Help needed using a AC DC converter.

[madnomad]

you might have only burned up a surface mount resistor that is inline with the led. open it up and check any resistors in the current path to the led with the ohmeter.

Thats above my level. I don't know how I would change a resistor, or even how to test them. I guess I'll just keep it for spare parts in case I figure it out one day. I think I'm going to buy another one the same because it was a good light for the price and its possible to buy them even cheaper without a battery. But I need to buy an adapter for it so I can run it off my battery. Does anyone know how many amps I can put into these? The charger puts of 8.4V 1A, but that didn't seem to be enough when I connected it straight to the light because the battery indicator was red.

 

[100volts+]

Unfortunately I blew up my 8.4v Cree bike light today so I'm using my USB powered one now. I stupidly put 12V 1.7A into it and it was obviously too much.

Don't worry that experiment was not in vain. At least I know now what the voltage/amp limit is for those cree lights.

I got a 9v 2a converter off ebay that someone put a link to and it works off my bikes 125v (30s lipo) mains very well.

you might have only burned up a surface mount resistor that is inline with the led. open it up and check any resistors in the current path to the led with the ohmeter.

madnomad since I am technically illiterate I used to think Dnmun thread replies were useless but that was because I couldn't use an ohmeter to check a resister on a circuit board, but I learned by doing. That is how you learn and understand. That blown light is not any good to you now so you might as well open it up and check it out even if you don't want to solder in a new resister if that is the cause.

Here are the guts to a 3.6v 800ma charger that is too weak for my cree lights so I did an autopsy. Since I have 2 lights to power I'm going to put the guts of two 8.4v1a converters in a small electrical box using shoe goo and mount it to my bike.

 

[madnomad]

I got a 9v 2a converter off ebay that someone put a link to and it works off my bikes 125v (30s lipo) mains very well.

Here are the guts to a 3.6v 800ma charger that is too weak for my cree lights so I did an autopsy. Since I have 2 lights to power I'm going to put the guts of two 8.4v1a converters in a small electrical box using shoe goo and mount it to my bike.

What lights are you using? I'm going to buy a couple of these:
http://www.ebay.co.uk/itm/4X-CREE-XM-L-XML-T6-LED-5200Lm-Bike-Bicycle-Light-Headlamp-Headlight-/231081957971?pt=UK_SportGoods_CyclAcces_RL&hash=item35cd8eda53
What would be the perfect amp output for a DC converter to power these, do you know? Does anyone know how many watts these use?

 

[100volts+]

What lights are you using? I'm going to buy a couple of these:

The description of the charger lists that input is 100v to 240v and it should be 8.4v output but doesn't list an amp output. I've got your standard Cree T6 but I'm using chargers that I bought for the conversion 9v 2amp I'll still have to see if they trip the polyfuse on the ca. For that test I'm waiting on female dc power jacks I got off ebay also.

 

[madnomad]

What lights are you using? I'm going to buy a couple of these:

The description of the charger lists that input is 100v to 240v and it should be 8.4v output but doesn't list an amp output. I've got your standard Cree T6 but I'm using chargers that I bought for the conversion 9v 2amp I'll still have to see if they trip the polyfuse on the ca. For that test I'm waiting on female dc power jacks I got off ebay also.

When you say standard cree t6, do you mean you have just one LED? Would you need a DC adapter with more amps if you have a light with more LEDs?

 

[dnmun]

i don't think that is a switch mode power supply in the picture.

 

[100volts+]

When you say standard cree t6, do you mean you have just one LED? Would you need a DC adapter with more amps if you have a light with more LEDs?

Therein is the quandary. I'm using 30s or 125v so I wouldn't need the amps you would at say 54v. you would need a little more than twice the amps I would think. For example if the light needs 30 watts then you would need aprox. 600ma (54 x .6=32.4 watts) where as I would need only 300ma (125 x .3= 37.5 watts)

 

[madnomad]

When you say standard cree t6, do you mean you have just one LED? Would you need a DC adapter with more amps if you have a light with more LEDs?

Therein is the quandary. I'm using 30s or 125v so I wouldn't need the amps you would at say 54v. you would need a little more than twice the amps I would think. For example if the light needs 30 watts then you would need aprox. 600ma (54 x .6=32.4 watts) where as I would need only 300ma (125 x .3= 37.5 watts)

Ah ha, I see. I didn't realise the voltage of my battery had anything to do with the amps it puts out through the CA. I thought the CA just had a 1a polyfuse, so I assumed everyone was limited to 1a from the CA power out. Or were you talking about taking it straight off the battery?

 

[100volts+]

either way since you're voltage is less than half of mine that light willl require a little more than double the amps to achieve the same wattage as me. Remember volts x amps equals watts

 

[madnomad]

either way since you're voltage is less than half of mine that light willl require a little more than double the amps to achieve the same wattage as me. Remember volts x amps equals watts

Just when I thought I was starting to get it... :/
I thought if I was running them through a DC converter then the amps would be whatever the DC converter puts out?

 

[100volts+]

now you're confusing me but I think it's the input you got to worry about not the output it's true the output will be the same.now that I think about it you are right....but the polyfuse in the ca might cutoff current because you'll need twice the amps as me going into the converter and make it necessary for you to run off the battery. I guess we'll both have to see. I know 9v2a converter works prefect for me. that means the light only draws 18 watts at most. that means I can run 2 lights and only draw 300ma from the ca. In any case if you run off the main you'll have to add an on off switch to your light where as if you ran off the ca when you shut the ca off you cut current to the light. PS EDIT: I just tried an 8.4v 1a converter and although the light worked the button turn red and only the low beam worked which means I have to go with two 9v2a converters ( it ran the light as it should) as a minimum and hope the polyfuse can handle two converters otherwise I might have to run off the mainsl

 

[100volts+]

Here is a quick vid showing cheap dual headlights powered by ca 3 aux power and 2 cheapie ac to dc converters.

[youtube]rnZ4LzYP0nI[/youtube]

 

[teklektik]

Works slick!
Thanks for the update