Grid Powered Charger Assembly Instructions Using
the Altenergy Printed Circuit Board Kit
This device is designed to connect a utility company powered 120vac battery charger to your wind or solar battery storage bank. When weather conditions cause your alternative energy production to fall off or stop, you can maintain a safe charge even while drawing power from the batteries. The device will reduce wear on batteries due to chronic under charge or deep cycling. It permits you to continue to use your batteries even if electric production from your alternative source is limited due to poor conditions.
These instructions are for users of the Grid Charger Voltage Switch printed circuit board kit. Follow the step-by-step instructions checking off each item as it is completed. All components are placed on the top side of the circuit board. This is the side that has the white layouts and printed lettering. Use a small soldering iron and rosin core solder made for electrical circuits. Pay close attention to the proper alignment of the regulator and PIC chip socket, the LED, and the electrolytic capacitor. Avoid large clumps of solder that may cause unwanted shorts between adjacent pins. Do not solder the PIC in place. Instead, solder a 14 pin DIP socket to the board and plug the programmed PIC into it after all assembly is completed.
Mount Components to the Board
_____ Solder the 14 pin DIP socket. Align the notch on one end of the socket so it matches the notch printed on the circuit board.
_____ Solder the 78L05 regulator chip in place over the holes marked U1. The rounded side of the chip should match the printing on the circuit board.
_____Solder the two 50K ohm potentiometers into the holes marked R3 and R4.
_____ Solder the LED to the holes marked LED1. Make sure the flattened face of the LED faces away from the DIP socket. If you plan to install the board in an enclosure, you may wish to solder wires to these holes that will allow you to extend the LED out to the surface of the enclosure.
_____ Solder the 32.768 khz crystal to the holes marked X1.
_____ Solder the .1 uf capacitor to the holes marked C1.
_____ Solder the 10 uf electrolytic capacitor to the holes marked C2. Be sure the positive terminal of the capacitor is connected to the regulator chip, U1.
_____ Solder the 2 Kohm resistor to the holes labeled R1
_____ Solder the three 10 Kohm resistor to the holes labeled R2.
_____ Solder the 100 Kohm resistor to the holes labeled R7.
_____ Insert the 18pf capacitors into the holes labeled C3 and C4.
_____ Solder 10 Kohm resistors to the holes labeled R5 and R6
_____ Solder the two jumpers or DIP switches to the holes labeled SW1 and SW2.
_____ Trim all soldered leads as close to the board as possible and inspect solder joints using a magnifying glass. Clean up and retouch any questionable joints.
The PIC Software
If you purchased a preprogrammed PIC 16F676 chip, plug it in to the 14 pin DIP socket. Pin 1 (in the corner where the little dot is on the face of the chip) should go on the side where the notch is on the end of the socket.
If you have the equipment and ability to program the PIC chip yourself, you can download the MPLAB assembler source code that you would build into a program file, or you can download the already built hex file that goes straight into your PIC programmer software.
Links are given to the left that will load these files straight into your web browser. Use the SAVE AS option in your browser's File menu to copy them to the final desired location on your computer.
The PIC 16F676 configuration bits are given below:
Oscillator: LP
Watch-Dog Timer: disabled
Power Up Timer disabled
Brown-out Reset: disabled
MCLR pin function: reset
Code: not protected
Data EEPROM: not protected
After you have programmed the chip, insert it onto the board as described in the paragraph above.
Tests and Adjustments
You will need a voltmeter and adjustable power supply capable of delivering from 5 to 15 vdc to test and adjust the unit.
1. To begin, turn the low voltage adjust pot, R3, fully counter clockwise.
2. Turn the overvoltage adjust pot, R4, fully clockwise.
3. Connect power to the board. The LED should blink ON, then OFF
Troubleshooting… If the LED does not blink when power is supplied, press the reset button to see if that turns it on. If it still does not blink there is something wrong with your assembly and you will need to troubleshoot the cause. Inspect it closely with a magnifying glass for bad solder joints. Check if the PIC or LED is placed backwards or if pins are not properly seated. Test the supply voltage between pins 1 and 14 on the PIC to insure it is 5v. If you did not use the supplied printed circuit board, double-check all your connections against the schematic.
4. Adjust the power supply to the maximum acceptable voltage for your battery bank. This can be measured conveniently between the points marked A and B at the upper right hand corner of the board. The maximum voltage you choose might be just under 15 volts, which is the over voltage cut-off on many inverters.
