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Transcript
Model: SR-5b Switching Type Battery Management System Rev:b 07/2011 VLF Designs 1621 Bella Vista Dr. Jackson, Mo. 63755 573-204-1286 [email protected] Functional Description The SR-5a is a complete battery management system utilizing analog and digital processing for accurate charge control and low heat generation. It is primarily intended for use with analog telemetry systems and sensors that require well regulated low noise power for optimum operation. The power source for the SR-5a is normally a solar panel or line operated DC power supply. The SR-5a features temperature compensated charging of 12 V lead acid batteries and an output voltage limiter to provide a stable output voltage under all charging conditions. In addition, there is an adjustable low voltage disconnect in order to protect the back up batteries during periods of adverse power input. The input and output are transient suppressed. The output is over current protected by a self resetting thermal fuse. The input and battery connections are protected from reverse polarity connection by means of automotive ATO type fuses. Specifications Charge Input Voltage Maximum: 23 VDC Input Voltage Minimum (for charging): 14 VDC Solar Panel Input Current: 7.5A max per panel (fused) DC Power Supply: 15-18 VDC DC Input Supply Current Limit: Adjustable (4A with recommended supply) Charge Voltage Range: 13.3 to 13.9 VDC at 70˚F (adjustable) Charge Voltage Set: 13.65 VDC at 70˚F Charge Temperature Coefficient: -12mV/1˚F Post regulator Voltage Range: 12.0 to 13 VDC adjustable Post Regulator Voltage Set: 12.9 VDC Load Disconnect Voltage Range: 11.2 to 12.0 VDC Load Disconnect Voltage Set: 11.9 VDC Load Disconnect Hysterisis: 350mVDC (other values available at time of order) LVDC Output Current:0.75A (other values available at time of order) Reverse Battery Polarity Protection: 15A non reset fuse (ATO auto style) Theory of operation Input power from the solar panel or power supply is routed to a series switching charge regulator through a transient suppression network consisting of V1, D1 and R2,C1. A yellow LED will illuminate for a charge power source input voltages over 14 VDC and indicate that the source is capable of charging the battery. When a solar panel is utilized for a charging source, the input current limiter should be set to the fully CW position so that no current limiting from this type of source occurs. All units will be supplied from the factory with the current limiter set to this position. Adjustment will be required if the unit is to be used with a line operated DC power supply. The series switch in the SR-5a can be current limited when used with an external DC power supply to prevent it from going into fold back current limiting. The optional standard (70W) switching type power supply that can be supplied with the unit is capable of producing a charge current of up to 4.6A, however the internal current limiter inside the BC-12 limits current from the power supply to approximately 90% of capacity (4A) to protect the external supply from damage in the event of a deeply discharged or defective battery. Any type of External DC supply can be used provided that the current limiter is set below the maximum output current from the power supply. A red LED indicates that an equalization charge sequence has begun. Termination of equalization charge will occur when the battery voltage reaches an upper voltage threshold and the charging current falls below 2.0A. The red LED is on for high charge rate(equalize) and a green LED is lit in the low rate (float) charge mode. The charge regulator is configured around a temperature compensated reference supply using an LM34 as a precision temperature sensor. The output of the charge regulator is normally set at 13.7VDC at 70˚F for sealed (AGM or gel) batteries. It provides a variation of approximately -12mV/˚F in charge voltage. This compensation level is accurate for all lead acid battery chemistries. However, If non sealed lead acid batteries are used (deep cycle marine) the regulator should be set for 13.6 VDC instead of 13.7 VDC at 70˚F. to help minimize the need to add water on a periodic basis. If a partially discharged battery is connected, charging will begin in the equalize mode as soon as the power source is capable of supplying at least a 2A charge current. The battery will remain in the high rate charge condition until the battery voltage reaches approximately 14.1 VDC (at 70˚F). High rate charge will continue until the battery charge current tapers to under 2A. At this point the charger will revert to a lower voltage float charge mode. All of the above mentioned voltage levels are a function of the temperature of the charger, and for best results the charger should be located near the batteries so that