Battery to power HUB + RPi + Wifi adapter + Webcam - Amps?

[cupcake]

There are various threads out there on various battery options. But I can't seem to find one that covers powering a system of an RPi plus some power hungry USB devices.

I'm currently using an AC adapter to power a HUB that then power/connects the RPi, a wifi adapter, and a webcam.

Powered HUB: CyberPower CPH420P
Wifi: TP-Link WN722N
Webcam: Microsoft VX-3000

The HUB has a stated input of 5V and 2.6A.

Question is: What amp rating will I need from a battery to power my system?

I'm looking at various battery sources. Many of them only provide 1-1.5A. Few seem to provide 2A or more.

Price is obviously also a factor. I'm currently looking at this one (link) - which claims to provide 12000 mAh with 5V/2A. Or this one (link) which claims to provide 10000 mAh with 5V/2.1A.

[CCitizenTO]

First, I will talk a bit about batteries. I am going to assume you want to use rechargable batteries and probably NiMH ones since you are looking at rechargable ones already.

Batteries provide a voltage which is usually 1.25V for most rechargables (1.5V for non-rechargable alkalines). It is also easy enough to find batteries which provide about 2500mAh in AA Cells. The thing is if you wire in series you increase the voltage (but not the capacity). If you wire in parallel you increase the capacity (but not the voltage).

1 Battery = 1.5V and 2500mAh. 4 Batteries in Series = 5V and 2500mAh.

Now if you kick it up to a rechargable D cell and set them up in series... The NiMH ones have 2200mAh-12,000mAh. I see about 10,000mAh as pretty standard.

Basically how long you want to run on battery is a determining factor to what you want to do. Batteries will deliver as many amps as needed within reason (if you draw too many it's posible for bad things to happen). They also only supply the amount of amps that the load demands of them.

2500mAh / 2600mA = .96 Hours (57 minutes)
10,000mAh / 2600mA = 3.84 Hours

(NOTE: If a load was like 10,000mA was put on a 2500mAh battery it'd only last 15 minutes! Batteries give as much amps as the load demands.)

Really if your load is smaller than your maximum it could last much longer. If you run at half load it'll run for almost double the durations listed here. I dont think that your Wifi and Webcam use 500mA each so your not looking at like 1700mA.

[cupcake]

Batteries give as much amps as the load demands.

Is that always the case? I'm confused by various rechargeable batteries and power banks claiming a maximum output of something like 1A. Or is that specific to batteries where the output is provided by USB?

[cupcake]

probably NiMH

I figured NiMH would be the easier choice as they are available in 5V, whereas LiPos all seem to be available in multitudes of 3.7V - requiring some regulation in between. Correct me if I'm wrong here.

[CCitizenTO]

I believe so...

However, the voltage decreases somewhat until it gets to a point where it wont be able to generate a charge anymore. So that 5V battery may actually deliver 5.2V when at 100% charge and 4.8V when almost depleted.