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I have been trying to DIY my own power bank for a while now using step up circuits but the problem I keep running into is that they're either too expensive to consider over an actual power bank from a reputable brand, or that they're simply too inefficient.
Pic is the results from my latest attempt with the mt3608 step up circuit. That's a measly 66% efficiency when capped at half an amp output.
I need your help /diy/. Is there anything I can do to improve efficiency of this? I don't mind keeping it at 0.5A output, but I want at least 80-85% efficiency if the output is so low.
This is my first diy project and I'm no electrician so I really appreciate any help I can get.
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>>1124190
The black thing with 222 written in it was extremely hot during the 1A output test.
Not sure what it is. Transistor?
Could I replace it with a more efficient one? Or am I wrong in thinking it would have much impact on efficiency?
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>>1124190
Get a dedicated circuit
Something like https://www.aliexpress.com/item/TPS61030-efficiency-3v-5V-to-5V-2A-LiFePO4-18650-Battery-boost-module/32721411807.html?spm=2114.01010208.3.184.fbJjVj&ws_ab_test=searchweb0_0,searchweb201602_1_10065_10068_10501_10503_10000032_119_10000025_10000029_430_10000028_10060_10062_10056_10055_10000062_10054_10059_10099_10000022_10000012_10103_10000015_10102_10096_10000018_10000019_10000056_10000059_10052_10053_10107_10050_10106_10051_10000053_10000007_10000050_10084_10118_10083_10000047_10080_10082_10081_10110_10111_10112_10113_10114_10115_10000041_10000044_10078_10079_10000038_429_10073_10000035_10121-10503_10501,searchweb201603_9,afswitch_1,single_sort_1_default&btsid=880138a2-efe7-4e47-a1d8-174f237754ca
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>>1124192
the little 222 thing by the blue potentiometer? that's probably part of the voltage divider and should not be hot at all. the entire board is getting hot i imagine and that's not the problem.
if you mean the '220' you could replace it with a 22uH inductor with a lower resistance
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>>1124383
Sorry I meant the round black one, the larger one.
It does seem to be an inductor after a quick search, thanks.
Would I be able to pull one from a dead laptop or something?
>>1124371
I wouldn't mind something like that, but I'm trying to use what I mistakenly bought. Thanks for the plan B though.
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>>1124190
The MT3608 is a very high frequency, non synchronous converter. Very high frequency is good for small inductors, not for efficiency. Not being synchronous is also a hit to efficiency at low output voltage.
It's the wrong IC for the task.
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>>1124396
Thank you so much for this vital information.
So the mt3608 has a 1.2mhz switching speed but I've noticed several other ICs with 500khz switching speed. Would they be offering better efficiency then?
Only from the switching speed (ignoring other variables) would it be a significant improvement?
What if I built my own circuit board? I've been looking at some of these Maxim ICs and I'm really liking the look of some of them, like the Maxim 1763.
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