Suggestions for a safe-n-fast charger for a bunch of 6th gen iPod Touch Devices? I have about 30 iPod touch devices that connect to a charger with multiple ports on it.

There are 4x 5V/2.4A ports and 4x 5V/1A ports on the device that charges them.

It seems as though the the 5V/1A devices never get charged but I read that the for the Apple cube chargers that come with the devices they are actually the correct ones.

These devices are used until their power is drained and then returned to the charger as evidenced by how many of them I pick up on the charger read please enter pin number after restart.

The 5V/2.4A charger seems to charge them faster, but the 5V/1A appears to be the correctly rated ones.

The voltage (a.k.a. electrical pressure) going into the devices is the same on both port types, but the amperage (a.k.a. the amount of electricity in the circuit) is much greater on the 5V/2.4A ports;

As I understand electricity, it's a bit like plumbing where too much water will cause a pipe to burst, and in electrical systems, too much electricity (amps) will cause a wire to catch on fire, they are sort of analogous. 

I also know that if a battery is fully charged, you really shouldn't leave a device plugged in, it's bad for the life span of the battery.

So my question is:


Is it dangerous to be using a charger that uses more than the recommend amperage, or can you get away with a little bit more?
How can I ensure that these devices are taken off the charger when they are full?
Excess amperage cannot "force" its way into a device (that's the danger of excess voltage).  A device will only receive what it draws.
That is an interesting question with a more nuanced answer:


'Smart' USB chargers, like those found on Amazon, determine the amperage they provide based on the draw trends of the plugged-in device; as long as the device is drawing, they will provide.  However, some can detect and identify the sharp drop-off of draw that accompanies the end of the charging cycle and cut power from the port.

You can find more info about this kind of thing from this answer:  https://electronics.stackexchange.com/questions/121366/how-do-usb-charging-and-smart-charging-ports-e-g-ankers-poweriq-work