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I'm building a portable speaker using a PAM8403 amp, 3.7v battery, and a battery charging module, all powered by USB input. What I want to do is be able to switch between

1) charging the battery from USB input

2) Power amp just from 3.7v battery.

3) power amp just from USB input(So when it is plugged into the wall it runs 5v. to the amp and gives it more power than when running off the battery).

I can't figure out how to do this without using switch for the battery, the power input, and to turn it all on and off. so many switches would be very user friendly. Is there a way to do this with less switches?

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As I understand the question, you want something like this:

This one is using a more powerfull amplifier than PAM8403, but works like you suggest.

This link has all the details and components used in the schematic presented above.

I suggest you to study this, and in case of any doubts just ask.

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  • \$\begingroup\$ I think I see a problem in this design because it looks like the 12.6v source is in parallel with the battery/protection circuit. Each loop has different voltage values. The amp would be fed by two different voltages at the same input. Also when the charging port is connected its going to be charging the battery while also powering the amp. I'm working with lower voltage and current values than the person who designed this and need a more efficient circuit. When I plug in my voltage source it needs to either power the amp or charge the battery not both at the same time. \$\endgroup\$
    – dom
    Commented Jun 3, 2016 at 19:36
  • \$\begingroup\$ There are thousands of commercial and kit/hobbyiest circuits that use this powering/charging scheme. This problem has been solved thousands of times. Go out and look at a few dozen schematics to see how it is done. There are several ways of accomplishing this depending on exactly what components you want to use. \$\endgroup\$
    – Richard Crowley
    Commented Jun 3, 2016 at 19:41
  • \$\begingroup\$ so..... your answer to my question is don't ask questions go figure it out yourself? \$\endgroup\$
    – dom
    Commented Jun 3, 2016 at 19:47

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