Yocan Uni 4.0 Box Mod 510 Battery

The Yocan Uni 4.0 is the latest evolution of the most popular universal cart battery ever made. The Uni series built its reputation on one thing: fitting any 510 cartridge regardless of size. The 4.0 keeps that universal fit — adjustable diameter from 8mm to 14mm, adjustable height over 42mm, two magnetic adapter rings (long and short) included — and adds a massive 1.26-inch full-color TFT display that shows voltage, battery level, puff count, and cartridge resistance at a glance. Variable voltage from 1.8V to 4.2V adjustable in precise 0.1V increments, a 1.8V 10-second preheat for thick oils, 650mAh battery with USB-C charging in about an hour, a peeking hole to check your oil level without removing the cart, and a refreshed cyber-industrial design with see-through accents. If you’ve been running a Uni Pro, Uni Pro 2.0, or Uni 3.0 and want the upgrade that finally adds a real screen and granular voltage control, the 4.0 is it. Available in five colors.

Fits Any 510 Cart — The Whole Point of the Uni

The Uni 4.0 continues the patented adjustable system that made the Uni series the best-selling box mod cart battery on the market. Two adjustments work together to fit virtually any 510-thread cartridge:

• Diameter dial: Twist the ring at the top to adjust the cartridge cradle from 8mm to 14mm wide. This accommodates everything from slim pen-style carts to thick CCELL-style tanks.
• Height slider: The rear slider adjusts cart height over 42mm, so tall 2g carts and short 0.5g carts all sit flush and secure.

Two magnetic 510 adapter rings are included — one long and one short — to match different cartridge base depths. Screw the appropriate ring onto your cart, drop it into the Uni 4.0, and the internal magnet locks it in place. No threading the cart in and out. Pull straight up to swap. THC, CBD, Delta-8, Delta-9, THCp, live resin, distillate — if it’s a 510 cart, the Uni 4.0 fits it.

1.26″ TFT Full-Color Display — Real Information, Not LED Guesswork

This is the biggest upgrade in the 4.0. Previous Uni models used small OLED screens or LED indicators that showed limited information. The 4.0’s 1.26-inch TFT full-color display shows four data points simultaneously:

• Voltage: Your current setting from 1.8V to 4.2V — confirmed to the tenth of a volt.
• Battery Level: Precise battery percentage so you know exactly when to charge.
• Puff Count: Running total of how many puffs you’ve taken. Hold the power button and “−” simultaneously to reset.
• Cartridge Resistance: Live ohm reading of whatever cart is connected — useful for matching voltage to cartridge specs.

The screen auto-sleeps to conserve battery and wakes when you press any button.

1.8V–4.2V Variable Voltage — 0.1V Precision

The Uni 4.0 offers variable voltage from 1.8V all the way up to 4.2V, adjustable in 0.1V increments using the +/− buttons. Hold either button for rapid adjustment. This is the widest voltage range and finest adjustment granularity in the Uni series — you can dial in the exact voltage that works best for your specific cartridge and oil viscosity:

• 1.8V–2.4V: Ultra-low — maximum flavor preservation, minimal vapor. Best for live resin carts and delicate terpene profiles.
• 2.4V–3.0V: Low-mid — smooth, flavorful draws with visible vapor. A solid everyday range for most carts.
• 3.0V–3.6V: Mid-high — fuller clouds, stronger hits. Works well with standard distillate carts.
• 3.6V–4.2V: Maximum output — thick clouds, heavy extraction. Best for thick oils that need more heat to flow.

Preheat Mode — 10 Seconds at 1.8V

Double-click the power button to activate a 10-second preheat cycle at 1.8V. This gently warms the oil in your cartridge before your first draw — loosening thick concentrates, clearing clogs, and ensuring smooth vapor from the first puff. Especially useful in cold weather, after your cart has been sitting idle, or any time the draw feels tight.

Peeking Hole — Check Oil Level Without Removing the Cart

A small viewing window on the back panel (next to the height adjustment slider) lets you peek at your cartridge’s oil level while it’s still seated in the device. No pulling the cart out to check, no guessing how many puffs are left. A quick glance through the peeking hole tells you whether it’s time to swap carts or grab a refill.

650mAh Battery — USB-C, One-Hour Charge

The 650mAh rechargeable battery provides solid all-day runtime for moderate use and charges from empty to full in approximately one hour via USB-C. Battery percentage displays on the TFT screen so you always know exactly where you stand. The Uni 4.0 is sized for daily carry — at just 28mm × 40mm × 75mm (roughly 1.1″ × 1.6″ × 3.0″), it’s compact enough to palm and pocket without any bulk.

Smart Safety Features

• 15-second safety cut-off: Automatically stops firing if the button is held too long — protects both the cart and the coil.
• Short-circuit protection: Detects and prevents firing if a cartridge connection is faulty.
• 1-hour auto shut-off: Powers the device off automatically after one hour of inactivity — no accidental battery drain.
• Minimum resistance: Compatible with cartridges rated above 0.8Ω.

Five Color Options

• Black
• Blue
• Pink
• Purple
• Silver

Browse more 510 thread batteries, explore 510 cartridge adapters and accessories, or check out the full product selection at Discount Vape Pen.

Package Contents

• 1x Yocan Uni 4.0 510 Battery (650mAh)
• 1x Short Magnetic 510 Adapter Ring
• 1x Long Magnetic 510 Adapter Ring
• 1x USB Type-C Charging Cable
• 1x User Manual

Note: Cartridge sold separately. Compatible with standard 510-thread oil cartridges (0.5g, 1g, and 2g) with a resistance above 0.8Ω. The Uni 4.0 is a battery only — it does not contain any cannabis, THC, or nicotine.