E-Bike Battery Compartment Measurement & Fitment Guide
How to Measure Your Battery Compartment for a Perfect Fit
Avoid fitment issues, pinched wires, and sizing errors. Measure your e-bike, e-dirt bike, or custom frame space before ordering a custom lithium battery pack.
Quick answer: Measure the narrowest interior first, then deduct cable bend space at 15mm to 20mm and foam at 3mm to 5mm per side, so width loses 6mm to 10mm total. Test with a cardboard mockup before you order, and send us L x W x H, voltage, BMS current, and photos if the shape is irregular.
4-Step Measuring Workflow
Measure Maximum Interior Space
Use a rigid tape measure or caliper to record the absolute maximum internal Length, Width, and Height of your frame tray or compartment.
Rule: Measure at the narrowest point, taking internal welds and bolt heads into account.
Deduct Cable & Plug Bend Clearance
Heavy-gauge cables and anti-spark connectors, QS8 and XT90, need bending space above or beside the pack. Thicker wire needs more bend space, check your wire gauge.
Rule: Deduct 15mm - 20mm from height or length where main discharge cables exit.
Account for Protective Foam
To prevent vibration damage on trails, packs are surrounded by high-density EVA foam padding.
Rule: Reserve 3mm - 5mm per side for EVA foam, so width loses 6mm - 10mm total.
Verify Lid Risers & Hatch Extensions
For factory dirt bikes, Sur-Ron and Talaria, high-capacity packs at 40Ah and 50Ah exceed OEM height. Check if you plan to use a 3D-printed or billet Lid Riser, and check that the latch still closes after the riser.
Rule: Specify if your height includes a Lid Riser extension, typically +20mm to +50mm, check your specific riser.
Common Sizing Mistakes to Avoid
Ignoring Weld Seams & Bolt Heads
Inner weld seams or protruding controller mounting bolts can subtract 3mm to 5mm of usable internal width. Always measure between protruding hardware, not flat walls.
Forgetting Cable Exit Location
If discharge cables exit from the top of the metal casing, rigid 8AWG wire needs vertical bending space under the frame latch. Top-exit packs need extra height clearance, thicker wire needs more.
Confusing Outer Shell Dimensions
Blue PVC adds about 1.5mm overall, metal armor adds about 3mm to 5mm overall, so a metal pack is about 2mm to 3mm larger than a PVC pack for the same cell block. Tell us which shell you need before we size the pack.
Standard Bike Frame Compartment Reference
| Bike Platform | Stock Space (W × D × H) | Max Fitment Without Riser | Requires Lid Riser | Recommended Connector |
|---|---|---|---|---|
| Sur-Ron Light Bee X | 150mm × 140mm × 380mm | 60V 30Ah / 72V 30Ah Slim | 60V 40Ah / 72V 50Ah (+20-50mm) | Sur-Ron OEM / QS8 Anti-Spark |
| Talaria Sting MX3 / MX4 | 155mm × 145mm × 390mm | 60V 40Ah / 72V 40Ah Direct | 72V 42Ah / 72V 50Ah (+20-40mm) | Talaria Plug / QS8 Anti-Spark |
| Talaria XXX (Supermoto) | 115mm × 135mm × 410mm | 60V 30Ah / 72V 30Ah Slim Slide | No lid riser, bottom slide only | Talaria XXX Direct Harness |
| Stealth Bomber / EEB Frame | 140mm × 200mm × 360mm+ | 72V 40Ah / 72V 60Ah Triangle | Custom Frame Side Panels | QS8 / QS10 Anti-Spark |
Slim means the PVC triangle version, metal version dimensions differ, check your specific pack spec before ordering. OEM plug only if your BMS current is within OEM rating, otherwise use QS8. Talaria 42Ah in the riser column is kept as in the original, check P count for that tier before ordering.
Frequently Asked Questions
Q: How do I test fitment before ordering a custom battery?
A: Build a cardboard box with your target pack dimensions, including connector protrusion, not just the cell block. Slide the mockup into your frame tray to test hatch closure and cable clearance.
Q: What is the thickness difference between Blue PVC and Metal Casing?
A: Blue PVC adds roughly 1.5mm overall. Metal armor adds 3mm to 5mm overall. For the same cell block, a metal pack is about 2mm to 3mm larger than a PVC pack.
Q: What if my custom frame has an irregular triangle or angled shape?
A: Take photos with a measuring tape along the edges, or submit a 2D diagram. In the custom form, paste your L x W x H, voltage, BMS current, and photos, so we can confirm fit before you pay.
