1) Safety First: Core Hazards and Controls

1.1 Electrical Shock & Short-Circuit

• Remove all metallic personal items (rings, watches) before working.*
• Use insulated tools and wear rubber gloves.*
• Never connect/disconnect under load; isolate sources before touching terminations.*
• Before placing batteries on racks/cabinets, measure voltage from battery terminals to rack/cabinet frame—this should read 0 V (no leakage to chassis).*

1.2 Chemical Exposure (Acid/Gel Electrolyte)

• Electrolyte (gel or liquid acid) is corrosive and conductive; it can burn skin and eyes.*
• If skin contact occurs: rinse immediately with water. If in eyes: use eye-wash solution or clean water and seek medical care.*
• Neutralize spills with sodium bicarbonate (≈ 1 lb per 1 gallon water).*

1.3 Fire, Explosion & Heat (Hydrogen Management)

• Lead-acid batteries can emit hydrogen during overcharge; eliminate ignition sources—no smoking/sparks nearby.*
• Do not charge in sealed cabinets/rooms. Provide ventilation and 0.5 in (≈1.25 cm) spacing between units for heat dissipation.*
• Ensure the room has adequate airflow to prevent hydrogen accumulation.*

2) Tools & Equipment Checklist

General tools

• Digital voltmeter.
• Insulated open-end spanners.
• Torque-adjustable wrench.
• Forklift or suitable lifting aid (batteries are 10–35 kg each).*
• Rubber gloves, face shield, apron, eye-wash solution, fire extinguisher.*

Optional/diagnostic

• Micro-ohmmeter or internal resistance/conductance tester.
• Battery resistance test set.
• 100 A load test kit.
• DC load (or AC load for UPS acceptance tests).*

3) Pre-Installation Preparation

1. Define string topology (series / parallel per system voltage). See examples below.*
2. Plan intercell, inter-row, and inter-rack connections and terminations.*
3. Prepare racks/cabinets and cable routes; confirm ventilation and service clearances.*
4. Inbound inspection: check for physical damage; verify that hardware (bolts, washers, terminal covers) is complete.*
5. Staging & logistics: use a temporary warehouse/staging area for pre-checks and transport readiness.*
6. Leakage & isolation checks: measure voltage
   • between rows,
   • between tiers,
   • between racks/cabinets,
   • and from each battery terminal to rack/cabinet structure (should be 0 V).*
7. Record all pre-install measurements on commissioning sheets (baseline for warranty/maintenance).*

4) Installation Sequence (Task Flow)

1. Place batteries into racks from bottom to top to maintain stability and safety.*
2. Maintain 0.5 in (≈1.25 cm) spacing for interconnect clearance and cooling.*
3. Uniform polarity orientation across the rack: all positives aligned in the same direction; same for negatives—prevents wiring mistakes.*
4. Clean terminals with a soft brass brush to remove oxidation that may have formed during transport.*
5. After torquing connections to specification, apply antioxidant grease (e.g., No-Ox-ID or NCP-2) at the contact surfaces to mitigate future oxidation.*
6. Do not use lubricants on racks/cabinets—hydrocarbons can degrade plastic battery cases over time.*
7. Number the batteries in drawings and on physical labels for easy maintenance tracing. Keep cable sizes consistent across series/parallel paths to preserve voltage balance.*

5) System Topologies (Examples)

• 360 VDC system: e.g., one three-tier rack with 30 × 12 V VRLA batteries connected in series.*
• 480 VDC system: e.g., two three-tier racks with 40 × 12 V VRLA batteries connected in series.*

Always confirm the required number of series cells:
If ( N ) batteries of nominal ( V_{\text{bat}} ) are in series, the nominal string voltage is
$$V_{\text{string}} \approx N \times V_{\text{bat}}.$$

6) Storage Guidelines (Pre-Commissioning)

• Store in a clean, dry, cool (≈ 25 °C) room away from heat sources (sunlight, condenser coils, etc.).*
• Avoid temperature swings—these increase self-discharge and shorten the allowable storage interval before a freshening charge is needed.*

7) Freshening Charge (Initial Recharge Before Service)

Use a freshening (boost) charge if:

• Any 2 V cell measures < 2.07 V, or a 12 V monobloc measures < 12.4 V (open-circuit).*

Charging set-points

• Charge at 2.40 V per cell (for a 12 V monobloc with 6 cells: (6 \times 2.40 = 14.40) V).*
• Duration: ~24 hours at 25 °C; perform every 6 months during storage if needed.*
• Current limiting: limit charge current per the manual’s guidance relative to the 20-hour rated discharge current.*

Inline formula reminder: Float/boost voltages scale with temperature in detailed specs; consult the individual battery datasheet for temperature compensation.**

8) Post-Install Acceptance

• Re-measure:
  • Inter-row, inter-tier, inter-rack potentials.
  • Terminal-to-rack potentials (should be 0 V).
• Verify torque on all intercell and bus connections.
• Document string voltages and individual unit voltages; retain as commissioning baseline.
• Where applicable, perform impedance/conductance tests and acceptance/capacity tests (or UPS load tests) per site procedures.*

Conclusion

A safe, reliable VRLA installation hinges on disciplined preparation, strict hazard controls, correct mechanical/electrical assembly, and a documented freshening charge. Consistent labeling, spacing, torqueing, and baseline measurements set you up for easier maintenance and longer service life.*