O2COOL Treva 5 Inch Review: A D-Cell Desk Fan for Power Outages
O2COOL's Treva is a 5 inch desk fan that runs on two D batteries, with two quiet speeds and a folding design for desks, windows and travel.
By Daniel Brooks
Updated October 30, 2026
The O2COOL Treva 5 Inch Battery Desk Fan is a 5 inch portable desk fan that runs on two D batteries, with high and low speeds and a folding design. For more models, see our Personal & Desk Fans page.
Our Verdict
The Treva is our top battery operated fan because it needs no charging. Keep a few D cells in a drawer and it will work through a power outage, at a campsite or anywhere else without an outlet.
Batteries are not included, airflow is modest and there is no USB option listed. If you will use it mostly at a desk with power nearby, a USB or rechargeable fan is cheaper to run.
O2COOL Treva 5 Inch Battery Desk Fan
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Key Specifications
| Feature | Specification |
|---|---|
| Brand | O2COOL |
| Model | Treva 5 Inch |
| Size | 5 inch |
| Power | 2 D batteries (not included) |
| Speeds | 2 |
| Design | Folding |
| Weight | 0.45 pounds |
| Use | Desk, window or travel |
| Color | Black |
Design
The fan is small and light, at about 2.87 by 7.12 by 6 inches and 0.45 pounds without batteries. A folding design lets it stand on a desk or floor, sit in a window or fold flat to pack in a bag.
To load it, slide out the battery door, insert two D cells following the markings and replace the door. O2COOL sells it in several colors and in 2-packs.
Controls
A single switch selects high or low speed. O2COOL describes both settings as quiet, so you can read or relax next to it.
Because it runs on standard D batteries, it is a common part of emergency and hurricane kits; you can swap in fresh cells when the power is out instead of waiting for a recharge.
Placement Tips
Put a personal fan close to you, within a few feet, and aim it at your face, neck or upper body. Moving air cools you by speeding up evaporation from your skin, so the breeze has to reach you to work. On a desk, angle it slightly upward; on a nightstand, aim it across the pillow rather than straight at your face.
A fan does not lower the room temperature, so switch it off when you leave. In a warm room, pairing a desk fan with your air conditioner lets you set the thermostat a little higher and still feel comfortable.
Running Costs and Care
Personal fans use very little power. A USB or rechargeable fan draws only a few watts, and even a plug-in table fan uses a small fraction of what an air conditioner needs, so running costs are minimal.
Wipe dust from the grille and blades every few weeks, since a dusty fan moves less air and makes more noise. For battery fans, avoid leaving them fully drained for long periods, and charge them before storing them for the winter.
How It Compares
Against the Gazeled F15 D-Cell Battery Fan, the Treva is lighter and simpler with two D cells, while the Gazeled uses four D cells for up to 214 hours on low and adds a timer and USB power.
Against the Honeywell HTF090B, the Treva has a larger fan and folds, while the Honeywell takes AA batteries or USB and has a handle for hanging.
Pros and Cons
| Pros | Cons |
|---|---|
| Runs on standard D batteries | Batteries not included |
| Works in power outages | Modest airflow |
| Two quiet speeds | No USB power listed |
| Folding design | Only two speeds |
| Light at 0.45 pounds | D cells add weight |
Who Should Buy It
| Who Should Buy It? | Who Should Look Elsewhere? |
|---|---|
| Emergency kits | Desk users with USB power |
| Hurricane preparation | People who want strong airflow |
| Campers | Buyers who want a timer |
| Anyone without reliable power | Those who prefer rechargeable fans |
For more options, see our picks for the best battery operated fans and the best travel fans.
Final Verdict
The O2COOL Treva 5 Inch Battery Desk Fan is a simple, dependable battery fan for outages, camping and anywhere you cannot plug in. You can check the current price and details for the O2COOL Treva 5 Inch Battery Desk Fan.
Frequently Asked Questions
What batteries does the O2COOL Treva use?
Two D batteries, not included.
How many speeds does it have?
Two, high and low.
Can it fold?
Yes, it has a folding design for travel or window use.
How much does it weigh?
About 0.45 pounds without batteries.
Is it good for power outages?
Yes, it runs on D cells, so it works without electricity.
About the author
Daniel Brooks is a home cooling editor at WikiCooling, covering window, portable, through-the-wall and mini-split air conditioners, fans, and dehumidifiers. He researches cooling capacity, energy efficiency, noise levels, installation requirements, and buyer feedback to help homeowners choose the right unit for their room size, climate, and budget.