5. Turn R3 clockwise until voltage at pin 8 of the 16F676 measures 2.5 volts
6. Adjust the power supply to the minimum acceptable voltage for your battery bank. There are several considerations to make when deciding upon the optimum low-end voltage. A higher adjustment will mean the grid charger will turn on more frequently, and you will consume more electricity from the power company, but you will afford greater longevity to your batteries. A lower voltage will mean you get more power from your batteries, but the deeper discharge cycles may shorten battery life. Consult your favorite experts. I chose 11.95 volts for my minimum battery voltage.
7. Turn R4 counter clockwise until the LED turns ON. If you overshoot this adjustment, turn R4 back 1/2 turn, press the reset button to turn off the LED, then slowly turn R4 counter clockwise until the LED lights
Making Connections to the Battery Bank, Relay, and Charger
_____ The 120 vac terminals on a solid state relay should be connected in series to one leg of a power cable that brings ac power from a grid powered wall outlet to your battery charger. For instance, connect one relay terminal to the hot (black) lead going to a plug that will go into a wall receptacle. Connect the other terminal to the hot (black) conductor of a receptacle that will receive the plug from your battery charger.
_____ Connect a 12 volt battery charger to the rectacle built in the previous step. Follow the manufacturer's instructions to connect it to your battery bank.
_____ Connect small gauge wires between the pads marked RELAY and the control pins on a solid state relay. Be sure the positive terminal of the relay connects to the pad on the right side when the board faces you with the lettering upright.
_____ Use the same gauge wire to connect the battery terminals to the positive and negative terminals of your battery storage bank. Be very careful not to acidentally reverse polarity of the power inputs, or you will likely destroy the voltage regulator chip and have to install a new one.
Once you connect the battery leads to the board, the unit will begin to work. When the battery voltage falls below the minimum acceptable low voltage the LED will light and the solid state relay will turn on, allowing grid powered AC to go to the charger. The unit will remain on for the time set by the jumpers, SW1 and SW2. If the battery reaches the high voltage cut-off, the relay will turn off. Now your batteries are protected from prolonged periods of clouds or calm.
Grid-Charger Voltage Switch Parts List
Switches
PB1 1 reset switch (momentary, normally open)
SW1,SW2 1 ON time select switches or jumpers
Capacitors
C1 1 .1uf electrolytic
C2 1 10uf electrolytic capacitors
C3, C4 2 18pf ceramic capacitors
Resistors
R1 1 2k 1/4 watt resistor
R2, R5, R6 3 10k 1/2 watt resistor
R3, R4 2 50k multiple turn potentiometer
R7 1 100k 1/4 watt resistor
Semiconductors
LED1 1 LED 5mm T1
U1 78L05 5v 3 terminal voltage regulator
U2 1 PIC 16F676
Miscellaneous
XT1 1 32.768khz crystal
DIP14 1 14 pin DIP socket
1 Printed Circuit Board or breadboard
1 120vac Solid State Relay
1 120vac Battery Charger
NOTES: The solid state relay must have a DC control voltage of 3-32 volts. The relay's AC current capacity should be 20-40 amps depending on the current demands of the battery charger you choose.
Automotive or storage type battery chargers should work fine in this application. Choose a size that can deliver sufficient current to your battery bank. I recommend Iota Engineering's DLS series of voltage converters/battery chargers for their capacity, reliability, rugged design and construction, and efficiency.
http://www.iotaengineering.com/dls.htm The charger will work in tandem with your alternative energy charge controller.Operation
The Grid Charger Voltage Switch begins operation when it is attached to the battery bank. When battery voltage drops below the low voltage setpoint, the LED and solid state relay will turn on, connecting the grid powered battery charger. The charger will stay on for a period specified by the jumpers, SW1 and SW2. This will be as follows (y=jumper, n=no jumper):
SW1 SW2 Duration
y y 1 hour
n y 2 hours
y n 3 hours
n n 4 hours
At the end of the specified time, the LED and relay turn off and the switch monitors battery voltage again, waiting for the next low voltage event.
If the battery voltage should exceed the high voltage setpoint, the switch will turn off the relay and LED.
The operation is completely automatic. However, the reset button will toggle the relay on and off. If the reset is used to turn the relay off, the LED will blink the number of times it had switched on since the last reset.