[Galaxy Note 4 Accessories] syngiun:
A quick overview for those who might be thinking about the OEM Samsung wireless charging replacement back cover for the Note 4. I also get into a bit of risk vs cost analysis towards the end.

I have compared both the Qi version and the Powermat version. This information applies to both. They are physically identical. The only difference is which charging standard they support.

Model EP-CN910IBU

Output 5.0v 800mA

S/N RCIFA

MSIP-REM-SEC-EP-EP-CN910IWK

Made in Vietnam

MSRP $39

Be aware these replacement covers add thickness to the handset.

Stock handset (non charging cover) plus glass screen protector: 0.360"

Handset plus EP-CN910IBU wireless charging cover plus glass screen protector, 0.425"

The charging cover adds a net thickness of 0.065." While this doesn't sound like much, it is enough to prevent most cases / enclosures from fitting over the charging cover.

These measurements are taken with a precision micrometer (certified to an accuracy of +/- 0.002")

As a common reference, an average US $0.25 quarter measures 0.065."

Imagine wedging a layer of quarters in between your phone and your case. Chances are it won't fit. Do you really want to use an $800 device with no case? The only case option would be a dimensionally forgiving non rigid rubber bumper.

When used with a Duracell powermat, the charging works as expected, albeit at the slow 800mA charging speed. The sensitivity of proper placement of the phone, centered on the powermat is still an issue. Even a small 0.25" movement out of center will stop charging.

Here are some simple calculations that allow us to directly compare *maximum* charging speeds using the basic electrical formula of Volts x Amps = Watts

Standard Wall charger 5V x 2A = 10W

Samsung adaptive fast charger 9V x 1.67A = 15.03W

Samsung wireless charging cover 5V x 0.8A = 4W

This comparison shows the wireless back covers charge at a rate of that is 60% slower than a standard wall charger and 74% slower than the adaptive fast charger that shipped with our Note 4 devices. In my opinion, this wireless setup is only practical for overnight use and possibly as a trickle charger in an office / desktop environment. It is not practical for use as a primary daytime charging system during frequent and heavy use of the handset.

The cover was $39, the powermat was $50 for a combined cost of $90. Car charging cradles are presumably another $50-$70. As a completely wireless charging solution, this costs about $200 and takes 3-4 times longer to charge.

I purchased this setup as a safeguard against damage to the usb port form a lifetime of plugging in charging cords. I have experienced usb port damage / degradation on previous devices.

Conclusion:

Consider that most of us carry an insurance policy through our provider for about $7 / month ($168 spread out over 2 years.) If you ever use the insurance due to damage, theft or loss, we pay a $200 deductible. Consider that most of us will upgrade to a newer handset within 2 years. This gives us a combined contractual insurance cost of roughly $370 across the 2 year lifespan of the device, and only if you end up replacing the device for *any* reason, not just usb port damage. Otherwise you pay only the ~$170 over 2 years.

The cost of "physical" insurance by way of wireless charging and a rubber bumper case is well over $200 all at the time of equipment purchase.

In my opinion, this high cost and slow speed of wireless charging is not sensible. I will be returning the equipment and returning to corded charging and my favorite case. I will keep the contractual insurance thought At&t. This risk vs cost analysis with corded charging is acceptable to me.