Hi everyone, have you guys boosted voltage from a 3.7V li-ion battery pack to power the backlight of LCD tft displays? Or is it better to step down a voltage from a higher voltage battery pack to provide power to the backlight of the display?
I am thinking about stepping down to keep the current because if I boost the voltage, doesn't that drop the amount of current I can utilize from the li-ion battery pack?
With so little information, the only real answer is “It depends.”
As for the lower current, that formula with the current being the inverse of the voltage gain is for a transformer so that the energy input and output are nearly equal (energy lost in transformer). Both boost and buck converters follow the same rule.
For a given battery volume, the energy stored by a large single cell and two smaller cells will be roughly equal. This means either converting method will end up outputting roughly the same energy.
The big problem here would be the lithium ion battery. Having multiple battery cells means multiple cell battery monitoring and charging with a multi-cell monitor. Frequently, especially with small cells, the single cell option will be easier and cheaper. Of course, there are exceptions where multiple cells are preferred.
So, having said all this, “lower current” is not a concern and the best answer is “It depends.”
You need to let us know which displays and preferable with a link to the technical information. Not all displays are the same or do the back lights work the same. As far as battery that is mainly design dependent as there are other devices besides the display involved.
I was planning on using a 3.7V 2500mAh li-ion battery pack like this one Battery
And I am trying to use that same battery to power my control board Adafruit ESP32 and a display like this one that has a different backlight voltage Display. But I would need to boost the output voltage pin of my controller or boost the voltage from the battery to the backlight since it has a voltage greater than what the battery supplies. Please excuse the elementary diagram but I have drawn an example of both scenarios.
Boost converter from 3V pin of my controller:
Boost converter from battery:
I was also doing some more research about efficiency and some sources say that its more efficient to use a buck converter compared to a boost converter. In this case I either have to find a higher voltage battery or if putting three or so battery packs in series would work?
To use multiple lithium ion batteries in series, you must have the correct battery management system wired to all of the batteries and power everything from the complete battery series. Please research this information before you make your decision and before wiring lithium ion batteries in series. Wiring lithium ion batteries in series without the correct protection circuit may result in parts damage or burning everything to the ground.
Your linear regulator is a bad choice because of two major reasons:
Pin numbers etc would help a lot. If you want to use 1 cell you will need more voltage for the ESP device.
The user did not select the voltage regulator, Adafruit did. They selected an AP2112-3. See here for information:
The numbers you somehow assumed were correct are actually rather wrong. There is nothing wrong with using this part number in this application.
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