Surlon Power NCM | 36V21Ah E-bike battery

Product Overview

The Surlon Power NCM 36V 21Ah E-Bike Battery is the higher-capacity option in our 36V NCM e-bike line. It is built for frames that already run a 36V system and need more energy per charge without stepping up to a 48V architecture, so builders keep their existing controller, motor and charger family and simply gain working time. The pack is designed and assembled in our own lab and factory in China, and each unit carries the model code EB02.

As a 36V high capacity battery for e-bikes, it is bought by three groups most often: manufacturers adding a long-range trim to a 36V platform, retrofit and repair workshops replacing a tired pack in an existing bike, and rental or share fleets that want one repeatable pack across a mixed fleet. All three care about the same things — a pack that fits the compartment, wiring that matches, and a range figure the rider can rely on.

Choosing it is a middle path. You get more assisted kilometres between charges than a compact commuter pack offers, and you avoid the controller and charger changes that a move to 48V usually brings. Later in the discharge the pack also holds its output more steadily, which is what a bike that works all day actually needs. Confirm the frame drawing, charger profile and connector against the specification before ordering — the port wiring and enclosure size are set out further down.

Frame Fit & Connection Points

• Enclosure size. 480 × 99 × 111.1 mm (18.9 × 3.9 × 4.37 in) is the room a 36V high capacity battery for e-bikes has to find inside the frame. Measure the compartment, the bracket and the clearance to the cranks before you commit to the frame design.
• Weight. 5.8 kg changes where the bike carries its mass. Check that the mount and frame fixings are rated for it, and think about how the pack will be lifted out for service.
• Charging port. DC2.1 wiring definition. Match the charger plug to this port, or plan an adapter as part of the build rather than as an afterthought.
• Discharging port. 3-pin wiring. Send your controller wiring pinout to our engineers and have it checked against the pack before anything is connected.
• Low-voltage switch. Fitted to the pack, so the output can be isolated during installation, transport and storage instead of leaving live terminals at the connector.
• On-pack controls. A USB port, a battery level display, a power switch, a keyed safe lock and a fuse access point sit on the black housing — useful for fleets that want a visible state of charge and a lockable pack.
• Service access. Leave room for the key at the lock, for the charge lead and for the discharge cable bend radius; a pack that cannot be unplugged cleanly becomes a workshop problem later.

Electrical Architecture & BMS Protection

Cell arrangement. The 10S6P layout puts ten cells in series, with six cells in parallel at every step. Spreading the current over six parallel cells per group keeps the load on each individual cell lower, so the pack holds its voltage better under acceleration and runs cooler when a rider works it hard on a long climb.

Battery management. A 30A battery management system monitors cell voltage, current and temperature continuously. It cuts charge or discharge when it detects over-voltage, over-charge, deep discharge, over-temperature or a short circuit, and it balances the cells so the weaker groups are not driven past their limits — the part that keeps usable capacity from drifting down over a season of hard use.

Discharge headroom. The 36V 21Ah NCM battery pack carries a maximum continuous discharge rating of 40A. That is the figure to compare with your controller's demand, because a low-power city motor and a high-torque cargo drive do not ask the same of a battery. If your peak current sits close to the rating, talk the duty cycle through with our engineers before the pack is specified.

Thermal and mechanical build. The sealed housing protects the cells and gives them a defined path for heat. It is not a substitute for sensible mounting: a pack boxed in behind a fairing will run hotter in summer than the same pack mounted where air can move around it.

What protection cannot do. The BMS guards the pack; it cannot correct a charger that pushes the wrong profile, or a cable assembly wired with reversed polarity. Both are worth checking before the first ride, whatever the battery.

Applications & Fleet Use

• Commuter and city e-bikes. A rider who charges at home and rides five days a week notices the extra capacity late in the week, when a smaller pack would already be asking for a top-up. The assist level stays consistent to the end of the charge.
• Rental and shared fleets. One pack specification across the fleet means one charger routine, one swap procedure and one set of spare parts. The keyed safe lock and the level display make handovers between riders easier to manage.
• Retrofit and repair workshops. When a customer's original 36V pack has reached the end of its life, this 36V 21Ah NCM battery pack gives the workshop a higher-capacity replacement to offer instead of rebuilding an old pack with cells of unknown history.
• Prototype and test-rig work. Development teams use the pack to benchmark controllers, motors and displays on a stable 36V supply before a custom enclosure is signed off, and the standard format keeps rig changes small.
• Light cargo and utility builds. Bikes carrying tools, deliveries or a second pack benefit most on hilly routes, where the motor works hardest and the extra capacity is spent fastest.

