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I'm trying to build a wireless led strip using the esp8266 controller and ws2812 addressable led strip using battery power, but I'm a bit stuck on how to build the circuit.

After a bit of research I'm seeing that step-down converters are rather inefficient due to heat loss, so I'm thinking I could use a 2 AA batteries in series, with the positive connected in parallel to one 5V boost converter for the led strip and one 3.3V boost for the controller. These are the converters I've found:

https://www.pololu.com/product/2565

https://www.pololu.com/product/2563

Here's a sketch of the circuit (sorry if my symbols are not quite right): enter image description here

Would this work as intended? I want to keep the price as low as possible, and the converters essentially double the cost of the project (~$15 for the strip and controller). However, if I use 4 AA batteries and step down converters then efficiency drops, and I want the battery to last as long as possible.

Any suggestions are greatly appreciated!

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  • \$\begingroup\$ Look into the distinction between linear voltage regulators, which are extremely wasteful, vs switching ones which can be quite efficient. \$\endgroup\$ – Chris Stratton Feb 10 '15 at 14:08
  • \$\begingroup\$ How would a switching voltage regulator help in this case? It would make sense the required voltage was right in between charged and discharged battery voltage, but I'm not sure I follow in this scenario \$\endgroup\$ – ayu Feb 10 '15 at 14:16
  • \$\begingroup\$ Pololu is a good source but tends to be more expensive than what you can get on ebay. Personally I'd use 4 AA and switching step down regulators. Should get 80%+ efficiency and modules should only cost you several bucks apiece. \$\endgroup\$ – I. Wolfe Feb 10 '15 at 15:39
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A step down or buck regulator tends to be just as or better than a comparable step up or boost regulator, in terms of efficiency. Both refer to switching regulators. There are also buck-boost regulators that can do both, allowing it to regulate through the input voltage range of a battery supply.

You are confusing a switching step down regulator with a linear regulator, essentially a large resistor, who's efficiency goes down sharply as input - output voltage increases as well as current increases.

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  • \$\begingroup\$ are there any low priced switching regulators, or are they all going to be in the $10+ range for 5v regulator? I noticed the LD1117 and L7805 can be had for cheap, but they look to be linear regulators \$\endgroup\$ – ayu Feb 10 '15 at 15:25
  • \$\begingroup\$ You can get entire modules with the regulator and all the passive parts for like a few bucks on ebay/dx. \$\endgroup\$ – Passerby Feb 10 '15 at 15:34
  • \$\begingroup\$ Actually, what if I were to run the 4AA batteries in 2 series 2 parallel, and use a boost regulator? I'd have the same number of batteries yet double the capacity, if I understand correctly. Even if the boost regulator isn't as efficient as the buck regulator, it should more than compensate, no? \$\endgroup\$ – ayu Feb 11 '15 at 6:07
  • \$\begingroup\$ 1.5V * 2 Ah * 4 Batteries = 12 Watt Hours. Doesn't matter if you put them in parallel or series, you have the same amount of power. Its only a concern if you need more current than the series batteries can provide. \$\endgroup\$ – Passerby Feb 11 '15 at 6:32

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