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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Batteries make flashilight hot.
On 02/23/2017 01:47 AM, micky wrote:
I have one of thoe little 2.5" LED flashlights, that have 9 small LEDs and use 3 AAA batteries. It's like the ones that Harbor Freight sometimes gives away free, same size, but nicer. The guy I bought the first one from said it would run for days on one set of batteries, but I forgot that it was still on and i put it in my pocket and an hour or two later, I noticed it was on because it was warm. It's still really bright, but if it's noticeably warm, how long can the baterries really last? Certainly not two days. ? I once, recently, forgot the screen was lit on my 5.5" smart phone and only noticed because it felt warm in my pocket. It's got a proximity sensor but I don't remember what it's supposed to do. YEAH, WELL I HAD MY LED LIGHT BULB IN MY KITCHEN HOOD ON ALL DAY AND IT WAS TOO HOT TO TOUCH SO WHAT'S YOUR POINT? |
#2
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Batteries make flashilight hot.
I have one of thoe little 2.5" LED flashlights, that have 9 small LEDs
and use 3 AAA batteries. It's like the ones that Harbor Freight sometimes gives away free, same size, but nicer. The guy I bought the first one from said it would run for days on one set of batteries, but I forgot that it was still on and i put it in my pocket and an hour or two later, I noticed it was on because it was warm. It's still really bright, but if it's noticeably warm, how long can the baterries really last? Certainly not two days. ? I once, recently, forgot the screen was lit on my 5.5" smart phone and only noticed because it felt warm in my pocket. It's got a proximity sensor but I don't remember what it's supposed to do. |
#3
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Batteries make flashilight hot.
On Wednesday, February 22, 2017 at 8:48:12 PM UTC-5, micky wrote:
I have one of thoe little 2.5" LED flashlights, that have 9 small LEDs and use 3 AAA batteries. It's like the ones that Harbor Freight sometimes gives away free, same size, but nicer. The guy I bought the first one from said it would run for days on one set of batteries, but I forgot that it was still on and i put it in my pocket and an hour or two later, I noticed it was on because it was warm. It's still really bright, but if it's noticeably warm, how long can the baterries really last? Certainly not two days. ? I once, recently, forgot the screen was lit on my 5.5" smart phone and only noticed because it felt warm in my pocket. It's got a proximity sensor but I don't remember what it's supposed to do. The heat is from the LEDs, not the batteries, and no, the batteries will not last indefinitely. I would guess (SWAG) that each LED will run about 50 ma. So you are pulling 450 ma, or thereabout per hour. If your AAA batteries are middle-of-the-road 1,000 MAH, you have a base of 3000 MAH, so, about 6-7 hours +/- or so. Under normal use, that is 'days'. Peter Wieck Melrose Park, PA |
#4
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Batteries make flashilight hot.
On Wed, 22 Feb 2017 20:47:57 -0500, micky
wrote: I have one of thoe little 2.5" LED flashlights, that have 9 small LEDs and use 3 AAA batteries. It's like the ones that Harbor Freight sometimes gives away free, same size, but nicer. Did you notice that almost all such flashlights are made from aluminum, not plastic, which would be cheaper? That's because aluminum makes a good heat sink to get the heat away from the LED's. LED's loose output and efficiency when hot, so it pays to keep them cool. The COB style of LED mounting is quite common in larger flashlights, which offer a heat conductive path from the LED to the aluminum heatsink case. The guy I bought the first one from said it would run for days on one set of batteries, but I forgot that it was still on and i put it in my pocket and an hour or two later, I noticed it was on because it was warm. It's still really bright, but if it's noticeably warm, how long can the baterries really last? Certainly not two days. ? No, it won't run forever. AAA alkaline batteries are good for 1000ma-hr each. At something less than 4.5V for 3 batteries, that's 4.5 watt-hrs. Commodity LED's generate about 50 lumens/watt, so if your Harbor Freight flashlight managed to belch 15 lumens, it will consume 0.3 watts. Runtime is therefore an optimistic: 4.5 watt-hrs / 0.3 watts = 15 hrs. It's probably less because I didn't bother throwing in losses in the current source, decrease in battery voltage as it runs down, and heating effects. But, it should give you a ballpark guess as to how long it will run. My guess(tm) is it will run about 8 hrs with a new set of batteries. I once, recently, forgot the screen was lit on my 5.5" smart phone and only noticed because it felt warm in my pocket. If your smartphone as a battery usage graph, like all Android phones, you'll find that it also has a list of which applications are sucking the most power. The backlighting for the OLED screen is invariably the highest. If you don't talk on your phone, and don't run any apps, the battery life of your phone will be totally dependent on the brightness setting and efficiency of the OLED display, which is about the same 50 lumens/watt as your white LED. (Yes, I know there are press releases for 100 lumens/watt, but those are under laboratory conditions). It's got a proximity sensor but I don't remember what it's supposed to do. Never heard of it. Maker and model number? -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#5
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Batteries make flashilight hot.
