Problem with 6v light

[barrymons]

can anybody plzz tell me what can be the problem i got one of these 1000000 candle light lights. it got a 6v 55w globe in it and a pc board with some diodes in parralell and about 2 transistors thats it. and a 6v battery.
when it is fully charged and i pull the trigger for the light to shine it works for about 10 sec then it goes weaker for the next 10 sec then the light is dead when i leave it for about half a minute it is strong again for a few second then goes weak again...

thanx for all the help
cheers

 

[stevez]

Measure the battery voltage continuously to see if it drops off. Sometimes batteries fail in that they'll hold a bit of a charge but not much. With little power draw their output voltage drops off quickly.

 

[barrymons]

I did measure it and yes it drops but after i released the button it slowly charges up again..

 

[audioguru]

I did measure it and yes it drops but after i released the button it slowly charges up again..

Your battery's voltage drops. Then it can't supply the current needed by the light. The current for a 55W light at 6V is 55/6= 9.2A. You need a pretty big battery to supply 9.2A for any amount of time.
What is the current or power rating of the 6V battery? What chemistry type?

 

[Nigel Goodwin]

What is the current or power rating of the 6V battery? What chemistry type?

As far as I'm aware they use sealed lead/acid batteries, I would imagine the battery has failed?.

 

[spuffock]

It's common knowledge that diodes dissipate no power, that's why they aren't fitted with heatsinks.
If the board under the diodes is charred black, suggest the charger has packed up due to diode failure.
Excuse the sarcasm, I fixed ANOTHER bit of kit from a reputable manufacturer today for that fault.

 

[audioguru]

It's common knowledge that diodes dissipate no power, that's why they aren't fitted with heatsinks.

Of course diodes get hot if they have a lot of current passing through them. 1V across a diode with 10A through it is 10W!
Rectifier bridge modules are in a package with a metal face and a hole for it to be fastened to a heatsink.
Try a few amps through a 1N400x rectifier diode that is rated at only 1A because it is small, and it will get too hot causing it to fail.

 

[mstechca]

It's common knowledge that diodes dissipate no power, that's why they aren't fitted with heatsinks.

Who told you that?

Of course diodes get hot if they have a lot of current passing through them. 1V across a diode with 10A through it is 10W!

Now that is "common knowledge" to me.
Anything can get hot if it has too much current passing through. even wires!

Anyone seen National Lampoons Christmas vacation? where Chevy chase has well over 500 lightbulbs lighting the whole place? and the moment they are on, and stay on, the hydro (electric for you americans) company's meter goes wacko? :lol:

I could imagine it being hot. I wonder if thats why I saw "RED" alarms at the hydro station! :shock:

You get the picture.

Let me tell you something funny.
When I was little, I thought of sticking a wire with both ends open into a socket (don't ask me why :lol: ) and what happened? POOF! black smoke covered the plug plate and the wire broke into two!

:lol: :lol: :lol: :lol: :lol:

 

[barrymons]

yes u are correct it is a sealed lead/acid battery.
it is a small battery and it is not modified in any way i bought it like that.
if u guess the battery died on me i would replace it and let u guys know what the result is

thanx for all the help
c-ya

 

[spuffock]

I DID say "excuse the sarcasm"!, I know diodes get hot, YOU know diodes get hot, but it must be common knowledge amongst manufacturers that they don,t, else why do we find the pcb charred black under so many of them? Check it out, you will find many bits of kit that still work, but with diodes that are about to unsolder themselves.
Coming back to the battery, it could well be failing to charge, through no fault of the battery. Please check that the charger circuitry works before throwing the battery away.