NuPhy Keyboard Battery and Charging Protection

Dear Users:

Some of you have, through various channels, sent us questions about overcharge protections on NuPhy's keyboards, and the general quality of their batteries. The following is a statement of facts and the measures we have taken and will take to address this topic.

Generally speaking, overcharge protection circuits can be divided into two categories, those built into the battery, and those fixed on the keyboard's PCB. We will start with the first kind: all NuPhy keyboards are, and have always been supplied with batteries that provide overcharge protection. For the Air 75/60’s 1N3339115 battery, the protection circuit is implemented in the form of a ME4057 constant current/voltage charging IC. The batteries have also been certified for South Korea's KC62133-2 standard(the Korean version of IEC62133-2 which includes overcharge tests), due to export requirements we have to meet. Additional information, including the certifications of this battery and datasheet of ME4057 can be downloaded here.

On-battery overcharge protection circuits however, don’t usually guard against high input supply voltage. The ME4057-D IC used on the batteries of Air75/60 produced and sold before September 2th, 2022, is rated for use with VCC<6.5V, while all NuPhy keyboards produced afterwards use ME4057-N, which increases its maximum VCC rating to 9V. As NuPhy keyboards were designed with standard 5V/1A chargers in mind, the battery’s built-in protection was believed to be adequate, and onboard voltage-regulators were not implemented. The growing use of high-power high-voltage fast charger for keyboard charging, however, had led us to produce revised designs include onboard voltage regulating ICs at the end of year 2022, which protect the batteries up to 16V of input supply voltage and at the time of publication, have been rolled out to all NuPhy keyboards in production. In the mean time, our recent analysis of customer complaints data have shown that, while cases of swollen batteries remain far and few between overall, with the reported swelling rate several times smaller than the industrial average, users of the presale batch of Air75 sold between September and November 2021 are disproportionately affected during the last two months, whether this could be attributed to natural degradation of the battery or the use of fast chargers is still being actively investigated.

Deeming that we should, to the maximum extent possible, strive to meet all of our users’ expectations of safety and peace of mind, especially in this period of transition, we decide to extend the warranty coverage of all issues related to batteries and charging components sold as parts of all NuPhy keyboards by one year. This change will be effective starting today.

Please be assured that NuPhy takes all quality/possible quality issues very seriously, that we review all of your advices and suggestions and take them into considerations when we make decisions, and will continue to do so as a company.

Thank you for your support,