PU cell-holding slot molded to your cell format and cell-stack layout. Replaces machined plastic or metal cell carriers with a fire-resistant, vibration-tolerant, electrically isolating geometry that the OEM's cell vendor can validate against.
Request slot drawing review Cell-format compatibility
What the buyer is trying to solve
Why battery mechanical engineers arrive at this page.
The buyers who arrive here are battery pack mechanical engineers at ESS and EV integrators who are specifying the cell-holder structure inside the pack. The cell-holder does three jobs: it locates each cell so the pack can be assembled without per-cell adjustment, it isolates each cell from the next so a swollen cell cannot pinch its neighbor, and it must survive a thermal event long enough to give the BMS time to react. The conventional machined plastic carrier does the first two jobs but fails the third. The PU cell slot is designed for all three.
Cell-format compatibility
The slot is molded to your cell format. Below is the matrix of formats we currently support as standard. Custom formats are part of normal scope - send a drawing.
|
Cell format |
Standard OD / W × H × T |
Slot family |
Status |
Notes |
|
18650 cylindrical |
18.6 × 65 mm |
CS-18650 |
Standard |
Compression rib variant available |
|
21700 cylindrical |
21 × 70 mm |
CS-21700 |
Standard |
Compression rib variant available |
|
4680 cylindrical |
46 × 80 mm |
CS-4680 |
Standard |
Larger rib, denser foam option |
|
26650 cylindrical |
26 × 65 mm |
CS-26650 |
Standard |
LiFePO4 traction pack |
|
VDA prismatic (PHEV2) |
~ {{120}} × {{85}} × {{varies}} mm |
PS-VDA |
Adapted |
Slot designed per cell vendor drawing |
|
Large prismatic (BYD / CATL) |
~ {{300}} × {{100}} × {{varies}} mm |
PS-LP |
Adapted |
Slot designed per cell vendor drawing |
|
Pouch with rigidizer |
{{varies}} |
PS-POUCH |
Adapted |
Rigidizer frame, not direct pouch contact |
|
Custom cell |
{{varies}} |
CS-CUSTOM |
Custom |
{{6}} weeks first article |
Cavity tolerance
{{±0.2}} mm on cavity dimensions (verify on first article for cell format fit).
01
Locating rib geometry
Single or double rib per cavity depending on cell format; rib height matches OEM datum.
02
Wire-routing channel
Optional wire-routing channel integrated; specify on RFQ.
03
Compression rib variant
For cylindrical cells where the slot also contributes to cell-stack compression, specify the rib-variant geometry.
04
Specifications
|
Material |
Polyurethane (integral skin foam or solid PU), UL94 V-2 standard / UL94 V-0 on request |
|
Process |
Reaction injection molding (RIM) or open-cast molding for low-volume; CNC-fixtured tooling for high-volume |
|
Cavity tolerance |
{{±0.2}} mm (verify per part) |
|
Wall thickness |
{{1.5–3.0}} mm (varies with cell format and slot span) |
|
Density |
{{300–900}} kg/m³ (integral skin: higher density skin, foam core) |
|
Flammability |
UL94 V-2 standard; UL94 V-0 on request |
|
Electrical |
Non-conductive; volume resistivity > 10⁸ Ω·cm |
|
Operating temperature |
−40 °C to +80 °C continuous |
|
Thermal conductivity |
{{0.2}} W/m·K typical (integral skin foam) |
|
Chemical compatibility |
Resistant to LiPF₆ and standard battery module electrolyte vapors |
|
Vibration tolerance |
Validated per IEC 60068-2-6 (10–500 Hz sweep); project-specific on request |
|
Compression set at design T |
< {{10}}% per ASTM D395 |
|
Cell format support |
18650, 21700, 4680, 26650, VDA prismatic, large prismatic, pouch-with-rigidizer, custom |
|
Color |
Black, grey, or custom RAL on request |
|
Design life |
15 years |
When not to specify PU cell slot
Cases where a different cell-holder is correct.
Four cases where we redirect
- Direct pouch cell contact. The PU slot is a rigidizer-frame design for pouch cells, not a direct-contact holder. For direct contact, see our module bracket page or a metal-rigidizer product.
- Cell formats above {{50}} mm diameter with very high thermal load. Very large cylindrical cells (above 4680-equivalent) may need additional thermal management. PU's thermal conductivity is moderate; project-specific thermal analysis is required.
- Pack operating temperature above +80 °C continuous. Above this temperature, PU compression set and creep accelerate. We specify a different polymer; tell us your pack ambient.
- Cell slot must be UL94 5VA rated. UL94 5VA is a higher rating than V-0 and is not available in our standard PU family. We can name a different supplier if you need 5VA.
Material comparison
|
Property |
Machined plastic (ABS / PC) |
Aluminum cell carrier |
Enbuss PU cell slot |
|
Mass per slot (21700 format) |
~ {{80}} g |
~ {{220}} g |
~ {{60}} g |
|
Electrical isolation |
Yes |
No - needs separate insulator |
Yes - integral |
|
Fire performance |
UL94 V-2 typical |
N/A |
UL94 V-0 available |
|
Vibration damping |
None - rigid plastic |
None |
Some integral damping |
|
Compression-set behavior |
Rigid |
Rigid |
Acceptable, tunable |
|
Cost at low volume (50–500) |
High (CNC) |
High (CNC) |
Low (RIM tooling) |
|
Cost at high volume (10k+) |
Mid (injection molding) |
Mid |
Mid (RIM + dedicated tool) |
|
Best use case |
Low volume, no fire need |
High thermal mass need |
Most ESS and EV packs |
Customization & OEM
Pack makers typically need a slot molded to their cell format and stack layout, with optional wire-routing channels, compression ribs, and grounding features. Send your cell-stack drawing and we return a slot drawing, a sample, and a fixed quote. First article {{6–8}} weeks; repeat {{4}} weeks.
Frequently asked questions
What is the typical lead time for a 5,000-slot order?
From PO to first delivery, typically {{6–8}} weeks for a standard cell format. Custom cell format adds {{2–3}} weeks for tool adjustment.
Can the slot include a compression rib to support cell-stack compression?
Yes. Specify the compression-rib variant on RFQ; we return a slot with the rib geometry validated against your cell-stack target preload.
Is the slot recyclable?
PU can be glycolyzed to recover polyol. We offer a take-back program in pilot regions.
How is the slot inspected in service?
Visual at pack service interval. Look for cracks, deformation, or swelling. Any visible defect is grounds for replacement. Pack service interval typically {{5–7}} years.
Does the slot react with LiPF₆ electrolyte?
The slot is rated for vapor exposure typical of a sealed module. Direct liquid exposure from a vent event is not tested; vented packs should be evaluated for slot replacement.
Can the slot be supplied in custom color?
Yes, full RAL range on request. Black and grey are standard for fast delivery.
What is the warranty?
10 years against material failure; separate from the pack warranty. Specific terms depend on cell format and pack operating conditions.
What documentation comes with each lot?
Per lot: dimensional inspection, UL94 certificate (if specified), lot-traceable resin record, cavity dimensional report.
Send your cell-stack drawing
Send the cell format, the stack layout, and any compression-rib or wire-routing requirement. We return a slot drawing, a sample, and a fixed quote.