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LOL I AM THE BEGINNER ! using lipo battery to light doll house with LED
Posted by withwings on 28 Nov, 2017 20:38 -
I have purchased 25 pito 3 volt lights to light a doll house and need it to be lit for 10 days. I can not use anything stronger then a 3 volt battery with these tiny lights. I understand the wiring with the LED UV lights but I don't understand the the LIPO conectors
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Also what size LIPO I need? this is where i bought the led'shttps://www.modeltrainsoftware.com/pin-connectors.html -
Is there any reason you need to use a LiPo battery? They are capable of delivering high current and have fairly high energy density but it doesn't sound like you need those traits here and LiPos are somewhat temperamental. They are easily damaged if excessively discharged and can burst into flames if over-charged or short circuited. I would think some old fashioned alkaline D cells might be a better option for a beginner.
You can determine the size of the batter you need by looking up the current that one of the lights draws, either that or measure it. Then multiply it by the number of lights you want to use and you can figure out the mAh they will consume and multiply that by the number of hours you need them to run and you will have the needed battery capacity. -
I need one that will last 10 days for the length of the display. I was told they would last that long
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Your link doesn't lead to a datasheet for LEDs, only connectors...
You need to know how many millamps the LEDs will require. Then you need to multiply by 10 days times 24 hours/day. A 20 mA LED (common type) would need a battery with 4,800 mAh capacity, At least...
A standard 18650 battery has about 2800 mAh capacity so 2 in parallel would be required. But that doesn't answer your question because I have no idea how many mA your string takes and you didn't specify (exactly) which battery you were going to use. And I haven't accounted for the voltage. 10 days is a LONG time.
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I think these are what he has: https://www.modeltrainsoftware.com/nano-string.html
Unfortunately, no info on current draw.
If it were me, I'd go for lower current, perhaps 8-10 ma. Most small LEDs like those would be just about as bright at that lower current. Arranging that would be trivial for most of us here, but he is an admitted beginner. So he needs easy to understand and implement suggestions. -
I think these are what he has: https://www.modeltrainsoftware.com/nano-string.html
Unfortunately, no info on current draw.
If it were me, I'd go for lower current, perhaps 8-10 ma. Most small LEDs like those would be just about as bright at that lower current. Arranging that would be trivial for most of us here, but he is an admitted beginner. So he needs easy to understand and implement suggestions.
Can't do that without nailing down some numbers. Everything else is a bad guess.
Apparently, a string of 12 LEDs runs on 3V but there is no indication of how many mA. One way is to just buy the strings, wire all of them to a pair of AA batteries and measure the current. Using the 18650 battery may require a diode in series with the battery to drop the voltage a bit.
It may turn out that a pair of D cells works just fine but it is all based on the unknown mA rating.
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Here is the right link, https://www.modeltrainsoftware.com/smd-chip-leds.html I have 25 of the smallest lights.The pico is the size and the 3 volt. I am a SHE and I do not understand anything the math or the language you are speaking lol. I am a artist/sculpture and I came to this sight to find someone smart to help me. Pretend you have walked into the kitchen and there is your mother and now you must explain this to her (because I am probably as old of your mother)..... I know ten days in along time but I was hoping that since they were so small that if I used a huge or strong battery that I could keep them running the whole time the doll house is on display.
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Welcome to the forum. LEDs will have a problem when running directly from a LiPo battery. A single LiPo cell has voltages of about 3.6 to 4.2V (when fully charged).
The problem with supplying anything more than 3v to the 3v LED version is that the LEDs might start drawing too much current and die/burn out.
If you wanted to use a higher voltage battery, you would need to lower the voltage to 3v by adding extra components such as a diode, a resistor, etc. You could also lower the brightness of the LEDs and make them run longer at less brightness. Before adding anything, exactly what to add needs some calculations first, and for this you need more data for the LEDs from the seller or manufacturer or a way to experiment/measure them.
Would size be a problem? If not, and if I got things right, they recommend this battery holder as the highest capacity one they have (AA is better than AAA): https://www.modeltrainsoftware.com/aa-holder-separate-switch.html
I don't know how long it would last, but you could buy more than one, and join them together for extra capacity (red wire with red wire, black wire with black wire, called a "parallel connection"). This should not be dangerous if you are using them (e.g. 2 packs joined together) with 4 fully charged batteries from the same pack. If one battery pack is less charged than the other, the "full" pack will try to "charge" the other "less full" one, until they are at a balance. This could cause problems. If this sounds like something to try out, before connecting them this way and following my advice, please have someone more knowledgeable than me confirm that it is safe. I am not a professional or experienced in electronics.
