KT-E09 — 48V Down-Tube / Shark Battery
The standard external down-tube pack: 367.5mm shark case, 17.5Ah on 18650 or 25Ah on 21700, mounted on a 57mm-pitch rail.
Key Details
- MOQ
- From 100 pcs
- Sample Lead Time
- 5–10 working days
- Mass Production
- 2–4 weeks after approval
- Voltage
- 48V
- Capacity Range
- 17.5–25Ah
- Form Factor
- Down-tube / shark
Cell Brands
The KT-E09 is the workhorse of the external down-tube range: a 367.5mm shark case that bolts to the outside of the down tube rather than hiding inside it. That makes it the platform for retrofit programmes, conversion kits and any frame that was not designed around an integrated cavity — and it makes the mounting rail, not the electrical specification, the first thing to check.
Two builds share the case. 91 18650 cells in 13S7P give 48V 17.5Ah; 65 21700 cells in 13S5P give 48V 25Ah. The cell blocks are nearly the same footprint — 305.0 × 119.2mm against 304.9 × 121.1mm — which is why the same enclosure takes either without a second tool. The 21700 build carries 43% more energy from 26 fewer cells.
The rail pattern is the fit decision
The KT-E09 rail runs 83.8mm from the case datum to the first fixing, then 57.0mm and 57.0mm — three fixing points. The KT-E09-PRO is otherwise the same pack on a four-point rail at 85.4mm then 60mm pitch. Frames are drilled for one or the other. If you are designing a new frame, either is available; if you are replacing packs on bikes already in the field, the existing pattern decides it and there is nothing to trade off.
For a taller pack in the same 367.5mm length, the KT-E33 runs the 52V platform in a 157.48mm-high case. Same length, 17mm more depth, different voltage — see the 48V vs 52V guide if the platform is still open.
Outputs and user-facing hardware
USB output, DC2.1/2.5 charge port and the power switch all sit on the right-hand face of the case. That matters more than it sounds: the switch position determines which side of the bike the rider reaches across, and on a step-through or cargo frame that is an ergonomics decision, not a wiring one. CE and UN 38.3 documentation is issued for the configuration you order.
Technical Specifications
| Enclosure Format | Down-tube / shark (external, removable) |
|---|---|
| 18650 Configuration | 91 cells · 13S7P · 48V 17.5Ah |
| 21700 Configuration | 65 cells · 13S5P · 48V 25Ah |
| Case Dimensions | 367.5 mm long · 140.0 mm high · 95.0 mm wide |
| 18650 Cell Block | 305.0 × 119.2 mm |
| 21700 Cell Block | 304.9 × 121.1 mm |
| Mounting Rail | 83.8 mm to first fixing, then 57.0 / 57.0 mm pitch (3 fixings) |
| Outputs | USB · DC2.1 / DC2.5 charge port · power switch (right-hand side) |
| Cell Format | 18650 or 21700 |
| BMS | In-house 13S BMS, current rating matched to parallel count |
| Connector | Specified per programme (XT60 / Anderson / Higo / Julet / custom) |
| MOQ | From 100 pcs |
| Sample Lead Time | 5–10 working days |
| Mass Production | 2–4 weeks after approval |
Inside Every Pack
The same engineering standards apply to every configuration we ship — from cell selection to the final welded enclosure.
Tier-1 Brand Cells
Samsung, LG, Panasonic, EVE and BAK cells — graded and capacity-matched before assembly.
Multi-Protection BMS
Over-charge, over-discharge, short-circuit and temperature protection on every pack.
Welded Construction
Nickel strips welded for low-resistance, vibration-resistant joints inside a sealed enclosure.
Applications
Certifications Included
Test reports and certificates are included in shipment documentation at no additional cost.
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From 100 pcs · Samples in 5–10 working days · Mass production 2–4 weeks after approval
Frequently Asked Questions
What is the difference between KT-E09 and KT-E09-PRO?
The mounting rail. Both use the same 367.5 × 140.0 × 95.0mm case and the same 17.5Ah / 25Ah electrical builds. The KT-E09 has three fixings at 83.8mm then 57mm pitch; the KT-E09-PRO has four fixings at 85.4mm then 60mm pitch. Choose on which pattern your frame is already drilled for.
Can this pack replace an existing down-tube battery on our frame?
Only if the rail pattern matches. Send us the fixing pitch and the tube face profile and we will confirm against the 83.8 / 57 / 57 pattern before you sample. Case length, height and width are the second check, in that order.
Is the USB output always fitted?
It is standard on this platform along with the DC2.1/2.5 charge port and a side power switch, all on the right-hand face. Deleting the USB port or moving the switch is a tooling change, so raise it at specification rather than after sample approval.
Related Products
KT-E09-PRO Down-Tube E-bike Battery
KT-E09-PRO 48V down-tube battery: same 367.5mm shark case and 17.5Ah/25Ah builds as the KT-E09, on a four-point 60mm-pitch mounting rail.
View Details
Catalog ModelKT-E33 52V Down-Tube E-bike Battery
KT-E33 52V down-tube e-bike battery: 14S8P 18650 at 20Ah or 14S6P 21700 at 30Ah in a 367.5 × 157.48mm shark case with USB and DC2.1 outputs.
View Details
Catalog ModelKT-E33-PRO 52V Down-Tube E-bike Battery
KT-E33-PRO 52V down-tube battery: 20Ah on 18650 or 30Ah on 21700 in the KT-E33 case, mounted on a four-point 60mm-pitch rail for load-carrying frames.
View Details