# parallel led array

Discussion in 'LEDs and Optoelectronics' started by lightman, Nov 6, 2015.

1. ### lightman

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Nov 6, 2015
hi fellas this is my first post i am wishing to build an IR Illuminator for ghost hunting i want to make it from 3 5w high power ir led and wire it in a parallel led array so each led gets same power i worked out if i run them of a 3.7 volt battery i would need to add a 2.7 ohm resistor to each led so not to over power the led thing is i am only getting around one and half hours continuous use so what would i need to do to run same set up of two 3.7 battery's any help please fellas ?

2. ### Gryd3

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Jun 25, 2014
Sounds like you know what you are doing... you scared me when you said parallel LEDs, but you are actually using a resistor on each one. Thanks! That gets missed by a LOT of people.
As far as running with two batteries, simply connect the two batteries in parallel and your light should last twice as long!

*Special Note : When you connect two unbalanced batteries in Parallel, you run the risk of causing current to flow between batteries. Never connect a fully charged battery in parallel with a used battery!
The battery with the higher voltage will actually cause current to flow backwards through the battery with a lower voltage. So either connect them when they are both freshly charged, or when they are dead. You can always use a multi-meter to confirm the voltage is the same prior to connecting them.

3. ### lightman

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Nov 6, 2015
hi thank you for your help the new battery holder olds two battery's not sure I understand wire the two battery's in parallel do you have a pic sorry for being so dum

4. ### lightman

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Nov 6, 2015
its ok I see what you mean two single battery holders + soldered + - soldered to - with just a single wire from both battery's + and - is that right ?

Gryd3 likes this.
5. ### dorke

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Jun 20, 2015
A solution for that problem is using Schottky diodes like this:
The diode will drop about 0.3V(typ.),should be fine with a 3.7V bat. and IR led.

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6. ### dorke

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Jun 20, 2015
GHOST HUNTING ???
Do post a pic if you catch one...

Anyways,
as per my post above a good choice would be this diode:
PMEG3050EP
If you have the Battery and LEDs datasheets post them here.

7. ### Gryd3

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Jun 25, 2014
Absolutely, but dorke posted a safer solution that wont require you having to balance your batteries before hand

8. ### lightman

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Nov 6, 2015
hi led data
Emitted Color : Infrared IR 850nm 5w
Viewing Angle: 135 degrees
DC Forward Voltage (VF): 1.4V
DC Forward Current (IF): 1400mA
Maximum Pulse Voltage: 1.7V
Maximum Pulse Current: 2000mA
battery data GTL 18650 3.7v Li-ion Rechargeable Battery 5300mAh

9. ### lightman

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Nov 6, 2015
would I need a diode on each + wire and what size would I need to get thank you so much for your time and help

10. ### lightman

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Nov 6, 2015
it will not let me open your diode link can you get them on ebay many thanks

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Nov 6, 2015
12. ### dorke

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Jun 20, 2015
yes, you need 2 diodes on each + wire, as shown in the #5
the diode is PMEG3050EP here is it's data sheet:
http://www.nxp.com/documents/data_sheet/PMEG3050EP.pdf

So,

see here(test of a GTL 2600mAh):

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Jun 20, 2015
14. ### lightman

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Nov 6, 2015
seems that make of battery are not very good were can I buy the diode I need please many thanks for your time and help

15. ### lightman

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Nov 6, 2015
your a star I will get two to try thank you so much for your help

16. ### Colin Mitchell

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Aug 31, 2014
Basically you cannot drive high power LEDs from a 3.7v battery and include a diode and current-limiting resistor.

You do not have enough head-room - any ghost buster will tell you that.

17. ### lightman

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Nov 6, 2015
that's cool Colin I will forget the diode

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Nov 6, 2015
19. ### dorke

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Jun 20, 2015
Colin,
Where does your bullshit come from...?