Silver-Fish Replacement E-bike Batteries

The aftermarket replacement battery market requires a level of precision that generic battery manufacturing cannot provide: exact dimensional matching to ±2mm, connector pinout verification, BMS parameter matching to the original discharge curve, and compliance documentation for warranty and customs purposes. Our precision manufacturing verifies replacement packs against the original specifications across all these dimensions.

Our matching process starts with the original battery label (voltage, Ah, model), connector photos, and if available, a sample unit for dimensional and electrical profiling. From that data, we produce a replacement that connects, fits, and performs equivalently to the OEM battery, with matching BMS cutoff curves, capacity ratings, and display communication protocols where applicable.

Every replacement battery passes the same quality control checks as our OEM production and ships with a 12-month warranty on cells and BMS, CE marking, UN38.3 transport documentation, and a warranty card template your team can customize. White-label packaging with your brand name, logo, serial number scheme, and instruction manual is available after MOQ and packaging scope are confirmed.

The two silver-fish platforms

Model	Extrusion	Lengths	Cells per length
KT-D02	108.00 × 76.00 mm	265 / 325 / 345 / 385 mm	65 / 78 / 91 / 104 × 18650
KT-D15	110.50 mm	285 / 325 / 345 / 385 mm	39 / 52 / 65 / 78 × 21700

Both are 13S-stepped, so a 48V build runs 13S5P–13S8P on the KT-D02 and 13S3P–13S6P on the KT-D15. The KT-D15 reaches comparable energy from about a quarter fewer cells, which also means about a quarter fewer welded joints per pack.

Length is the fit constraint, and it caps capacity

Silver-fish packs come in five case lengths — 265mm, 285mm, 325mm, 345mm, and 385mm — built on the KT-D02 and KT-D15 platforms. The case has to match the mounting rail on the bike, so length is fixed by the frame before capacity is even discussed. That constraint then sets the cell count: 65 to 104 cells in 18650 format, or 39 to 78 in 21700.

Those counts map cleanly onto series-parallel configurations. A 48V pack is 13S, so 65 cells is 13S5P and 104 cells is 13S8P; in 21700, 39 cells is 13S3P and 78 is 13S6P. This is the arithmetic behind an answer buyers sometimes find frustrating — a longer case is the only way to reach a higher Ah figure at a given voltage. Where a customer needs more capacity than the original case allows, moving to 21700 cells recovers some of it within the same length, which is why the platform accepts both formats.

What to send us, and what you get back

Start with the original battery label showing voltage, Ah, and model, clear photos of the connector and the mounting base, and the case length measured on the bike. A sample unit is better still: it lets us profile the discharge curve and verify the connector pinout directly rather than inferring it. Connector options include DC2.1, 3-pin, aviation connectors, or an OEM-matched pinout.

What comes back is a pack that fits the existing rail, connects without an adapter, and matches the original BMS cutoff behaviour and display communication where applicable — not merely a battery of the same nominal voltage. Documentation ships with it: CE marking, UN38.3 transport paperwork, a 12-month cell and BMS warranty, and a customizable warranty card. Distributors reselling into the EU should also read our checklist on verifying battery certificates, because the paperwork is what customs and warranty claims turn on, and not every certificate offered in this market survives a check.