rechargable spotlight

[stevenet150]

I have a hand held rechargable spotlight and the resistor has failed and I can not read the colour code on it to replace it. It has a 6v 25w bulb and a 6v 2.3Vh battery can any one help me please,

 

[Sceadwian]

What resistor? There shouldn't be a resistor in a flashlight, there should be a switch going right to the bulb and the battery that's it. If it's rechargeable there may be a diode in there somewhere to prevent reverse connection of the charger but I can't see any reason there would be a resistor in there. Post a good photo so we can see what you're talking about.

 

[stevenet150]

Sorry but I am new to P.C's and I dont no how to send a photo, but the resistor? comes from the switch to the charger jack, I will find out how to send a photo and send it if you still need it, thanks.

 

[Sceadwian]

It's likley not a resistor steve. It's probably a diode.

 

[stevenet150]

Thanks for your help Sceadwian, can you tell me wot value diode I should get as a replacement please.

 

[ericgibbs]

Thanks for your help Sceadwian, can you tell me wot value diode I should get as a replacement please.

hi,
The cheaper chargers do use a resistor to limit the battery charge current, most seem to burn out after a while.
[Especially if you switch ON the lamp during charging!]

Without knowning the voltage from the charging transformer/rectifier, its difficult to guess the resistor value.

What does the charger 'label' say regarding the charge voltage.?

 

[Sceadwian]

Really? Most cheap chargers I've seen just rely on the transformer rating to limit the charge rate.

Steve, pictures of your particular device particularly the component you think is burnt out are needed. We can't just guess.

 

[ericgibbs]

Really? Most cheap chargers I've seen just rely on the transformer rating to limit the charge rate.

Steve, pictures of your particular device particularly the component you think is burnt out are needed. We can't just guess.

Ive had to modify some lamps, added a Vreg, gives a faster more reliable charge than a series resistor.

Some actually use a 12Vdc wart via an internal resistor to charge the 6V battery!!

 

[rmn_tech]

I have repaired a few of these for a firm that I do work for and have found that 10Ω 5W do the job and are better than the underrated 2W resistor that these cheaper torches usually contain.

 

[stevenet150]

Hi again, the charger has output value of 12V 500mA 6VA, sorry to be a pain but I use my lamp for my phography.

 

[ericgibbs]

Hi again, the charger has output value of 12V 500mA 6VA, sorry to be a pain but I use my lamp for my phography.

I would fit a 10R 5W as 'rmn' suggests'.

Your local Maplin store may have one in stock.

 

[Sceadwian]

Guess I was wrong again =) Just seems like a silly (and poor) way to make a charger. I hate seeing stuff like that in commercial products.

Reminds me of your typical cordless phone, the ones that use NiCads and constantly trickle charge them when they're on the hook, usually last about 1 day off the charger and go bad inside 6 months from memory effect on the Nicads. Finally bought a decent (still inexpensive) Panasonic cordless set they last 2-4 days off the charger and at a year and a half old they still hold a full charge. Better yet the battery pack is a simple frame around 2 AAA NIMHs so when they do finally age down replacing them will take less than a minute.

 

[ericgibbs]

Guess I was wrong again =) Just seems like a silly (and poor) way to make a charger. I hate seeing stuff like that in commercial products.

Reminds me of your typical cordless phone, the ones that use NiCads and constantly trickle charge them when they're on the hook, usually last about 1 day off the charger and go bad inside 6 months from memory effect on the Nicads. Finally bought a decent (still inexpensive) Panasonic cordless set they last 2-4 days off the charger and at a year and a half old they still hold a full charge. Better yet the battery pack is a simple frame around 2 AAA NIMHs so when they do finally age down replacing them will take less than a minute.

There usually is space to fit a 7805, with a couple of voltage level adjust resistors to give about 6.9V charge voltage from the 12Vdc wart.

This arrangement charges the battery faster and completely.

 

[stevenet150]

Thank very much to everybody, you advise has been a great help to me.