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| 5v WS2812 5m led strip from battery?? :( |
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| mariush:
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 1.8A Let's say you have 8 rechargeable AA batteries in series, each 2500mAh in capacity, so you have 8x1.2v = 9.6v and 2.5Ah A 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 = ~ 1.1A You can look in a datasheet for batteries : http://data.energizer.com/pdfs/hr6-2650_eu.pdf You 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) |
| Steelman14a:
You are my GOD! Thanks for the really complete answer!!! Thanks A lot! :-+ :-+ :-+ :-+ |
| frozenfrogz:
--- Quote from: mariush on August 12, 2019, 12:41:04 pm ---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. --- End quote --- How 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). |
| Steelman14a:
Thanks mariush for 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! |
| Buriedcode:
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. |
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