just for simplicity, the blue sea is wired to be a transfer cable, when it is advertised as a charger. For apple that might be good, or not, Idk. I know apple tablets charge on it, but at what rate Idk. I know that certain tablets won't charge on it, but most will, or should, even if amp limited. A samsung my girlfriend had wouldn't, nexus tabs charged at a lower rate. All devices are different though.
I guess the reason blue sea is wired like that is for apple stuff. I don't keep current on apple proprietary stuff. Nor am I an expert on usb protocol. I'm just an android nerd and I've dealt a lot with usb otg and and trying to find a usb c that would charge at a proper rate. The blues sea doesn't. Nor will it charge anywhere near 2000ma, or even 1300ma.
The blue seas are fine, they aren't garbage, they're going to charge your stuff. They're just a little misleading about they are offering.
some more reading.
B
ut, it gets even worse. A properly designed USB 2.0 port that sees no data activity after a timeout period is supposed to drop from a 100mA current limit to a 2.5mA current limit. Now, there are plenty of USB ports that don't bother with that part of the spec. But some do, and using that "charging" cable will get you basically no charging at all, rather than just 1/5th of what you'd likely get with a proper USB cable.
If you're connected to a charge-only port, and it's up-to-date, you'll follow the USB Battery Charging Standard. Now, it's actually possible to make a cable without the data wires, that follows this protocol... sort of. The convention for the USB Battery Charging Standard, 1.2 version (aka "BC1.2"), is that D+ and D- be connected together. So rather than run all four wires, a "charging cable" could simply short D+ and D- together at the "B" port, to tell your device that you're connected to a charge-only port. And if you plugged that into a charge-only port, you'd get the higher current charge... but as above, if you used a data port, even just to charge.
This will cause even more problems with older devices. Prior to BC1.2, a bunch of proprietary conventions were established to let devices know they were plugged into a charge-only port. This usually involved biasing D+ and D- ports with specific voltages, so that the device would know that it's connected to a charge-only port -- Apple's convention, for example, puts a low voltage on D+ and a variable voltage on D- depending on whether its a 0.5A or a 1A charger. The BC1.2 protocol makes it easy for devices to support both old and new protocols, but using the "charging cable", the kind of charge will not be known by the device under charge -- it's going to assume it's a new-style battery charging port (if D+ and D- are shorted) or it'll be completely confused if there's just no wire there. With current devices, the charging cable does charge correctly if it's made with D+ and D- shorted at the "B" end.
In short, know what you're buying. There's usually no reason to use a charge-only cable in most places. And in fact, since they're made in much lower volumes than standard USB cables, you'll likely pay more for the same length cable, and it won't necessarily work properly.
*https://www.quora.com/What-is-the-difference-between-a-USB-charging-cable-and-a-data-cable