Make your own LED Battery Level Indicator
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- Опубликовано: 9 фев 2025
- Rapid prototypes ($2 for 10 PCBs 10*10cm): jlcpcb.com
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In this video I will show you how we can use the classic LM3914 IC to create an LED Battery Level Indicator. Along the way I will show you how the IC works and explain why it is not the most precise circuit for a Li-Ion battery pack. And at the end I will show you how I created my own, more precise Battery Level Indicator circuit with a couple of simple components.
Websites mentioned in the video:
www.powerstrea...
www.akkuteile.de/
lygte-info.dk/r...
www.akkuteile....
Thanks to JLCPCB for sponsoring this video
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Music:
2011 Lookalike by Bartlebeats
Killing Time, Kevin MacLeod
(incompetech.com)
i honestly have no idea half the things you said in your videos but it stills captivate me every single time
Brilliant!
A project using a couple of IC's and not an Arduino or Raspberry Pi in sight, what a breath of fresh air :)
@Petronilo
You missed the point, NO PROGRAMMING is required!
i'm not a big fan of promotions or adverts, but i want to thank you for putting something relevant (jlcpcb) instead of something completely unrelated (like lootcrate or something)
l o o t c r a t e
@@camilomason4560 is shit
raid shadow legends
@@varunsreedharan5347 is more than a piece of crap lmao
Man, I just love this channel. It's so educational and provides hours of entertainment. Keep it going GREAT Scott!!!
I just searched how to do this about 3 hours ago and now you upload a video on it. Crazy coincidence.
I have created many beautiful circuits with LM3914 and LM3915 =)
I love these ICs!!!
Electronics Projects - Stefano91ste me to
The quality of your channel is unmatched. Awesome!
I have been watching your videos religiously for over a year and a half. I have not learned a single thing. I will still watch your videos because they are great. I truly suck at electronics and have not gotten anything to work as I truly don’t understand how it works.
Over the past 4 to 6 years of watching your channel, I have seen many of your neat projects, but this one, is really well explained, and thought out. Thank you
The LM3914 is an interesting chip. We used to make crude oscilloscopes combining a LM3914 and a 4017 decade counter /decoder. Thanks for another great video!
You're welcome :-)
The LM324/4017 O-Scope would make an ideal project. Would probably include 4011's or 4093's for trigger control and time base.
Every time I click one of your videos I find myself still watching hours later =P Thanks for the great content!
Hf man hurt free
Same!
This video really saved a lot of my time. I made that LM324 battery indicator for my little Li-Ions, working Great.
Dude, I am amazed by your skills. It is just unbelievable, at least in my world.
Just a tip, a dash "-" in a model number is just that - a dash, not a minus. I get super confused when you say minus.
a dash is *
Brandon Garven
Wait what ??
Why
Dash -
Multiply *
. dot
, comma
- dash
* asterisk
/ forward slash
+ plus
Yes, the DVD Forum would get angry if you call DVD-R DVD minus R.
Technically a dash is longer. A single '-' is called a hyphen. A dash is often made up of two hyphens unless the font you're using supports a true dash like an em-dash (-). But most people call them dashes anyway, including me :D
In this method, you're not consider voltage drop of internal resistance. State of charge value may have different terminal voltage according this relation: V=Voc-R*I, (V=terminal voltage; Voc=Open circuits voltage, R=internal resistance).
Two simple method for SOC estimator are:
1) Coulomb counting: integration of current in time.
2) Soc(voc): inversion of R-C battery's model.
But he can also just use his indicator circuit while the main load is turned off. So V = Voc
Open circuit voltage isn't very useful, Gordon. Li-ion cells, particularly tired ones, will experience quite a bit of rebound after a surprisingly short period of time. You can have a battery that is effectively dead and sagging down below 2.7v that rebounds above 3.2v before you can get your multimeter leads on it. Lygte-info.dk (where GreatScott! got his battery curves from) has an article on this.
That's true. I assumed a situation were he used a quadcopter for instance and immediately measures the remaining capacity after usage
I waited for this video a VERY long time. Thanks Scott!
Been a subscriber for about 5-6 years now, if I can remember correctly.
Thanks for watching :-)
Thanks for being the RUclipsr you are.
Btw got a quote I think you might like. I think you said you were self-taught to program the Arduino so I believe you did this:
"Code to learn. Not learn to code."
