Tej’s Lab · Kit No. 002
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: it takes a charge at minus thirty, keeps delivering down to minus forty, and holds over 5,000 cycles.
Four cells, free shipping worldwide. Ships direct from the manufacturer.
−30°C
Takes a charge this cold
5,000+
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 a charge at thirty below, where an alkaline is long dead and a lithium ion pack refuses entirely, and it survives five thousand 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 70 °C
- Cycles
- 5,000+
- Service life
- 10 years
- Recharge
- USB‑C on the cell, or direct 5 V
- Chemistry
- Lithium titanate
Figures from Tej’s own bench test of the cell.
Built for
- Trail and wildlife cameras
- Survival and expedition kit
- Remote sensors and IoT
- Anything on AA that lives outside
Four cells,
$59 CAD.
Free shipping worldwide, direct from the manufacturer. Or leave an address and hear about the next thing off the bench instead.