a 20 Amp version of this control with current and voltage LED bar graph metering. Heliotrope's warranty deserves mention and emulation. If the device fails during the first year of replacement is made at no charge. For years 2 through 5 replacement will be made for a service fee not to exceed 25% of the current list price and for years 6 through 10 for a service fee not to exceed 50% of the current list price. The very fact that Heliotrope can offer such a wonderful warranty is a tribute to their intense dedication to quality control. Conclusion We recommend the Heliotrope PWM Battery Charge Controllers. They are a new approach to battery state of charge control. A dedicated computer that keeps your batteries as full as possible. They offer extremely reliable, high current, operation at a reasonable price. The Heliotrope unit is well made and backed by a super warranty. We're proud to have one in our system. Contact Heliotrope General at 3733 Kenora Drive, Spring Valley, CA 92077 or phone: in CA 800-552-8838 or outside CA 800-854-2674.