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E-Bike front light Power supply question

projlight

Jun 29, 2023
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Hello everyone.

I have an E-Bike front light question. I have an e-bike that uses a Bafang 500W motor and a 48V 17.5 AH battery.

https://www.amazon.ca/BAFANG-Electric-Conversion-Chainring-Display/dp/B07QH4PZZW/

I purchased a Magic Shine ME2000 bike front light

https://magicshine.com/collections/e-bike-lights/products/me-2000
https://www.magicshine.us/wp-conten...ine®-ME-2000-e-Bike-Headlight-User-Manual.pdf[/img]

a few weeks ago. The light requires 12V, 24W to reach its max. Lumen output of 2000 lumens.
I got a buck converter to drop the voltage from 48V to 12V:

https://www.amazon.ca/dp/B0789WJLGM

I split the battery output in parallel with this splitter:

https://www.amazon.ca/dp/B0B4R5LCF6

After connecting the light, I was disappointed with the light output. I have a 500 lumen (Light & Motion) stand-alone light and it is brighter than this one although it has a quarter lumen output of the ME2000.
The manual states that the light requires 24W of power to operate at full 2000 Lumens. I measured the current draw and it is 0.21A on high, 0.14A on medium and 0.1A on low. Obviously, that is not enough current to drive this light properly. Also, the light enclosure is cool to the touch (the 500 lumen light gets very warm / hot)

So, to remove the buck converter from the picture, I connected the ME2000 light directly to a 12V 1.5Ah dewalt battery. There was no improvement in the light output or current draw. In fact, it was identical.

Any ideas what could be wrong, and how to fix this? Thank you.
 

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kellys_eye

Jun 25, 2010
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The light is faulty - more likely is the fact that the manufacturers over-stated the lumens (a common issue). Return the item as defective and/or get a different one.
 

projlight

Jun 29, 2023
7
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Jun 29, 2023
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Hello kellys_eye,

Thanks for your reply. I'm aware that alot of companies overstate the lumens, however, this company, Magic Shine, seems to have high reviews and it has been in business since the 90s. I have email them and this is their reply

"
...
Your lights are not defective, the lights will get hot under full power output during the process of high lumen value lighting up to extinguishing, but don't worry, most of our series lights have built-in heat sink in the design expenditure, which will be activated automatically when the lights reach a certain temperature.

As your motor output is 0.2AX12V=2.4W, the lumen output is about 240lm-300lm, so it is lower than 500Lumen.
"

I forgot to mention in my initial question that the extention cable that plugs into the barel connector of the ligh is rtather on the thin side. There are no markings on the wires to indicate the AWG value. Would it be possible that the extention cable is too thin to carry the 2Amps needed? The other strange thing is that I'm getting exactly 1/10th the current required. The mutlimeter is reading 0.2 and it's set on a 10A setting of the dial (could I be reading the multimeter wrong?).
 

Delta Prime

Jul 29, 2020
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You have massive I squared R losses show me your setup photo of your rig. Your connections your modifications
 

Bluejets

Oct 5, 2014
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As your motor output is 0.2AX12V=2.4W
This is a bit confusing.
Manufacturer says above quote.........So you are NOT running from the motor output as recommended initially........
Perhaps they are confused as to what you are up to as well.

The mutlimeter is reading 0.2 and it's set on a 10A setting of the dial
Load will only draw what it needs and the circuit dictates.

Also, did you read the bit where there is a daylight sensor in the fitting which reduces light output for (I guess) daytime or higher than normal ambient light..??

All seems rather expensive for a 2 bob Chinese light....I think they see you greenies coming a mile off.
 

projlight

Jun 29, 2023
7
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Jun 29, 2023
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This is a bit confusing.
Manufacturer says above quote.........So you are NOT running from the motor output as recommended initially........
Perhaps they are confused as to what you are up to as well.


Load will only draw what it needs and the circuit dictates.

Also, did you read the bit where there is a daylight sensor in the fitting which reduces light output for (I guess) daytime or higher than normal ambient light..??

All seems rather expensive for a 2 bob Chinese light....I think they see you greenies coming a mile off.
I'm splitting the battery in parallel with a v-splitter cable. I'm using the DC-DC buck converter to droip the voltage from 48V to 12V. It's a 17.5AH battery. The buck converter is 12V, 10A, 120W. I'm testing the light in near-complete darkness at night in my garage. No urban street environemt will be that dark.
 

projlight

Jun 29, 2023
7
Joined
Jun 29, 2023
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You have massive I squared R losses show me your setup photo of your rig. Your connections your modifications
I've simplified the setup to make it easier to follow. I've connected the light to a 12v, 1.5 AH dewalt battery. The current reading is exactly the same, as that on the previous setup (0.22A), far lower than what it needs to draw (2A).

I have a 30W motorcycle light. When I connect the motorcycle light to the same 12v battery, I get a 2.8A reading. Could the light be defective?
 

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Last edited:

Alec_t

Jul 7, 2015
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The light you have clearly isn't in accordance with its advertised ratings. That is contrary to Consumer Law in Europe and the UK (at least).
 

projlight

Jun 29, 2023
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Jun 29, 2023
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More than 'could' - the word 'is' comes to mind.
I was hoping this would not be the case. Exchanging/returning this light most likely will be an 'interesting' process.

I did some more research on the light itself, and it is using 2x Luminus SST-40 LEDs. The LED is capable of outputting 1800+ lumens. Shouldn't the combined lumen output of the light be in the range of 3000+ luments and not the 2000 lumens they claim? Something about this light does not 'add up'.
 
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