On Thu, 23 Feb 2017 08:44:26 -0800, Jeff Liebermann
wrote: If your smartphone as a battery usage graph, like all Android phones, you'll find that it also has a list of which applications are sucking the most power. The backlighting for the OLED screen is invariably the highest. No brain function before my morning tea. That's wrong. There is no backlighting in an OLED display. That should be the LED "screen" power consumption, not backlighting power consumption. https://www.howtogeek.com/244748/how-to-see-which-apps-are-draining-your-battery-on-an-android-phone-or-tablet/ -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#6
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Batteries make flashilight hot.
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#7
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Batteries make flashilight hot.
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#8
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Batteries make flashilight hot.
On Wednesday, February 22, 2017 at 5:48:12 PM UTC-8, micky wrote:
I have one of thoe little 2.5" LED flashlights, that have 9 small LEDs and use 3 AAA batteries. It's still really bright, but if it's noticeably warm, how long can the baterries really last? Certainly not two days. ? The internal resistance of the batteries, and the internal resistance of the LEDs used, is very much a part of the design of those flashlights. Both the LEDs and the batteries do get warm in normal operation, and (as you suspect) it's likely that a fresh set of batteries will last well under a day of ON operation; Duracell AAA claims 3.5 hours at 1/4W output, so a three-cell light could deliver over half a watt for a useful amount of time; hours, not days. https://d2ei442zrkqy2u.cloudfront.net/wp-content/uploads/2016/03/MN2400_US_CT1.pdf |
#9
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Batteries make flashilight hot.
In sci.electronics.repair, on Thu, 23 Feb 2017 19:41:35 -0000, MJC
wrote: In article , says... On Wed, 22 Feb 2017 20:47:57 -0500, micky wrote: It's got a proximity sensor but I don't remember what it's supposed to do Isn't it just to switch off the screen and touch sensitivity when adjacent to your head so your ear doesn't swipe at random? Yeah, that's it. I guess I thought the screen would go off in my front pants pocket too, light weight pants, but it didn't. I hadn't relied on that, just forgot, and I won't rely on it in the future. I guess my pants pocket won't swipe anything ilke my ear could. Mike. |
#10
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Batteries make flashilight hot.
Funny thing, these types of lights are often give-away items at Solar Energy conferences - I have been to my fair share, and how they came into my hands. Otherwise I would not touch this cr*p on a bet. FUNNY THING, THESE TYPES OF SEXUALLY TRANSMITTED DISEASES ARE OFTEN GIVE AWAY ITEMS AT GAY ORGIES. PETER WRECK HAS BEEN TO HIS FAIR SHARE, AND HOW THEY CAME INTO HIS HANDS. OTHERWISE HE WOULD TOUCH SITRE MAGANA'S DICK FOR FREE. Melrose Park, PA |
#11
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Batteries make flashilight hot.
On Thursday, February 23, 2017 at 2:25:19 PM UTC-5, mike wrote:
Might want to check that math. OK. 50 x 9 = 450. 9 LEDs at 50 ma each. 3 x 1000 = 3000. 3 cells at 1000mah each. 3000 / 450 = 6.67. At 450 ma, that will go 6.67 hours. The reality is probably different as all the shots/assumptions are center-mass. If the LEDs are 100ma outliers, if the cells are 1.4mah outliers, things do change, of course. Peter Wieck Melrose Park, PA |
#12
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Batteries make flashilight hot.
On Fri, 24 Feb 2017 09:36:12 -0800 (PST), "
wrote: On Thursday, February 23, 2017 at 2:25:19 PM UTC-5, mike wrote: Might want to check that math. OK. 50 x 9 = 450. 9 LEDs at 50 ma each. 3 x 1000 = 3000. 3 cells at 1000mah each. 3000 / 450 = 6.67. At 450 ma, that will go 6.67 hours. The reality is probably different as all the shots/assumptions are center-mass. If the LEDs are 100ma outliers, if the cells are 1.4mah outliers, things do change, of course. Peter Wieck Melrose Park, PA 3 cells at 1000 mah each do NOT give you 3000 mah. They give you 1000 mah but at a higher voltage (4.5 vs 1.5). If you use mwh (watts) instead of mah (amps), then you can add them. (If the cells are wired in parallel instead of series, then you are correct, but that isn't very common.) |
#13
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Batteries make flashilight hot.