--> Learning by doing ^-^
StormyIceLeopard please, if you need a battery indicator like this, a much simpler solution is to either use one of the specialized "fuel gauge" ICs that are designed for this job or use any small microcontroller that has an ADC. Then make a lookup table to compensate for the nonlinear discharge curve. A much easier, more compact and a lot more robust solution than having to tweak 6 pots (and making sure they don't drift or move!). I like GreatScott's videos but some of these constructions are best kept only as educational experiments and not really deployed as a practical solution.
@@TheIceLeopard that makes sense and is a cool saying.
Could you not have made one with one RGB LED and change the color based on the power level?
Possible
You'd have to choose 3 voltage points and hook up each to one of the 3 colors. I currently can't think of a way to make a combination color of rgb while still being able to choose r,g,or b by itself. Maybe through the use of diodes to prevent two or 3 pins from being permanently connected?
there is a prob, some people are colour blind
or you can use a cheap ass Attiny 13 and some coding, damn, uC is so cheap now
That would be cool
SO surprised that you don't have 1M subscribers yet. Your videos are awsome!
Well, it's 2024 and GreatScott has roughly the same subscriber count as @TechnologyConnections . Also known as rougly 2 million for both, although the difference is roughly 320,000 subscribers. Or 1/10 of @williamosman . Roughly.
It's crazy how they stuff all these components in that little chip package
Well, this is one of the less dense chips in that regard. A 6502 processor from 1975 has many times more transistors and resistors on a die area not much larger. AND IT'S FROM 1975!
I just like his video no matter what...
this guy is a legend
Thanks for the video!
I‘ve built a similar battery level indicator for my lead acid battery a while back. Of course, if I draw a lot of power, the voltage collapses (even though the battery is still charged) and the battery level doesn‘t show the charging state correctly anymore. You have to keep that in mind, but since LiPos are offen built for high current demands, the problem shouldn‘t be as big.
I was just changing batteries today in my wall clock and I thought it'd be cool to have something that just takes in a couple of AA cells and lets me know how much juice is left in them(for testing my remaining stash of batteries). Boom! Here it is!
Nice project! Just want to point out that the discharge curve changes dramatically depending on the current draw, but perhaps you used the curve that will suit the draw of your specific project. :)
You don't need a boost converter! Instead use a reference voltage ic or zener reference, that is lower than the lowest battery voltage. The best approach is to go with TL431 Precision Programmable Reference which will give you 2.5 Volts (Adjustable). Then divide the input voltage using a resistor divider so that it is lower than the 2.5 when the battery is full. You can use one of the LM324 op-amps as a buffer.
LM324 already has a voltage reference built in.
It's quite a good project an I never thought about making my own IC clone. I have solved similar problems with a high quality frequency generator and a microprocessor, for detecting the actual charge, which is total overdoing. Well done, my friend!
A few points.
1) You could replace one of the LM324 with a LM358, as you're only using 2 of 4 opamps. Less power usage.
2) The 20V supply is not needed, use a voltage divider to reduce the voltage from the battery so you only sample say half of it.
Not complex, 2x 10k resistors in series across the battery, then connect the inputs on the Opamps to the middle of the two resistors.
3) It should be pointed out the max supply voltage for the Opamps is 32V, so your limited to 7 lithium cells in series (aka 24V nominal voltage battery).
I was thinking the same while watching the video. We can use a reference voltage ic/zener which is below the discharged battery level voltage, then use resistors to make voltage divider to scale the 0% to 100% voltage levels inside that reference voltage. That way the circuit can even be powered by the battery itself, and obviously no need for boost module :P
Nasha UT probably use 3915 or 16, one of them is logarythmic like the battery curve is. As we all say it could be done more simpler.
Sir, I am a hobbyist in electronics and surprisingly I am 13 years old. From 3 years I am watching your videos and they are literally awesome but slowly the topics are getting boring. So, I am requesting you to make an interesting video. And ya! I am from India.
Thank you
Your Genuine Viewer
Very nice approach, using the old and good analog way. I made myself a flashlight using an Arduino Pro Mini to control the power led with an external Mosfet and LC filter for PWM. It worked as a charm, and for battery capacity I measure the voltage with Arduino and made the flashlight to blink from 0 to 9 in morse code.
Good idea
It's not bad if you are using alkaline primary cells. But with Li-ion cells under high loads there isn't much voltage differential between 80 and 20 percent unless you have a large amount in series.
