DIY LiPo Charge/Protect/5V Boost Circuit

DIY LiPo Charge/Protect/5V Boost Circuit


During a previous Project video Series of mine I showed you how to create this Battery-powered Raspberry Pi Handheld game console Which is still a ton of fun to play With Nevertheless I’m Currently Working on a successor though that most Importantly Should Be smaller and Lighter That is Why I will have to scrap the idea of using Nickel Metal Hydride batteries and Instead focus on lithium Polymer Battery as the Main Power Source Only problem is that the Nominal voltage of 3.7 volts of a Lipo Battery is not sufficient for the system So we would at Least Need a Circuit that can Boost the battery voltage Up to 5 volts and Deliver Up to 1 amp of Current. But It Would make sense to also integrate a constant Current constant voltage Charge circuits as Well as an Over discharge and Short-Circuit Protection Circuits. I already Tested a Potential candidate for Such a Circuit in a previous video, Which Unfortunately lack the Protection Features and could not provide enough current. Other Candidates on Aliexpress lack Electric Protection Features as Well and reusing a Power Bank circuits Would be novical at least in my opinion. So to solve this dilemma I will show you in this video how I designed created My own Lipo charge Protect Boost circuits that Fulfils all my Listed Requirements Let’s Get started. [music plays] As You might Know i’ve Been using the free online circuit design software called Easy eda for quite a While now and Since It can Also Transform Schematics Into Port Layouts i Will be using it for this Project and To make Things even Simpler for us we can use their partner component store Called lcSc Which are only offers Very low prices but also has its component database integrated into easy eda Which means that Not Only the schematic Symbols are available but also The Layout of the components for the port design Which Will save us a Lot of time and to conclude This trinity of Convenience we Can Let our Directly Export The board design to the easy eda pcB Manufacturing service Which is Actually Handled By The Company Jlc pcb Not Only are They the sponsor of This video but also offer Ridiculously Low prices and an overall Very Pleasing pcB quality But more about that Later for Now Let’s search for suitable charge ic as You can See here this selection Is quite big but there’s one i see a the Tpu 4056 Which i utilized before Without Any problems so Let’s Go with This one According to its data Sheets It Is a constant Current constant voltage a single cell lithium ion charge ic Which thus obviously also Works with a lipo cell and at The end of the data Sheets we Can See a typical application Schematic Which will pretty Much Only have to rebuild Within the Ez eda software By Utilizing The passive components of the database The Only Thing We Have to add By Ourselves so far is a Microusb Port For The Power inputs and a two kilo ohm resistor to set the charge current to 580 milliamps Next We Need a Protection Ic The first Entry The Dw 01 Pretty Much offered all the Protection Features i care about So i chose it without wasting any Time Again a Typical application Circuit Was present whose Rebuilding and the software was no problem at All but The two mandatory Mosfets were still missing a Simple Search for Dual n Channel Mosfet IC quickly look at me at the fs 8205 IC though Which can Withstand 20 volts 6 amps and has a Low gate voltage of Only 0.45 volts Perfect So I integrated this IC into the schematic and Edit solder Pads Full lipo Battery Which means we Were Pretty Much done with the charge and protect Part of the circuit. Next I added a Small Toggle switch to later Turn on and off The 5v boost Function and Started Searching For a suitable Boost converter ic What i found was the sdb628 Which according to its Datasheet has a Low input voltage a high efficiency and delivers Up to two amps There was also an Example circuits But This time Without Values for the components To determine them we have to look a Bit further down in the data Sheets Firstly we Can Set The output voltage By Utilizing in this formula. I went with the Values of 7.5 kilo ohm and 1 kilo ohm for the feedback Resistors Which Sets the output voltage to 5.1 volts Next the Datasheet Recommends an inductor value Between 4.7 and 22 micro Henry went with the biggest value and Continued By Adding input and output Capacitors with a value of 22 micro Farad’s and a suitable Schottky Diodes All of Course according to the Datasheet And After Adding Solder Pads For The 5 volts and Ground Outputs It Was time to push the convert project to pcB button and Start Designing the board Layouts What i came up with at the end looked something Like This Which Was Certainly