On Friday, February 24, 2017 at 1:16:23 PM UTC-5, Pat wrote:
On Fri, 24 Feb 2017 09:36:12 -0800 (PST), " wrote: On Thursday, February 23, 2017 at 2:25:19 PM UTC-5, mike wrote: Might want to check that math. OK. 50 x 9 = 450. 9 LEDs at 50 ma each. 3 x 1000 = 3000. 3 cells at 1000mah each. 3000 / 450 = 6.67. At 450 ma, that will go 6.67 hours. The reality is probably different as all the shots/assumptions are center-mass. If the LEDs are 100ma outliers, if the cells are 1.4mah outliers, things do change, of course. Peter Wieck Melrose Park, PA 3 cells at 1000 mah each do NOT give you 3000 mah. They give you 1000 mah but at a higher voltage (4.5 vs 1.5). If you use mwh (watts) instead of mah (amps), then you can add them. (If the cells are wired in parallel instead of series, then you are correct, but that isn't very common.) The three similar lights I have, they are in parallel. Which is why I probably wrongly assumed these were as well. Funny thing, these types of lights are often give-away items at Solar Energy conferences - I have been to my fair share, and how they came into my hands. Otherwise I would not touch this cr*p on a bet. Peter Wieck Melrose Park, PA |
#14
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Batteries make flashilight hot.
On Fri, 24 Feb 2017 10:45:18 -0800 (PST), "
wrote: On Friday, February 24, 2017 at 1:16:23 PM UTC-5, Pat wrote: On Fri, 24 Feb 2017 09:36:12 -0800 (PST), " wrote: On Thursday, February 23, 2017 at 2:25:19 PM UTC-5, mike wrote: Might want to check that math. OK. 50 x 9 = 450. 9 LEDs at 50 ma each. 3 x 1000 = 3000. 3 cells at 1000mah each. 3000 / 450 = 6.67. At 450 ma, that will go 6.67 hours. The reality is probably different as all the shots/assumptions are center-mass. If the LEDs are 100ma outliers, if the cells are 1.4mah outliers, things do change, of course. Peter Wieck Melrose Park, PA 3 cells at 1000 mah each do NOT give you 3000 mah. They give you 1000 mah but at a higher voltage (4.5 vs 1.5). If you use mwh (watts) instead of mah (amps), then you can add them. (If the cells are wired in parallel instead of series, then you are correct, but that isn't very common.) The three similar lights I have, they are in parallel. Which is why I probably wrongly assumed these were as well. Funny thing, these types of lights are often give-away items at Solar Energy conferences - I have been to my fair share, and how they came into my hands. Otherwise I would not touch this cr*p on a bet. Peter Wieck Melrose Park, PA I just checked 3 of mine... Two give-aways and one UV of similar design. All three have the AAA batteries connected in series. That got me wondering how the LEDs are wired, but I was too lazy to take them apart. All have 9 LEDs so I will guess 3 sets of 3. Is 4.5v enough to power a 3 LED string? Just went to look it up and the answer to my own question is "no". UV and White LEDs typically have a Vf of 3.3 volts. So, all 9 are in parallel with their own current limiter? If so, why 9? Is there a cheap IC that supports 9 LEDs? If anyone knows, please educate us. Pat |
#15
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Batteries make flashilight hot.
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#16
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Batteries make flashilight hot.
