LED bulbs

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LED bulbs

Postby vivian maxine on March 22nd, 2015, 2:25 pm 

Can an LED bulb, if it overheats, turn itself off? I have a magnifying glass with a tiny LED bulb. Once in a while it gets accidentally turned on when I put it in its protective sleeve and, because it is so small, I do not see that it is on. Later I try to use it and find it not working. I turn off the switch for a ten or fifteen minutes and turn it back on to find the LED bulb again lit up and again working.
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Re: LED bulbs

Postby Watson on March 22nd, 2015, 3:09 pm 

It might be a feature of the magnifying glass. I doubt the bulb would have any say in it. On until the power is done.
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Re: LED bulbs

Postby vivian maxine on March 22nd, 2015, 3:26 pm 

Watson » March 22nd, 2015, 2:09 pm wrote:It might be a feature of the magnifying glass. I doubt the bulb would have any say in it. On until the power is done.


The power comes from a battery and apparently is still trying to power the bulb. At least I am guessing that since the bulb will not light up if I turn it off and immediately turn it back on. I have to wait a while.

The magnifier was made in Germany by Eschenbach - the best in the field, I'm told. Maybe they've invented something new?

Thank you for your answer.
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Re: LED bulbs

Postby Watson on March 22nd, 2015, 3:36 pm 

A smart bulb?? I suppose it could happen with some kind of heat sensor to shut it off. That doesn't explain why you have to wait before turning it back on, unless it's not just a smart bulb, but a smart ass bulb.
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Re: LED bulbs

Postby vivian maxine on March 22nd, 2015, 3:48 pm 

Watson » March 22nd, 2015, 2:36 pm wrote:A smart bulb?? I suppose it could happen with some kind of heat sensor to shut it off. That doesn't explain why you have to wait before turning it back on, unless it's not just a smart bulb, but a smart ass bulb.


Trying to teach me to stay alert? I did for a while but got careless. Some time when I'm in the store where I bought it, I'll see what they say. Thanks.
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Re: LED bulbs

Postby Dave_Oblad on March 23rd, 2015, 4:39 pm 

Hi Vivian,

There are no LED bulbs that auto shut down that I am aware of. It is possible that the flash light may have a circuit built into it that auto shuts off... but honestly... that would be a rather stupid and dangerous feature.

I have had several flashlights do what you describe.. it is because they have old carbon cell batteries in them.

Some chemical (carbon) batteries will discharge down to near zero (note: LED bulbs never discharge a battery to full zero for electrical diode reasons). After removing the load off the battery (shutting the lamp/LED off) the battery will auto recharge to some level. Carbon cells can actually recharge themselves back to "Full Voltage" (not to be confused with "Full Capacity"). However.. once the load is engaged again (lamp is lit) the old battery cell will discharge very very rapidly.. usually only lasting a minute or so.

When this starts to happen it's definitely time to replace the batteries, especially before they build up internal pressure and leak battery acid all over.

Regards,
Dave :^)
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Re: LED bulbs

Postby vivian maxine on March 23rd, 2015, 5:04 pm 

Thank you, Dave. Best I replace the battery then. I seldom use the light. Once in a while there is a need for it but not often and not for long. This isn't a flashlight. It is an extra-strength magnifying glass which includes this very bright light. A blessing when needed.

I'll take care of that.
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Re: LED bulbs

Postby Darby on March 23rd, 2015, 5:16 pm 

Just to add to what Dave said, on battery tech.

Battery tech for handheld electronics (i.e., D, C, 9v, AA, AAA) has finally, at long last, started to reach the point where alkalai batteries are finally becoming obsolete. The latest generation of rechargeables (aka fifth gen or high cycle 'low self discharge') has nearly closed the gap on charge retention (meaning if you take a fully charged example of both batteries and sit them unused in a cool dark place for say 5 years, they'll both have comparable levels of charge remaining). The alkalai still holds an edge in total energy stored, and a slight edge in voltage, but the rechargeables can be reused a hundred+ times, and doesnt destroy the device its in if it ruptures and leaks when it expires.

I phased out all of mine several years ago, once the 5th gens landed, and havent missed them (this after having tried all 5 generations as they came out).

Eneloop is a decent brand, if you want to take a peek on amazon.

This is a great LED lantern BTW ... highly recommended. You can even use it with rechargeable AA's if you fit them into D adaptors, although the run time is much shorter. Great for both infrequent emergency use, and camping.

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