This is a Battery Holder Contact Springs Collection — a family of custom compression, torsion, and leaf springs engineered to hold cylindrical or prismatic cells firmly against PCB pads or busbars. Th
This is a Battery Holder Contact Springs Collection — a family of custom compression, torsion, and leaf springs engineered to hold cylindrical or prismatic cells firmly against PCB pads or busbars. The concrete benefit: we hold spring free length tolerance to ±0.01 mm, pitch runout under 0.05 mm, deliver in 7–12 days, and heat-treat to 40–50 HRC so your contacts survive 10,000+ insertion cycles without permanent set.
Battery holders fail when contact force drifts. We control spring rate within ±5% of your specified N/mm value, and we verify free length on every batch using a digital height gauge — not a sample. For a typical 18650 holder spring, we hold free length at 8.00 mm ±0.01 mm, which translates to a consistent 1.2–1.5 N contact force across the full compression range. We also check solid height to prevent coil binding at full compression, a common cause of plastic housing cracks.
We stock four spring-grade materials in our Dongguan factory: music wire (ASTM A228) for general use, stainless steel 302 (ASTM A313) for corrosion resistance in humid environments, phosphor bronze (ASTM B159) for low electrical resistance, and beryllium copper (ASTM B197) for high-cycle applications. After coiling, we stress-relieve at 300–350°C, then optionally shot-peen for fatigue life above 1 million cycles. For battery contacts, we recommend stainless 302 with electropolishing to reduce surface friction and achieve Ra 0.4 µm.
We produce contact springs from 0.10 mm to 3.00 mm wire diameter. Coil geometry options include closed ends, ground ends, open ends, and double-closed ends. We can also make conical springs for recessed battery contacts, or barrel-shaped springs for side-terminal cells. Maximum outside diameter is 25 mm, maximum free length is 100 mm. If you need a spring that fits a 5 mm deep pocket in a plastic holder, we can coil a conical spring with a 4.8 mm OD at the base and 3.5 mm OD at the tip — no extra tooling charge.
Bare music wire gives Ra 0.8 µm, which is fine for dry contacts. But if your battery holder operates in a vibrating environment, we recommend nickel plating (2–5 µm) or gold flash (0.5–1 µm) to reduce contact resistance below 50 mΩ. We also offer passivation for stainless springs to remove free iron and prevent rust spots. All plating is done in-house with a barrel process, so we control thickness uniformly across the entire spring — no bare spots on the coil ends.
Every production lot goes through a 3-step inspection. First, we measure free length, OD, and wire diameter on 5% of parts using a calibrated optical comparator. Second, we test spring rate on a compression tester at 3 different heights — not just one point. Third, we perform a 100% magnetic particle inspection on ground-end springs to catch micro-cracks from grinding. We include a dimensional report with each shipment, and you can request a material certificate from our steel supplier for full traceability. For high-volume orders, we also run a load test at 50% compression to verify no set after 10 cycles.
| Parameter | Specification |
|---|---|
| Wire diameter range | 0.10 mm – 3.00 mm |
| Outside diameter range | 0.50 mm – 25.00 mm |
| Free length tolerance | ±0.01 mm (for lengths under 20 mm) |
| Spring rate tolerance | ±5% of specified N/mm |
| Hardness (music wire) | 40–50 HRC after heat treatment |
| Surface finish (bare) | Ra 0.8 µm; Ra 0.4 µm after electropolishing |
| Pitch runout | ≤0.05 mm |
| Lead time (custom) | 7–12 days after drawing approval |
| MOQ | No MOQ — samples accepted from 10 pcs |
| Plating options | Nickel 2–5 µm, Gold flash 0.5–1 µm, Passivation |
Standard springs have open ends, which can scratch your PCB pads. We offer closed-ground ends for flat seating, or closed-not-ground ends for tighter tolerances. For springs that need to be spot-welded to a nickel strip, we can supply with a 90° bent leg — we grind the tip flat to improve weld consistency. We also make extended hook ends for battery holders that require a latching mechanism. Tell us your assembly method (press-fit, glue, weld, or screw) and we will adjust the end geometry accordingly.
Springs are shipped in anti-static bags with VCI (vapor corrosion inhibitor) paper inside. For stainless or plated springs, we use neutral pH paper to avoid tarnishing. We pack in small quantities per bag (100 or 500 pcs) to make your line-side inventory easy to count. Each bag is labeled with part number, batch number, and date of manufacture. For air freight, we use rigid cartons with foam inserts to prevent coil deformation during transit. We export from Shenzhen or Hong Kong airport — most orders reach the USA in 5–7 days.
Battery holders are safety-critical. A spring that loses force after 500 cycles can cause intermittent power loss in a medical device or a power tool. Our precision manufacturing process — CNC coiling with servo-controlled feed, followed by 100% load testing — ensures every spring maintains its specified force for the life of the product. We have served automotive and medical clients for 20 years, and we apply the same traceability standards to small spring orders as we do to million-piece runs. For more on how tool selection affects your spring's geometry, see our CNC cutting tool selection guide. And if you are designing the plastic pocket that holds the spring, our CNC machining tolerances guide explains how to specify pocket clearance without over-constraining.
For a standard music wire spring, 1.2 mm wire diameter, 6 mm OD, 8 mm free length, closed-ground ends: unit cost is $0.04–$0.08 at 10,000 pcs. Add nickel plating for $0.01 per piece. Add a 90° bent leg for $0.015 per piece. Tooling is free for standard wire sizes. For beryllium copper, expect a 30% material surcharge. We quote each drawing individually because spring rate and end geometry drive cost more than raw material. Send us your drawing and we will return a firm price within 12 hours.
We have no MOQ — you can order 10 pieces for prototyping or 500,000 pieces for production, and the unit price scales with quantity.
Yes, we customize wire diameter, OD, free length, coil count, end type, plating, and material — just send a drawing or a sample and we will match it within ±0.01 mm.
We inspect 5% of parts for dimension and 100% of parts for load at 50% compression, plus we include a dimensional report with every shipment.
Prototype samples ship in 3–5 days, and production orders ship in 7–12 days after you approve the sample — faster if you accept our standard wire sizes.
Get a firm quote within 12 hours. Send your drawing or sample spec to sc@bquq.com, or message us on WhatsApp at +86 13713157787. We will confirm spring rate, material, finish, and price — no MOQ, no hidden tooling fees. Precision manufacturing, made in China, with 20 years of spring experience behind every coil.
| Parameter | Capability |
|---|---|
| Materials | SUS302/304/316, SWC piano wire, SWP music wire, 65Mn, phosphor bronze, beryllium copper |
| Types | Compression, extension, torsion, wire forms, battery springs, touch springs |
| Wire Diameter | 0.05 - 12.0 mm |
| Tolerance | ±0.02mm standard, ±0.01mm on request |
| Surface | Zinc plating, nickel, black oxide, passivation, shot peening |
| Machines | CNC spring coiling machines, torsion machines, wire forming machines |
| Prototype | 72 hours, no MOQ on samples |
| Inspection | Load test per batch, fatigue test data on request |
