Solar Speakers (High Power [14.8v])

Hello all!

I’ve been working on a medium sized “portable speaker” project and am dialing in the right sound, but am a little stuck on the power supply circuitry necessary to accomplish my goal. The concept is to charge a 4-cell 14.8v 4.4Ah lithium ion battery pack from a 12v power supply (car or backpacking solar panel). On the other side is power consumption: the battery will provide power for a amplifier (10 to 18v) and bluetooth audio board (5v). It would also be convenient to have an auxiliary 5v USB jack for powering my phone/mp3 player on the go (probably sharing the +5v with the bluetooth module?).

My questions are:

→ Will it be most efficient to run the amplifier board (primary power need) with power from the battery pack unregulated?

→ Are there pre-designed or example circuit boards that can perform the described charging/power supply?

Right now, I am just planning on using a 3-way switch to toggle between amp to battery for using, off, and charging.

Here’s the battery pack: http://www.tenergy.com/31892 and charger: http://www.all-battery.com/UniversalSma … AuNa8P8HAQ