Hi all,
I have been looking everywhere but I can not find the maximum amperage/voltage for these crimp types:
-JST XD
I am working on a 12 V system, although it would be interesting to know the answer for other voltages too.
It would be easier to look up the maximum current for the wire guage. If that is too much for your application then you don't have to worry about the connectors.
Thank you for your answer!
I have thick wires and according to their specifications, they do not pose any issue. That is the reason why I wanted to check on the connectors, in case they are "the weakest slab in the chain".
JST XH series are 3A, I've seen both 1A and 3A for Dupont headers, I'd play it safe with the lower figure.
JST XH will work for AWG 22-26 and rated for 3A using 22 gauge. You need a reliable crimper or pre crimped wires to even approach this rating.
Further if you are pushing your current rating to max, you will have to consider additional factors including temperature, wire length, peak and steady current and so forth. Also consider if what you’re plugging into can handle that amount of current.
As you go up in voltage your current drops for the same amount of power. This relationship is best explained by Ohms law and Watts law. For our low voltage system consider the current for the wires and connectors.
5V 1A and 12V 1A are different in terms of power. But can be passed through the same wire or connector that’s rated for 1A.
Hope this short explanation helps and perhaps leads you to understand this better.
If you are thinking of putting high current through a protoyping breadboard, don't!
Thank you again everyone for your answers.
I crimp the cables rather than soldering them. I have heard only good things about crimping.
To get a bit more in detail, I am building a system with several modules. They could all act "one at a time" but I would prefer if they could all act simultaneously. My biggest problem is a Peltier system as it draws the most current when powered. These are a list of interconnected problems:
-Problem 1: 1 Module uses 24 V, the rest 12 V. I then need a voltage regulator but I do not know which one. Maybe:
-Problem 2: the voltage (24 V) is too high to go through a jack barrel (7-12 V recommended, 5 A max), so I do not know what adaptor to use to power the system. I have been recommended to power the arduino with a different source (because of ground bouncing).
-Problem 3: the peltier draws too much current. I thought of either run it solo and don't design the system for the peltier running at max (a pity) or to look for connections designed for higher amperage.
the barrel jack should be fine at 24V. I believe this is more of a convention than a rule so people don't accidentally plug in 24V to a 12V device.
24V 2.5 A should be ok.
For power supply planning, selecting the wires and connectors should be the last step. Unless you're working with high voltage (>50V) just about any connector or wire will offer sufficient insulation, and you only have to worry about the current flowing through those wires and connectors.
The start is this list of your devices with their current and voltage requirements. I see you did that - two issues: an Arduino takes 10-100 mA at 5V (depending on the version of the board), the 150 mA for the servo looks suspiciously low. Check the value for the stall current of your servo.
So you need to plan your power supply for about 1A at 24V, 8A at 12v, and 1-2A at 5V. Seeing those numbers I'd probably be looking at a beefy 12V supply, a boost converter for the 24V and a buck converter for the 5V. Note that 1A at 24V output requires just over 2A at 12V input, and the 1-2A at 5V output roughly 0.5-1A at 12V input.
Add that together and I'm getting close to 15A, so maybe a 20A supply for your 12V.
Now you can start planning for wiring. Especially that Peltier module needs good wires, 1.5mm2 comes to mind. The rest can be thinner wiring, 0.5-0.75mm2 will do. Use appropriate connectors, you may look for screw terminals for the higher currents.
The Servo needs at least 1A.
Thank you everyone for your answers, especially wvmarle.
I really appreciate you showing your train of thought, calculations and devices required to be purchased. In a couple of paragraphs you solved all my issues!
I have never worked with step downs or buck converters and thanks to you I now understand how to put all together. I just ordered all the parts.
The great thing about step up/down converters is their efficiency. In an ideal one power in = power out, so if your output is 1A at 5V (total 5 W), the input is also 5W so at 12V that'd be 5/12 = 0.42A. Of course real life efficiency is a bit less, typical 90-95%, so you have to compensate for that.
Good luck with the project!
Thanks for the info! I bought two models and I will check on efficiency as well.
I bought this model that I saw everywhere:
I have been trying to buy the right cable to avoid issues but I have not found anything suitable. Can you guys point at me in the right direction?
I bought the 30 A version because of the low extra cost. I am aware that it needs extra ventilation. If someone thinks I made a poor choice, I am happy to get recommendations on a different power supply as well.
Lots of different wires are readily available. I don't know how you can not find anything suitable. Setting the wrong requirements maybe?
Indeed, that was the issue. Thanks again for your help!