darkside501st
New Member
Driving 10 - 15 LEDs, using 4 CR2450s or a cell phone battery
I was drawn to this site from the following post:
This post was made on another thread back in 2011. I have searched for related articles but didn't find any. I was wondering if anyone could elaborate on how you can drive 20 LEDs on a CR2450 battery.
I will be using 12 to 15 ultra bright 5mm flat top LEDs. I am trying to use 4 CR2450s to drive the LEDs. I am not that technical when it comes to the intricacies of power supplies, required currents, etc. I would really appreciate your assistance if you have any help or advice to offer.
I have looked up a couple different listings for LEDs on ebay and here are the specs:
Listing 1:
color - White
Forward Voltage(V) at 20mA - 3.2 to 3.4
Dominant wavelength(mm)K at 20mA - 5000 to 6500
MCD at 20mA - 16000 20000
Reverse current(uA) Vr=5V - 10
Angle (deg) - 120-140
Listing 2:
Reverse Current (uA) : <=30
Viewing Angle : 180 Degrees
Absolute Maximum Ratings (Ta=25°C)
Max Power Dissipation : 80mw
Max Continuous Forward Current : 24mA
Max Peak Forward Current : 75mA
Reverse Voltage : 5~6V
Lead Soldering Temperature : 240°C (<5Sec)
Operating Temperature Range : -25°C ~ +85°C
Preservative Temperature Range : -30°C ~ +100°C
I have read a couple of articles saying that you can't get the required current from a CR2450 or any other coin cell to drive that many LEDs. Although, I have seen it done and the post I quoted said it is possible so I am trying to find out what is the best way. It looks like the forward voltage for the LEDs I want to use is between 3 - 3.2 volts and the recommended mA is between 20 - 25 mA.
I am not sure what would be the best way to arrange the batteries either. If I just hook them up in parallel to quadruple the capacity it would give the power source a voltage of 3 - 3.4 volts. Would that be enough voltage? I have read that if the power source matches the forward voltage you don't even have to use resistors. Although, when the batteries start to drain and the voltage drops below 3 volts the LED won't even light any more, right? That would leave a lot of unused capacity in the batteries. If that is the case maybe it would be better to hook up the batteries with two in series and two in parallel. This would make the power source 6v and it would double the capacity. I would have to use resistors for sure then. However, resistors unproductively consumes some of the power in the batteries though. Any assistance or recommendations you can provide would be a big help.
PS - this needs to be low profile due to the compact nature of the design. It is going to be used on an LED Arc Reactor. Like the one that Tony Stark/Iron Man wears on his chest.
I was drawn to this site from the following post:
Originally Posted by barry82226 View Post
I'm new to this area. Ive been working on a circuit to turn on 6 leds and blink to conserve power. It will run in 10 to 15 second intervals running off an exising timiming circuit. I'd like it to run off of 2 cr2450 coin batteries or a 6v camera battery. Through my testing LED"s, i found that brightness is a function of current not always mcd's. Looks like 100mA drives most of the small LED"s I tested the best. I'm looking at led driver booster chips (linear LT3591) but not sure how much current it can handle. Also can i get that much current from coin batteries? Need long battery life too. I'm open fro suggestions on LED's as well.
How about giving us the LED's that you plan on using specifications. LED's do not always need the the full current for the intensity you want. As a side note I have built circuits that run over 20 LED's on 1 CR2450 battery.
This post was made on another thread back in 2011. I have searched for related articles but didn't find any. I was wondering if anyone could elaborate on how you can drive 20 LEDs on a CR2450 battery.
I will be using 12 to 15 ultra bright 5mm flat top LEDs. I am trying to use 4 CR2450s to drive the LEDs. I am not that technical when it comes to the intricacies of power supplies, required currents, etc. I would really appreciate your assistance if you have any help or advice to offer.
I have looked up a couple different listings for LEDs on ebay and here are the specs:
Listing 1:
color - White
Forward Voltage(V) at 20mA - 3.2 to 3.4
Dominant wavelength(mm)K at 20mA - 5000 to 6500
MCD at 20mA - 16000 20000
Reverse current(uA) Vr=5V - 10
Angle (deg) - 120-140
Listing 2:
Reverse Current (uA) : <=30
Viewing Angle : 180 Degrees
Absolute Maximum Ratings (Ta=25°C)
Max Power Dissipation : 80mw
Max Continuous Forward Current : 24mA
Max Peak Forward Current : 75mA
Reverse Voltage : 5~6V
Lead Soldering Temperature : 240°C (<5Sec)
Operating Temperature Range : -25°C ~ +85°C
Preservative Temperature Range : -30°C ~ +100°C
I have read a couple of articles saying that you can't get the required current from a CR2450 or any other coin cell to drive that many LEDs. Although, I have seen it done and the post I quoted said it is possible so I am trying to find out what is the best way. It looks like the forward voltage for the LEDs I want to use is between 3 - 3.2 volts and the recommended mA is between 20 - 25 mA.
I am not sure what would be the best way to arrange the batteries either. If I just hook them up in parallel to quadruple the capacity it would give the power source a voltage of 3 - 3.4 volts. Would that be enough voltage? I have read that if the power source matches the forward voltage you don't even have to use resistors. Although, when the batteries start to drain and the voltage drops below 3 volts the LED won't even light any more, right? That would leave a lot of unused capacity in the batteries. If that is the case maybe it would be better to hook up the batteries with two in series and two in parallel. This would make the power source 6v and it would double the capacity. I would have to use resistors for sure then. However, resistors unproductively consumes some of the power in the batteries though. Any assistance or recommendations you can provide would be a big help.
PS - this needs to be low profile due to the compact nature of the design. It is going to be used on an LED Arc Reactor. Like the one that Tony Stark/Iron Man wears on his chest.
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