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I won't have a problem hiding the battery so yes I would try ANYTHING !!!
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I just noticed/realized we are talking about 10 days, that is a long time unless the brightness/current is limited.
How bright do they need to be? -
It is surprising that the current is not given. FYI on some LED basics.
https://learn.sparkfun.com/tutorials/light-emitting-diodes-leds
they talk about current (you do not need to know everything in the article)
here is a calculator
http://ledcalc.com/
they say use 20ma if you do not know it.
If you read this data page on SMD LED, this one is 20ma (about 1/2 down). So you can use 20ma for the calc everyone is asking for.
http://uk.farnell.com/avago-technologies/hsms-c191/led-smd-he-red/dp/1058373
If you google "d cell mah" you get 20,000 mAh so divide this by 500 you get 40 hours. So it is going to be hard to last 10 days. Is there anyway you can plug into the wall?
Using a 18650 is tricky for so many reasons.
Using D cells, you would need 6 of these
https://www.ebay.com/itm/1pcs-2-x-D-Size-Cell-Battery-Holder-Box-3V-Case-With-Wire-Lead-UM-1x2/192351107886?hash=item2cc904fb2e:g:YbEAAOSwH-dZ-cna
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Where does the battery have to go? Ie, does it have to fit inside the dollhouse somewhere or can it sit underneath, out of the way etc.
A simple plug and play solution would be to use a 6v lantern/torch battery, then buy one of these cheap DC/DC modules to set the output to 3v.
https://www.ebay.com.au/itm/LM2596-3A-Adjustable-DC-To-DC-Step-Down-Converter-Buck-Module-Voltage-Regulator/232274686302?hash=item3614a6715e:g:j3EAAOSw4A5YzI3H
In fact you will be able to set the brightness to your liking, and it will stay at that for the 10 days. You'll need a multimeter to check the output voltage before hooking the LEDs up otherwise you'll burn them out in seconds if the voltage is too high. Also 20mA per LED may be overly bright. -
Here is the right link,https://www.modeltrainsoftware.com/smd-chip-leds.html I have 25 of the smallest lights.The pico is the size and the 3 volt. I am a SHE and I do not understand anything the math or the language you are speaking lol. I am a artist/sculpture and I came to this sight to find someone smart to help me. Pretend you have walked into the kitchen and there is your mother and now you must explain this to her (because I am probably as old of your mother)..... I know ten days in along time but I was hoping that since they were so small that if I used a huge or strong battery that I could keep them running the whole time the doll house is on display.
I, OTOH, have no artistic ability whatsoever - kudos to those who do!
I imagine that measurements are out of the question so why not start with a pair of D cells and experiment? Is there enough time to try that before going live?
If one pair of D cells doesn't last long enough, try two pairs.
Less technical answer than I gave above: the current required by the string of LEDs is like the mileage your car gets. So many milliamp or so many miles per gallon (actually, gallons per mile, but who's counting) - both are the rate at which energy is consumed. So, if you have a very long trip to take and you can't stop for gas, you need to figure out whether your tank is large enough or you need to carry gas cans.
Same thing with the batteries. You need so many milliamp-hours to light the LEDs (milliamps is the instantaneous current, milliamp-hour is the instantaneous current times the number of hours) for some long period of time (similar to miles) so all you need to do is figure out how big the batteries need to be. HOWEVER, we know the hours, what we don't know is the milliamps. We need to know the milliamps for one string and we need to know how many strings. Measuring the value is the easiest and most probably correct solution. Get some LEDs and a cheap Digital Multi-Meter (DMM) and we can talk you through it.
OR, you can just grab a couple of large batteries (D cells) and try it. Kind of like bringing a tow truck on your long trip. Just see how it works and leave the math for others.
