GRAVL Sigma 35 Compact 10,000mAh Power Bank with 35W Fast Charging

10,000mAh. 35W output. Built-in Type-C and Lightning cables. Airline compliant. Four-year warranty.

The GRAVL Sigma 35 is a 10,000mAh power bank with 35W Power Delivery output and built-in Type-C and Lightning cables sized for a pocket, fast enough for a full working day, and covered by GRAVL's 4-year warranty. It is the compact option in GRAVL's range: not the highest capacity, not the highest output, but the one built for daily carry where size and weight matter as much as charge speed.

Output and Charging Speed

35W Power Delivery

The Sigma 35 outputs 35W through its USB-C port, fast enough to take most modern smartphones from flat to 50% in under 30 minutes. That is meaningful charge speed in the time between a meeting and a flight, or between lectures, without needing to be tethered to a wall socket for the better part of an hour.

Built-In Type-C and Lightning Cables

The Sigma 35 ships with Type-C and Lightning cables built directly into the unit. There is no separate cable to pack, forget, or lose. The Type-C end covers Android devices and USB-C accessories; the Lightning end covers iPhones. The only thing that needs plugging in is the device itself.

Size, Weight, and Daily Carry

The Sigma 35 is sized to fit a jeans pocket or the front compartment of a laptop bag without adding noticeable weight. At 10,000mAh it carries enough capacity to fully charge most modern smartphones twice—enough for a full day of navigation, calls, and payments without rationing use.

The trade-off for that size is capacity ceiling: the Sigma 35 is built for phones, earbuds, and tablets, not laptops. For laptop charging, the GRAVL Axis 67, with 20,000mAh capacity and 67W output, is the correct starting point. For two devices charging simultaneously, see the laptop power bank collection.

Airline Compliance

The Sigma 35 sits at 37Wh, well within IATA's 100Wh carry-on limit. It travels as carry-on on every airline without prior approval. For a full breakdown of India's current power bank rules for flights, see Airline Rules for Laptop Power Banks: What's Allowed on Indian & International Flights in 2026.

Battery and Safety

The Sigma 35 uses a lithium polymer cell with multi-layer protection covering overcharge, over-discharge, and short circuit. For travellers or daily carriers who want a power bank built on a lower-risk battery chemistry, the GRAVL Core 30 uses semi-solid state battery technology that significantly reduces thermal runaway risk compared to conventional lithium-ion at the same 10,000mAh capacity. See Semi-Solid vs Lithium-Ion: Which Battery Is Safer for a full comparison.

Warranty

The Sigma 35 carries GRAVL's 4-year warranty: 1 year unconditional from the date of purchase, plus 3 years on the battery once the product is registered. The same terms apply across every product in the GRAVL range.

Choosing the Right GRAVL Power Bank

The Sigma 35 is the right fit for single-device daily carry—a phone or two between charging points, slim enough to go everywhere. For higher output or multi-device charging, the correct options are in the laptop power bank collection. For semi-solid state battery chemistry at the same capacity, the Core 30 is built around that priority specifically. For wireless charging, see the GRAVL Qi Surface.