5v WS2812 5m led strip from battery??  :( - Page 1
Forum section: electronics / projects

author: Steelman14a
author_rank: Contributor
timestamp: August 12, 2019, 10:51:55 am
content: Hi guys! I need some Help from electric masters.I need to power 5 meters of 5v WS2812 smart led strip from batteries. To put it in coat so it glows from underneath.What i got now is i use 8 AA bats -> through DC-DC so in the end i got 5v -> going to led controller and then to -> led strip.And it starts, but after 5min batteries getting very hot, and all shuts down:(Please help me! What i'm doing wrong? Maybe i need some other batteries? Or something im missing.Any help is appreciated.

author: coromonadalix
author_rank: Super Contributor
timestamp: August 12, 2019, 10:58:06 am
content: Have you checked how much the strip consumes, simple batteries like you used is not enough, you have to use bigger batteries bank,. Ie: more output current / wattageWhat autonomy do you need ?

author: Steelman14a
author_rank: Contributor
timestamp: August 12, 2019, 11:06:06 am
content: The strip is 5m 30leds/per meter so, its 150 leds.The info i've found on them is max current 60mA / per led and max power 0.3W / per led.So its 45watts i think.

author: Steelman14a
author_rank: Contributor
timestamp: August 12, 2019, 11:07:18 am
content: And i need it to work for 2-4 hours.

author: MagicSmoker
author_rank: Super Contributor
timestamp: August 12, 2019, 11:20:52 am
content: Quote from: Steelman14a on August 12, 2019, 11:06:06 amA good quality alkaline AA cell will deliver around 2.5Ah when drained at low current, but perhaps only 1Ah at moderate currents of 0.5A or so. An 8 cell battery would then be able to deliver around 8Wh at a 0.5A drain, and you need 90-180Wh... So, it's no surprise that the battery is getting hot and dying quickly.

author: Steelman14a
author_rank: Contributor
timestamp: August 12, 2019, 11:24:54 am
content: So how do i power it then? What batteries to use so it work and its mobile?

author: frozenfrogz
author_rank: Frequent Contributor
timestamp: August 12, 2019, 11:29:11 am
content: Check your numbers to see that your plan does not add up properly.A suitable 12 V battery that can deliver up to 4 A continuously to power your step down converter would look something like this:Link is in German, just for reference.It is basically an e-bike battery.Additionally you’ll need a proper step down converter that is able to deliver 5 V @9 A continuously.As coromonadalix already stated, 8 AA batteries will most likely take you nowhere.You should start by measuring the actual maximum current draw from your LEDs when running the animations you intend to.

author: MagicSmoker
author_rank: Super Contributor
timestamp: August 12, 2019, 11:35:33 am
content: Quote from: Steelman14a on August 12, 2019, 11:24:54 amI already gave you the math to figure this out!? Determine Amp*hour (Ah) capacity of cells (note - often given as mAh - just divide by 1000) and multiply by average cell voltage to get Wh (watt*hours).For example, a typical 18650 lithium-ion cell will deliver 3.5Ah at an average of 3.6V, so has a capacity of 12.6Wh. You need 90Wh - 180Wh, so that would require 7 to 15 cells. Good pre-made batteries to consider are those for laptops and ebikes.edit- grammar

author: amyk
author_rank: Super Contributor
timestamp: August 12, 2019, 11:46:24 am
content: 45W input is alotof light for LEDs. That's roughly a 250W(!) incandescent lamp equivalent. Are you sure you need that much power? It sounds like you're only doing decorative lighting, so consider reducing the brightness a bit.

author: Steelman14a
author_rank: Contributor
timestamp: August 12, 2019, 12:05:22 pm
content: What i need is addressable led strip so chasing effect could be achieved.And ws2812b is only strip that i found.And mine is most economical one 30leds/meter, but there is 144leds/meterI actually dont have any idea how to make it other ways. Plus it was big surprise for me that LEDs could be such a bastards in power consumption.

