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Silver Fish Battery Cases

Tapered shells that slide into a frame or seat-post carrier — the retrofit standard for folding bikes, mountain frames and conversion builds.

27 models 36 V – 72 V 18650 / 21700 MOQ 1 piece

Showing the 16 models with a full spec page. The complete range of 27 is series. Every one is an empty shell — you supply cells, BMS and harness. Measured openings and cell ceilings for every model: see the full dimensions table.

Silver Fish battery case range

27 models. Every Silver Fish / rear plug-in housing we mould. Everything below is an empty housing — no cells, no BMS.

ModelCellsCommon configurationsOpening / sizeFitmentMaterialVoltage
ALX02118650 — 78 / 104 / 117 / 130 cells · 18650 — 78, 104, 117, 130 cells18650: 13S10P · 16S8P · 14S9P · 20S6POpening 265 / 325 mm Body width 61.74 mm—ABS36 V – 72 V
ALX027——Opening 155 / 172 mm Body width 61.06 mm—ABS + aluminium alloy36 V – 72 V
ALX035————ABS36 V – 72 V
ALX035B18650 — 65 cells · 21700 — 39, 52 cells18650: 13S5P · 16S4P · 10S6P · 20S3P · 21700: 13S4P · 10S5P · 16S3P · 14S3POpening 285 mm———
ALX03618650 — 78 / 104 / 117 / 130 cells · 18650 — 78, 104, 117, 130 cells18650: 13S10P · 16S8P · 14S9P · 20S6POpening 265 / 325 mm Body width 61.43 mm—ABS36 V – 72 V
ALX03818650 — 65 / 78 / 91 / 100 cells · 18650 — 65, 78 cells18650: 10S10P · 20S5P · 14S7P · 16S6POpening 285 / 325 mm Body width 63.22 mm—ABS + aluminium alloy36 V – 72 V
ALX04018650 — 65 cells · 21700 — 39 / 52 cells · 18650 — 65 cells · 21700 — 39, 52 cells18650: 13S5P · 16S4P · 10S6P · 20S3P · 21700: 13S4P · 10S5P · 16S3P · 14S3POpening 285 mm Body width 63.22 mm—ABS36 V – 72 V
ALX042B18650 — 65 / 78 / 91 / 100 cells · 18650 — 65, 78 cells18650: 10S10P · 20S5P · 14S7P · 16S6POpening 285 mm Body width 65.47 mm—ABS36 V – 72 V
ALX05018650 — 65 / 78 / 91 / 100 / 104 cells18650: 13S8P · 10S10P · 20S5P · 14S7PBody width 63.3 mm—ABS + aluminium alloy36 V – 72 V
ALX05118650 — 65 / 78 / 91 / 100 / 104 cells · 18650 — 65, 78 cells18650: 13S8P · 10S10P · 20S5P · 14S7POpening 285 mm Body width 63.3 mm———
ALX05718650 — 65 / 104 cells · 18650 — 65 cells18650: 13S8P · 10S10P · 20S5P · 14S7POpening 160 / 285 mm Body width 60.52 mm—ABS36 V – 72 V
ALX06118650 — 91 / 130 cells · 21700 — 78 / 91 cells · 18650 — 91, 130 cells · 21700 — 78, 91 cells18650: 13S10P · 16S8P · 14S9P · 20S6P · 21700: 13S7P · 10S9P · 14S6P · 16S5POpening 265 / 380 mm Body width 60.62 mm—ABS36 V – 72 V
ALX061B————ABS + PC36 V – 72 V
ALX06318650 — 91 / 130 cells · 21700 — 78 / 91 cells · 18650 — 91, 130 cells · 21700 — 78, 91 cells18650: 13S10P · 16S8P · 14S9P · 20S6P · 21700: 13S7P · 10S9P · 14S6P · 16S5POpening 160 / 265 mm Tube coupling 18.75 mm—ABS36 V – 72 V
ALX07218650 — 65 / 78 / 91 / 100 cells · 18650 — 65, 78 cells18650: 10S10P · 20S5P · 14S7P · 16S6POpening 285 / 325 mm Body width 63.22 mm—ABS36 V – 72 V
ALX072B18650 — 65 / 78 / 91 / 100 cells · 18650 — 65, 78 cells18650: 10S10P · 20S5P · 14S7P · 16S6POpening 285 / 325 mm Body width 63.32 mm—ABS + aluminium alloy36 V – 72 V
ALX07518650 — 65, 78 cells18650: 13S6P · 10S7P · 14S5P · 16S4POpening 285 / 325 mm———
ALX076B——————
ALX08018650 — 52 / 65 cells · 21700 — 39 cells · 18650 — 52, 65 cells · 21700 — 39 cells18650: 13S5P · 16S4P · 10S6P · 20S3P · 21700: 13S3P · 16S2P · 10S3P · 14S2POpening 285 / 325 mm Body 72.4 × 75.4 mm—ABS36 V – 72 V
ALX113——Opening 150 / 160 mm—ABS + aluminium alloy36 V – 72 V
ALX113B——Opening 160 / 173 mm———
ALX129——Opening 156 / 160 mm———
ALX134——Opening 192 mm———
ALX136——Opening 173 / 189 mm———
ALX136D21700 — 140, 160 cells21700: 16S10P · 20S8P · 14S10P · 13S10POpening 189 / 380 mm———
ALX144——Opening 160 mm———
ALX181——Opening 530 mm———
About this series

