Feeding stereoids to 3$ solar lantern  - Page 1
Forum section: electronics / beginners

author: dave_j_fan
author_rank: Regular Contributor
timestamp: November 13, 2017, 12:57:53 pm
content: This lamp is pretty dim , just checked the internals of this guyIt has 4.5V AAA cells and cap dropper . Lets join hands to boost this LAMP to max bright .I have done some mode1 - diffuser cover removed makinh it 20% more bright2-added SM5050 X4 removed the original LEDS -- made it light up more areasThe solar panel cant go >3.6V inside room , where i want it to get charged .some people have made Joulethief boosted chargers .Expert suggetions needed here .I am planning to mod it by adiing one more 1.2v AAA. Opinions are needed to enhance it .Ithink JT boost reduces current , will it take any other of fthe shelf parts booster circuit like this will work keeping backup same ?http://3.bp.blogspot.com/-r5xlAIdAf-Y/T0g-u16bE0I/AAAAAAAAAH8/0-3Ckuobpe8/s1600/stepup%252Bconverter%252Bdc%252Boscillator2.JPG

author: Mr. Scram
author_rank: Super Contributor
timestamp: November 13, 2017, 01:15:59 pm
content: Isn't that one of those camping lights of death?

author: dave_j_fan
author_rank: Regular Contributor
timestamp: November 13, 2017, 05:42:15 pm
content: yes it is..comes with JUST warrning!on the cartoonbut cheap so ....canbe used to help many people by improving it

author: Ian.M
author_rank: Super Contributor
timestamp: November 13, 2017, 05:59:31 pm
content: Is there enough space in there to Frankenstein it with a single cell LiPO USB power bank? If so ditch the dangerous mains input and capacitive dropper, and simply charge it from USB (micro B socket).

author: Zero999
author_rank: Super Contributor
timestamp: November 13, 2017, 07:29:28 pm
content: Quote from: dave_j_fan on November 13, 2017, 12:57:53 pmGood luck trying to get it charged inside a room, under artificial light, which is under thousandth of the brightness of sunlight. It doesn't appear to be the case, because the eyes compensate for the change in light levels. You will need a larger solar panel, than can be fitted to this tiny thing.As others have said: don't connect this thing to the mains!Want maximum efficiency? Get big and expensive LEDs and underdrive them to 2% to 15% of their rated current. The exact current which gives maximum efficiency, depends on the LED. I've Googled the best current for maximum LED efficiency and the flowing links stood out. The Digikey article says 15% of the rated current is optimal and TI's says as low as possible is best. Check the LED data sheet.http://www.ti.com/lit/an/slyt617/slyt617.pdfhttps://www.digikey.co.uk/en/articles/techzone/2011/oct/identifying-the-causes-of-led-efficiency-droop

author: dave_j_fan
author_rank: Regular Contributor
timestamp: November 14, 2017, 07:59:33 am
content: Task is to do that with minimalist cost not expensive partsBattery upgrade to 4v sla is possible .what about JT charger dumb circuit do the charginghttps://www.youtube.com/watch?v=VE0zUM_e4iowith input as the solar panelI assume the room light 7hours , 2 hours full sun

author: Zero999
author_rank: Super Contributor
timestamp: November 14, 2017, 08:50:53 am
content: Quote from: dave_j_fan on November 14, 2017, 07:59:33 amYou've made an incorrect assumption. Room light is more like 7 weeks, compared to 2 hours of full sun.

author: IanMacdonald
author_rank: Frequent Contributor
timestamp: November 14, 2017, 09:41:51 am
content: A white LED takes about 3.5v for a good light output, and will work down to about 3v. Consequently it can be lit from three AA NiMh so long as you are prepared to accept some dimming as the batteries run low. The internal resistance of AAAs may be why you are not getting a good light.The three AA's can be changed via a resisitor and schottky diode from USB. (A normal diode loses too much voltage, the full charge voltage per cell being about 1.5v)As mentioned lithium is a superior option but only take this route if you understand the safety aspects.