not the best Solution But more about that in a Second for Now i click the fabrication output button Change the pcB quantity to ten boards and order them all for Only two Dollars But You can also Directly order Pcbs from Jlc PcB By Uploading Your cover files there and you would still Get this Insanely Low price Even With a Bull time of Only 48 Hours Any Way one Week after i ordered my pcBs I received them and Once I was done inspecting them all I did not notice any Kind of problem of them So i gathered all The Required smd components and started soldering them to the pcb and if you Have no clue how I did that then make sure to have a look at my How to solder properly video. Once I was done the soldering i hooked Up a Lipo battery and Connected five volt power to the micro usb Inputs as you can See the Red led lighted Up and the battery started Charging But with the current of Only 300 milliamps since the Battery Was already almost completely Charged Up After a Couple of Minutes of Charging though The led turned Green at a Cut-Off voltage of Around 4.209 Volts Which Seemed reasonable So it Was time to flip the toggle switch and measure the voltage at if i put outputs Which Revealed That the Boost circuits did in fact Work Well At Least Until i connected a Load of 6.9 ohms according To ohm’s Law a Current of 732 milliamps Should Have Flown but Instead the output voltage Broke down which means that Was a Problem That is Why i unsold Out the boost converter Ic and replaced It Over until year three 608 Ic Which Pretty Much Has the same pin out and Datasheet as the previous boost converter ic The Only differences that I have used this boost converter before and never had problems But Sadly Though This modification did not solve the Breakdown of the output voltage Which means there Was something Wrong With my board Design So i enlarged the boost converter copper traces and Rearranged a Couple Of The components Which Resulted in an overall Smaller size of The Board’s 4.3 centimeter By 1.9 centimeter to be exact After Once Again Waiting for Week i received the new version of My pcbs to Which i immediately soldered all of the components but I did not Only use the mt R3608 IC year as the only new Ic i Also Utilize The Fs 312f Protection ic Once Again The data Sheets of The olds and new Protection ics are Pretty Similar But The difference in which led me to this Icea is the higher over this charge protection voltage of two point Nine volts Instead of The old 2 Point 4 volts Which is pretty Low for lipo Battery Anyway after Finishing The soldering of The components i Added a Lipo Battery to the circuits and tested Out the charging feature Which like Before Worked Without a problem more Importantly though Was Whether the voltage Would Break down again Which it did not so i unsoldered the lipo battery and connected My lab Bench Power Supply instead to simulate different battery voltages and thus test the Board properly First off i Connected its Outputs to my diy power Logger and Connected a Variety of different Loads While Utilizing three different input Voltages in order to calculate the overall efficiency of the Boost converter As you can see in this diagram The average efficiency is Around 80% but a low input voltage and a Higher output current amounts can decrease This value a bit What is more important is that The output current Limit of the Boost converter is Around 1amp Since the output voltage Does Break down a Bit While lowering the input voltage to a value of 3 point 4 volts Not Perfect but It still fulfilled My requirement for the circuit Next i lower the input voltage Steadily Until i reached a value of Two point nine volts Which deactivated the Boost converter Even increasing The voltage to a normal value WouLd did not reactivate it only a Charged Impulse from the tpu 4056 allow the reactivating of The five volt Outputs Which means that the over discharge protection Worked Flawlessly Last But Not least i Showed a T5 Word Outputs of the circuits Which immediately It turned off the Boost converter Which means the short circuit Protection feature also Worked Like a Charm And My lipo Chart Protect Boost circuits Passed all my Tests and Due to its low quest and current of Only 4.7 micro amps Without the boost converter it can Also Safely Be used Even with small lipo batteries and if you a Need for such a circuits then you can Check out the video description you can Find the Gerber files and The easy eda Project Which you can utilize to for Example order Through Jl Cpcb Who made This project possible to begin With AnyWay i hope You enjoyed Watching This video if so don’t forget to like share and subscribe Stay Creative and i will see you next time

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