9V battery keep blowing up!!!
February 22, 2009
Ok I have a problem that just does not make sense but since I am a newbie I thought I would throw this up and see if I can get some pointers.
I had and I say HAD two 9V Duracell batteries (Alkaline not NiMh) that I hooked up to my bread board. In line I have either a SPDT or a DPDT switch (how do I tell, it has three leads but three positions one marked 1 the other marked 2 with the center position as the third). Wierd thing is that as long as the switch is in the 'ON' position and my circuit is receiving current, the 9V battery is just fine but once I turn the switch to the 'OFF' position it is only a matter of time before the 9V blows. I don't think it is a Duracell thing (I read some posts on the Net that said they were prone to spontaneous blowing up) because when I hooked up the second Duracell it also blew. Again if the switch is in the on position everything is hunky dory but as soon as it is switched off it is like the battery is shorting somehow and getting really hot and then boom (sounds kind of like a firecraker).
I checked voltage coming back to the battery and got back a very minute amount of voltage (I thought ok its somehow getting charge back to the battery and trying to recharge an alkaline). I am not sure if this is because of my voltmeter or if I can truly trust it.
One last idea, is it possible the switch is defective or is there a limit on the amount of voltage that can be passed through some of them. Could current somehow jump the open circuit.
I have since taken the switch out of the circuit to protect my new NimH batteries.