The China smartphone market has been somewhat slow to jump on the wireless charging bandwagon despite Samsung and later Apple including wireless charging as a standard feature in successive flagship models. One possible theory for the somewhat tepid response from China Inc. was that higher power and faster wireless charging was needed before wholescale consumer adoption would really take off – providing charging speeds that closed the gap with traditional wired or plug-in charging.
Oppo and sister company OnePlus have both made significant wireless charging announcements within the last month that are likely to change the adoption dynamic in China and reshape the future of wireless charging.
OnePlus released the 8Pro model with ‘Warp Charge 30 wireless’ – capable of a whopping 30W wireless charge to take the smartphone from 1-50% in just 30 minutes. This compares favorably to a plug-in wired charge of 23 minutes. The 8Pro marks a number of firsts for OnePlus as this is their first model with wireless charging. It also marks a foray into the higher-end phone market retailing at around $899.
OnePlus has deployed their largest battery (4510 mAhr) to date in this 5G-ready model, which is certainly needed to help 5G users through the day on a single battery charge. In general, we are seeing 5G phones with larger batteries to support increased functionality which will require faster wireless and wired charging speeds.
The 8Pro is supported by the Warp Charger Transmitter stand which provides easy screen viewing while on the charger. The stand design optimizes natural thermal convection which is further augmented by fan cooling to facilitate higher charging speeds. OnePlus has included an interesting feature that reduces the fan speed at night when the need for fast charging is not so critical. This reduces any possibility of annoying audible noise from the fan placed on a bedside table while sleeping.
The Warp 30W speeds can only be achieved when the OnePlus Warp Transmitter and 8Pro model are used in combination. The devices recognize one another and enter into a proprietary mode of fast wireless charging.
However, the good news is that the 8Pro is certified to the Wireless Power Consortium (WPC) Qi standard with up to 10W of charging on any Qi-certified Extended Power Profile (EPP) charger available today. This is a significant improvement from the Qi Baseline Power Profile (BPP) of 5W which was previously the common denominator for wireless charging.
Within the same week, OnePlus’s sister company, Oppo, set a new land-speed record of 40W wireless charging with the announcement of their Flagship Reno Ace2. The technology known as ‘AirVOOC’ charges the 4000 mAhr battery in under one hour.
The Oppo Ace2 charges at up to 40W on the AirVOOC wireless charging pad (image courtesy of Oppo)
Similar to OnePlus, the Oppo Ace2 only supports 40W when in proprietary charging mode with their new AirVOOC wireless charging pad. However, both smartphone receiver and transmitter are certified to the WPC Qi standard for 10W charging.
Interestingly, both Oppo and OnePlus have included the reverse wireless charging feature – the ability for the smartphone to act as a power source (or transmitter) and provide charge to another phone or smart accessory such as a smartwatch or earbud case.
Things are set to heat up over the summer with both Xiaomi and Huawei announcing plans to introduce high power 40W models…but where will it end?
Well, the answer is somewhat unclear at this point, but the limiting factors are the efficiency of the wireless charging transmitter and receiver power paths – including the coils and the power semiconductors, the thermal-mechanical design of the wireless power transmitters and the efficacy of the forced cooling used, the surface area and the tolerable surface temperature of the phone – no one feels good when picking up a ‘hot’ phone from a charger. Another very important issue is being able to accurately detect the presence of a foreign metal object between the transmitter and receiver. This becomes more tricky at higher power levels:
“Ye canna’ change the laws of physics, Captain!”
- Montgomery “Scotty” Scott Chief Engineer, Starship Enterprise to Captain James T. Kirk
…or can you?
For more information on the physics of wireless charging, visit renesas.com/wirelesspower.
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