Tej’s Lab · In development
It charges at
−30°C
Alkalines quit in the cold and lithium ion refuses to charge below freezing. This is a 1.5 volt AA built on lithium titanate, so it takes a charge at minus thirty and keeps working colder still.
Not for sale yet. No price, no date, nothing to pay. Leave an address and you will hear once it exists.
−30°C
Takes a charge this cold
3,000+
Cycles, not hundreds
1.5V
Regulated, drop-in AA
The test
Frozen in a block of ice, still charging.
Not a chart. Tej set the cell in ice, put a USB‑C cable on it and it kept taking charge. An alkaline is dead well before this and a lithium ion pack refuses the charge entirely.
Why it works
Lithium titanate, and what it costs.
Lithium titanate is the reason. It is a slower, heavier chemistry than the lithium ion in a phone, and it gives up energy density in exchange for two things that matter outdoors: it accepts charge far below freezing, and it survives thousands of cycles rather than hundreds.
The cell recharges over USB‑C, so there is no dock and no proprietary cradle. Put it in the device, take it out to charge it from anything with a USB port.
The spec
Winterwatt
- Format
- AA, drop-in replacement
- Output
- 1.5 V regulated
- Capacity
- 800 mWh
- Charging
- −30 °C to 50 °C
- Discharging
- −40 °C to 65 °C
- Cycles
- Over 3,000
- Recharge
- USB‑C on the cell, or direct 5 V
- Chemistry
- Lithium titanate
Measured on the prototype. Not yet certified, and not yet through UN 38.3 transport testing.
Built for
- Trail and wildlife cameras
- Survival and expedition kit
- Remote sensors and IoT
- Anything on AA that lives outside
Leave an address.
One email when it goes on sale. Nothing else, ever, and it is not passed to anyone.