The two standards of Type-C power charging are Google Universal Type-C Charger 60W and the Apple 29W USB Type-C Power Adapter which were the first two USB Type-C chargers made available in the market respectively.

Apple's USB Type-C Power Adapter, the 29W USB-C Power Adapter, provides 29.6 watts (14.8 volts at 2 amps) or 12.5 watts (5.2 volts at 2.4 amps). It's a lot smaller than the Google Universal Type-C Charger 60W which provides 15, 36, or 60 watts.

I purchased the Apple 29W USB-C Power Adapter at the Apple Store in Westfield Valley Fair Mall in Santa Clara, California.

You'll want to only use Apple's USB Type-C Power Adapter with the Apple MacBook (Early 2015).

To look at the Apple 29W USB-C Power Adapter's support of power, we used the USB Power Test App from Granite River Labs with the Granite River Labs USB Power Delivery Compliance C2 Tester to produce the following test results.

The USB Power Test App first negotiates a power contract for every PDO supported by the Apple 29W USB-C Power Adapter, and increases the load gradually to find the threshold where over current protection (OCP) kicks in and voltage and current start to drop for safety reasons.

The USB Power Test App also reports out all the PDO's supported by the Apple charger and their OCP thresholds.

PDO	OCP (A)
PDO#1 Fixed: 5V 2.4A	2.8
PDO#2 Fixed: 14.8V 2A	2.29

The USB Power Test App takes this data to produce an I-V curve which graphically shows the relationship between voltage and current for each PDO. We can observe as the current increases beyond the OCP threshold, the voltage immediately shuts off.

The USB Power Test App can also use the Granite River Labs USB Power Delivery Compliance C2 Tester integrated with the GW Instek APS-7100 programmable AC power supply to compare the charger's power output vs power input so that power efficiency can be measured and compared to regulatory limits from United States of Energy (DOE) Level VI or European Union's CoC Tier 2 requirements. We can repeat the power efficiency tests for different PDO's, current load conditions, and different AC input ranges, allowing us to get a complete picture of power efficiency ranges across all different usage scenarios.

Using the USB Power Delivery Compliance C2 Tester from Granite River Labs to run just a subset of the full USB Power Delivery compliance test suite, unfortunately all compliance failures were observed for the Apple 29W USB-C Power Adapter so just be careful when using this charger.

USB-IF High Level Mapping Summary

Sl No	Test Category	Test Group Description	Test Result
2	PHY_PRIMARY_RX	BMC Physical Layer Receiver	FAIL
3	PHY_PRIMARY_MISC	BMC Physical Layer Miscellaneous	FAIL
4	PROT_PRIMARY	Protocol Specific Primary	FAIL
5	POWER_PRIMARY	Power Source/Sink Primary	FAIL

Result Summary

Sl No	Test ID	Test Name	Test Result
3	TDA.2.1.2.2	TDA.2.1.2.2 BMC PHY RX INT REJ	FAIL
4	TDA.2.1.2.1	TDA.2.1.2.1 BMC PHY RX BUSIDL	FAIL
5	TDA.2.1.3.1	TDA.2.1.3.1 BMC PHY TERM	FAIL
6	TDA.2.1.3.2	TDA.2.1.3.2 BMC PHY MSG	FAIL
7	TDA.2.2.1	TDA.2.2.1 BMC PROT SEQ GETCAPS	FAIL
8	TDA.2.2.2.1	TDA.2.2.2.1 BMC PROT SEQ CHKCAP P PC	FAIL
9	TDA.2.2.2.2	TDA.2.2.2.2 BMC PROT SEQ CHKCAP NOMARK P PC	FAIL
13	TDA.2.2.7	TDA.2.2.7 BMC PROT BIST NOT 5V SRC	FAIL
15	TDA.2.2.9	TDA.2.2.9 BMC PROT GSC REC	FAIL
17	TDA.2.3.2.1	TDA.2.3.2.1 POW SRC TRANS P PC	FAIL