I have a standard "Bosch" type SPDT relay that will activate and send 12v of power to a power resistor (to automatically drain a battery). All I'm trying to do is to send power through the resistor and also turn on a LED to let you know that it is receiving power.

Let me apologize for the bad drawing, but this is what I have:

It works fine if I connect it directly to a 12v source, but when connected through the relay, the relay will spasm and open and close non-stop very, very quickly.

The circuit leading to the relay works fine as I can activate the relay and turn on a simple light bulb- the problem is something to do with this little resistor setup.

Any idea why this is happening?

 

Hello,

Do you have the complete schematic (including the relays) ?
The part you gave does not tell us how the relays is connected.

Greetings,
Bertus

 

I don't have the entire thing drawn up but hopefully this will help you:

 

Hello,

How is the relays coil powered?
Is the 12 Volts stable when the relays is "flapping"?

Greetings,
Bertus

 

Hello,

How is the relays coil powered?
Is the 12 Volts stable when the relays is "flapping"?

Greetings,
Bertus

Yes, the coil voltage is stable.

 

Are you powering the relay coil from the battery that you are discharging?

Consider using (an) incandescent bulb(s) instead of a power resistor. When an incandescent bulb's filament is cold, it has much lower resistance than it does when it's hot; it's resistance is non-linear. This is just the kind of response you want from a load when discharging a battery.

 

The first thing that comes to mind is that when the contacts are closed the load is so severe that it pulls the coil voltage down below Holding Voltage. Then the contact open and the voltage rises until the voltage reaches contact Pull In. The end result is a buzzer!

(1) Are we to assume that the 12V that powers the relay coil is the same 12V battery that you're attempting to discharge, or is this circuit being powered by a wall wort?
(2) Are you building a Battery Cycler, ie: a circuit that charges a battery and then discharges it repeatedly until it's lost its memory?

The pictorial you posted leaves many unanswered questions, like what is the value of the power resistor? Why do you have a Schottky diode directly across the battery when the contacts are closed?