A weighing instrument that determines a price or a declared quantity is one of the few pieces of industrial electronics whose correctness is certified by law, and its battery does not escape that scrutiny. The compliance campaign for a battery-powered onboard or portable scale spans four layers at once: legal-metrology type approval so that weight readings are legally valid across the rated voltage and temperature envelope; electrical safety and ingress protection suited to a wash-down, vehicle-mounted environment; electromagnetic compatibility so the scale neither disturbs nor is disturbed by radios and motor drives around it; and battery performance, safety and transport evidence for the rechargeable source. This final paper maps that complete campaign for a nickel-metal hydride powered weighing indicator - OIML R76 and its European transposition EN 45501 under the Non-Automatic Weighing Instruments Directive 2014/31/EU, the OIML R60 accuracy class of the load cells, IEC 61010-1 electrical safety, IEC 60529 ingress ratings up to IP68, the IEC 61000 EMC series, and IEC 61951-2, IEC 62133-2 and UN 38.3 for the cells - showing how supply voltage is treated as an influence quantity in type testing and why a supplier that provides complete, lot-traceable NiMH documentation shortens the route to a certifiable, legal-for-trade product.
OIML R76 defines metrological requirements and tests for non-automatic weighing instruments - accuracy classes, number of verification scale intervals, maximum permissible error, disturbance and influence-factor tests, and the marking that accompanies approval. In Europe, EN 45501 is the harmonised standard and the NAWI Directive 2014/31/EU the legal instrument, requiring the CE mark together with the supplementary metrology 'M' mark; in the United States the parallel requirements appear in NIST Handbook 44. The load cells themselves are separately approved, commonly to OIML R60 class C3.
Critically for battery design, supply voltage is an influence factor: type testing exercises the instrument at nominal, high and low voltage and during slow voltage decay, requiring it to remain within maximum permissible error, to flag a low battery and never to display a misleading valid weight. This is why the battery's discharge curve and the indicator's shut-off thresholds must be co-designed and evidenced, and why a battery that powers only an actuator - as one OIML certificate carefully notes - sits outside the weighing approval whereas the source feeding the bridge sits inside it.
The indicator and its battery compartment are assessed for electrical safety under IEC 61010-1 (the general safety standard for electrical measurement and laboratory equipment), covering insulation, clearances, protection against electric shock and thermal hazards, and the safety of an internal rechargeable supply under fault. Onboard and platform hardware is additionally sealed against water and dust under IEC 60529, with load cells and connectors frequently rated IP68 for high-pressure wash-down and outdoor use.
The pack design supports these requirements through welded, insulated interconnects, integral fusing, a sealed carrier and keyed connectors, so a cell fault cannot expose a live contact or propagate into the measurement circuitry even when the enclosure is hosed. Materials and venting are chosen so that repeated thermal cycling from cold store to warm dock does not compromise the seal.
A forklift scale operates beside motor controllers, ignition systems, walkie-talkies and its own wireless module, so it must meet the IEC 61000 EMC series - conducted and radiated emissions, electrostatic discharge, radiated and conducted immunity, surge and electrical fast transients - and continue to weigh within tolerance during the most severe disturbances. The battery and its wiring are part of the EMC design: a low-impedance source with proper decoupling prevents a printer or radio transient from modulating the sensitive analogue front end.
Immunity tests are deliberately repeated with the instrument on battery at a low state of charge, because a high-impedance, nearly exhausted pack is the worst case for supply-borne disturbance. Demonstrating that the weight reading holds through an ESD or RF field while the printer fires is precisely the through-line that links cell internal resistance to metrological robustness.
Vehicle-mounted and portable scales face environmental tests under IEC 60068 - cold, dry heat, damp heat, sinusoidal and random vibration, bump and free fall - chosen to reproduce mast vibration, dock impacts and drops from a vehicle. The first animated figure layers the standards stack; the second sequences the qualification campaign. Battery packs are exercised through the same vibration and shock profiles to confirm tab welds, cell retention and connector contact reliability.
Temperature testing is doubly important for legal metrology: it must cover both the instrument's rated operating range and the cold-store extremes where lead-acid weakens, providing the evidence base for the runtime-versus-temperature claim made in the design paper and for the low-battery threshold set during type approval.
The sealed NiMH cells carry their own standardised evidence. IEC 61951-2 defines performance tests for portable sealed nickel-metal hydride cells and batteries - capacity, charge retention, endurance and internal resistance - which the vendor extends with high-rate discharge, wide-temperature and cycle data relevant to shift duty. IEC 62133-2 provides the safety requirements for sealed secondary cells and batteries under charge, forced discharge, external short circuit, vibration, shock, free fall, thermal abuse, crush and pack-level protection-fault conditions.
UN 38.3 supplies the transport test summary needed to ship cells and packs by any mode; because NiMH is not a lithium chemistry, replacement packs move under simpler transport rules than lithium equivalents - a practical advantage for worldwide delivery of spare batteries to forklift and scale-service fleets. Together these three documents give the scale manufacturer a complete, lot-traceable battery dossier for the technical file.
The final technical file weaves every layer into one package: the OIML R76 / EN 45501 type-approval report with voltage-as-influence-factor cases passed at battery worst case; OIML R60 load-cell certificates; IEC 61010-1 and IEC 60529 evidence for the enclosure and battery compartment; IEC 61000 and IEC 60068 results captured on battery at low charge and temperature extremes; and the IEC 61951-2, IEC 62133-2 and UN 38.3 battery dossier. The through-line is that the rechargeable source is tested as part of the weighing function, never as a disconnected accessory.
A battery manufacturer that supplies matched, wide-temperature NiMH cells with all three battery-standard documents, internal-resistance and high-rate characterisation, and engineering support for the low-voltage influence and EMC-on-battery tests removes the most variable element from that file. With that backbone the weighing-instrument maker can certify an onboard scale that stays within maximum permissible error, preserves every legal record and survives the loading dock - the foundation on which trade confidence, fleet uptime and regulatory acceptance depend.
Weijiang Power designs and manufactures sealed nickel-metal hydride cells and matched industrial packs for remote, off-grid and safety-related equipment, and supports OEM partners with IEC 61951-2 performance files, IEC 62133-2 safety evidence, pulse-load characterisation, wide-temperature testing and charger/pack co-validation. Tell us your duty cycle, peak current, temperature envelope, autonomy target and the standards your product must meet, and our engineers will specify a cell-and-pack combination that protects runtime, reliability and service life. Review the range on the products page.