Why don't you use a simple linear regulator to get the constant voltage for the circuit and devide the battery voltage with two resistors? That way you could get rid of the boost converter.
Good idea
Yes.
Make a video about this ! Thankss
Cle mens efficiency?
Boost converter would be less efficient than a voltage regulator
left handed guy doing electronics. Seems like there is a hope for me
That's a nice 2.5bit flash ADC you got there.
Sir your voice and explanations are very nice......
This works assuming you don't draw any current from the battery. The voltage will fall as soon as a load is put on the battery. Like if you are drawing 10A from a 4.0V lipo, it's not going to stay 4.0V forever. Maybe for a future project, have a circuit measure the current being drawn and compensate the voltage thresholds? Other than that, pretty good video.
BoomBrush the drop under draw depends on the internal Résistance of the cell , that voltage sag isnt calculated in most power indicators
Peter Zingler Quitw the opposite - most consumer devices show the battery indicator while using them, so it’s important to be able to use this indicator while using the device itself.
Artūrs Savickis most consumer devices doesnt drain enough current to create a large voltage drop
I came here to say something like that. The voltage is never decreasing in a linear fashion, it will bounce up and down depending on use. Yes, in the long run it will steadily go down, but for shorter periods the values might not make any sense whatsoever...
Yep. This is really a bad design for a battery life indicator, especially for LiIon. Correct solution would be a current sense and coulomb counter circuit.
Better still would be NOT using a top-balancing BMS. (Unless you hate your batteries.)
Deine Videos sind echt gut gemacht und super informativ! Weiter so @GreatScott!
Great Scott! Thanks for explaining what is required.
Doesn't an arduino have AtoD that could be used measure volts with the discharge profile in rom?
Load could then be incorporated into the result with multiple profiles per battery based on current of battery. This could then be used to detect charge/discharge modes and show the actual state of charge under all conditions.
That would give you a universal battery state indicator.
Could extend it to measure individual state of charge per cell through switching the cells into the AtoD.
Using leds for level is a great idea, 10 leds make a lot of sense intuitively, though 4 is probably adequate.
What am I saying? You've essentially given me another project to do....one day! Cheers, and thanks again for your fantastic video series - I enjoy them immensely.
You can find the LM3914 in old electronics that have indicator lights for the control buttons. Most things that have the play rewind eject or record or dials that light up.
It's also likely used for the VU meters in old cassette decks, though I'm not completely sure on this one.
Best channel, i'm brazilian
My favorite chip!! The bar graph ic! That was the first chip I used to make a pcb and the one that made me understand how analog circuits work.
Excellent work !
Highly useful...
But sometimes many important details are over looked or skipped. I wish you could make these DIY videos a little more detailed so as for us to get a better picture of the build
What steps are skipped? I will not explain the basics of electronics in every video. That is why there are my electronic basics videos.
I absolutely loved this video, it was perfect and beautiful. There is nothing wrong with it, i actually have no complaints. But I have one complaint, the LEDs weren't RGB. It would have been cooler if all LEDs were on and they were all green if the battery is full, and the colour slowly changes to red and less LEDs get put on as the battery is closer to death.
Mal wieder ein sehr gutes Video du hast immer sehr guten Kontent mach weiter so👍
whatever you said and did was just AMAZING, even though i didn't understand what's exactly is going on...😂😂
Well this was well timed, I was reaserching this chip last night.
Constant current output 🙏🙏 it's so beautiful
Nice video as usual. Very informative. Keep up the good work
5:45 This is why EVs tend to use coulomb counters rather than relying on voltage. That voltage knee is abrupt in practice as well. Especially since voltage will sag under load.
Perfect bro you are a real creator 😜😝
Great video scott!👍😁
I use a 14s battery in my ebike, the problem I have with charge indicators is that when my battery is full it is at ~58v and I like the lowest point to be ~51V (at this point there is very litle charge left and starts to get dangerous to over discharge since you draw high current out of it so it is needed to be on the safe side), but when the battery is at about 53 or 54v and you would accelerate hard, the voltage would drop to 51 or less. So even at full chage if you accelerate hard, the meter would say "low charge" an you can't get an accurate battery level. I tried making a level with a arduino and a display, but even if I "smooth" the reading when you accelerate hard you get a high to nothing read all the time. Ideias are gladly accepted :)
This could be done with a single op amp, LED's, resistors, and nothing else, exploiting the voltage drop across the LED's. Add a bridge rectifier and a capacitor to smooth out the flickering and you can measure AC with the same circuit(Like audio). The only down side would be the LED's fade gradually instead of giving harsh steps, but I think that is a good thing.