Range in Real Riding Conditions

1. Start from the two reference figures. With light pedal assist in ECO mode, the pack is rated for up to 70 km on a charge. Ridden hard in TURBO, that figure falls to about 50 km.
2. Read both as an upper-bound estimate. The published numbers assume a favourable route: moderate rider weight, flattish ground, mild weather and correctly inflated tyres.
3. Adjust for load and terrain. Cargo, a heavier rider, long climbs and repeated acceleration all draw more current and shorten the distance. As a 36V high capacity battery for e-bikes, this pack still leaves more buffer on those routes than a smaller pack would.
4. Adjust for weather. Cold mornings cut usable capacity and raise internal resistance; heat costs less range but stresses the cells. Expect winter figures to sit below summer figures on exactly the same route.
5. Check your own route. A test ride with the real rider, load and assist levels you plan to use is worth more than any catalogue number. Use that result to set the range you are willing to promise your own customers.
6. Plan charging around the display. The battery level display on the housing lets a rider judge whether the current charge will finish a shift, instead of guessing from the odometer.

Specifications

Customization & OEM Supply

• Capacity and configuration. Pack voltage, amp-hour capacity and the series/parallel arrangement are reviewed against your motor, controller and target runtime, not copied from a catalogue.
• BMS functions. Which protections, thresholds and functions the proposed battery management system includes are confirmed for your controller and charger before the design is frozen.
• Mechanical integration. Enclosure fit, mount points, cable clearance and service access are checked against the frame or compartment drawing you send, so the sample arrives closer to production-ready.
• Labels and branding. Private-label printing and pack marking can be discussed as part of the project; the available options and final specification are subject to project review.
• Sample evaluation. Ask your sales contact about sample availability and the validation steps that apply to your project. A sample tested on your own bike, with your own charger, tells you more than any datasheet.
• Documentation. Through our lithium battery OEM service we can review which test reports, handling instructions and transport documents are relevant to the market your finished bikes will be sold in.
• Continuity. Once a configuration is agreed, the same process and the same bill of components are used for repeat builds, which is what makes a second order predictable.

Quote & Delivery Details

1. Send the application details first. The frame or compartment drawing, controller voltage range, continuous and peak current, charger model, target runtime per charge and expected order quantity give us enough to review a configuration.
2. Check the standard build against your requirements. Compare voltage, capacity, port wiring, enclosure size and weight with what the bike actually needs before asking for changes.
3. Agree the sample and validation scope. Decide what will be measured — fit, runtime, connector polarity, behaviour under load — and who signs it off on your side.
4. Confirm the documents. Test reports, handling instructions and lithium transport papers depend on the destination market and the finished equipment, so tell us where the packs are shipping.
5. Confirm the commercial terms with your sales contact. Order quantity, lead time, payment terms, packing and shipping method are quoted per project and are not fixed by the product listing.
6. Confirm warranty cover for your order. Cover varies with the application and the market, so ask your sales contact to state in writing what applies to your packs.
7. Agree a route for field issues. Whether you handle cases locally or return packs to us, settle the process before the first shipment, and treat our lithium battery OEM service team as the technical contact when a pack behaves unexpectedly.

Reliability and Performance in Any Situation

In a durable, sealed housing, we have enclosed not only high quality cells, characterized by a long lifespan, but also an integrated battery management system that constantly monitors the battery's operating parameters. It provides all the necessary protections that ensure safe use, including protection against deep discharge, overcharging, overheating, and also balances the voltage between cells to extend battery life. Built-in 30A BMS is a high-output energy source for the electric motor of your bike, which means maximum performance on even the steepest climbs. Use 100% of your E-Bike potential!

Technical Support & Model Matching

Technical questions reach the people who build the packs. Our engineering group in Shenzhen reviews your device's voltage window, load profile, enclosure space and charger before proposing a configuration; our sample group then builds units so you can validate fit and runtime before production. Cell selection, BMS design and pack assembly stay in-house, with quality checks in process and at final inspection, and a documentation team handling certificates, test reports and shipping papers. When a unit behaves unexpectedly in the field, our engineers help trace the fault and advise on installation and commissioning.

FAQ