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They sell the "nano" LED on another page, as I suspected they are simply 20 mA SMD LEDS, nothing out of the ordinary.Quote
The chips draw 20 milliamps each. So check your power supply to see how many milliamps it lists. A 1000 milliamp supply can run 50 chip
https://www.modeltrainsoftware.com/smd-chip-leds.html
But as you all know (but not the OP) there is no reason to run them @ 20 mA if you want to conserve power. Simply add a resistor. I work with these quite often on my model RR and they are very bright @ 20 mA. You can easily cut the current in half and they will still be bright. Up to the OP's requirements of course. -
I have purchased 25 nano 3 volt lights to light a doll house and need it to be lit for 10 days. I can not use anything stronger then a 3 volt battery with these tiny lights. I understand the wiring with the LED UV lights but I don't understand the the LIPO conectors
??
Also what size LIPO I need? this is where i bought the led'shttps://www.modeltrainsoftware.com/pin-connectors.html
OK, I have read this and the following posts.
Firstly I second what everyone else said: you do not want to use a LIPO battery.
I strongly recommend you use a 6 V lantern battery, like one of these: http://data.energizer.com/pdfs/1209.pdf
They have a large capacity, they are easy to use and they are safe.
Since it is a 6 V battery you can put two of your 3 V LEDs in series (connect the wires end-to-end) before connecting to the battery. You should be able to run about 4 LEDs like this for 10 days off one battery. It will require many batteries to run 25 LEDs.
Unfortunately this kind of task is better suited to mains power. Is it not possible to buy a string of Xmas tree lights and use that? It is the right season to buy them after all. -
If you use ordinary alkaline batteries you can use series pairs of two cells, and as many pairs as necessary can be ganged up in parallel to get the lifetime you need. I don't think 10 days is unreasonable for LEDs, a lot of modern LEDs can be very bright with only a few mA. We have a little string of LED christmas lights that came on a decorative tree and that string of 10 lights with some blinking and some steady run for about a week on 4 AA rechargeable cells.
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Welcome to the forum. We do have several female members - but most are male, so that is the presumption, unless we are otherwise informed. We have been informed
We can appreciate you don't understand the maths and the language. We do - and we will try to help as much as possible.
There are two main points we need to get a firm hold of to be able to offer some answers - and they both are details about the LEDs. The first is the current that each LED draws when it is working and the second is the voltage across the LED at the same time.
Don't panic about the following - it's more me talking out loud...
The type of LED used is a surface mount package, size 0603 (1608 metric) - but that doesn't help a lot with the current and voltage numbers we need. There are LEDs that run from 5mA to 20mA - but if we use the top of the range for our calculations, then you should be reasonably well covered for getting the right capacity of battery. AHA! I found a reference to the current: 20mA. https://www.modeltrainsoftware.com/smd-chip-leds.html (halfway down the page)
The main trick is to get the voltage right. One more detail that will help is the colour. Different colours operate at different voltage ranges - and even for a given colour the actual voltages can vary between one model of LED and another.
I found the following statement: "Get these chips already wired, tested, guaranteed, and fully ready to connect to your power supply. No resistors need to be added, we have done that part!". This is good news - to a point. In the images given, there is a resistor in the 9V version (which is to be expected), but I can't see any resistor for the 3V version. They mention 3V supplies using AAA, AA and coin cells which suggests the LEDs could run at around 3.0V or 3.1V ... but that's a guess.
Lipo batteries can provide voltages around 3.7V to 4.2V which is far too much for these LEDs. The forward voltage drop of a diode might be a step in the right direction, but there are still some issues to address.
Ah, wow.... 9 replies while I was typing this up!! -
If you use ordinary alkaline batteries you can use series pairs of two cells, and as many pairs as necessary can be ganged up in parallel to get the lifetime you need. I don't think 10 days is unreasonable for LEDs, a lot of modern LEDs can be very bright with only a few mA. We have a little string of LED christmas lights that came on a decorative tree and that string of 10 lights with some blinking and some steady run for about a week on 4 AA rechargeable cells.
Something doesn't quite add up though. According to the web page ( https://www.modeltrainsoftware.com/smd-chip-leds.html ) the LEDs draw 20 mA each. Yet they say you can run 10 chips from a 3 V coin holder. That would be 200 mA from a coin cell. I don't think a coin cell could do that for very long, if it all. So I'm not sure. I would want to get one of them and measure it. I might also want to increase the series resistance to reduce the current draw. Possibly put 3 LEDs in series on 6 V rather than just two.
All of this is very technical for the person asking. For us it is trivial, but for the OP not so much. -
I, too was a little curious about the run time....
