is relay the perfect thing for my situation?electronic problem?
i have a 6V 4.5Ah Rechargeable Battery,And a small custom made 20W inverter hooked up with a CFL (compact Florescent lamp)
and i also have an external charger 7.5V 1A with alligator clips at the end..i have a small switch on the wire going to the inverter(from battery) and i use it to turn it on..and when i want to charge it…i have to reconnect the alligator clips of the ext. charget all the time..
my BASIC question is…i WANT to make this system fully automatic..like..when the pow from the mains is comming..then it will trun off the lamp and charge the batt…when the power fails ..it turns on the lamp using the battery,
NOTE:I DONT CARE for overcharging..i DONT need any over charging circuit..and i damn care if my battery explodes right in front of my eyes..I JUST NEED THE AUTOMATIC THING…please dont tell me circuit for charging and over charging cut-off..
now.. someone told me that i can use a thing called relay..exactly for this purpose…i got one rated at 12V..now..it has 5 Pins…2 are on one side..and 3 are on the other side…now that man told me that give it 12v frm mains via transformer…i thing my charger can be used for this purpose..it gives 7V and ..can it drive the 12V relay?..if so..
where to connect these things..
2 pins are on left side..on the corners..and 3 pins are on the right side..2 of them are in corners..and 3rd in center..is slightly closer to the left pins..i found no pic..on the google..
NOTE: it is NOT a car Relay..it is a PCB mountable small pins relay
what pins among them are the switches..?and where are the 12v voltage input pins to control the switch ?
Tagged with: 1a • alligator • alligator clips • batt • compact florescent • florescent lamp • google • input pins • mains • pcb • pow • rechargeable battery • switches • voltage input
Filed under: Electronic Circuit Problems
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Yes, a relay would work. However, what you really should have done is figure out how you want the switching to be done before buying the relay. From your description of the relay it appears to be a SPDT relay – two pins for the relay coil and three pins for the SPDT switch. If the way you are planning to hook up the relay will allow you use it like an SPDT switch then you probably can use the relay you have.
However, relay pinouts are not all standard so if you don’t have a pin diagram you will have to use an ohm meter to figure out the pins. The two pins that have resistance ( not 0 resistance but somewhere between 50 – 1000 ohms) will be the relay coil pins. I would try and hook up the 7.5 volt charger output to these pins and see if the relay ernergizes. You should hear a click sound if it does. If the relay does not energize then you can’t use it. As for figuring out the other pins …
With no power to the relay, the two pins that have 0 resistance are the common and NC pins. Apply power to the relay (to the relay coil pins) and now the third pin and one of the two previous pins should now have 0 resistance. The third pin is the NO connection and the other pin is the common.
So with the charger on, the relay would be energized and the NO connection would be closed. The charge circuit should be flowing between the common and NO pins. When the power from the mains goes off, the charger ouput is lost so the relay de-energizes and the NC and common connection is now closed and the battery should now be powering the lamp.
Hope that helps you.
Yes, a relay would do what you want.
A relay will usually operate with an applied voltage some 30% lower than its design voltage, and, perhaps, with an even lower voltage.
However, at reduced voltage, a set of closed contacts will not be held so firmly together as they would normally be and that will reduce their current carrying capacity.
It would be much better to use a relay with a coil which operates either from the mains or from between 6 to 9V.
You should insert a 2A diode between the charger’s output and the battery, unless the charger already has a diode in series with its output.
The normally closed (that’s what your other respondent’s NC means) relay contacts should be connected between the battery and the inverter.
And the relay’s coil energised by either the mains or the charger’s output, depending on your choice of relay.