EVE 21700-50E 3S Battery Pack 11.1V 5000mAh Balanced BMS – 4A XH2.54 Pre-wired for 12V DIY Electronics
Description
Safe 11.1V power with cell balancing, ready for your DIY projects.
This EVE 21700-50E 3S Battery Pack features three genuine EVE 21700-50E high-capacity cells connected in series (3S), delivering a nominal 11.1V voltage (12.6V full charge) and a solid 5000mAh capacity.
What sets this pack apart is its integrated Balanced Protection Board (BMS). The balancing function ensures all three cells remain at the same voltage during charging, maximizing battery life and safety. The board also provides comprehensive protection against overcharge, over-discharge, over-current, and short circuits.
Pre-wired with a default XH2.54 2-pin connector, it is ready to plug into your custom electronics. Important: Due to the protection board, the continuous working current is limited to 4A (peak 8A). This pack is designed for low-to-medium current devices requiring 11.1V/12V, such as portable audio gear, DIY electronics, LED lighting, and sensors. It is not intended for high-drain RC vehicles or power tools.
Key Features
3S Series Configuration (11.1V): Provides a higher 11.1V nominal voltage (12.6V full charge) for devices requiring a 12V power source.
Balanced Protection Board (BMS): The built-in balancing circuit keeps all three cells perfectly synchronized, preventing voltage drift and extending the pack's lifespan. Includes full overcharge, over-discharge, and short-circuit protection.
Safe 4A Continuous Current: Specifically designed for low-to-medium current devices. (Max continuous 4A, peak startup 8A).
Pre-wired & Plug-and-Play: Comes with a default XH2.54 2-pin connector (red/black leads, 8-15cm) for easy integration.
Compact 3-Cell Layout: Shrink-wrapped with the side protection board, measuring approx. 73.5mm (H) x 65mm (W) x 22mm (D).
Parameters
| Parameter | Specification |
|---|---|
| Cell Model | EVE 21700-50E (3 cells in series) |
| Configuration | 3S1P (Series) |
| Nominal Voltage | 11.1V (Full charge: 12.6V) |
| Nominal Capacity | 5000mAh |
| Continuous Working Current | ≤ 4A |
| Peak Startup Current | ≤ 8A |
| Protection Board | Yes (Balanced BMS, Overcharge, Over-discharge, Over-current, Short circuit) |
| Connector Type | XH2.54 2-Pin (Red + / Black -) |
| Wire Length | Approx. 8-15cm |
| Dimensions | Approx. 22mm (D) x 65mm (W) x 73.5mm (H)* |
| Weight | Approx. 200g |
*Dimensions are approximate and include the protection board and heat shrink wrap. Please allow ±1-2mm tolerance.
Applications
Recommended For:
11.1V/12V DIY Electronics: Perfect for custom 12V audio amplifiers, portable speakers, and electronic circuits requiring 11.1V.
Portable Devices: High-capacity replacement for devices designed for 3S Li-ion power (within the 4A limit).
LED Lighting (Low Power): Suitable for 12V LED strips, camping lights, or emergency lighting drawing under 4A.
Sensors & IoT Nodes: Reliable 11.1V power for long-term standalone deployments.
Not Recommended For:
High-Drain RC Models or Power Tools (>4A): Do not use in RC cars, drones, or power tools that draw more than 4A continuously. The protection board will trip and cut off power.
Devices Requiring Bare Cells: If your device's battery tray expects a standard flat-top cell, this pre-wired pack will not fit.
Single-Cell 3.7V or 7.4V Devices: Do not use this 11.1V pack in lower-voltage devices, as it will damage them.
FAQ
Q1: What does "3S" mean and how does it differ from a single cell?
A: "3S" means 3 cells in Series. This triples the voltage to 11.1V (12.6V full charge) while keeping the capacity at 5000mAh. It is used for devices that require a 12V power source.
Q2: What is a "Balanced BMS" and why is it important?
A: A balanced BMS ensures that all three cells are charged and discharged evenly. Without balancing, one cell might drift out of sync, reducing the overall lifespan and safety of the battery pack. This BMS automatically manages that balance.
Q3: What is the maximum discharge current?
A: Because of the protection board, the continuous working current is limited to 4A (with a peak of 8A for short startups). It is not designed for high-drain devices like RC cars or power tools.
Q4: Can I use this for my RC car or power tool?
A: No. RC cars and power tools typically require 15A to 30A+. The 4A limit on this protection board will cause it to shut off immediately under load.
Q5: How do I charge this 11.1V pack?
A: You must use a dedicated 3S Li-ion charger (12.6V output) or integrate it into a custom charging circuit. Do not use a single-cell 4.2V or 2S 8.4V charger.
Payment & Security
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This was my first 3S pack and it made the transition from single cells easy. Clear labeling on the leads.
Left it for six weeks and it only dropped slightly. Self-discharge seems low.
Lightweight enough for backpacking and powers my QRP radio. Very happy with it.
The BMS balances well but I wish it had a thermistor for temperature cutoff. Still a good pack.
Second one I bought and the build quality is consistent. Happy with both.
Refund Policy
Last updated: November 3, 2026
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