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Lipo MT3608

LiPo battery sparks when used with DC step up convertor

animesh I’m using a LiPo battery 700mAh 3.7V with MT3608 DC-DC step up boost converter module 2V-24V 2A. The problem is when I connect these to anything or even the wires just touch each other they produce a spark. I want to hide or remove them so that it doesn’t harm my ESP32. Also is there any way with…batterieslipobuck-boostTony Stewart Sunnyskyguy EE75All step-up converters spark unless you have soft start. Do you understand transformed equations for V,I,Z ratios? animesh@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 tlfong014706Ah, 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. Andy aka@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? tlfong014706This 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. Tony Stewart Sunnyskyguy EE75Tue 19:47@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 Graham StevensonMaybe 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. tlfong014706@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. 🙂 Tony Stewart Sunnyskyguy EE75In 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 tlfong014706@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, … Tony Stewart Sunnyskyguy EE75I 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 tlfong014706Tue 19:47Your 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.htmlUsually 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.:)I read a MT3608 boost converter with the following remark: “The chip is supposed to have overload and temperature protection, but it is not reliable, I trashed two modules during the test.. (1) “MT3608 DC-DC booster module 2A booster Evaluation Report lygte-info.dk”: lygte-info.dk/review/…. Si I think it is a good idea to be very careful when playing with this boost converter.@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.  2 days later… tlfong01yst 8:46I must confess that I know very little about NTC as ICL. My only limited experience is using it in temperature compensated sensor circuits. This morning I found the following interesting: electronics.stackexchange.com/…. I am thinking of read the datasheet of the NTC ICL in my junk box.  2 hours later… tlfong014706yst 11:04So I googled the datasheet of my cheapie ¥0.07 NTC5D7.

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It appears that my NTC5D7 resistance is 5Ω at room temperature, and might drop to 0.3Ω at 2A. I think I need only these two parameters to design my MT3608 test setup.So I read the above EESE Q&A electronics.stackexchange.com/… with the following comments:(1) I purchased some cheap boards at about $1 each. The first one I quickly destroyed. But I pretty much knew the problem then. It cannot be powered up without a load present. (It destroys itself without one.) Adding a simple resistor was all that was needed. I’ve had zero problem with the rest of them. . – @jonk 2020Sep02(2) The alternative is to go ahead and buy cheap stuff from the surplus or China market, and test everything as it comes in the door. For instance, I’m pretty sure those power supply modules that are so ubiquitous are just copied from vendor’s data sheets, without any characterization or testing. – @TimWescott 2020sep02@jonk does not say what resistor load he uses. I guess 5R should ba a good start. I also more or less agree with @TimWescott that I should test everything with the seemingly fake MT3608 boost converteres. This is what I am going to do next. Stay tuned, …I have never heard “AeroSemi”. So I asked my friend Goggle.About AeroSemi
aerosemi.com/aboutus.html

西安航天民芯科技有限公司成立于2011年2月, 公司依托雄厚的航天资源优势和品牌优势,以核心团队的技术优势为中心,专注于开发新能源汽车动力电池管理系统、动力电池充电管理芯片、电池电源管理系统芯片、智能家居和物联网芯片、电机管理系统芯片、LED绿色照明驱动芯片、高集成度移动信息终端电源管理单元(PMU)、高低压DC/DC、AC/DC转换器等系列化战略新兴产业电源管理芯片产品及解决方案。

目前公司产品谱系包括动力电池BMS管理系统芯片、32BIT ARM M0系列MCU芯片、BLDC电机控制和管理芯片、高速高精度ADC和DAC芯片、WLED DRIVER、SWITCH CHARGER、HV BUCK DC/DC、AC/DC转换器、音频功放、LED TV专用芯片等。

经过多年的发展,已成长为一家年销售额过亿的规模集成电路设计企业。公司已通过国家级集成电路设计企业、高新技术企业、ISO9001:2015质量体系等多项资质的认证。 tlfong014706yst 11:58AeroSemi profile is impressive. MT3608 is as impressive. All these years I only know LM2596 step up converter, and almost nothing about step down stuff, and so have developed a slight inferiority complex. Learning MT3608 should be self healing, and stop my bad friends LOL at me, and begin to respect me more than I deserve.I was surprise the find MT3608 uses many new things in converters: (1) Use MOSFET, (2) 1.2MHz switching frequency, (3) built in soft start to limit inrush current and extend battary life, (4) Pulse Frequency Modulation (I don’t know what is this for, but should be good stuff. 🙂

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Ah, locking down lunch time! Would come back later.  2 hours later… tlfong014706yst 14:08Now I am testing MT3608’s regulation. (1) Lipo = 3.58V, adjusted to 12V no load. (2) With around 200 mA load, Lipo drops to 2.9V, MT3608 still has 11.9V. Conclusion is that the regulation good at least at 200mA load.

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  2 hours later… tlfong014706yst 16:36Now I am testing MT3608 5V stepping up to 12V. I am using a 5V switching PSU as input to MT3608 whose output is adjusted to 12V. Regulation is OK when loading current is within 500mA. At 800 mA, output drops from 12V to 6.6V.My quick and dirty conclusions:(1) MT3608 works OK if output current is within 500mA range. At 800mA, regulation is poor (12V drops to6.6V)(2) MT3608 has internal software pull up, therefore no inrush current limit (ICL) or current limiting series resistor at input or output side is required. I have not tested using such protection, and so far so good. Of course this is only a preliminary test, and results is not conclusive.(3) Next is do more tests, such as (a) short circuit/over current (>4A) protection(b) Also needed to compare MT3608 with other boost converters.(c) Lipo x2 (7.2V), x3 (11.1V) to 12V output, to see if regulation is good.(4) No spark is detected when connecting either connecting wires direct to load, or by switching the rocker switch. The OP’s spark incident is perhaps caused by his wearing nylon fabric, static electric charge induced clothing. Perhaps using a anti-static electric charge wrist band, connecting to ground might verify it.This is the pictures for 5V to 12V tests.

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tlfong014706yst 17:02There is an error in the above picture. Below is the corrected one.(removed)

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Locking down jogging/supper time. Will continue later.  16 hours later… tlfong0147069:32The OP is worrying about risk/protection of his ESP32 on using boost converter MT3608. Me hobbyists know very little about risks, so I searched this forum and found the following the good: Boost converter with overvoltage protected output – Olin Lathrop, EESE, 2018
electronics.stackexchange.com/….  2 hours later… tlfong01470611:13I found MT3608 interesting, but not too many forum discussions around. So I googled, and found a couple of discussions in Chinese. Below is a discussion by poor hobbyists like me.MT3608 Boost Converter Tutorial – Tai Wan Hobbyist Shop
ruten.com.tw/item/…tlfong01470611:30I read a couple of negative comments on MT3608. The following is an example” The alternative is to go ahead and buy cheap stuff from the surplus or China market, and test everything as it comes in the door. For instance, I’m pretty sure those power supply modules that are so ubiquitous are just copied from vendor’s data sheets, without any characterization or testing. – @TimWescott 2020sep02Me poor hobbyist always worry that the cheapie stuff I bought Up North are fake goods, so I usually do a fact check. I found one possible reason that those cheapy (MT3608 in this case study) are cheapy is that they are like ex-startups Uber: selling services or products at a losing money price, with a short term goal to grab market share, with an ambitious long term goal to become a Unicorn and more, …  The last message was posted 2 hours ago.

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