Beware of LED sellers who do not publish current consumption. That is the only way to know how many Watts that bar really is. Based on a total of 40 LEDs, I would guess the real power is closer to 40W than to 120W.
EDIT1: I noticed further down the web page they post current input: 16A at 12V, 8A at 24V. That is 192W input that if true would indicate you are really getting a 120W bar.
EDIT2: On the other hand, they report the same 16A at 12V, 8A at 24V for their 240W bar, so who knows which bar model those figures really belong to.
^ Yes they usually falsely spec them by just multiplying 3W * # of LEDs regardless of real drive current. It can't be a 120W bar, the heatsink isn't close to large enough for that if the vehicle isn't moving and/or it's not winter.
A customer review from "Starry" read as follows: "I used a precision digital ammeter and digital voltmeter and measured a current of 6.9 Amps at 12.20Volts. This is a power level of 84.18 watts"
However that's INPUT power before driver losses. If we give them the benefit of the doubt that it's at least 90% efficient which it may not be, that's 76W.
It's not all bad though, you won't get much higher than 76W real drive current for $28 and usually less, though if you buy a more expensive bar with Cree LEDs, you'd get more lumens in the same space IF drive current and all else were equal.
^ Yes they usually falsely spec them by just multiplying 3W * # of LEDs regardless of real drive current. It can't be a 120W bar, the heatsink isn't close to large enough for that if the vehicle isn't moving and/or it's not winter.
A customer review from "Starry" read as follows: "I used a precision digital ammeter and digital voltmeter and measured a current of 6.9 Amps at 12.20Volts. This is a power level of 84.18 watts"
However that's INPUT power before driver losses. If we give them the benefit of the doubt that it's at least 90% efficient which it may not be, that's 76W.
It's not all bad though, you won't get much higher than 76W real drive current for $28 and usually less, though if you buy a more expensive bar with Cree LEDs, you'd get more lumens in the same space IF drive current and all else were equal.
When I buy LED lights on I always open them up if possible to see what LED driver they are using. My most recent purchase of 10W flood lights are using 5W drivers. An older purchase of a 15W recessed light had a 5W driver inside. However I have also purchased some 7W recessed lights that had 7W drivers in them, so not everybody is cheating.
The thing is that if you drive a 3W LED with say 1W of electric power, you only get 1/3 of the light output that LED is capable of. Why would a vendor use an undersized LED driver? To save manufacturing costs is one possible reason. A 1W LED driver is considerably cheaper than a 3W one. Also the size and cost of the heat sink needed is less when the LED is driven at 1W instead of 3W. Most people who look at that 3W LED being driven with only 1W of electric power will not be able to tell they are being cheated because even at 1W the LED will be quite bright.
^ Well the answer is a bit long for a deal post but here goes:
- 3W is only an upper limit, one that requires higher quality heatsinking, and more surface area.
- Driving an LED at less than full power it becomes more efficient, and lowering die temperature promotes longer life, not just til failure but till permanent lumen reduction (gradual process).
- Driving more LEDs at lower power to equal same total power reduces thermal density at the die, and with these semi-generic, presumably Epistar LEDs, it could be cheaper to use more LEDs than use better heatsinking.
- It's not an undersized LED driver. It's X amount of light, a combination of components that works together to give great value for $28.
- You're not being cheated to get a 3W LED ran at 1W (actually it's much closer to 2W actual drive current) EXCEPT that they make the bogus total wattage claim, but if they didn't, they would just sell you a 76W light for $28, not a 120W light for $28, so you're still getting what you paid for even if misled about the performance.
It stinks to false advertise like that but it's so rampant that nobody can effectively stop it at this point or at least places like feel it isn't in their best interests to interfere so long as the products keep selling.
If enforced truth in lumen specs, the products would look inferior to those with fraudulent advertising almost everywhere else, at other online merchants.
- 1W LEDs wouldn't be all that much cheaper in total construction cost. They'd still be better under driven to reduce the LED die thermal density so you'd need more of them, over twice as many to reach 76W then you need double the reflectors too which means either worse throw or a much wider or taller product.
That would allow for more heatsink area in the back, so keeping the heatsink design the same otherwise it could support higher total power, but then you'd need even more LEDs to get there. If you can accept a longer product for more light, they sell those too. This product is about what you can accomplish with 24" and $28.
- A good design does not run the LED at maximum power. That's only an upper limit and less efficient, hotter running, shorter lived... not that any will last 50K hours like so many claim, but I've seen generic LEDs driven at full power that lasted less than 1000 hours!
