I am trying to build a portable light source - running (exclusively) on a 12v electrical bike battery. Have it operate approx 1 hour on a charge and produce the maximum possible lumens.

What would be the best approach Led and driver wise? (Strip/die?) A bit lost trying to calculate what components will fit best.

  • 1
    \$\begingroup\$ What is your battery mAh rating? and why should you consider this as an exclusive thing? \$\endgroup\$
    – ahm_zahran
    Jul 6, 2018 at 17:41
  • \$\begingroup\$ Not really limited, assumed might be easier with 12v considering some Led drivers require it \$\endgroup\$
    – Boris
    Jul 7, 2018 at 7:02
  • \$\begingroup\$ You don't need a light sabre for running in the night. You should not try to dazzle the other oncoming runners. \$\endgroup\$
    – Uwe
    Jul 9, 2018 at 9:55

2 Answers 2


Your battery pack consists of 5 parallel strings of 13 series 18650 Li-ion cells.

enter image description here

Type : Li-ion battery pack
Nominal voltage: 48V
Capacity: 12 AH
Specification 13S5P (18650 Cells x 3.7v, 2500mah)
Size: 420 mm x 100 mm x 100 mm
Weight: about 4.2kg

I recommend the 1120 mm (44") Bridgelux EB-Series Gen 2 strips
BXEB-L1120Z-40E4000-C-B3 @ $12 each.

enter image description here

EB Series Gen 2 Linears are designed for use in premium indoor or industrial applications where a high level of efficacy is required. The new generation uses the high-efficacy SMDs to achieve up to 180lm/W, which enables designers and fixture manufacturers to meet DLC Premium requirements. They are designed for linear troffers, pendants and other luminaires in indoor commercial and industrial applications.

Magnified photo of an EB strip. It is about 1" (24 mm) wide.

enter image description here

You can easily run these EB strips at 1 Amp in open air without a heatsink.
That would be about 40 watts for ≈7,000 lumens @ CCT=4000K CRI=80

At 40 watts (40V x 1A) with a 46.8V 12 AH battery you should be able to power 12 of these strips (84,000 lumens) for at least 1 hour. This would be the equivalent of over one hundred 60 watt clear incandescent light bulbs.

If you need diffused light, that could reduce the lux significantly.

The project is a mobile art installation

4000K CRI 80 is a middle of the road light source.
If the strips are to illuminate art then a 90 CRI would be better.
The ideal CCT would depend upon the colors being illuminated.
Example: lower CCT like 2700K would bring out the reds much better.

The voltage output of the battery over its discharge cycle will range from ≈47V, full charge, down to 39V cutoff.

A Mean Well LDD-1000H LED driver for each strip would keep the output consistent and uniform by providing a constant current of 1 Amp throughout the entire discharge cycle. The LDD driver would add a cost of about $5.00 per strip.

The LDD a fixed constant current source with no dimming.

enter image description here

enter image description here

  • \$\begingroup\$ Great, sounds like multiple Samsumg LM301B would be the best - and switch off some to control brightness and batter usage. Has anyone done a similar project and can point to all parts need to buy or perhaps even a write-up of their work? Thanks! \$\endgroup\$
    – Boris
    Jul 7, 2018 at 7:12
  • \$\begingroup\$ I have done many similar projects. I need to know exactly what kind of battery you want to use, physical size of end product, how bright you want it to be, and what you are trying to accomplish. Can you design a PCB? \$\endgroup\$ Jul 7, 2018 at 22:43
  • \$\begingroup\$ The project is a mobile art installation. The battery originally planned was something like this: Electric scooter battery (A quality mobile powersource at ~$300) \$\endgroup\$
    – Boris
    Jul 8, 2018 at 7:25
  • 1
    \$\begingroup\$ Why only 1 hour? Look at Bridgelux EB-Series Gen2 and Samsung F-Series Gen 3 strips. They are currently the least expensive (600+ lumens per $1) way to produce lots of lumens. I do not trust eBay battery vendors especially a product with only 2 five star reviews. Can you find the "BOTTLE" without the 65 Li-ion 18650 cells in it and buy the batteries separately? I do not like using no name batteries. For 18650 cells I like Panasonic and Samsung. I prefer Bridgelux: digikey.com/products/en/optoelectronics/… \$\endgroup\$ Jul 8, 2018 at 21:59

Suppose the battery is 10AH, then you can draw 12x10 = 120W for 1 hour, so you can use a DC-DC converter and a 100W, 32V LED panel. You can get the whole kit on Amazon for ~$35.

  • \$\begingroup\$ How could a 12V battery power a 32V LED? \$\endgroup\$
    – ahm_zahran
    Jul 6, 2018 at 17:38
  • 2
    \$\begingroup\$ @AhmedM.Zahran It's in the nature of DC-DC converters to do that sort of thing. \$\endgroup\$
    – stark
    Jul 6, 2018 at 17:43
  • \$\begingroup\$ 100W 32V LED, means the LED is consuming about 3 amps of current. How 10Ah battery is going to last in an hour? \$\endgroup\$
    – ahm_zahran
    Jul 6, 2018 at 17:47
  • \$\begingroup\$ @AhmedM.Zahran 10AH = 10A for 1H. 100W at 12V = ~9A (leaving a little for converter efficiency). \$\endgroup\$
    – stark
    Jul 6, 2018 at 17:52
  • \$\begingroup\$ @Boris Of course if you run this a whole hour, you probably won't be able to start your bike because the battery will be flat, but you asked for the "maximum possible", not necessarily the most practical. \$\endgroup\$
    – stark
    Jul 6, 2018 at 17:57

Not the answer you're looking for? Browse other questions tagged or ask your own question.