Kastar 4-Pack BP-21 Battery and AC Wall Charger Replacement - Extra

In this review the Kastar 4-Pack BP-21 Battery and AC Wall Charger replacement is presented as a budget-conscious power kit for photographers who use Sigma SD1, SD1 Merrill, SD14 and SD15 cameras. The bottom line: this bundle is for people who need multiple spare BP-21 compatible batteries and a compact charger that accepts worldwide AC voltage. The package includes four 2400mAh lithium-ion cells and one foldable-pin AC charger, making it a simple way to extend shooting time without carrying proprietary or single-use power solutions.

Key Features

• High capacity cells: Each battery is 2400mAh at 7.4V, offering substantially longer runtime than many original cells when shooting stills or limited video clips.
• Compact wall charger: The included AC charger folds its flat pin for easy storage and travel, so it tucks into a camera bag without adding bulk.
• Wide input range: The charger accepts AC 100~240V 50~60Hz, which allows use in most countries with an appropriate adapter.
• Clear charge indication: A red LED shows charging and a green LED shows standby or full charge, making it easy to know battery status at a glance.
• Compatibility: The batteries and charger are compatible replacements for Sigma BP-21 and Sigma BC-21 models and cross-compatible with several Konica Minolta, Pentax and Samsung models listed by the maker.

Who It's For

This kit suits hobbyists and working photographers who want multiple spare batteries for long shoots, travel, or field work and prefer a single compact AC charger rather than multiple single-use power sources. It is especially useful for owners of Sigma SD-series cameras and compatible Konica Minolta, Pentax, or Samsung cameras who value capacity and cost savings over OEM branding.

Those who need in-car charging, a European plug included, or a branded OEM charger with bundled accessories should look elsewhere, since the package does not include a car adapter or alternate plug types and focuses on the 4 batteries plus one AC wall charger only.

Pros & Cons

Pros

• High 2400mAh capacity per cell provides extended runtime for long sessions.
• The foldable-pin AC charger is compact and accepts 100-240V, useful for travel with a local adapter.
• Simple LED indicators make it clear when batteries are charging or ready.

Cons

• No car adapter or alternate plug types are included, so additional accessories may be needed for some users.

Specifications

Battery Type	Lithium-Ion
Battery Voltage	7.4V
Battery Capacity	2400mAh
Charger Input	AC 100~240V 50~60Hz
Charger Output	DC 8.4V 600mA
Package Contents	4-Pack Batteries + 1 AC charger

Our Verdict

The Kastar 4-Pack BP-21 kit is a practical, cost-effective option for photographers who need multiple spare batteries and a compact charger with international voltage support. It delivers good capacity and simple LED charging feedback, making it a smart buy for Sigma SD-series users and compatible camera owners who prioritize runtime and value over OEM packaging.

Frequently Asked Questions

Are these batteries compatible with Sigma BP-21?
Yes, these lithium-ion batteries are listed as replacements compatible with Sigma BP-21 battery models.

Does the charger work worldwide?
The charger accepts AC 100~240V 50~60Hz so it will work worldwide with the appropriate local plug adapter; a European plug or car adapter is not included.

How many batteries are included?
The package includes four 2400mAh batteries and one AC wall charger, with no car adapter or alternate plug types included.