Li battery and charge controller for BT speaker

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polakse
 
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Li battery and charge controller for BT speaker

Post by polakse »

Hi, I'm new here. Found this site while looking for battery charge controllers. I have no experience on the subject, but I'm hoping some of you can provide guidance. I'm interested in building a Bluetooth speaker. At the heart of the device will be some really nice speakers and a Class-T amplifier... those aspects I've already figured out. What I'm struggling with is spec'ing a power source for the amp. I'd like for the system to be battery powered, but also work when a charge source is connected to the battery (i.e. to charge the battery and power the amp at the same time). The amp has a 12V DC input and comes with a 12V/2A DC power adapter/supply. Ideally, I'd just mount the back panel of the amp onto the back face of my speaker enclosure, and then - internally - re-wire the 12 V DC input from the amp panel into a charge controller for the battery. The battery will need something like 4 A-hr capacity (less is OK). How do I go about selecting a battery and charge controller? Is my plan even feasible, or am I neglecting something important? Thanks in advance for the feedback!

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adafruit_support_bill
 
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Re: Li battery and charge controller for BT speaker

Post by adafruit_support_bill »

All of our LiPo batteries and chargers are 1S (3.7v nominal).

There are lots of sources for 3S (11.1v) packs and chargers. You might also consider 12v NiMH packs. You can find these on Amazon, as well as the major hobby stores and battery vendors.

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polakse
 
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Re: Li battery and charge controller for BT speaker

Post by polakse »

Oh, good to know! Am I going to find 3S battery packs and charge controllers that allow simultaneous connection of load and source? Is there some specific terminology or device I should be searching for? I like the lightweight and small footprint of the LiPo batteries, I assume NiMH will be larger and heavier? I apologize for my ignorance. Thanks for the feedback!

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Re: Li battery and charge controller for BT speaker

Post by adafruit_support_bill »

LiPo does tend to pack more power into a smaller space than NiMH. But LiPo is fussy to charge. When you have more than one cell in series, you need to use a 'balance charger' to charge them safely. The problem is that most balance chargers don't have provisions for powering the load while charging. You may be able to find one, but I don't know of any off-hand.

Another option you could look at is a 1S battery with a boost converter to boost the output to 12v. The problem there is that boost converters are not 100% efficient, so much of the power density advantage over a NiMH pack would be lost. You would also need about a 15AH 3.7v cell to get an effective 4AH at 12v.

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