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I'm looking to set up a 1-meter strip of WS2812B LEDs (60 LEDs) with an off-the-shelf RF LED controller with a remote. The LEDs want a 5V supply - I've tried running them off 3.7v but the colour accuracy goes out the window and they start flickering and doing all sorts of other nonsense.

To work around that I'm considering using a DC boost converter like one of these pololu ones. I'll wire up a couple 18650 batteries in parallel to supply the voltage and my plan is to hook them up to the LEDs via the boost converter.

Idiot question time: is it safe to wire the boost converter directly to the output terminals of the battery/batteries and take the 5V off the +5v pin using a common ground? Or am I doing something dumb?

Also, I'm not 100% sure how to go about charging this setup. One option would be to put the batteries in cases and use an external charger with replaceable cells.

Would it make more sense to get one of these? This should be able to handle both charging AND stepping up the voltage, am I right?

closed as off-topic by MichaelT, Juraj, Greenonline, VE7JRO, sempaiscuba Apr 24 at 2:38

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "This question does not appear to be about Arduino, within the scope defined in the help center." – MichaelT, Juraj, Greenonline, VE7JRO, sempaiscuba
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  • How many LEDs are you going to be using? – Majenko Apr 23 at 14:47
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    Interesting question, but it's off topic. Try Electrical Engineering SE – MichaelT Apr 23 at 15:39
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is it safe to wire the boost converter directly to the output terminals of the battery/batteries and take the 5V off the +5v pin using a common ground?

Yes. That is the normal way of using them.

Also, I'm not 100% sure how to go about charging this setup. One option would be to put the batteries in cases and use an external charger with replaceable cells.

That is the simplest option, yes. You shouldn't charge Li-Poly / Li-Ion batteries whilst using them - the load messes with the charge termination detection and can cause your batteries to over-charge and explode.

Would it make more sense to get one of these? This should be able to handle both charging AND stepping up the voltage, am I right?

That gets around the problem of charging while running, yes. A proper charger like that should bypass the battery when charging so the load is running from the incoming charge power rather than the battery.

One option you haven't considered though is to not use step-up. Step-up is harder to manage with heavy loads. As you can see that first step-up module you link to has an upper limit of only 1.2A. If you have 60 LEDs per meter, and 1 meter of LED strip, that's a maximum of 3.6A (60 * 0.02 * 3) which is 3x what that module can provide.

A better solution would be to use two batteries in series, not parallel, to give you about 7.2V. Then you can use a step-down switching regulator to give you your 5V and have far higher current limits. Looking for a "UBEC" or "SBEC" in a model RC supplier shop is usually a good bet. For example:

These are all designed for use with two or more LiPoly batteries in series.

  • Great answer. (Voted.) – Duncan C Apr 23 at 16:04
  • Would those work with Li-ion batteries as well? Li-poly batteries are a bit wide for what I'm looking to do - the cylindrical form factor of the 18650 batteries feels like a better option. I like the idea of using a step-down regulator - I hadn't considered that! Thank you!. – poolski Apr 23 at 16:06
  • @poolski Yes, for all intents and purposes Li-Poly and Li-Ion are interchangeable. The main difference is the binding used to contain the battery components which gives the different shape. – Majenko Apr 23 at 16:07
  • @Majenko How would charging be handled with a step-down regulator? Those both look like they're just for regulating power, not charging. Would I need to build a charging circuit in or use removable cells? – poolski Apr 23 at 16:28
  • Would wiring in something like this deal with the charge control and making sure that the circuit is powered from the right source while charging, do you think? Edit: that seems like it has the same problem - it can't output more than 1A :( – poolski Apr 23 at 16:36

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