When dealing with up to 50Amps of continuous power delivery there are some rules we need to follow to make sure all this power flows correctly.
Maximum current and fuses
- Total power continuous (5v, 12v or 24v) = 50Amps
- 5v = 250w
- 12v = 600w
- 24v = 1200w
- Maximum fuse for a single input terminal = 30Amps
- Maximum fuse for a single output terminal = 10Amps
- 5v = 50w
- 12v = 120w
- 24v = 240w
Maximum cables sizes supported
- Input 9.5mm barrier terminals
- Using fork crimp up to 10AWG/5.2mm2 is supported
- Output 5.08mm pluggable terminals
- With wire ferrule a maximum cable size of 14AWG/2mm2 is supported
To support up to 50Amps of power with as little voltage drop as possible the power-5 has 3x 9.5mm barrier block input terminals which can each take up to 10AWG/5.2mm2 cable coming from the same power supply.
As noted on the board each input is rated for max 20Amps thus if you wish to use the full 50Amps capability of the board you will need to hook up all 3 input terminals (both for positive and negative).
! Using fewer input cables lowers total board current capabilities
Suggested input cable thickness
To minimize voltage drop it’s recommended to use at least 3x 12AWG/3.3mm2 cables from the power supply finished with fork style crimps.
Especially for 5v applications even preventing the smallest amount of voltage drop at this point in the setup is advisable so using 10AWG/5.2mm2 or 8AWG/8.3mm2 is preferred. For 12v and 24v this is a bit less important since although the amount of voltage drop will be the same, percentually it’s less because of the higher voltage.
! Using thinner cables then suggested will cause more heat and voltage drop!
Total fuses and rated continuous load
As can be seen above the board can have 12x 10Amp output fuses bringing the total amount of current to 120Amps total but the total continuous rated power however is “only” 50Amps.
While designing your setup you need to take this into account but also please read the following:
Especially with LEDs we’re dealing with very varying or high transient power demands. At one point total power draw might be 30Amps while a few seconds later 70Amps might be drawn. As long as these are peaks and continuous load remains at or below 50Amps it’s fine to use the board like this.
*I recommend using the 50% RGB white values from my power sheets to calculate nominal load
The main reason for the power rating is heat, the more current passes through the board the higher the amount of resistance and thus heat that will be generated within the copper planes and fuses on the board. The boards have been designed to only increase ~25c above ambient when running 50Amps of current through them. In a 25c room that means that the board at it’s hottest point will become 50c. So in a scenario with a widely varying load having big spikes and then lower falls in power demand is perfectly fine as long as the average doesn’t exceed the rated 50Amps.
*If despite the above you do still require more continuous current please consider using a “HC” (High Current) version board
Suggested Power Supplies
There is a dedicated article talking about suggested power supplies (with or without fan) for your 5v, 12v or 24v project.
Spreading the heat
One thing to take into account when designing your setup is to spread out the potential heat where possible. In designing a system I often speak about edge connections and middle connections with LED strips or LED pixel strings. Roughly speaking an edge connection will draw about 4Amps maximum and a middle connection double that.
When wiring these up to your powerboard try and spread out the high current demand wires over the board with low or medium current demand cables in between. This will allow for the best usage of the power planes on the board (lowering voltage drop) and also spreading out the heat to a larger area keeping the board cooler.
[flir image of localized heat vs flir image of spread out heat]