Review of the Ostation 2 Pro 3-in-1 Smart Battery Charger

The Ostation 2 Pro 3-in-1 Smart Battery Charger, replenishing a load of 24 batteries

Removing the Clutter

I have a drawer in my kitchen filled with battery chargers. Some work only with one device; others are limited to specific sizes or battery chemistry.

Yesterday, in a rare attempt at organizing my kitchen, I threw away every charger associated with the antiquated cellphones and digital cameras that have long since been disposed of.

Then I closely examined the remainder; did I really need two devices that could recharge 18650 lithium cells? In fact, since I owned a rechargeable flashlight that used this type of battery, did I need any at all?

Aside from the flashlight, the only battery-operated devices I own use AA and AAA cells. With that in mind, I decided to pick up a charger that could handle these types of cells in either lithium-ion or NiMH battery format.

Today, I am taking a close look at the Ostation 2 Pro.

For transparency, Ostation provided me with a sample of their new battery charger to test and review. I have not received payment for this article and am not using an affiliate link. The device was photographed using my Oppo Find X5 smartphone.

A few of the many battery chargers that I have collected over the years

Description

This battery charging station is designed to charge and store up to twelve AA and twelve AAA batteries. It is compatible with all NiMH batteries in these formats, as well as lithium batteries manufactured by Ostation.

The outer casing primarily consists of gray semi-transparent plastic. The unit weighs 2.73 pounds and measures 8.91 inches in height, 6.26 inches in depth, and 3.52 inches in width.

Each of the two top-mounted lids secures compartments designed for AA and AAA batteries, each accommodating up to twelve cells. The charging system automatically checks and adjusts polarity, allowing batteries to be inserted without concern for orientation.

A maximum of two AA and two AAA batteries can be charged simultaneously. The front-facing display indicates each battery's charge level, tracks the number of successfully recharged cells, and records any rejected batteries.

After charging, each cell is deposited into its designated storage bin, while new batteries are moved into the docking area. Any defective cells are placed into an invalid battery bin.

Additionally, a fold-down panel on the right side enables wireless charging for up to two OLIGHT flashlights.

This kit includes the Ostation 2 Pro charging station, a USB charging cable, a power adapter, and a user guide. Twelve NiMH AAA batteries and twelve lithium-ion AA batteries were also provided.

Front and top view of the charging system

Specifications

• Brand: Ostation
• Type: AA and AAA cell charger and storage unit
• NiMH compatible: Yes (AA and AAA)
• Lithium-ion compatible: Ostation AA batteries
• Power source: USB-C PD
• USB-C input: PD 3.0 12V, 1.5A
• Storage capacity: 12 AA plus 12 AAA
• Weight: 2.73 pounds
• Polarity‑free charging: Yes
• Intelligent diagnostics: Yes
• Touchscreen: Yes

Polarity Free Charging

Each battery slot is fitted with independent contacts at each end, a microcontroller that detects which side is positive, and a switching circuit that routes charging power to the cell correctly. If you insert the battery backwards, the charger internally flips the polarity to the proper orientation.

Left-side view of the Ostation 2 Pro

Bad or Incompatible Battery Rejection

Before charging, the system identifies the battery's chemistry, checks for damage, and confirms the cell is safe to charge. If not, the cell is routed to the invalid battery bin.

The Problem with NiMH Batteries

Repeated shallow cycles or overcharging can create voltage depression by promoting the growth of large crystalline structures inside the electrodes, increasing internal resistance, and lowering operating voltage. In this situation, the actual capacity remains good, but the voltage curve shifts downward. Batteries suffering from this problem will have a shorter runtime and may seem unable to hold a charge.

To prevent this issue, the Ostation 2 Pro adjusts charging current based on battery temperature. It also utilizes a 5‑layer protection system to safeguard against overcharge, overcurrent, overheating, overvoltage, and short circuits.

If voltage depression occurs, it can often be alleviated by completely discharging the battery and then charging it with the Ostation station.

Rear view of the charger

Setting up the Charging Station

I connected the power station to power and fed my 12 Ostation lithium-ion AA batteries into the AA feed chute. Because I wanted to ensure polarity would not be a problem, I deliberately fed several of the batteries into the opening backwards.

While Ostation supplied enough 800mAh AA cells to fill the second chute, I replaced four of them with EBL 1100mAh batteries.

As I waited, two AA and two AAA cells dropped into the charging dock.

Testing the Ostation 2 Pro

After the batteries dropped into their dock, they were checked for polarity, condition, and battery chemistry. Then the touchscreen lit up, displaying the cells' charge level. Three showed a level of 35 percent, but the older EBL battery was down to five percent.

As each battery reached a full charge, it dropped into the storage bin below and was replaced by a new cell. This was quite noisy. In fact, at first, I thought I'd heard ice falling from the roof of my house!

It took 5.5 hours to complete this task. The NiMH cells were replenished relatively quickly, but the high-capacity lithium-ion batteries required more time to charge.

View of a set of Ostation AA and AAA batteries

Secondary Test

I removed four batteries from each storage drawer. Then I placed two elderly Ni-CD AA batteries into the AA chute and two Alkaline AAA batteries into the AAA chute. After performing its checks, the charger rejected both alkaline batteries and one of the Ni-CD batteries. Unexpectedly, the device then proceeded to charge the remaining Ni-CD cell.

Ni-CD Test Observations and Conclusions

The underlying chemistry of NiMH and Ni-CD cells is similar. In this case, the aging process of the Ni-CD cell produced changes that made its voltage behavior, internal resistance, and test-current response closely match those of an NiMH cell.

This cell was charged by the Ostation 2 Pro, but not optimally. It would have been slightly undercharged or mildly overcharged. As Ni‑CD chemistry is very robust, this battery would probably not have been damaged by a minor overcharge condition.

This misidentification did not damage the Ostation system. Smart chargers are designed to handle cells with abnormal voltage curves, batteries that don't match expected chemistry, and mild overheating conditions.

Screenshot from the OLIGHT application

Overall Impression

Ostation aimed to develop a device capable of efficiently and safely charging and storing a substantial quantity of NiMH and lithium-ion AA and AAA batteries. The company has largely achieved this objective; however, its proprietary lithium-ion cells are the only type supported.

The device individually tests each battery, identifying and rejecting defective units or those with incompatible chemistries. While it is larger than standard chargers, this device also functions as a battery storage unit. It can simultaneously charge two AA and two AAA batteries, automatically transferring each recharged cell to the storage compartment and subsequently moving additional batteries into the charging slots. The **Ostation 2 Pro 3-in-1 Smart Battery Charger** is recommended.