All step-up converters spark unless you have soft start. Do you understand transformed equations for V,I,Z ratios?

@TonyStewartSunnyskyguyEE75 What is a soft start, sir? Please tell me about it, I'm still learning. I don't know much about Transformed eq.

@TonyStewartSunnyskyguyEE75 And also please tell how I can reduce the amps in the circuit? Thanks

Ah, let me see. When your LiPo connects/touches the MT3608 guy, there will not be any spark yet. It is only when you disconnect (breaks the circuit), then the scary spark jumps out. A couple of solutions: (1) Use a little manual power switch, eg, 125VDC, 2A to power off off the Lipo power bank. The way, the spark still jumps out, but at the power switch contacts, and some how "kills/absorbs" by the little manual power switch.

@animesh what do you have connected as a load on the 24 volt output? What are your expectations of maximum load current on the 24 volt output?

This is an example of the power switch I am referring to: Miniature Rocker Switch / Single pole Double throw SPDT 120VAC 6A - US$2 (10 pcs) fr.aliexpress.com/item/…. Acutally you can use any other similar power switches under 125V 2A.

This is the MT38608 module schematic, for our future discussions.:mt3608stepupmodule.files.wordpress.com/2017/11/‌​…

Another precaution you might to take is the following: (2) Do not connect the load before setting up and switch on power, to avoid big rush of current when you switch on power. Also you can start with a small test load, and increase loading gradually, or in small steps, to verify if the big load is making the trouble. I know ESP32 takes very little current, but are you also connecting a BLDC motor to the boosted up 24VDC?

Another general trick is to use "delay start up" circuit. The idea is first switch Vcc/Lipo power, by using a cap to delay the MT3608 PSU enable signal. The red square in the following LM2596 PSU shows how to do it. (3) i.imgur.com/Z582tZe.jpg. WARNING: Me just a friendly hobbyist, no guarantee no nothing would melt down or blow up. Good luck and cheers.

@tlfong01 your assumptions that a step up converter input impedance is inductive is wrong. it is capacitive and the soft start is not possible on this simple switcher unless you use an ICL component.(Digikey e.g.j

Maybe the best advice is to suggest that 'arcen/sparken' are a normal consequence of connecting 'hot' circuits ! Live with the sparks or fit a switch.

@Tony Stewart Sunnyskyguy EE75, many thanks for pointing out my mistake. I made the wrong suggestion because I thought MT3608 is like LM2596 which can use the same delay startup recommended by the LM2596 datasheet. I also wrongly thought that LM2596 input is inductive because I know it uses an inductor in it switching circuit. BTW, I heard of Digikey but I never heard of "ICL" component. I only started relearning electronics after 2008. I still remember my big surprise when I revisited the electronics supermarket that they are selling magazines specially for "SMD" I almost knew nothing. :)

In the time you wrote this you could search google for ICL Digikey and learn faster... try that next time, instead of sharing what you aren't sure about

@Tony Stewart Sunnyskyguy EE75, many thanks for your advice. So I googled and found the following: "Honeywell ICL Inrush Current Limiters are an effective way of limiting the Inrush of current that can damage components in a switching power supply and other power devices when the equipment is turned on.". But there is a problem. I found DigiKey selling ICL155R006-01 at USD$4 digikey.com/en/products/detail/…. / to continue, ...

I did not ask you to Google any webpage . search by design parameters on DK. E.g. 1A $0.19 digikey.com/en/products/detail/cantherm/MF72-033D9/1190942. It I’m sure you can find local sources

Your link seems to be a source where minimum order is 3,000 pieces. I search local sources but for small orders the price is still US$4!: AliEXpress ICL155R006-01 ICL 5 OHMS 20% 6A 15MM - US$4 aliexpress.com/i/4000535372712.html

Usually I shop a TaoBao, which is local, and cheaper than AliExpress. But the price is still we poor hobbyists cannot afford - ¥32: "ICL155R006-01 ICL 5 OHM 20% 6A 15MM ¥32" detail.tmall.com/…. But my MT3908 step up power supply is only ¥2: "TaoBao MT3608 DC-DC 2A 2-24V step up 5/9/12/-28Vadj ¥1.55": item.taobao.com/….

@animesh, in case you are like me, a poor hobbyist, and worrying of frying the MT3608 boost converter one day, you might like to get prepared: "Repair: MT3608 boost converter": youtube.com/watch?v=-3tBw6WSZVM. Good luck. Cheers.

@Tony Stewart Sunnyskyguy EE75, I googled & found TaoBaos selling ICL at ¥1, ie 32 times cheaper than DigiKey: (1) NTC ICL/Thermistor Spec trigger.ru/content/Catalogue/pdf/ntc.pdf, (2) TaoBao NTC5D-7/-9/-11/-13/-15/-20 NTC Thermistor ¥0.1 - 1.0 item.taobao.com/…. Actually I have been using those cheapie thermistors for temperature comprehension of ADCs for a couple of years. I only knew NTC was for temperature comprehension, but I did not know those dirt cheap NTCs are also for ICL.:)

@animesh, It appears that MT3608 convert booster is a bit tricky to use. The following Q&A hints the problem: (1) "MT3608 Step Up Booster Problem - EESE 2020sep02": electronics.stackexchange.com/questions/519685/…. I think "jonk's advice at 2020Sep02/22:33" seems good. I might try to verify that later. Cheers.