author: Ian.M
author_rank: Super Contributor
timestamp: November 14, 2017, 09:59:22 am
content: Typical cheap AAA NiMH cells have a capacity of roughly 700mAH, and a three cell pack will store about 2.5WH (9KJ). With a high effeciency charging circuit, total energy effiency may reach 70%. The battery will therefore require 3.6WH to fully recharge.Average Direct Normal Irradiance for India is about 4.8KWH/m2/day. Assuming 20% efficient solar cells, 1m2of panel area in a fixed position and optimally tilted, can be expected to produce 4.8*0.2=0.96KWH per day.Therefore the minimum panel area to recharge the battery in 1 day is 3.6/960=0.00375m2or 37.5cm2. That's slightly over 6cm x 6cm of active panel surface.There's no way that lantern has that much active panel area, (only exposed silicon surface counts, not bus strips, interconnects etc), and it is extremely unlikely its got 20% efficiency cells and unless you tilt it just right in an un-shaded location you aren't going to get that much irradiance.Take a photo of the panel with a ruler in shot for scale and we can probably calculate if the panel could provide any useful recharge capability if the charger circuit was improved, or if its essentially worthless.Fitting higher power LEDs certainly wont have helped. You should measure the current drawn by the original LED (hook it to the USB output) with the battery fully charged and time the discharge till it reaches 1V per cell on load or the LED effectively extinguishes, and repeat with the new LEDs you have fitted. Then we'd have some figures to go on.

author: dave_j_fan
author_rank: Regular Contributor
timestamp: November 15, 2017, 06:01:22 am
content: Quotevery true it seems ...As of now i have ripped apart the bulb diffuser4pieces of bright SM5050 added , just 4.5E dropperThe result .. brighter lamp , light spread is good .Next mod i want to do is add extra AAA cell . Skipping the solar . the Mains charging at first .Many JT chargers here :---USB charging is avoided . Many villages may not have USB charged phones

author: Zero999
author_rank: Super Contributor
timestamp: November 15, 2017, 09:48:31 am
content: Quote from: dave_j_fan on November 15, 2017, 06:01:22 amAlso, referring to my previous post: you mentioned charging it under artificial light. Look at those figures again: 4.8kWh/m2/day, the average power per 1m2, over an average of 12 hours of daylight is 400W. No artificial lights the the home or work place output that much power. It will take a long time to charge indoors, without a huge solar panel.

author: Ian.M
author_rank: Super Contributor
timestamp: November 15, 2017, 10:05:52 am
content: Bright artificial light (e.g. a well lit office) typically has an irradiance three orders of magnitude down on direct noon sunlight normal to the surface. Also the spectrum may not be a good match to a silicon solar cell so there are further losses. I would be very surprised if a 60cm x 60cm panel on an office desk with no natural daylight could charge that battery in under a week.

author: IanMacdonald
author_rank: Frequent Contributor
timestamp: November 15, 2017, 10:50:11 am
content: For that matter it will take literally ten times as long on a cloudy day as in full sunlight.Also, I hope you realise that mains charging port is highly unsafe. As there probably isn't enough room to fit a proper mains transformer etc, your best option is a wall wart. Blank off or remove the figure 8 socket before someone electrocutes themself with it.

author: soubitos
author_rank: Frequent Contributor
timestamp: November 16, 2017, 06:45:38 am
content: I am waiting pcb and parts from easyeda to build my first batch from the little board bellowhttps://easyeda.com/catech75/TP4056FLEXADV_V3_00-9fe9350f414a4cacb9a8683de565d007It is charging a Li-Ion battery (or more in parallel if you need more runtime) which can be a recycled one from old laptop batteries etc and lights a common 12V led strip... I have tested it with strip lengths from 5-250cm long for several minutes at a time without any issues and with a 20-30cm strip for 8-9hours with given used battery.Hope you like the idea and i would appreciate any and all comments to help me improve my little frankenstein projectshttps://easyeda.com/catech75

author: Zero999
author_rank: Super Contributor
timestamp: November 16, 2017, 01:10:47 pm
content: Quote from: soubitos on November 16, 2017, 06:45:38 amThat sounds interesting, but please start your own thread, rather than derailing someone else's.

author: soubitos
author_rank: Frequent Contributor
timestamp: November 16, 2017, 01:13:30 pm
content: Quote from: Hero999 on November 16, 2017, 01:10:47 pmYou are right.. THAT was the wrong link.... the correct link is this onehttps://easyeda.com/catech75/TP4056FLEXADV_V3_00-9fe9350f414a4cacb9a8683de565d007and i dont see how it is not relevant to the original post when it comes to serve exactly the same purpose/function

author: Zero999
author_rank: Super Contributor
timestamp: November 16, 2017, 02:09:31 pm
content: Quote from: soubitos on November 16, 2017, 01:13:30 pmYou misunderstood. I meant create a new topic to discus your project. Don't derail this thread!Click hereto start a new topic.

author: dave_j_fan
author_rank: Regular Contributor
timestamp: November 18, 2017, 06:08:08 pm
content: Quote from: soubitos on November 16, 2017, 06:45:38 amwonderful , although its a different one .But I may have one set input in that case and have a good light .I have damn simple 12V led that gives 9-11hr with pwm btw i may case that as well