The non-inverting input of the opamp is connected to the battery, the inverting input is a voltage divided output to set the gain(the gain depends on how many volts it takes to overcome all of the LED's forward voltage at the batteries max voltage), and each LED is hooked in series, each with their own resistor to ground. The resistors to ground could be set as to produce a non-linear behavior of the LED intensity as well, to account for the non-linear discharge curve of the battery.
Another possibility is to still use the TI part, reduce the number of LED indicators from 10 to, say 6, and use certain LED to display the voltages that you chose on your design. You can also set a min voltage set point as another degree of freedom. No need for so many pots.
What about a live subscription counter? DIY or Buy ??
You can buy a subscription counter?
JoeyLovesTrains sounds cool , it could probably be done easily with an 8x8 matrix and an esp8266 or something
Maxx B Duh.. there are many tech/geek youtubers that has different types of LED subscriber counters sitting on the shelfs in background. Techmoan being one such example from the top of the head.
I wrote a library for this, if you google "arduino youtube api" or search for "youtube" on the library manager you should be able to find it. It works on ESP8266 or ESP32
Artūrs Savickis And do you know of any youtuber who *bought* his/her subscriber counter? He asked whether you can *buy* them, not if they existed.
Seems like a lot of work, space, complexity, and money for something a tiny mcu (like the attiny85) could do. It's the digital age, man!
I learned so much from this one video. You should do some math videos.
Finally!Thank you for this video.Loved it!👍
Awesome work, dude! Really nice! 😀
great video :) been waiting a while for this one
Great work dude.
YEEEEEES FINALLYYYYY THANK YOU CARBON UNIT
I using a microcontroller, ADC and lookup table, I also massure the current flow and calculate the total consumption, it's easier and more accurate
I always like your videos!
You're a master, sir
This is some cool stuff, thanks for sharing :)
Using a boost converter only to reach your reference voltage seems very overengineered to me. A simple voltage divider at the input would do the job just fine.
Cheers!
A more elegant solution is to use a voltage reference and divider
Wessel Lemmer - exactly
That’s fine untill your voltage drops below your needed 20v
What if you need a 20s battery voltage indicators? At some point arduino gets cheaper than using 20 lm3914 or lm324 i guess...
you can get 10x LM324 for 1€ on ebay, they are sufficient for up to 40s packs
but a small arduino will save space and probably save of power consumption too
Where?
the bad thing is no dot mode unlike the lm3914
Goddamm just use a voltmeter and memorize the capacity/voltage curve and then just could measure up to 150s packs
Very interested in the intricacies of charging li-ion battery packs. I see a lot of conflicting information about BMS boards - mostly about whether they're actually effective. Could you do a video on that, maybe test and review some boards for, say, 3s or 4s?
You might know this but most RC enthusiasts who use lipo or li-ion packs only discharge to 3.6v (at rest).
This usually is based on the capacity rating or most lipo batteries being rated at fully discharged (80%) at 3.6v. 3.3V would be fine if the current is very low but in our experience you would destroy the li-ion capacity quickly if it was discharging at higher amps.
As always, awesome video.
But, I would simply use a microcontroller for this purpose.
Avra Mitra
Same. Read actual voltage, decide in software which LED to light. You can then also add extra features like flashing LEDs to show a low voltage warning, chase them during charging, etc.
tin2001 exactly! Using a microcontroller makes it more efficient.
+1. And you could map out the non linear voltage/charge curve too.
Sure, the logarithmic voltage decrease may make a slight difference, mainly when your battery is practically empty anyway. It's not really worth the effort of correcting for though, both versions are very inaccurate since they are purely based on the voltage which changes significantly under load. Your battery indicator will jump up and down when you connect and disconnect large loads.
If you want a reasonably accurate and steady battery level indicator, you'll have to measure the current draw and added it up to see how much of the capacity has been drawn (like laptops and phones etc. do to determine the battery level) and use the voltage to correct for inascuracies while the battery is not in use.
It's not quite as easy as it sounds, since your battery's apparent capacity will also change depending on the current draw, the voltage the battery is pulled down to and even temperarure.
