Molded part guide: battery housings
Cells change size as they age, they get hot, and when one fails it vents. The plastic around them has to plan for all three, on top of holding everything in place.
The job
Closing a two-piece shell is covered in the general enclosure guide. What makes a battery housing different is what sits inside it.
Cell holders set the spacing between cells, and that spacing controls how heat moves through the pack and how far a failing cell sits from its neighbors. Holders are often molded as one part per layer, with a pocket for every cell and openings for the busbars or nickel strips to reach the terminals.
Cell diameters and lengths vary between suppliers and between lots. A pocket sized for a nominal cell either rattles or binds. Crush ribs inside the pocket, or an adhesive gap that gets filled at assembly, take up that variation.
If you plan to bond cells with UV-cure adhesive, tell us early. Some clear polycarbonate grades let enough UV through to cure the adhesive from outside the holder, and that choice has to be made before the resin is locked in.
Cell format
General behavior. Your cell supplier's datasheet and your pack design set the real requirements.
| Cell format | What the plastic does | What to watch |
|---|---|---|
| Cylindrical | Holders with one pocket per cell, top and bottom | Pocket fit across cell lots, and keeping the vent end of each cell clear |
| Prismatic | Frames and spacers between cells, end plates that hold the stack | Cells grow through life, so frames either allow for it or carry the clamping load |
| Pouch | Frames that support the soft cell, often with foam pads between cells | Swelling is larger than on hard cells, and sharp frame edges can damage the pouch |
| Consumer packs and battery doors | Compartments, contacts, and a door the user opens | Door latch wear, spring contact retention, and reverse polarity keying |
Service tiers
Cell holders, swelling, and the vent path. Upload CAD with the cell, the seal, and anything that touches the housing called out in notes.
| Tier | Environment | What matters most | Typical molded route | Quote path |
|---|---|---|---|---|
| 1 Cylindrical | One pocket per cell | A nominal pocket rattles or binds | Crush ribs, or a gap filled at assembly | Upload CAD; send the cell |
| 2 Prismatic | Frames between the cells | Cells grow through life | Frames that allow the growth, or that carry the clamp | Instant quote; note the growth |
| 3 Pouch | A frame around a soft cell | Swelling, and a sharp edge can cut the pouch | Room to swell, and no sharp frame edge | Upload CAD; note the pouch |
| 4 Vent path | Open space in front of each cell vent | A lid against the vent traps the gas | A channel that leads the gas away from the neighbors | Instant quote; mark the vent |
| 5 Door | A compartment the user opens | The latch wears, and a cell can go in backwards | A latch, retained contacts, and a polarity key | Upload CAD; note the door |
Materials
One primary family per shell line item. Put swelling clearance and the vent path in comments.
| Family | Typical use on this part type | Notes for instant quote |
|---|---|---|
| Drawing resin | Shells and holders named on the drawing | Field the grade, and the supplier's listed thickness |
| PC | Clear holders when UV has to reach the adhesive | Field PC; name the adhesive |
Venting and heat
Cells that fail vent hot gas and particles. The housing either routes that away or traps it.
The vent on each cell needs open space in front of it. A holder that caps the vent end, or a lid that sits right against it, turns a single cell event into a pack event. Many designs mold a channel or plenum that collects gas from the cells and leads it to one exit point, away from the neighbors.
Sealed packs also need to breathe during normal use, because temperature swings pump air in and out. A pressure equalization vent with a membrane is usually welded or snapped into a molded port. The port geometry and its sealing face are part of the housing design.
Thermal pads, gap filler, and cooling plates change how much heat reaches the plastic. Tell us what touches the housing so resin choice and wall layout account for it.
Closing the pack
The choice affects the tool, the resin, and whether a pack can ever be repaired.
Avoid these
Two choices that mis-fit a cell, or trap gas in the pack.
A pocket sized only for the nominal cell. Lots vary, so the cell rattles or binds. Add crush ribs, or leave a gap that gets filled at assembly.
A holder or a lid that caps the cell vent. Gas from one cell then stays in the pack. Leave open space in front of the vent, and lead it away from the neighbors.
Drawing
Most of this comes from your cell and pack design, not from the housing CAD.
Cell part number and datasheet, including where the cell vents
How cells are held: pressed into pockets, bonded, or clamped
Expected cell growth over life, if your supplier gives it
Flame rating the product needs, so resin grade and thickness can be matched
Busbar or contact design, and whether it is insert molded
Closing method, sealing requirement, and any pressure equalization vent
Keep reading
Materials and methods that battery housings depend on.
Housings when the drawing names PC/ABS.
PC/ABS blendTough, and available in clear grades for UV bonding.
PolycarbonateMolding busbars and contacts into the holder.
Insert moldingSoft seals molded onto the lid or flange.
OvermoldingChoosing how to close a sealed pack.
Ultrasonic welding vs adhesiveKeeping large pack shells flat.
Uniform wall thicknessGeneral two-shell closure and parting lines.
EnclosuresThe plug that brings power in and out.
Connector housingsEvery part-type guide, grouped by family.
Molded parts libraryPacks, modules, and chargers.
Battery systemsFAQ
The rating belongs to the resin grade, and it applies at the thickness the resin supplier lists. We mold with the grade you specify. Walls thinner than the listed thickness are outside that rating, so check them during design.
No. NetProto manufacturing is ISO 9001 certified. Pack safety testing and certification is done by your team and an accredited lab.
Usually not. Holders need tight pocket control and often a different resin from the shell. Keeping them separate also lets the holder be reused across pack sizes.
No. We mold the housing parts and can handle secondary operations on the plastic. Cell handling and pack assembly stay with you or your pack assembler.
Some clear polycarbonate grades let UV through, so the adhesive can cure from outside the holder. That choice has to be made before the resin is locked in.
Temperature swings pump air in and out. A membrane in a molded port lets the pack breathe without leaving an open hole.
Next step
Upload the housing CAD with the cell datasheet. DFM feedback covers pocket fit, vent clearance, and how the pack closes.