Read here: https://www.modeltrainsoftware.com/3v.html
"In our tests, 6 lights lasted over 12 hours on one battery. By 12 hours they were noticeably dimmer. A test of the battery at 12 hours showed the voltage was down from 3.0 to 2.6 volts. The lights continued to stay on at a nice level for several additional hours before another battery was needed."
This was on a single CR2032? Hmmm...... -
This was on a single CR2032? Hmmm......
Energizer CR2032 specs -QuoteTypical Capacity:
240 mAh (to 2.0 volts)
(Rated at 15K ohms at 21°C)
http://data.energizer.com/pdfs/cr2032.pdf -
It sounds like they may be relying on the internal resistance of coin cells to limit the current to the LEDs. Sometimes you can get away with running an LED directly from a battery without a separate current limiting resistor but it's not something I would recommend. If in doubt, use a resistor, you can always reduce the value or eliminate it if needed.
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I just want to say welcome to the forum. LEDs are amazingly good at showing some output at extremely low levels of current. You may be able to get incredibly long life with even a moderately sized battery if you reduce the current down to just a few MA you may have enough brightness. I have LEDs that light surprisingly brightly at 2-3 ma.
Why does it have to run all night? -
Why does it have to run all night?
My guess is that it will be part of a larger display - and once set up, everybody will be banned from the area until the end of the event. -
IMHO the best option would be to connect them in series strings, add a resistor to limit the current and run them from a higher voltage. Eight strings of three, (yes you'll have one left over) each consisting of three LEDs with the two wires to the middle LED each soldered to ONE wire of the OTHER colour of the end LEDs. That will give a string that takes 20mA max and has a bit under 9V across it when running. If you want a lot of brightness, add a 270 ohm resistor (solder it to the free red wire of the end LED) and you'll have a string that will be quite happy running from a 12V Lead Acid battery, as long as the battery isn't connected to a fast charger or a running vehicle. A float (trickle) charger would be OK. The strings would connect in parallel - free lead wires of all the resistors together, then via a 1A fuse to the battery positive (and also via a switch if you want one), all free black wires togethyer and to the battery negative. You can use as much flex as you need between the joined LED string connections and the battery - cheap thin flat twin cable (aka 'bell wire' - get the stuff with a stripe down one wire so you don't get them mixed up), will do nicely. Put the fuse at the battery end.
Over 10 days, running 24/7 they'll need a bit under 35AH. If you want a lead acid leasure battery to survive in cyclic use, you don't discharge it past 40%, and it may be difficult to get it above 90% charge on a cheap charger so only 50% of the nameplate rating is really usable. Therefore the minimum battery capacity would be 70AH. A 60AH battery would be discharged to 35%, which is pushing it a bit but would be OK for a one-off. A >100AH car battery from a scrapyard would probably also do, but you can never be sure how much capacity a scrapyard battery's got left. Charge the battery beforehand taking it off-charge no more than a couple of days in advance, and if you want the battery to survive, get it back on charge within a day of the end of the display. DO NOT leave it running till the battery is flat - I figured for 10 days, if you go over that the odds of killing the battery stone dead go up steeply with each extra day.
For the odd one out, if you *MUST* use it, use a 720 ohm resistor then treat it like one of the three LED strings. It will start off a bit dimmer with a fully charged battery and end up a bit brighter. Alternatively you could do two strings of two, with 470 ohm resistors. Again the brightness wont match, but four slightly different may be easier to distribute artistically than one.
N.B. you cant switch individual LEDs On/Off - you could however switch any string as a whole.
If you want lower brightness, try using higher value resistors - I wouldn't advise going lower for brighter as there is a big risk of blowing the LEDs.
If in doubt *ASK*! -
So far my favorite answer is use LED Christmas lights. The second one is use a 6 volt lantern battery with two LEDs in series.
It would be nice if you let us know how you solve the problem and post some pics of the dollhouse. It is very easy to attach pictures.
According to this
http://www.techlib.com/reference/batteries.html
The 6v has 11,000 mAh. So for 24 LEDs (I assume you bought 25 and you have to use 2 in series) you have a current of (24/2) x 20ma = 240ma. So if you divide 11,000 mAh by 240ma you have 46 hours (watch the units divide out). This gives about 2 days, so you need 5 of these connected together. This is doable but painful ($).
We are getting into the area of golf cart batteries. I am surprised 25 LEDs would use so much power in 10 days.
This is a very simple problem that is not easy to solve
Good luck