Why buyers choose Silver Fish

The Silver Fish profile is the classic retrofit shape: a tapered shell that slides into a bracket on the frame or seat post. If you are replacing a Silver Fish case or building a conversion kit, this is almost certainly the family you want.

Material options run from straight ABS through ABS+PC for higher impact toughness to ABS with aluminium-alloy reinforcement for heavier duty cycles. Several models are available with the internal structure exposed as a technical drawing.

Volume pricing moves once you are ordering in the hundreds, but the minimum stays at one piece — repair workshops buy single units from us every week.

Also known as: also searched as a seat-post or seat-tube battery case, or simply a “fish” case. Bracket spacing varies between suppliers — if you are matching an existing mount, send the bracket dimensions with your enquiry.

  • The retrofit standard — Fits frame and seat-post carrier brackets already on the market.
  • ABS, ABS+PC or aluminium-reinforced — Pick the duty cycle, not just the price.
  • Wide voltage coverage — Most models span 36 V to 72 V.
  • Repair-shop friendly — Single-unit orders ship the same way as container loads.
Get a Quote Compare all six formats
Silver Fish battery case mounted on a folding e-bike
Silver Fish on a folding frameSeat-post carrier, retrofit fit
Other fitments

Compare with the rest of the range

Hailong Battery Cases

The universal fitment. Waterproof ABS and PC+ABS shells with key lock, cable exit and mounting kit options, sized for 18650 or 21700 packs.

Integrated & In-Frame Battery Cases

Hidden housings that sit inside the down-tube, plus conversion kits with aluminium-alloy reinforcement.

Downtube Battery Cases

Housings that sit inside the down-tube, taking 18650 packs to 104 cells. The largest family we hold tooling for.

Rear Rack Battery Cases

Flat rack-mounted housings for cargo, delivery and long-tail builds — to 104 cells, without widening the bike.

Water Bottle Battery Cases

Mounts on standard bottle bosses — the lowest-cost way to add range to a frame with no down-tube space.
Ten Haitian injection moulding machines running in a line at the ALX factory in Guangzhou
Moulded in house10 Haitian injection moulding machines
Finished e-bike battery cases racked ready for dispatch
Racked and readyEmpty shells, inspected before dispatch
Start here

Tell us your voltage, cell type and dimensions

That is all we need to point you at the right case. Quoted within five hours, MOQ one piece.

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Common questions about Silver Fish

How many cells fit in a Silver Fish battery case?
Across our 16 Silver Fish housings the largest mould takes 130 cells on 18650 and 91 on 21700 — the same mould physically holds fewer of the fatter 21700 format. Cell count per model is listed on each product page.
What voltages do Silver Fish cases cover?
Across the 16 models the range spans 36 V to 72 V. Voltage follows the cell count you build to — 10S is 36 V, 13S is 48 V, 14S is 52 V — so pick the case by cells, not by the label voltage.
Can I order a single Silver Fish case?
Yes — MOQ is one piece on every model in this series, quoted within five hours. Single-piece orders ship from stock for the common moulds; rare configurations are moulded to order.
Where does a Silver Fish case mount?
On the down tube, low and close to the frame, with the pack sliding out sideways. It is the format that disappears visually — popular on city and folding bikes where the case is part of the silhouette.