Lead-Acid Battery Soldering
Purity-controlled Pb-Sn alloys for soldering posts, COS straps and interconnections of automotive, traction, UPS and stationary batteries
Purity-controlled battery grade Pb-Sn alloys for post, COS strap and VRLA interconnection soldering. Dickmann industrial supply since 1902 with ISO 9001:2015 certification. See also tinning anodes for ultra-high purity applications.
Why Batteries Require Specialty Alloys
Standard 50/50 is not enough: purity is the critical technical differentiator
Impurity Limits in Battery Grade Lead
The real technical differentiator: why traces matter in lead-acid batteries
Metallic impurities present in the solder alloy do not remain inert: during battery operation they migrate into the sulfuric acid electrolyte. Even a few ppm can cause dramatic effects on performance, useful life and safety.
Effects of impurities on batteries
- Accelerated gassing (H₂ and O₂ evolution) → water consumption, explosion risk in sealed VRLA batteries
- Anomalous self-discharge → battery discharges even without load, losing nominal capacity
- Reduced useful life: from 5-10 years to just 1-2 years in case of contamination
- Accelerated corrosion of positive Pb-Ca or Pb-Sb grids
- Catalytic decomposition of the electrolyte with loss of H₂SO₄ concentration
- Drop in nominal capacity and charge/discharge efficiency
| Element | Symbol | Critical effect | Typical limit | Criticality |
|---|---|---|---|---|
| Nickel | Ni | Critical gas-generator, hydrogen evolution | < 1-5 ppm | 🔴 Extreme |
| Tellurium | Te | Severe gassing | < 1-5 ppm | 🔴 Extreme |
| Manganese | Mn | Electrolyte decomposition catalyst | < 1 ppm | 🔴 Extreme |
| Cobalt | Co | Anomalous self-discharge | < 5 ppm | 🟠 High |
| Iron | Fe | 10 ppm already harmful on negative active materials | < 5-10 ppm | 🟠 High |
| Chromium | Cr | Gassing | < 5 ppm | 🟠 High |
| Zinc | Zn | Promotes gassing | < 5 ppm | 🟠 High |
| Cadmium | Cd | Promotes gassing, banned in EU | < 5 ppm | 🟠 High |
| Antimony | Sb | Excess gassing, but intentional grid additive | < 30 ppm in 'low-Sb' | 🟡 Controlled |
| Selenium | Se | Gassing (but intentional use 200-300 ppm in some alloys) | Controlled | 🟡 Controlled |
| Arsenic | As | Gassing (intentional additive 0.10-0.35% for hardness) | Controlled | 🟡 Controlled |
| Copper | Cu | Anomalous self-discharge | < 50-100 ppm | 🟡 Medium |
| Bismuth | Bi | Non-gassing, tolerated | < 500 ppm (0.05%) | 🟢 Low |
| Silver | Ag | Non-gassing, tolerated | < 50 ppm | 🟢 Low |
VRLA Golden Rule
Golden rule for VRLA batteries (Valve Regulated Lead Acid, sealed): all gas-generating impurities must stay below 1 ppm. Traditional flooded batteries tolerate slightly higher limits, but still 10-100 times more stringent than standard 50/50 sheet metal alloy.
Source Lead Purity Standards
ASTM B29 — Pure Lead
99.94% Pb min
American standard for refined lead. 'Low-Bismuth Lead' variant requires 99.97% Pb (max 0.025% Bi)
BS EN 12659 — Refined Pure Lead
99.97-99.99% Pb
European standard. De facto battery grade standard in EU. Dickmann supplies lead compliant with this specification for battery applications.
Battery Grade Premium
99.985% Pb min
More stringent specification required by premium VRLA manufacturers. Available on request with complete spectrometric analysis certificate.
Soft Lead / Refined Pure Lead
99.97% Pb
Common commercial designation in the sector. Indicates thermally refined lead for battery use, with controlled gas-generating impurities.
