SLIM K4 4-BAY USB-C CHARGER - EFEST

Slim K4 4-Bay USB-C Charger - Efest

The Efest Slim K4 lets you manage up to four batteries in a compact USB-C powered station. It is designed for users who rotate between multiple battery sets and want to quickly check the progress of each slot.

The current is distributed based on the number of cells: up to 2 A on a single slot, 1 A with two batteries, or 0.5 A when three or four slots are occupied. Each channel is monitored separately and charging stops automatically when the cell reaches its final voltage.

Why choose this battery charger?

• Four slots to organize a complete rotation
• Automatic current distribution based on the number of batteries
• USB-C input and independent indicators

Technical specifications

• Brand: Efest
• Slots: 4
• Batteries: Li-ion 3.6/3.7 V
• Common sizes: 10440 to 26650, including 18650, 20700, and 21700
• Input: USB-C 5 V/2 A
• Currents: 2 A x1, 1 A x2, or 0.5 A x3/x4
• Automatic cutoff: 4.20 V ±0.05 V
• Function: low voltage activation
• Protections: reverse polarity, short circuit, overcharge, and overvoltage

Which batteries to use?

Check the size, voltage, and chemistry of each cell before placing it in the charger. Diameter compatibility does not always guarantee that protected batteries, which are longer, can fit into the slot. Never try to force a cell and always respect the polarity indicated on each slot.

For a dual-battery mod, keep a pair of the same brand, same capacity, and with the same number of cycles. Recharge both cells together and replace the entire pair if one shows abnormal wear.

Tips for safe charging

Inspect the insulating wrap of the battery before each charge. Do not use a cell with torn wrapping, a deformed shape, or one that has been dropped. Place the charger on a stable, dry, and clear surface, away from heat sources. Use a cable and adapter that match the specified input, then remove the batteries when the cycle is complete.

Maximum current is only relevant if the battery and power source support it. A gentler charge may be better for smaller capacities. Do not leave charging unattended for long periods and always transport batteries outside the device in an insulated case.

Batteries and chargers compatible with your gear

Compare this model with other battery chargers, check out the selection of batteries and chargers for e-cigarettes, or browse all vape accessories. The product pages specify the slots, currents, and verified sizes so you can choose without guesswork.