author: mariush
author_rank: Super Contributor
timestamp: August 12, 2019, 12:41:04 pm
content: These WS2812 leds don't allow you to control the individual brightness of each led, so you get approximately 60mA for each LED when it's powered on.If you keep using these, you need to resort to power saving tricks in order to reduce your power consumption.For example, you say you have 150 leds, so in your Arduino or whatever you use, you can separate them in 5 x 30 led groups.Instead of lightning all 150 up, light up only 30 leds at a time... think of it as having 30 groups of 5 leds.Send the data from your arduino to light up every 5th led in the strip, and for the others, send black... so they don't turn on.Wait around 5 ms, then turn off all leds and send the data to turn on every 2nd led from each set of 5 leds . Wait 5 ms and do it again with every 3rd led from the 5 led groups.This way, within 25ms, you have only 1 out of 5 leds lit up, each for 5ms, but the human eyes aren't that sensitive, so they'll basically see all the leds being lit but at lower brightness.So now, your total power consumption is 30 leds x 60 mA = 1800mA or 1.8ALet's say you have 8 rechargeable AA batteries in series, each 2500mAh in capacity, so you have 8x1.2v = 9.6v and 2.5AhA DC-DC converter can convert 9.6v to 5v at 2A (you need 1.8 but let's be safe and go for 2) at around 95% efficiency. 5v at 2A is 10 watts... assuming 95% efficiency, let's say 10.5 watts are gonna be taken by the dc-dc converter.So the current taken from the battery pack will be 10.5w /9.6v = ~ 1.1AYou can look in a datasheet for batteries :http://data.energizer.com/pdfs/hr6-2650_eu.pdfYou can see there on the Typical performance graph (green curve on bottom left drawing on page 1) that at 1.325A, the battery will get down to 1.1v in around 2 hours...So even by turning on only 1 out of 5 leds at a time, you'll only get around 2 hours from a 8 pack of batteries.18650 batteries will give you higher voltage and capacity, typically 3.7v..4.2v and 2500..3000 mAh, so you could have 4 in series for a total of ~ 16v or you could have 2 groups of 2 batteries in parallel for ~ 7..8v but at 5-6000 mAh if you picked a dc-dc converter that can't handle high voltages.You can go further and make groups of 8 leds if it makes the program easier for you ( you turn leds on or off by seeing if a bit is set in a byte or not for example)

author: Steelman14a
author_rank: Contributor
timestamp: August 12, 2019, 01:15:08 pm
content: You are my GOD! Thanks for the really complete answer!!! Thanks A lot!

author: frozenfrogz
author_rank: Frequent Contributor
timestamp: August 12, 2019, 01:29:38 pm
content: Quote from: mariush on August 12, 2019, 12:41:04 pmHow so? That is nonsense.Main point for using this type of LEDs is that they are individually addressable - hence the WS2812 driver chip per three diodes cluster in a 50/50 case. It is not simply on/off, but rather PWM control for three channels per "pixel". You can have any configuration of R/G/B you like (or warm white/cool white for the white variety of those chips).

author: Steelman14a
author_rank: Contributor
timestamp: August 12, 2019, 01:53:02 pm
content: Thanksmariushfor a quite idea!But! Im using sp105 controller. And i'm totally not a programmer:(Can anyone recommend a programmer or take responsibility to make a program? Not for free, i'll pay!

author: Buriedcode
author_rank: Super Contributor
timestamp: August 12, 2019, 02:12:38 pm
content: I'm just going to add to frozenfrogzs' reply - WS2812 strips can be controlled. If you halve the brightness so each LEDs value is 127, you halve the current consumption, and you really won't notice much of a difference. So, say the average individual die current is ~10mA. With three dies on each LED, it'll only draw 3*10 = 30mA when ALL LED's are on - when it is white. If you're doing animations, it is unlikely that the EWS2812 will be displaying white all the time, so that'll reduce the current further to perhaps an average of 10mA per LED.Again, some maths. 30LEDs/m strip, with 5 metres is indeed 150 modules. At an Average of 10mA thats 1.5A. With heavy usage animations maybe 15mA per WS2812, thats 2.25A. At 5V we're talking max 11.25-12W. For say 3 hours, that is 36Wh - roughly what you'd get from a laptop sized lithium battery. For convenience, and low cost I suggest one of those "portable chargers". They output 5V (which is what your strip and controller needs), they have the capacity, they are easily available, and you can test how long it lasts with your animations. for 36Wh, with an average battery voltage of ~3.7, that is:36/3.7 = ~10Ah or 10,000mAh. THere are loads of 10000mAh portable chargers on the market, and they will fit in a coat pocket.Again, AA's won't cut it, but it doesn't sound completely ridiculous.

author: SiliconWizard
author_rank: Super Contributor
timestamp: August 12, 2019, 02:20:13 pm
content: Yeah as already said. If you really need up to 45W during up to 4 hours continuously, that would be 180Wh.Let's add to that a conservative 80% overall efficiency (including switching converter and various losses), you now really need 225Wh. This is huge.Even on a 12V battery, that's 18.75Ah. Quite big stuff. Were you prepared for that?As also said above, your LED strip probably won't draw that much power continuously. But still. Let's assume it only draws 1/10 of that on average. You'd still need 22.5Wh. Getting that from AA batteries is going to be tough. In theory, the raw capacity of 8 very good AA batteries should be close to 8x3x1.5 = 36Wh. Not that bad. Problem is, with so many batteries in series, their internal resistance will add up and yield significant losses at this relatively high current. Even just one AA battery will not quite have 3Ah of capacity at high current draw. If you really want to use this kind of batteries, using the bigger ones may be an option, such as R14 or bigger. Good R14 batteries can typically have up to 8Ah capacity and much lower internal resistance, so that could be an option. 6 in series followed by a step-down converter would be enough.Anyway, those numbers are just estimates. I'd suggest measuring the actual average current draw of the strip powered by an external power supply in the typical lighting scenarios you're going to implement so you have a more realistic idea of the required power, and then chose an appropriate battery. It will probably be a relatively chunky 12V battery, or maybe a smaller/lighter LiPo battery pack (2S or 3S) such as those used for RC models. As said above, maybe 6 GOOD NiMh R14 batteries in series would do.Also check the efficiency of the step-down converter you're going to use. I don't know what you tried.

