Hailong 48V Downtube Battery
The universal downtube pack. The Hailong ("Shark") case bolts to almost any frame and is the most common replacement battery on the market.
Safety notes
E-bike battery fires are overwhelmingly caused by uncertified packs and chargers. Buy only UL 2271 (battery) / UL 2849 (system) certified packs with genuine name-brand cells, never charge on or near exits, and stop using any pack that swells, smells, or runs hot. See our Safety hub before charging an unlisted battery indoors.
The Hailong/Shark form factor is the de-facto standard for downtube batteries, which means cases, mounts, and chargers are easy to find and cross-compatible. A quality pack uses brand-name 21700 or 18650 cells (Samsung, LG, Panasonic), a robust BMS, and a locking mount with a keyed cutoff.
Capacity is everything here: a 48V 14Ah pack is ~672Wh, good for 30–50 real miles depending on assist and terrain. Spend up for genuine cells — the difference between a pack with real Samsung 50E cells and a no-name pack is range, lifespan, and, critically, fire safety.
Where to buy
Two paths — match your spend to the build. Quality picks last longer and come with real support; affordable picks get you rolling for less. Always confirm fitment, voltage, and connectors for your bike first.
Quality picks
Affordable picks
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Pro tips from our test team
- Match voltage to your controller exactly — a 52V pack on a 48V controller can damage it.
- A 14Ah pack with genuine cells outlasts a no-name 20Ah pack within a couple of years.
- Register the pack and keep the receipt; cell provenance matters for warranty and insurance.