they are both in an equal temperature regime. This method of charging maximizes battery life and returns approximately 90% of the battery capacity in the shortest possible time. Following the charge regulator is a post regulator stage. Its function is to regulate the output voltage to provide a stable voltage to the load under all charge conditions. It is a very low dropout MOSFET series type regulator. This regulator is normally set at 12.10VDC. However, when the battery voltage drops below the regulator setting, the output will track the battery voltage within a few 10’s of millivolts. The low voltage disconnect (LVDC) is provided to maximize battery life under low charge conditions. The LVDC is normally set at 11.9VDC (5% remaining charge for load currents below 300mA with a nominal 100AH battery). It has approximately 350mV of hysterisis; thus the load will not reconnect until the battery voltage rises above 12.25 VDC. R32 may be increased to increase the hysteresis if desired. The low voltage disconnect thresholds are unaffected by temperature. The output is protected against reverse polarity and overvoltage transients. A polyfuse self resetting fuse is used to prevent damage to the regulator if an accidental short circuit occurs at the output. Non-resettable fuses are used for reverse polarity protection in the input and battery circuits. The battery fuse will only open if the battery is connected in reverse polarity to the charger. It is 15A standard automotive type plastic bodied fuse. The input circuit fuse is 7.5A Connections Inputs and outputs from the regulator are by means of a single 8 position Phoenix type connector. Provision has been made to connect 2 batteries in parallel configuration to the regulator. These batteries will be connected in parallel as soon as the connector is plugged into the regulator. Both batteries should be in a similar state of charge prior to connecting them to the regulator, otherwise damage to the regulator may occur as the batteries equalize with one another. If batteries of dissimilar charge are to be connected to the regulator they should be connected together in parallel for at least 15 minutes before they are connected individually to the regulator. It is important that the polarities of each battery be correct prior to connection as there is no provision for reverse polarity connection of one of the two batteries relative to the other. Input power common, battery common and load common are all connected together inside the case. The case is floating relative to all regulator connections. Adjustments: Refer to Figure 1 for adjustment locations AC current limiter This adjustment should only be performed when the SR-5a is used with an external power supply. The ac current limiter is set with a 2 ohm 50 watt resistor connected to the battery terminals through a 10A DC ammeter. Set R4 fully CCW and plug in the dc power supply. Adjust R4 for a reading of 4A (or 95% of maximum supply output current) on the ammeter. Charge regulator adjustment Because the charge regulator contains a temperature sensor, the charger should be allowed to come to the ambient room temperature prior to adjustment. Connect a DC voltmeter and a 200-500 ohm resistor across one of the battery terminals of the regulator. Adjust R9 for the desired float voltage according to the following table. The float voltage may be interpolated linearly for temperatures between those in the table. Float Voltage Table Temp 90˚F 80˚F 70˚F 60˚F 50˚F AGM Battery 13.46 VDC 13.58 VDC 13.70 VDC 13.82 VDC 13.94 VDC Deep Cycle (non-sealed) battery 13.36 VDC 13.48 VDC 13.60 VDC 13.72 VDC 13.84 VDC High rate charging may be verified by connecting a 10 ohm 25 watt resistor in parallel with a 100,000 uF capacitor across the battery terminals. The red light should light for about 12 seconds and the output voltage should increase 400 to 500 mV above the float level during that same period. Post regulator adjustment Connect a DC power supply set for 14VDC to the battery terminals. Set the post regulator adjustment R30 for the desired voltage at the LVDC load terminals. The regulator may be set for voltages below the LVDC thresholds, as these thresholds are determined from the battery voltage not the output voltage. The factory setting for this adjustment is normally 12.9 VDC with no load. LVDC adjustment Connect the DC power supply set for the desired LVDC threshold voltage to the battery terminals of the regulator. Turn R25 fully CCW, and then adjust R25 slowly CW until the blue LVDC load LED is extinguished. The factory setting for this adjustment is 11.9 VDC. Then increase the power supply voltage until the blue load LED just lights. This is the reconnect voltage and can only be changed by a component change, (R32) in the regulator. Figure 1: SR-5a Adjustment locations and parts layout