Test of 9V Batteries and Bridge Wires.

Batteries vs Bridge Wires

So I finally got around to construct my Ejection Timer for my next project. This device will carry a 9V battery to power the circuit and burn the bridge wire that ignites the ejection charge. I though tit would be appropriate to test my battery with the bridge wire to see how fast it ignites the charge.

Below is an example of the steel wool I used in this test. I also tested 40awg nichrome wire

Panasonic Carbon-Zinc
To my surprise, the wire barely got heated with the power from these 9V carbon-zinc Panasonic batteries. At first I thought the battery was dead on arrival (or DOA), so I ordered another one of the same brand just to make sure. Unfortunately the result was the same.

My next bet was to try the nichrome bridge wire. I quickly constructed the ignitor and switch on the batteries, this time using both batteries in parallel for more amperage. They failed, terribly. The nichrome didn't even glow


Duracell Alkaline
At that point I start having doubts for this ejection system and considered abandoning the electronics. I made one last attempt and try a different brand and type of battery: Duracell / Alkaline.

I'm happy to announce that this battery burned the thick steel wool in an instant! Hope has been restored to my project and tomorrow I will begin soldering.

One thing I will be sure to do, is to have a test battery different from launch battery. The launch battery will be brand new and unused. I just cant risk launching a high powered rocket that fails the recovery.

Conclusion
Stick with Duracell or Energizer alkaline batteries, or better. My guess is that Carbon Zinc based batteries wont be able to deliver the current we need for ignition. Lithium based batteries probably have more punch, but that was not tested here.