Making an accurate battery leven indicator really isn't that easy. But your version is the least accurare, at least assuming you use your battery, at rest I'm sure it's relatively accurate. Of course it can still be very useful, especially considering that you get similar battery level indicators like those for a euro/dollar/pound or two from China, but it may be worth mentioning, that it's only accurate at no or very little load.
Nice, but using arduino seems a little bit simpler, even if more expensive. Also it is worth having a switch/button in the circuit to avoid constant current draw by the display, and having it lit briefly just to check.
i was waiting for this video thankyou.
So it's a flash ADC but without the logic to convert the output to binary. I made one of these from op amps as one of my first IC projects. I connectected the input to the capacitor through a buffer on a 555 in astable mode. Didn't think to use it as a battery tester. Maybe as a VU meter. The lm3914 definitely makes for a much smaller circuit than having 4 or 5 dual op amps connected to a ladder resistor network.
thank you great episode , but how do you know about existence of such ICs ?
Great video and explanation 👍
Great video brother!
Yes matter how hard it is, just
don't get discouraged. when to buy!
Did mine with LM339. Because they were in the bin next to me :D
1 oled
1 microcontroller
a voltage regulator, a few passives
job done with way smaller sized board
Another interesting project! Thanks
posted 15hours ago... what?
If you're using this much space anyway, you could just paint the graph you shown on pcb and place leds in marked points with just the LM3914
Great Vid !!
Very nice video
I like ur video 👍
I tried to make something that was a bit similar and spent 6 hours on it. Then I realized it was not precise because the LM317 did everything but staying in its Reference Voltage tolerance.
Thats works with only resistors and leds in series too, without a problem
And dont forget on lion cells most capacity sits between 3.8 and 3.5 v where on lipos you shouldnt go lower then 3.8 at all
The problem with this is that the voltage discharge curb will be temperature dependent. in a cold environment, the voltage will be lower and in a hot environment will be higher. It will not be accurate unless you can guarantee the same temperature all the time.
Old school method is analog meter with masking tape and felt pen marking the %. Done in about 2 minutes.
He just made an engineer and tech editor’s year by saying that data sheet was well written.
What are those metal wires he uses to bridge the solder connections. Like at 0:54, where can i buy some?
They are just solder bridges. He just melts solder in a line
Thanks bfor sponsoring me for no reason
Analog read and knowledge of the discharge curve.
Look at the subtitles in the diy soldering station video. Each time that he says full bridge rectifier, the subtitles say: *ECHOING VOICE* FULL BRIDGE RECTIFIER
The redstoneblock I know this ECHOVOICE FULL BRIDGE RECIFIER from electric boom.... Maybe an error causing this here... Or maybe am gag
Lol
MIIIINE DIIIAAMONDSS
Haha XD
Nice project
That’s beautifully precise! Nice job!
Please, make one video talking about how to find the correct IC to design a custom circuit to drive some LEDs in constant current mode.
great video thanks, what size fuse did you use and what is the spec on the black capacitor and the red component pls?
In the next DIY or buy section try to make BMS for li ion
Damn how do you solder those potentiometers like the one at 5:06? I always fail to solder them properly and loose the connection between the pin and the metal line which goes inside.
You dont need to solder them in
Hi Scott great Video, I m new to electronics what is that plastic matrix where u solder chips is it pcb? U also show it opening intro of your videos where leds are stacked and then light to great Scott
how does he generate the 16.4 and 11.6 V?
One thing that I would love to see someone make in a pedagogical manner, is a battery voltage indicator/display based on an Arduino, for each section in larger battery packs. For my bike batteries I don't feel that I need something else than a solution like this, since I balance charge after every ride. But for my 5 kWh homemade Li-ion packs in my van, that sit for weeks at a time, I'd love to have a way of measuring, displaying and warning me if voltage is going low in any of the sections. I got 4 x 3S packs and I measure with my multimeter every now and then to see that they are balanced. But this is something that should be easy to automatize and shouldn't be a human job :)
If anyone has any suggestions to how to do this or if someone already made it, I'm interested. I'm not overly talented when it comes to electroengineering so I leave this to others. I can't come up with a good way to measure the voltage when there is no common ground, without using an unreasonable amount of relays/MOSFET:s/optocouplers or whatever, but that doesn't feel like the most efficient route to take.