Solar back cover · Tesla Model 3 / Model Y

Reservations open · 500 spots

Daylight Fob

A replacement back cover for your key fob with an indoor solar cell. It keeps a rechargeable coin cell topped up from the light in the room.

Reserve for $5See the swap

$44.99 at launch. The $5 comes off the price and is refundable at any time.

00:00:00:00

    02 · The swap

    Turn it over

    Scroll to pop the stock cover, swap the coin cell, and seat the solar cover.

    1. Stock fob
    2. Turn it over
    3. Cover and cell out
    4. ML2032 in
    5. Solar cover on
    6. Glass live

    Stock fobStock back cover with a CR2032 inside.

    03 · Light

    How much light it needs

    The fob draws about 80 µW on average. Around 220 lux on the glass covers that, which is a bright room or a desk lamp. A fob that spends all day in a pocket gets little light and still needs a new cell every few years, so rest it glass-side up when you set it down.

    400lux

    Beside a window

    Light in
    0 µW
    Fob draw
    80 µW
    Charging

    04 · Numbers

    The power budget

    80µW

    Average draw of a Model 3 key fob, worked back from Tesla's rating of about one year on a CR2032.

    220lux

    Light on the glass that covers that draw. A bright room or a desk lamp reaches it.

    90days

    Reserve from a full ML2032 in total darkness, with margin.

    Figures are estimates from the feasibility study. Prototype measurements replace them before anything ships.

    Flat lay of the kit: the Daylight solar back cover, an ML2032 cell, an amber pry tool, and a printed range test card

    05 · In the box

    What ships

    1. 1Daylight solar coverSnaps into the stock battery slot. About 1 mm thicker than stock.
    2. 2ML2032 rechargeable cell3.0 V and the same size as the CR2032 it replaces.
    3. 3Pry toolPlastic, so the fob shell stays unmarked.
    4. 4Range test cardThe measured lock and unlock distance for your fob, stock cover against ours.
    $44.99

    Launch price, with your $5 reservation taken off. Two-year warranty on the cover and charger, and 60 days to return it.

    Reserve for $5

    06 · Reserve

    Pick your fob

    The most-reserved fobs get built first. Every fob below uses a CR2032, so the same rechargeable cell fits all of them. A fob goes to tooling at 80 reservations.

    Used for reservation updates only.
    Helps us plan the prototype placement test.

    Your spot is saved

    Pay the $5 refundable deposit to hold your place in the first 500. Checkout runs on Stripe. Without the deposit you stay on the waitlist.

    Pay the $5 deposit

    07 · Questions

    Common questions

    Does it affect my warranty or the car?

    The cover is a passive part. It attaches to the shell and charges the cell, and the fob's radio and software stay as they came from the factory. Your car sees the same fob it always has. We publish the measured range for each fob model before shipping.

    Why a cover instead of a rechargeable coin cell on its own?

    ML2032 cells exist today, and charging one means pulling it out and putting it in a desk charger. The cover charges the cell in place.

    Why an ML2032 cell?

    It runs at 3.0 V like the CR2032 it replaces, so the fob stays inside its designed voltage range. Lithium-ion LIR cells peak at 4.2 V, which is why the kit uses ML chemistry.

    Is it safe around small children?

    The battery door opens with a tool and is tested to the US federal coin-cell compartment standard by an outside lab. Swallowed coin cells are a medical emergency, which is why the door is designed and tested this way.

    When does it ship?

    Once the first fob clears its reservation goal, prototypes go into a 30-day placement test, then tooling and safety certification. Realistic delivery is six to eight months after the goal is met, and your $5 stays refundable the whole way.

    Daylight Fob

    Solar back cover for the Tesla Model 3 and Model Y key fob.

    Reserve for $5Watch the film again

    Reservations open · $5 refundable