Application-Specific Compositions
Batteries use different alloys depending on component function
| Application | Typical composition | Regulatory/patent reference | Notes |
|---|---|---|---|
| Automotive posts/terminals | Pb-Sb 2.75-3.25% / As 0.05-0.20% / Sn 0.15-0.40% / Cu 400-600 ppm | Patent US6300007B1 | Torch soldering, high mechanical strength |
| Automotive COS strap (Cast-On-Strap) | Pb-Sb 3.0-3.5% / Sn 0.2-0.4% / As 0.1-0.2% / Se 150-250 ppm | Battery industry standard | Automatic COS line, internal cell connection |
| Sealed VRLA interconnections | High purity Pb-Sn, gas-generating impurities < 1 ppm | Premium VRLA spec | Maximum stringency - sealed batteries gassing-sensitive |
| Post repair (maintenance) | Pb-Sb 4-6% (high antimony, classic) | Historical repair standard | Oxy-acetylene torch, high hardness |
| Active oxide / grid material | Pure Pb 99.97-99.99% (no additives) | BS EN 12659 / ASTM B29 | Not for soldering, but for raw material production |
| Pb-Ca grids (maintenance-free) | Pb-Ca 0.07-0.09% / Sn 0.3-1.5% | Modern VRLA technology | Low-Sb alternative for reduced self-discharge |
⚠️ The standard 50/50 alloy (Sn 50% / Pb 50%) intended for sheet metal, coffins and caskets is NOT suitable for any battery soldering application. Composition too rich in tin (50%) and uncontrolled gas-generating impurities. For battery production and repair, use exclusively battery grade alloys formulated based on ASTM B29 / BS EN 12659 standards.
Battery Grade Customer Sectors
Who our purity-controlled alloys are intended for
Automotive Battery Manufacturers
SLI (Starting-Lighting-Ignition) battery makers for cars, trucks, buses. Recurring supply of Pb-Sb 3% alloy for post soldering and COS alloys for automatic line. Consistent batches for stable QC.
Industrial Traction (Forklift, AGV)
Traction batteries for forklifts, AGVs (Automated Guided Vehicles), golf carts, earthmoving machinery. High-capacity batteries with deep cycles. Post repair with high-antimony alloys.
UPS and Stationary Telecom
Data center UPS maintainers, -48V stationary batteries for telecom central offices, off-grid solar storage systems. Stringent VRLA specs with gas-generating impurities < 1 ppm.
Reconditioning and Rebuilding
Companies specialized in industrial battery reconditioning, rebuilding of spent traction batteries, post and cell repair. We supply alloys in 25 kg boxes and pallets for specialized workshops.
European Regulatory Framework
Regulatory compliance for Pb-Sn alloys intended for lead-acid batteries
RoHS 2011/65/EU — Annex IV exemption 21
Explicit exemption for lead-acid batteries
The RoHS directive contains an explicit exemption for lead in lead-acid batteries (Annex IV, exemption 21). The use of Pb-Sn alloys for battery soldering is therefore fully legitimate in the EU.
EU Reg. 2023/1542 — Batteries
New EU battery regulation (replaces 2006/66/EC)
Defines EU requirements for production, labeling, collection and recycling of batteries. Sets metal trace limits and documentation obligations along the supply chain. Our alloys are produced to these standards.
REACH Reg. EC 1907/2006
Lead as SVHC with authorized use
Lead is in the SVHC Candidate List, but industrial use for battery applications is authorized. It is not in Annex XIV. Our supplies are accompanied by REACH-compliant Safety Data Sheets (SDS).
Italian D.Lgs 81/2008 — Worker safety
Protection of workers exposed to lead
Regulates worker safety in battery production: ventilation, PPE (FFP3 mask, gloves, goggles), health surveillance with blood lead monitoring. Our SDS include occupational exposure limit values (TLV).
Battery Grade Alloy vs Standard 50/50
Why sheet metal alloy must NOT be used on battery posts
| Characteristic | Dickmann Battery Grade | Standard 50/50 | Consequence |
|---|---|---|---|
| Composition | Pb-Sb 3% / Sn 0.3% / As 0.2% (formulated) | Sn 50% / Pb 50% (balanced) | Opposite compositions |
| Nickel (Ni) impurity | < 1-5 ppm | 20-100 ppm (uncontrolled) | Severe gassing |
| Tellurium (Te) impurity | < 1-5 ppm | Unspecified | Severe gassing |
| Iron (Fe) impurity | < 5-10 ppm | 50-200 ppm | Negative active reduction |
| ICP-OES analysis certificate | Yes, for each batch | Not always available | Manufacturer QC impossible without |
| Batch traceability | Complete batch → customer | Typically absent | Audit difficult |
| Expected battery life | 5-10 nominal years | 1-2 years if contaminated | 60-80% life reduction |
| Cost per kg | Premium (purity) | Standard | False economy: batteries lasting 1/5 cost 5x |
Saving on standard alloy purchase is zero: a battery with life reduced from 8 to 2 years costs the end customer 4x more in replacements. Serious manufacturers use exclusively certified battery grade alloys.
Frequently Asked Questions on Battery Soldering
Technical, regulatory and operational specifications for the battery sector
Request the Chemical Analysis Certificate
For standard 50/50 alloy (sheet metal, coffins, caskets) see the 50/50 tin-lead solder sticks hub. For ultra-high purity applications see tinning anodes.
Phone
+39 02 6604 7053