author: mariush
author_rank: Super Contributor
timestamp: August 12, 2019, 03:43:04 pm
content: Quote from: frozenfrogz on August 12, 2019, 01:29:38 pmWhat I meant to say is that there are LED driver ICs which can control up to n channels (ex 18 channels, 6 x 3 colors) and allow you to send commands like "set brightness to x % on channel n " , separately from "set r,g,b to values x,y,z"The WS2812 don't seem to have a way of setting brightness with a command, and then leaving the work of PWMing the leds to the controller inside the led.Considering the fixed frequency the leds expect and the long chain (150 leds) it may take quite some time to pump the 3 bytes per led x 150 leds , so I don't think it's quite that easy to pwm the leds as in turn them on and off hundreds of times a second ... 100 updates a second should be doable.So if an Arduino is used and groups of leds are turned on and off , at least you know you'll have a sort of constant average power consumptionIf you PWM 150 leds, you still have to deal with higher peaks of current, so you'd probably have to add some capacitance on output of the dc-dc converter to reduce the "stress" which can make the "control box" bigger.Steelman , that controller is kind of a black box, I'm not sure you can control the brightness or implement these tricks to reduce the power consumption. You may be able to find some other solution that allows you to customize these things.

author: frozenfrogz
author_rank: Frequent Contributor
timestamp: August 12, 2019, 03:54:48 pm
content: @mariushPlease read up on WS2812B LEDs and how controlling them with e.g. an Arduino and FastLED library or similar is done before posting more ridiculous assumptions.1024 individual addressable "pixels" driven @ 800 kHz will give you about 30 FPS refresh rate on the whole strip.The main issues you are running into with these LED strips are related to voltage drop, so best to make sure you have a couple of insertion points.Depending on the micro controller you could run into SRAM issues, when addressing a lot of these LEDs. However, if you do not need to address every single LED but could live with repeating animations among several strips, just connect the data line in parallel.Signal strength on the data line is usually no problem if powered correctly since every WS2812 controller acts as a repeater.

author: Steelman14a
author_rank: Contributor
timestamp: August 13, 2019, 09:43:57 am
content: Ok guys here is an update:Ive removed 8 AA batteries holder and soldered an usb a connector. Then plugged it to my portable 20000mAh powerbank.It worked but usb socket was hot a bit.Then i soldered dc-dc converter in between usb and controller.\AND))It working for 1.5 hour now and there still 60 percent capacity in power-bank left. )))I dont know why is that so, because on dc-dc converter there is 4.8v on input and 4.8v on output!!?? So it doing nothing actualy. But usb port and powerbank batteries is still cold.Plus i've connected the USB Doctor in between power-bank and dc-dc and it shows 2.6 amp max...I'm frustrated now why is that so...

author: mikerj
author_rank: Super Contributor
timestamp: August 13, 2019, 11:19:22 am
content: Quote from: Steelman14a on August 13, 2019, 09:43:57 amThat suggests you have a USB socket or plug with a poor connection. Adding the additional DC-DC converter will only reduce efficiency (increased current draw from power bank) but it's possible that you simply have a better connection on the USB plugs/sockets of the converter and power bank which is reducing the heat.

author: Steelman14a
author_rank: Contributor
timestamp: August 13, 2019, 11:38:23 am
content: Its all weird, tried connecting with out dc-dc, and USB doctor now says 3,2 amps. And when lots of white light shine, whole system shuts down.But when its connected through dc-dc, USB doctor says 2.3-2.7 amps, and no problem with white at all...Could be that dc-dc adds some pwm??

author: frozenfrogz
author_rank: Frequent Contributor
timestamp: August 13, 2019, 11:45:05 am
content: USB connectors are available with a maximum rating of up to 3 A, though most common grade ones are 1 - 1.5 A max.My bet is, that the maximum current allowed per outlet on your power bank is around 2 A.You are lucky, that the power bank seems to have some kind of emergency shut down in place, otherwise you and your contraption might already have ended up in fire and smoke.

author: Steelman14a
author_rank: Contributor
timestamp: August 13, 2019, 11:55:35 am
content: Quote from: frozenfrogz on August 13, 2019, 11:45:05 amThe led controller run animations on led strip so 2.7 its max peak when lots of whites shine, but average is about 1.7-2.0.Im testing it now and it already 2.5 hours on. Usb port is warm but not hot.So hopefully it will work)