I have an Apple Bluetooth keyboard. The thing turns on all the time when I put it in my backpack. This is bad because it blocks the soft keyboard on my phone. It runs on 2 AA batteries. Lately, I have been turning one of the batteries around to make sure it can't turn on. This works as intended, but my questions are:

  1. Can this damage the electronics?
  2. Will this drain the batteries faster?
  • \$\begingroup\$ Why not just put a small piece of paper over the end of one of the batteries? No risk of damage that way. \$\endgroup\$ – Craig Oct 12 '12 at 19:58
  • \$\begingroup\$ I thought about that but it's just one more thing I have to either keep around when it's not in use or re-create. Fewer loose parts is better. \$\endgroup\$ – Kent Oct 12 '12 at 20:01

No to both questions. Turning one cell around in a two-cell pack simply creates a pack that has zero net terminal voltage, and this can't harm either the circuit or the cells themselves.

  • 4
    \$\begingroup\$ This is correct as long as those two batteries are in series, and there are no other sources of power in the system. If the batteries were in parallel, you'd be shorting them both across each other, and you'd definitely know by now that something was very wrong! If there was some sort of charger built into the keyboard, to recharge the AA batteries when the keyboard was plugged in, you'd essentially be short-circuiting the output of the charger. Neither of those is likely to be the case here, of course. \$\endgroup\$ – Stephen Collings Oct 12 '12 at 19:59
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    \$\begingroup\$ This is correct as long as the batteries are of the same type/chemistry and same state of charge. Assuming that that they came out of the same box (or charger), and were replaced at the same time, chances are that you'll be fine. \$\endgroup\$ – HikeOnPast Oct 12 '12 at 20:03
  • \$\begingroup\$ They are in series. \$\endgroup\$ – Kent Oct 12 '12 at 20:04
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    \$\begingroup\$ What if the batteries are at different voltages? \$\endgroup\$ – geometrikal Oct 12 '12 at 21:31

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