LED Driver Wattage Question

[chopnhack]

Hi all, I am looking at some LED drivers from Flea-Bay ;-)

I am confused on the markings and I am thinking its just cheap marketing techniques to get you to buy under rated products.
Here is an example:

http://www.ebay.com/itm/Constant-Cu...17535af&pid=100009&rk=1&rkt=1&sd=221706249074

Its listed as a 3w constant current driver for between 10-18 3W LEDs. If I do the math, that means that this driver is capable of sourcing between 3x10 or 3x18 watts, 30-54 watts. The listed output on the device states between 30-60 volts and 650mA max. Again the math leads to 30 to 60v x 0.65A = 19.5-39W. It would seem to me that this particular driver is under powered to provide for that many LED's.

I should think ten 3W LED's would be the upper limit, don't these units need some headroom to operate? Or is that different for switch mode devices?

Would this driver be more adequate for twelve 3w units?

Thanks!

 

[Bluejets]

At the top of the add in your link it says ....40W

 

[chopnhack]

At the top of the add in your link it says ....40W

I don't believe everything I read without some thought, especially from an unknown vendor, hence why I ask. The math correlates with 39 watts, true enough, but the aforementioned questions stand unanswered.
Thanks.

 

[cowdough]

dude...just plug as many bulbs up to it as you can till it doesnt work then back off 2 or 3 bulbs. simole. NEXT?!

 

[chopnhack]

. simole. NEXT?!

simple, true, but I don't have the unit, so instead of ordering it and finding it not to work, I ask the questions first. Smart, eh?

 

[Audioguru]

The ad for a cheap no-name-brand product can say anything. Do you trust the lies?

 

[chopnhack]

That is kind of why I was leaning towards getting the larger unit, assuming that the specs are not what they say. As you say, can you trust ANY of the labeling, which you have a good point - whether the 40w or the 650mA x 60V is all suspect. I guess I will get the larger one and hope it works. Thanks all.

 

[cowdough]

i mean...what sense would it make to lie about a product youre posting for sale to the whole world? in the event it is falsified info 1 valid provable complaint and the seller is banned from ebay...i mean...shoot go for it. if its junk contact ebay and theyll straighten it out. may take 3 months but youll be refunded

 

[chopnhack]

i mean...what sense would it make to lie about a product youre posting for sale to the whole world? in the event it is falsified info 1 valid provable complaint and the seller is banned from ebay...i mean...shoot go for it. if its junk contact ebay and theyll straighten it out. may take 3 months but youll be refunded

Since I need 36watts, or close to it, the smaller unit may or may not work. As for falsifying specs, I am sure it happens all the time, so long as it works most of the time for most of the people, it becomes a numbers game. How many units can I sell vs. how many are returned. Just my opinion.

 

[cowdough]

Since I need 36watts, or close to it, the smaller unit may or may not work. As for falsifying specs, I am sure it happens all the time, so long as it works most of the time for most of the people, it becomes a numbers game. How many units can I sell vs. how many are returned. Just my opinion.

i know from experience that ebay is NOT messed up about freezing your account. lol. long story. i see your point though. ive never had any issue with cheap knockoff stuff on their site except for a blow off valve i bought for my conquest...it didnt work. so idk man sometimes u just gotta jump in with both feet.good luck

 

[Audioguru]

There must be a lot of people who are happy paying little for ebay junk.

 

[chopnhack]

There are plenty of suitable finds on e-bay. Don't forget, all the electronics manufacturing takes place in China (at least a fair majority) and so naturally its an easy way to purchase items at wholesale or factory pricing. 1w and 3w led's for literally dimes a piece, etc. If you are careful about what you buy, its not all trash. Your mileage may vary...

 

[hevans1944]

I would opt for the larger unit. The main difference seems to be the compliance voltage range since both are rated to deliver the same constant current. For a couple bux more and the same wait time, why chance having to purchase another one if the smaller one doesn't deliver the power you need? OTOH, eBay vendors are always a crap shoot..You pays your money and you takes your chances. Or build your own from parts purchased from a reliable distributor at ten times the cost... plus S&H.

 

[chopnhack]

. Or build your own from parts purchased from a reliable distributor at ten times the cost... plus S&H.

The thought did cross my mind , but being a switch mode psu - I really didnt want to spend the next year or more figuring that out . I actually went a different route with 1w led's and saved about 60 % of the cost of the whole project .

 

[hevans1944]

Aww... a year to figure out a SMPS? You buy a chip, an inductor, a few capacitors and download an Instructable. Might take a few days to get it working, so purchase extra parts... just in case.

 

[chopnhack]

LOL - maybe, I need the end result of this project sooner than that! I did read a bit on swItchers and posted a video recently in our general q's section so I have some basic understanding of the operation.