On Wed, 22 Feb 2017 20:47:57 -0500, micky
wrote: I have one of thoe little 2.5" LED flashlights, that have 9 small LEDs and use 3 AAA batteries. It's like the ones that Harbor Freight sometimes gives away free, same size, but nicer. The guy I bought the first one from said it would run for days on one set of batteries, but I forgot that it was still on and i put it in my pocket and an hour or two later, I noticed it was on because it was warm. It's still really bright, but if it's noticeably warm, how long can the baterries really last? Certainly not two days. ? I once, recently, forgot the screen was lit on my 5.5" smart phone and only noticed because it felt warm in my pocket. It's got a proximity sensor but I don't remember what it's supposed to do. I buy these at Walmart for $1 each. I use them a lot. I have left them on overnight and they still work, but that greatly shortens the battery life. If they are not left on for long periods of time, they last weeks and that is being used almost daily. For a buck each, I usually buy 5 at a time and that keep me with working flashlites for a few months. I keep one in the car, one in the truck, one in the house and a few other places. Unless I can buy batteries real cheap at some dollar store, (like 8 batteries for a buck), it's not worth replacing the batteries. I just toss them and buy more flashlights which cost $1 WITH batteries. I have never had any of them get hot or cause any problems at all. I did have a few with switch problems, but very few. Since I have plenty ones with dead batteries, I just swap the batteries from one with a bad switch to one that still works. I have saved the LEDs from a lot of them that I toss. Not sure why, but some day they might have a use... I guess these are just meant to be used and disposed..... But I have replaced the batteries a few times too. Either way, they are 1000X better than the old flashlights I grew up with, that had very short battery life and almost always developed switch problems after a month or less. |
#17
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Batteries make flashilight hot.
Pat wrote:
On Fri, 24 Feb 2017 10:45:18 -0800 (PST), " wrote: On Friday, February 24, 2017 at 1:16:23 PM UTC-5, Pat wrote: On Fri, 24 Feb 2017 09:36:12 -0800 (PST), " wrote: On Thursday, February 23, 2017 at 2:25:19 PM UTC-5, mike wrote: Might want to check that math. OK. 50 x 9 = 450. 9 LEDs at 50 ma each. 3 x 1000 = 3000. 3 cells at 1000mah each. 3000 / 450 = 6.67. At 450 ma, that will go 6.67 hours. The reality is probably different as all the shots/assumptions are center-mass. If the LEDs are 100ma outliers, if the cells are 1.4mah outliers, things do change, of course. Peter Wieck Melrose Park, PA 3 cells at 1000 mah each do NOT give you 3000 mah. They give you 1000 mah but at a higher voltage (4.5 vs 1.5). If you use mwh (watts) instead of mah (amps), then you can add them. (If the cells are wired in parallel instead of series, then you are correct, but that isn't very common.) The three similar lights I have, they are in parallel. Which is why I probably wrongly assumed these were as well. Funny thing, these types of lights are often give-away items at Solar Energy conferences - I have been to my fair share, and how they came into my hands. Otherwise I would not touch this cr*p on a bet. Peter Wieck Melrose Park, PA I just checked 3 of mine... Two give-aways and one UV of similar design. All three have the AAA batteries connected in series. That got me wondering how the LEDs are wired, but I was too lazy to take them apart. All have 9 LEDs so I will guess 3 sets of 3. Is 4.5v enough to power a 3 LED string? Just went to look it up and the answer to my own question is "no". UV and White LEDs typically have a Vf of 3.3 volts. So, all 9 are in parallel with their own current limiter? If so, why 9? Is there a cheap IC that supports 9 LEDs? If anyone knows, please educate us. Pat I cut open one of the Harbor Freight nine LED flashlights that was damaged. All nine LEDs are in parallel, and all three cells are in series. They use the internal resistance of the cells to limit he current. The forward voltage of a white LED is typically 3.7 to 4.2 volts, so parallel cells would require a boost converter which would double the cost of the electronics in a flashlight. BTW, the Harbor Freight flashlight will slip into a cheap microphone boom for a handy bench light. Mic-Arm-Stand-Microphone-Suspension-Boom-Scissor-Holder-For-Studio-Broadcast http://www.ebay.com/itm/272436300096 -- Never **** off an Engineer! They don't get mad. They don't get even. They go for over unity! ;-) |
#18
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Batteries make flashilight hot.
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#19
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Batteries make flashilight hot.
