Chargerless

Why Chargerless?

Timespan: Jan 2025-now

Published: 2025-08-23

Hello!

Usually I write up a project after it's done, but this time I'm going to explain it to you as it's happening. Check out the website at chargerless.xyz


Chargerless Manifesto

Between 20-40% of the US adult population owns a fitness tracker, and I haven't met a single person who likes how they look. At best the wearable is tolerated, "discreet enough" ; at worst it sticks out like a stain on a nice white shirt.

Chunky, chunky, chunky

Chunky, chunky, chunky


But do wearables today "earn their keep" through their functionality in spite of how they look? No! Outside of the top 1% most fitness-brained users, I'd argue that everyone else mostly uses it to check the time. That is, when their device isn't dead.

What's up with this? If everyone is wearing ugly bricks on their wrists, why hasn't anyone showed up with a nice, sleek, "looks like jewelry" wearable yet? The answer is an old way of thinking about the core component that all wearables share: the battery.


Oops! All Battery

Oops! All Battery


It goes something like this: the engineers say "this feature needs this much power per day", and the designers say "this should only get charged once a week", then they ship the product. Since everyone has access to the same battery technology, this means that today's wearables all carry around 200mAh of lithium to power their sensor and communication stack, which is why they're all the same size and can barely last a week.

Can we do better?


Going Chargerless

Chargerless is a rethinking of the way personal devices have always been powered. Instead of making the user top up their watch every day, what if wearables charged themselves just by being worn around? What if, like the previous generation of self-winding watches, our wearables could power themselves using the heat or light or motion they see every day?

First, it'd be incredibly convenient to never worry again about charging your watch. And as a second order effect — if your wearable is always charging, we can use a much smaller battery to get the same functionality that we're used to: heart rate, sleep, and activity tracking without any of the hassle.


Why now?

Energy harvesting has been studied for decades, but only recently have low-power microcontrollers caught up. The current generation of chips can run sensors, process data, and transmit signals wirelessly, all from a silicon chip smaller than a salt grain — the primary limitation is a way of thinking about power: how to use it and where it comes from.


Now is the right time:


Financials

A 2019 Pew Research survey reports that 21% of US adults regularly wear a fitness device. Applied to the US, we get ~70 million devices in circulation and a market size of ~80 B (source).

Chargerless is more fashionable and convenient than any other tracker, appealing to both current fitness tracker users and non-users. But how many people is that? An NIH study reports about 20% of current and ex-users dislike the aesthetics or short battery life of their device. This is a sizable chunk of the existing user base. We will also mention that this does not account for any non-users for whom the "chargerless"ness pushes them to finally get a tracker. If we converted only existing users, our userbase would have ~14 million devices in circulation.


Marketing

  1. More data, more insights. Today's trackers can tell your sleep impacted your day, but not much more, which makes it hard to justify the daily maintenance. We want to do more than that, to expand the data sources that a user can analyze and self-improve upon, and deliver novel insights across the mind-body axis.
  2. Modern wearables do not lean into the social spread factor because the modern wearable is a bad gift — it looks like a device, and needs daily maintenance. Chargerless can be gifted to your grandma or your kid or your dog because it works "for free" and has a minimal look, and we'll focus marketing on families, couples, and friend groups, which we believe is a stickier way to get people to care about their health, and is an angle that other wearable companies can't compete on.

Our target audience is primarily people in their mid-20s to late 40s — with friends and family members to care about and keep up with through day-to-day wellness. A lot of outreach will happen via word-of-mouth, gifts, being active on forums, and I will also tweet a lot. We'll also focus a bit on traditional web media — we have some advisors helping with tech journalists, but we're always looking for more!

Why you?

My name is Andy Kong, welcome to my website!

I'm the only person I know at this intersection, and if you know someone else I'd love to meet them! My email is andy at chargerless.xyz

How's it going?

It's going great, and there's a lot left to do!

Chargerless was loosely started ~fall 2024 as a series of disconnected experiments; Digikey deep dives, napkin math, and de-risking various pieces of the puzzle. The vision coalesced around January of this year, then in July I incorporated and moved to SF to work on Chargerless full-time.

Programming on test boards

Programming on test boards


We're making strong progress thanks to our early angel investors. Today, all the technical components have been derisked, and we are currently integrating the hardware and embedded into one tiny package. At our current rate of development, we'll have 100 beta devices ready by November 2025 to send out to a select group for tuning and testing — around the same time, preorders will open for the first public offering shipping next summer.

Keep up on our twitter page or by joining our mailing list on the website!