I have a few simple projects under my belt. They were low power so didn’t run across this before. But now I have a project using a lot of WS2811b LEDs (168 of them,) and I can easily get to 2.2A (and beyond if I run them at full white.) Controlled by a knock off Arduino nano. So everything runs on 5v – nano and the LEDs. Battery I’m using is sealed lead acid and says 12 Ah on it, so should run a few hours at 2A.
Short story/question: how to run off a 12v (or a 6v) battery and drop down to 5v - to power everything. Right now I'm set up to run right at 2 amps by limiting the brightness. But future revisions it could bump up the amps. Maybe to 3 or 4 amps.
Long way around...Bear with me, a lot of description of my process to get to the questions.
I am using a small cheap voltage regulator (http://www.readytoflyquads.com/rtf-1v-17v-adjustable-voltage-regulator). No data sheet is given, but a few specs from the above page state:
Non-isolated step-down module (BUCK)
Input 4.75-23V DC
Output 1-17 V (adjustable with small screw on board)
Output current: Rated current 2A (3A MAX)
I’m assuming the 3A max is a short burst at a time. So for sake of this conversation, I’ll say the 2A is the max.
My assumption – before I knew about watts and power, was I could take a battery say a 12v which is under the maximum input, and use this regulator to go down to 5v. After tying this, and running at 2A you could imagine my surprise when I started smelling something hot. Way to hot for my comfort. Too hot to touch. Of course it was the regulator. So I unplugged and started researching. I found a good article (don’t have the link) that basically said, “Yup this gets every noob.” And I learned you need to check power. So the change in volts across the regulator, or other device, (12v down to 5v = 7v) x amps (2A) = 14 Watts. The description on the regulator page doesn’t have anything about watts. I assume I’m going beyond what this little guy can handle.
QUESTION 1:
So this is a lesson of cheap parts and not knowing full specs of it then? Just because something says it can handle 2A doesn’t mean you can run it at 2A since you probably will exceed the watts? And this is the difference of having a data sheet and not having one? Maybe it's a lesson of "with the right heat sink you can run at full amps given on the specs."
My solution – I switched to a 6v battery so now my power is (6-5v) x (2A) = 2 Watts. And it doesn’t get too hot.
QUESTION 2:
What is a good way to power projects from a 12v battery that needs to step down to 5v? For low amp projects the regulators mentioned above are just fine. Maybe better to ask this question: What is a good way to step down 12v (or even 6v) to 5v when you are running a circuit at 2A or even more?
What I’ve read is a linear regulator dissipates as heat and they get hot if running high amps – so I’m assuming the one I used is a linear regulator. And I’ve read a little on switching regulators are better since they don’t dissipate as heat as much as linear regulators. Which I assume would increase the life of the battery as well? I am interested in extending the battery life.
Any good examples of some products or solutions anyone uses to go from 12v down to 5v and run at 2 or 3 or even more amps?
Looking for “off the shelf” part, not make your own with parts on PCB (but would be curious how that is done as well or if it's even worth it.) No need for adjustable, a non-adjustable 5v output would be fine. I've seen LM-xyz parts mentioned but a few posts I've read said they really are for 1A or less. And is that a linear regulator not the switching type?
Short story/question: how to run off a 12v (or a 6v) battery and drop down to 5v - to power everything. Right now I'm set up to run right at 2 amps by limiting the brightness. But future revisions it could bump up the amps. Maybe to 3 or 4 amps.
Long way around...Bear with me, a lot of description of my process to get to the questions.
I am using a small cheap voltage regulator (http://www.readytoflyquads.com/rtf-1v-17v-adjustable-voltage-regulator). No data sheet is given, but a few specs from the above page state:
Non-isolated step-down module (BUCK)
Input 4.75-23V DC
Output 1-17 V (adjustable with small screw on board)
Output current: Rated current 2A (3A MAX)
I’m assuming the 3A max is a short burst at a time. So for sake of this conversation, I’ll say the 2A is the max.
My assumption – before I knew about watts and power, was I could take a battery say a 12v which is under the maximum input, and use this regulator to go down to 5v. After tying this, and running at 2A you could imagine my surprise when I started smelling something hot. Way to hot for my comfort. Too hot to touch. Of course it was the regulator. So I unplugged and started researching. I found a good article (don’t have the link) that basically said, “Yup this gets every noob.” And I learned you need to check power. So the change in volts across the regulator, or other device, (12v down to 5v = 7v) x amps (2A) = 14 Watts. The description on the regulator page doesn’t have anything about watts. I assume I’m going beyond what this little guy can handle.
QUESTION 1:
So this is a lesson of cheap parts and not knowing full specs of it then? Just because something says it can handle 2A doesn’t mean you can run it at 2A since you probably will exceed the watts? And this is the difference of having a data sheet and not having one? Maybe it's a lesson of "with the right heat sink you can run at full amps given on the specs."
My solution – I switched to a 6v battery so now my power is (6-5v) x (2A) = 2 Watts. And it doesn’t get too hot.
QUESTION 2:
What is a good way to power projects from a 12v battery that needs to step down to 5v? For low amp projects the regulators mentioned above are just fine. Maybe better to ask this question: What is a good way to step down 12v (or even 6v) to 5v when you are running a circuit at 2A or even more?
What I’ve read is a linear regulator dissipates as heat and they get hot if running high amps – so I’m assuming the one I used is a linear regulator. And I’ve read a little on switching regulators are better since they don’t dissipate as heat as much as linear regulators. Which I assume would increase the life of the battery as well? I am interested in extending the battery life.
Any good examples of some products or solutions anyone uses to go from 12v down to 5v and run at 2 or 3 or even more amps?
Looking for “off the shelf” part, not make your own with parts on PCB (but would be curious how that is done as well or if it's even worth it.) No need for adjustable, a non-adjustable 5v output would be fine. I've seen LM-xyz parts mentioned but a few posts I've read said they really are for 1A or less. And is that a linear regulator not the switching type?