On Fri, 24 Feb 2017, Pat wrote:
On Fri, 24 Feb 2017 10:45:18 -0800 (PST), " wrote: On Friday, February 24, 2017 at 1:16:23 PM UTC-5, Pat wrote: On Fri, 24 Feb 2017 09:36:12 -0800 (PST), " wrote: On Thursday, February 23, 2017 at 2:25:19 PM UTC-5, mike wrote: Might want to check that math. OK. 50 x 9 = 450. 9 LEDs at 50 ma each. 3 x 1000 = 3000. 3 cells at 1000mah each. 3000 / 450 = 6.67. At 450 ma, that will go 6.67 hours. The reality is probably different as all the shots/assumptions are center-mass. If the LEDs are 100ma outliers, if the cells are 1.4mah outliers, things do change, of course. Peter Wieck Melrose Park, PA 3 cells at 1000 mah each do NOT give you 3000 mah. They give you 1000 mah but at a higher voltage (4.5 vs 1.5). If you use mwh (watts) instead of mah (amps), then you can add them. (If the cells are wired in parallel instead of series, then you are correct, but that isn't very common.) The three similar lights I have, they are in parallel. Which is why I probably wrongly assumed these were as well. Funny thing, these types of lights are often give-away items at Solar Energy conferences - I have been to my fair share, and how they came into my hands. Otherwise I would not touch this cr*p on a bet. Peter Wieck Melrose Park, PA I just checked 3 of mine... Two give-aways and one UV of similar design. All three have the AAA batteries connected in series. That got me wondering how the LEDs are wired, but I was too lazy to take them apart. All have 9 LEDs so I will guess 3 sets of 3. Is 4.5v enough to power a 3 LED string? Just went to look it up and the answer to my own question is "no". UV and White LEDs typically have a Vf of 3.3 volts. So, all 9 are in parallel with their own current limiter? If so, why 9? Is there a cheap IC that supports 9 LEDs? If anyone knows, please educate us. Are you talking about the really cheap LED flashlights? I've taken some apart, and I don't see anything but the LEDs. So they have to be in parallel, and rely on the bettery itself to supply some level of series resistance. The cheap ones sometimes aren't even soldered together, just sort of pressed together, which may account for why some of the LEDs don't light, bad contact. Of course, these are just white LEDs in some package, not "chip" LEDs like in better LED flashlights and LED light bulbs. Michael |
#20
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Batteries make flashilight hot.
In sci.electronics.repair, on Fri, 24 Feb 2017 18:47:01 -0500, Michael
Black wrote: On Fri, 24 Feb 2017, Pat wrote: On Fri, 24 Feb 2017 10:45:18 -0800 (PST), " wrote: On Friday, February 24, 2017 at 1:16:23 PM UTC-5, Pat wrote: On Fri, 24 Feb 2017 09:36:12 -0800 (PST), " wrote: On Thursday, February 23, 2017 at 2:25:19 PM UTC-5, mike wrote: Might want to check that math. OK. 50 x 9 = 450. 9 LEDs at 50 ma each. 3 x 1000 = 3000. 3 cells at 1000mah each. 3000 / 450 = 6.67. At 450 ma, that will go 6.67 hours. The reality is probably different as all the shots/assumptions are center-mass. If the LEDs are 100ma outliers, if the cells are 1.4mah outliers, things do change, of course. Peter Wieck Melrose Park, PA 3 cells at 1000 mah each do NOT give you 3000 mah. They give you 1000 mah but at a higher voltage (4.5 vs 1.5). If you use mwh (watts) instead of mah (amps), then you can add them. (If the cells are wired in parallel instead of series, then you are correct, but that isn't very common.) The three similar lights I have, they are in parallel. Which is why I probably wrongly assumed these were as well. Funny thing, these types of lights are often give-away items at Solar Energy conferences - I have been to my fair share, and how they came into my hands. Otherwise I would not touch this cr*p on a bet. Peter Wieck Melrose Park, PA I just checked 3 of mine... Two give-aways and one UV of similar design. All three have the AAA batteries connected in series. That got me wondering how the LEDs are wired, but I was too lazy to take them apart. All have 9 LEDs so I will guess 3 sets of 3. Is 4.5v enough to power a 3 LED string? Just went to look it up and the answer to my own question is "no". UV and White LEDs typically have a Vf of 3.3 volts. So, all 9 are in parallel with their own current limiter? If so, why 9? Is there a cheap IC that supports 9 LEDs? If anyone knows, please educate us. Are you talking about the really cheap LED flashlights? I've taken some apart, and I don't see anything but the LEDs. So they have to be in parallel, and rely on the bettery itself to supply some level of series resistance. Sometimes one or two of the bulbs go out, so I think that also means parallel. The cheap ones sometimes aren't even soldered together, just sort of pressed together, which may account for why some of the LEDs don't light, bad contact. Of course, these are just white LEDs in some package, not "chip" LEDs like in better LED flashlights and LED light bulbs. Michael |
#21
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Batteries make flashilight hot.
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#22
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Batteries make flashilight hot.
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