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[RC-3141]

Hi,
I'm looking into electronics for my kit, and I know enough about all of the different numbers and units that I'm confused and not sure how to proceed. I am planning on mounting lights and fans in my helmet, and I want to wire these off of a USB power source, through switches in my gauntlets, and back up to my helmet.

I am looking at a power bank that outputs 5v and "up to 3A". I'm planning on running fans off of one of the ports in the bank, and embedding lights in my earcaps that will run off of the other port.

The question I have is: Can I run multiple 5v items off of one 5v power source as long as the total amperage doesn't exceed the output? If I wanted to run higher voltage lights off of the 5v source would I be able to step up the voltage?

In two semi-related questions that may need their own threads:
1. Does anyone have recommendations for helmet fans?
2. Does anyone know where you could source unwired/ready to solder LED bulbs? If all else fails, I've got the rest of an LED strip that I can pirate lights off of

[rlobrecht]

The question I have is: Can I run multiple 5v items off of one 5v power source as long as the total amperage doesn't exceed the output? If I wanted to run higher voltage lights off of the 5v source would I be able to step up the voltage?

Yes, you can run multiple items off a single 5V battery pack.  They will all share the current (the Amps).  Most LED lights are going to be less than 5V, but if you did need to step up the voltage you need a boost converter.  A lot of people will use cheap LED flashlights for pre-wired LEDs.  They are typically run off of 3 alkaline batteries (4.5 V).

[Fi-8015]

Hi, as rlobrecht already told, you can run several devices from a powerbank. 3 A seems enough to power everything you could ever stuff into a helmet (for example about 20 fans). In case you should run out of USB ports on the powerbank, you can use splitter cables or hubs to connect more devices.
Using switches on the Gauntlet sounds like a cool idea, but you will have at least 4 wires that you'll have to disconnect in case you want to take off the helmet. Best solution would be a 4 (or more) pole plug connection inside the helmet and at the gauntlet.
I guess most people try to place everything inside the helmet to avoid this complication.
To power devices with higher voltage you'll need a step up or boost converter. I use some like these. I like, that they already come with a micro-USB socket.
I use 5V radial fans for my fan sets. You can also use 12V fans but you'll need a boost converter and they are significantly louder.
Bare or prepared LEDs should be available on ebay, if you don't have a local store which sells single components. I sometimes order at mouser.com as well, if I need exotic parts. They have almost everything.

[RC-3141]

Ok, just to make sure I understand everything:
A) Voltage is consistent across the system and amperage is treated as a pool to draw from? Will having too many amps overload things?
B) If I need to step something up or down, I would use a step-up converter (for up) or resistors (for down)?

Using switches on the Gauntlet sounds like a cool idea, but you will have at least 4 wires that you'll have to disconnect in case you want to take off the helmet. Best solution would be a 4 (or more) pole plug connection inside the helmet and at the gauntlet.
I guess most people try to place everything inside the helmet to avoid this complication.
...
Bare or prepared LEDs should be available on ebay, if you don't have a local store which sells single components. I sometimes order at mouser.com as well, if I need exotic parts. They have almost everything.

I was planning on placing a connector at the helmet and gauntlets, sure beats being stuck in the suit once you get it wired up.

Thank you for the keywords there, I was having trouble finding stuff because I couldn't figure out what words to use when searching.

[Fi-8015]

Yes, your description works for your case.
You'll have constant voltage from the powerbank and all the connected devices should have an operating voltage of 5V, too. Those devices will then draw their required current. The currents of all devices will add together and cannot exceed 3A.
I can't tell you for sure what to expect, but I would say the fans will just turn slower and the lights shine darker, once you should exceed the limit. But drawing that much current will heat up the powerbank anyway so you should try to keep it low.
To reduce voltage for some LEDs, you can use a matching resistor. For other purposes I would use a step down converter.