Battery Power
#1
I have 5 Pine64+ 2G models I just received today.  I am planning to build a Wimpy Cluster and starting with 5 to prototype the idea.

The inspiration came from this paper:

http://coen.boisestate.edu/ece/files/201...ter_v2.pdf

In his paper, he created a custom PCB to both power the board from the 5V input and twidle with an LED.

In my setup, I am planning to use the battery input from a standard PC Power supply instead to simplify cabling (and I see the jumper on the board to switch to battery).

The main question I have is do I need to add a ploy (or other) fuse (as he describes) to protect from short circuits?

Also, I cannot think of any reason, but I would not expect a performance decrease just because I am on battery power?

And no, I am not an EE.

Thanks,
-henry
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#2
(06-11-2016, 10:55 PM)clackamas Wrote: I have 5 Pine64+ 2G models I just received today.  I am planning to build a Wimpy Cluster and starting with 5 to prototype the idea.

The inspiration came from this paper:

http://coen.boisestate.edu/ece/files/201...ter_v2.pdf

In his paper, he created a custom PCB to both power the board from the 5V input and twidle with an LED.

In my setup, I am planning to use the battery input from a standard PC Power supply instead to simplify cabling (and I see the jumper on the board to switch to battery).

The main question I have is do I need to add a ploy (or other) fuse (as he describes) to protect from short circuits?

Also, I cannot think of any reason, but I would not expect a performance decrease just because I am on battery power?

And no, I am not an EE.

Thanks,
-henry
Battery power will not decrease the board performance. The poly fuse is for cautious measure and considers a good option.
  Reply
#3
(06-11-2016, 10:55 PM)clackamas Wrote: The main question I have is do I need to add a ploy (or other) fuse (as he describes) to protect from short circuits?
Hi Henry,
Since you're using multiple pine64 boards in an array, I would be tempted to put standard glass fuses inline with the power supply line into each pine64. A polyfuse is good as it self-resets, but that can also hide a problem, unless you know that the device has triggered the fuse and why. Plain glass fuses are cheap, and if you were to put 1.5/2A fuses on each pine64, I don't see why they would blow those fuses unless something went wrong (as I have yet to see a properly working pine64 need more than 800ma @ 5v for just the main board+wifi, without the LCD or peripherals on the USB). 
At an absolute minimum, you would want a single fuse between the power supply and the cluster, rated at just more than what you expect the maximum power from the cluster to be (for 5 pines, a fuse between 7.5A -10A would do), so the power supply doesn't get overloaded (although modern computer power supplies do have good self-protection circuitry in them, and generally shut down if anything goes wrong, but it's never good to blindly rely on that!). 
Pete
  Reply
#4
(06-12-2016, 06:00 PM)pfeerick Wrote:
(06-11-2016, 10:55 PM)clackamas Wrote: The main question I have is do I need to add a ploy (or other) fuse (as he describes) to protect from short circuits?
Hi Henry,
Since you're using multiple pine64 boards in an array, I would be tempted to put standard glass fuses inline with the power supply line into each pine64. A polyfuse is good as it self-resets, but that can also hide a problem, unless you know that the device has triggered the fuse and why. Plain glass fuses are cheap, and if you were to put 1.5/2A fuses on each pine64, I don't see why they would blow those fuses unless something went wrong (as I have yet to see a properly working pine64 need more than 800ma @ 5v for just the main board+wifi, without the LCD or peripherals on the USB). 
At an absolute minimum, you would want a single fuse between the power supply and the cluster, rated at just more than what you expect the maximum power from the cluster to be (for 5 pines, a fuse between 7.5A -10A would do), so the power supply doesn't get overloaded (although modern computer power supplies do have good self-protection circuitry in them, and generally shut down if anything goes wrong, but it's never good to blindly rely on that!). 
Pete

Thank you.  That is very helpful.  I am trying to keep the cabling simple so, the glass fuses meet that criteria.  I eventually play to build a 33 node cluster but the 5 boards are to prototype.
  Reply


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