I just bought a dirt-cheap wireless lapel microphone with transmitter and receiver. But, I think there may be a problem with battery life.
The transmitter is powered by a 9V alkaline battery, and I rigged it up to test the current draw, which was 38 ma. The receiver is powered by a single AAA battery, and it draws 52 ma. In both cases, that's with the power-on LED indicators disconnected to save power.
Back in the day I've used an external battery pack to extend the life of a digital camera which didn't operate well on rechargeables. The pack was just a Radio Shack holder for four C cells, plugged into the AC jack on the camera, to take the place of the usual four AA's. The C's lasted a long, long time, at not much more cost than four AA's, but at the cost of "wearing" the battery pack in some position.
With the wireless mic, there may be times when I want to use it over an extended period of several hours without having to stop and change batteries, and without having to wonder if it's gone dead.
In the case of the receiver, I could attach a twin AA holder to the back, and power it from that, but with the holder wiring modified so that the batteries are in parallel. That would give me two AA's in the place of the one AAA, which should significantly extend the life.
The transmitter is a bit more of a problem. The best I can think of is to mount two external 9V's on the back, probably with tape, and wire the connectors together in parallel, possibly also leaving the internal 9V still connected, which would give me three 9V's in parallel.
Well, I have a couple questions:
- Is there a better way to do this?
- Is connecting the batteries in parallel going to cause any problems? They will remain connected to each other even when the power switch is off. Will the batteries do bad things to each other connected that way for extended periods even when no current is flowing to the external circuit?
I don't know yet how much voltage drop the devices will tolerate and still operate. I'm testing that now. The answer might give me other options.