48V 15Ah Hailong Down Tube Li-ion Battery for Electric Bicycles

Looking for a 48V electric bike battery that fits a standard down tube mount? This is a 48V 15Ah lithium-ion battery built in the genuine Hailong case — the most widely used e-bike battery format — making it a straightforward replacement or upgrade for many e-bikes and conversion kits. It is stocked in the UK and qualifies for free UK delivery on orders over £50.

Below you will find everything you need before you order: how to check it fits your bike, what range to expect in real riding, and how to charge and care for it.

Technical Specifications

Every value above comes from the physical battery and charger, not a copied manufacturer sheet. The energy figure is a straight calculation — 48V × 15Ah = 720Wh — so you know exactly where the number comes from.

Will It Fit Your E-Bike?

Battery fitment comes down to three things: system voltage, physical mounting, and the connector. Check all three before ordering.

Motor and system voltage

This is a 48V battery, so your e-bike's motor and controller must be rated for 48V. Voltage must always match — a 48V battery should never be fitted to a 36V-only system.

If you run a high-power motor or a high-current controller, contact us before ordering and we will help you check the battery is a sensible match for your setup.

Frame and mounting

The battery uses the genuine Hailong down tube case, one of the most common formats on e-bikes and conversion kits, and the matching mounting rail is included in the box. The rail fixes to the frame's down tube, usually using the bottle-cage bosses, and the battery slides on and locks with the included keys.

Before you buy, check the space inside your frame triangle. Down tube batteries need clearance along the tube to slide on and off the mount — measure your available space, and if you are unsure, send us a photo of your bike and we will help you check.

Connector

The battery discharges through a 4-pin socket in its base, with the polarity marked on the housing. It connects automatically as the battery slides onto the included mounting rail — there is no separate discharge cable to plug in. If you are replacing an existing Hailong base-discharge battery, the mounting and connection work the same way. Unsure? Send us a photo of your current battery's base and mount, and we will confirm the match before you order.

Upgrading from 36V?

Many riders move from 36V to 48V for more performance. Two things to know:

First, your controller must support 48V. Some controllers (such as dual-voltage KT models) accept both 36V and 48V; many are single-voltage only. Check your controller's rating before upgrading — if it is 36V-only, a 48V battery is not compatible.

Second, what actually changes: a 48V system runs the motor at a higher voltage than 36V, which raises both the motor's speed and its torque. Riders upgrading from 36V typically notice stronger hill climbing and quicker acceleration.

Real-World Range

Range claims on battery listings are often optimistic. Here is an honest way to estimate what this battery will do for you.

Take the battery's energy — 720Wh — and divide it by how much energy your riding consumes per kilometre:

• Light pedal assist on flat terrain typically uses around 6–8Wh per km
• Mixed riding with moderate assist typically uses around 10–15Wh per km
• Heavy assist, hills, or heavier loads can use 20Wh per km or more

On that basis, 720Wh gives roughly 50–70km of mixed riding, stretching towards 90–120km with light assist on flat routes, or noticeably less with heavy assist on hilly UK roads.

Your actual range depends on rider weight, terrain, tyre pressure, temperature and assist level — treat these figures as a guide, not a promise.

Charging

A matching charger is included in the box. It outputs 54.6V at 2A, and a full charge from empty takes around 7.5–8 hours — an overnight-style routine or charging after work covers most riders easily.

Always charge a 48V battery with a charger designed for it. A 48V lithium-ion battery charges to 54.6V when full. Never use a 52V (58.8V) or any other mismatched charger — using the wrong charger can damage the battery and is a safety risk.

Basic charging practice:

• Charge indoors, at room temperature, on a hard surface — the charger is for indoor use only
• Use only the correct, undamaged charger
• Do not charge below 0°C; let a cold battery come up to room temperature first
• Do not charge a battery that is damaged, swollen or has been in a crash

Battery Care & Winter Storage

The battery's own label sets two rules: store it in a cool, dry place, and give it a full charge at least every 60 days when not in use. Alongside that, standard lithium-ion practice will keep it healthy for years:

• Avoid leaving the battery at 100% or near-empty for long periods between rides
• Store it indoors — not in a shed or garage through freezing weather
• Keep the contacts clean and dry
• This battery is not waterproof: never submerge it, keep it out of drenching rain, and remove or cover it when washing the bike — never use a pressure hose

Safety & Certifications

The battery carries CE, RoHS and UN38.3 markings on its label. UN38.3 is the United Nations transport test standard for lithium batteries — it means the pack design has passed the tests required for batteries to be shipped safely.

Use the correct charger, keep the battery away from extreme heat, and stop using any battery that shows damage, swelling or unusual smells. Do not open the casing.

E-bike batteries must never go in household waste. When this battery reaches the end of its life, take it to a battery recycling point — most household waste recycling centres in the UK accept e-bike batteries.

What's Included

• 1 × 48V 15Ah battery
• 1 × 54.6V 2A charger
• 1 × discharge connector (4-pin mounting rail)
• 2 × keys

No printed manual is included — this page covers fitting, charging and care, and we are a message away if you need help.