- A 1W driver cost vs 3W isn't relevant because it's not one driver per LED, rather parallel series of LEDs. They are usually wired 3 LEDs in series, though that doesn't divide into 40 total evenly so it could be 2 in series or a resistor added to the last series, but it doesn't change the overall circuit much, just the current regulation number and minimum input voltage which is always going to be designed lower than the 12V to 24V vehicle electrical systems it's meant for, so let's go with 3 average.
Instead of 3 in series with 3W LEDs, they'd still put 3 in series with 1W LEDs since the forward voltage is nearly the same, but need more series of 3 in parallel using 1W LEDs to total the same output power. It's actually going to take a more expensive driver to run 1W LEDs to the same output power but the cost difference is still not much.
Comments & Reviews (7)
EDIT1: I noticed further down the web page they post current input: 16A at 12V, 8A at 24V. That is 192W input that if true would indicate you are really getting a 120W bar.
EDIT2: On the other hand, they report the same 16A at 12V, 8A at 24V for their 240W bar, so who knows which bar model those figures really belong to.
A customer review from "Starry" read as follows: "I used a precision digital ammeter and digital voltmeter and measured a current of 6.9 Amps at 12.20Volts. This is a power level of 84.18 watts"
However that's INPUT power before driver losses. If we give them the benefit of the doubt that it's at least 90% efficient which it may not be, that's 76W.
It's not all bad though, you won't get much higher than 76W real drive current for $28 and usually less, though if you buy a more expensive bar with Cree LEDs, you'd get more lumens in the same space IF drive current and all else were equal.
When I buy LED lights on I always open them up if possible to see what LED driver they are using. My most recent purchase of 10W flood lights are using 5W drivers. An older purchase of a 15W recessed light had a 5W driver inside. However I have also purchased some 7W recessed lights that had 7W drivers in them, so not everybody is cheating.
The thing is that if you drive a 3W LED with say 1W of electric power, you only get 1/3 of the light output that LED is capable of. Why would a vendor use an undersized LED driver? To save manufacturing costs is one possible reason. A 1W LED driver is considerably cheaper than a 3W one. Also the size and cost of the heat sink needed is less when the LED is driven at 1W instead of 3W. Most people who look at that 3W LED being driven with only 1W of electric power will not be able to tell they are being cheated because even at 1W the LED will be quite bright.
- 3W is only an upper limit, one that requires higher quality heatsinking, and more surface area.
- Driving an LED at less than full power it becomes more efficient, and lowering die temperature promotes longer life, not just til failure but till permanent lumen reduction (gradual process).
- Driving more LEDs at lower power to equal same total power reduces thermal density at the die, and with these semi-generic, presumably Epistar LEDs, it could be cheaper to use more LEDs than use better heatsinking.
- It's not an undersized LED driver. It's X amount of light, a combination of components that works together to give great value for $28.
- You're not being cheated to get a 3W LED ran at 1W (actually it's much closer to 2W actual drive current) EXCEPT that they make the bogus total wattage claim, but if they didn't, they would just sell you a 76W light for $28, not a 120W light for $28, so you're still getting what you paid for even if misled about the performance.
It stinks to false advertise like that but it's so rampant that nobody can effectively stop it at this point or at least places like feel it isn't in their best interests to interfere so long as the products keep selling.
If enforced truth in lumen specs, the products would look inferior to those with fraudulent advertising almost everywhere else, at other online merchants.
That would allow for more heatsink area in the back, so keeping the heatsink design the same otherwise it could support higher total power, but then you'd need even more LEDs to get there. If you can accept a longer product for more light, they sell those too. This product is about what you can accomplish with 24" and $28.
- A good design does not run the LED at maximum power. That's only an upper limit and less efficient, hotter running, shorter lived... not that any will last 50K hours like so many claim, but I've seen generic LEDs driven at full power that lasted less than 1000 hours!
- A 1W driver cost vs 3W isn't relevant because it's not one driver per LED, rather parallel series of LEDs. They are usually wired 3 LEDs in series, though that doesn't divide into 40 total evenly so it could be 2 in series or a resistor added to the last series, but it doesn't change the overall circuit much, just the current regulation number and minimum input voltage which is always going to be designed lower than the 12V to 24V vehicle electrical systems it's meant for, so let's go with 3 average.
Instead of 3 in series with 3W LEDs, they'd still put 3 in series with 1W LEDs since the forward voltage is nearly the same, but need more series of 3 in parallel using 1W LEDs to total the same output power. It's actually going to take a more expensive driver to run 1W LEDs to the same output power but the cost difference is still not much.
Thank you!