Odd Battery Test Result

[Anonymous]

Greetings. I’m having odd results with some batteries. The question for those who don’t want to read the whole story is: Is it possible for Alkaline batteries to test nearly good for voltage, yet actually have almost no power?

The story: My kids and I built a launcher for model rockets. The standard commercial Estes launcher uses 4 AA batteries in series for a nominal 6v charge. The igniter has a resistance of .75 ohms and the wire has a resistance of .5 ohms for a total of 1.25 ohms. I calculate this to produce a 4.8 amp load heating the igniter. This works as intended. i.e. the rockets launch.

We had misinformation prior to seeing the commercial product, and thought it required a nominal 12v charge. We built our launcher based on this misinformation, using 2 A23 batteries in parallel for 12v. My wire is slightly larger gauge, resulting in .4 ohms resistance in the wire itself. So, a total of 1.15 ohms and 12v should produce over 10 amps… Continuity and voltage to the contacts tests good. Yet, even in a bench test, the igniter will not burn with my 12v launcher, although it reliably burns with the Estes 6v launcher.

Now the battery question… These may be weak/expired/old batteries. However they still test to 11.5 volts, which should still push more than 2x the amperage of the Estes launcher. Wondering what might explain the failure. Can voltage be near expected levels, but actually there is nothing left in the battery?

Thanks in advance for any info.

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