Keeppower Batteries: Reliable Li‑ion Cells and Packs

Keeppower builds rechargeable lithium‑ion cells and custom battery packs for enthusiasts and professional equipment. The range covers compact 14500 and 16340 cells through high‑capacity 21700 and 26650 formats, with options for protected and unprotected use, high‑drain performance, and OEM pack integration.

What Keeppower Offers

• Protected and unprotected cylindrical Li‑ion cells (3.6–3.7 V nominal).
• High‑drain IMR/INR options for devices with strong current draw.
• Button‑top and flat‑top variants for device contact requirements.
• Custom packs with protection and balancing for OEM applications.

How to Choose the Right Keeppower Cell

Decision point	Choose	Use if	Avoid if
Protection	Protected cell (with PCB)	Your device lacks built‑in battery management; you want added safeguards against over/under‑voltage and short circuit.	Your device has tight length tolerances or its own protection; protected cells are typically 2–6 mm longer.
Current draw	High‑drain IMR/INR	High‑output lights and electronics that demand higher continuous current.	Low‑drain devices where maximum runtime (capacity) is the priority.
Capacity vs. size	Higher capacity variant	You need longer runtime and the device does not pull high current.	The device needs fast bursts of current; a high‑drain model may perform better.
Top style	Button‑top	Many flashlights and devices that require a raised positive contact.	Devices designed for flat‑top cells or packs with spring contacts.
Fitment	Exact size match (e.g., 18650, 21700)	The device specifies a precise format; verify both diameter and length.	Assuming all 18650/21700 cells are the same length—protected cells can be longer.

Tip: Check your device manual for required size, top style, and whether protected cells are recommended.

Common Sizes and Typical Uses

Size	Nominal voltage	Typical capacity	Typical uses	Fit notes
14500 (AA‑size Li‑ion)	3.6–3.7 V	600–1000 mAh	Compact lights, small electronics	Not interchangeable with 1.5 V AA unless device supports Li‑ion.
16340 (CR123A‑size Li‑ion)	3.6–3.7 V	600–900 mAh	Compact lights, sensors	Only use where rechargeable 16340 is specified (not primary CR123A only).
18350	3.6–3.7 V	900–1200 mAh	Short body lights, space‑constrained builds	Often high‑drain; check device length tolerance.
18650	3.6–3.7 V	2400–3600 mAh	General‑purpose lights, instruments, small power banks	Protected versions are longer; confirm fit.
21700	3.6–3.7 V	4000–5000 mAh	High‑output, longer‑runtime devices	Larger diameter than 18650; ensure tube clearance.
26650	3.6–3.7 V	4500–5500 mAh	Extended runtime lights, specialty gear	Check both diameter and length; may not fit 26 mm‑tight tubes.

Actual specifications vary by model—review the product datasheet for exact capacity and discharge ratings.

Quick Runtime Estimate

Approximate runtime (hours) = capacity (mAh) ÷ device draw (mA). Example: a 3000 mAh cell powering a 1000 mA (1 A) device offers roughly 3 hours; at 2 A, about 1.5 hours. High‑drain use and temperature can reduce runtime.

Charging and Care

• Use a quality Li‑ion charger (CC/CV). Start with 0.5C charge rate unless the datasheet specifies otherwise.
• Do not leave cells charging unattended. Stop if a cell becomes hot, vents, or smells unusual.
• Store at ~30–60% charge (around 3.6–3.8 V) in a cool, dry place; check every 3–6 months.
• Avoid deep discharge. Re‑charge before dropping below ~3.0 V per cell.
• Inspect wraps and insulators regularly; replace or rewrap damaged cells.

Safety Notes

• Match cells by model, age, and state of charge when used in series or parallel packs.
• Never mix old and new cells or different capacities in the same device.
• Keep cells away from metal objects; use protective cases during transport.
• Follow device and local regulations for handling, shipping, and recycling lithium batteries.

When Keeppower Is a Good Fit

• You need protected cells for consumer devices that lack built‑in protection.
• High‑drain electronics where stable output under load matters.
• Projects requiring consistent cell dimensions and OEM pack options.

Alternatives to Consider

• NiMH AA/AAA (for devices designed for 1.2 V cells) when simplicity and low self‑discharge are priorities.
• Primary CR123A or AA alkaline/lithium (non‑rechargeable) for long shelf life in emergency kits—only if the device supports them.
• Device‑specific proprietary packs if required by the manufacturer.

FAQ

Are Keeppower cells protected?

Many models are offered in both protected and unprotected versions. Check the product title and specifications for “Protected” and verify the length if space is tight.

What’s the difference between button‑top and flat‑top?

Button‑tops have a raised positive terminal and are often required in flashlights. Flat‑tops are shorter and used where spring or tab contact is sufficient. Choose what your device specifies.

What charge current should I use?

Unless the datasheet specifies otherwise, a conservative 0.5C is a safe starting point (e.g., 1.5 A for a 3000 mAh cell). Lower current extends longevity; higher current shortens charge time but may increase heat and wear.

Can I mix different cells together?

No. Do not mix capacities, ages, brands, or states of charge in the same device. Use matched cells from the same model and batch when multiple cells are required.

How long will a Keeppower cell last?

Cycle life depends on temperature, depth of discharge, and charge rate. With gentle use and proper storage, many Li‑ion cells deliver hundreds of cycles before noticeable capacity loss.