Forklift batteries are not one-size-fits-all. The correct size is determined by voltage, amp-hour (Ah) capacity, and physical dimensions—all of which must match your specific forklift model. This guide provides a comprehensive reference for understanding and selecting the right battery size.
Key Battery Specifications Explained
Specification What It Means Typical Range
Voltage Electrical pressure; must match forklift motor 24V, 36V, 48V, 72V, 80V, 96V
Capacity (Ah) Energy storage; determines runtime 100Ah – 1,200Ah
Dimensions (L×W×H) Physical footprint; must fit compartment Varies by model
Weight Acts as counterweight; affects stability 400 – 6,000+ lbs
Critical Rule: Voltage must match exactly. Installing a 48V battery in a 36V forklift can overheat motors and cost $2,000+ in repairs.
Typical Battery Sizes by Forklift Class
Forklift Class Voltage Ah Capacity Weight Common Applications
Class I – Electric Counterbalance 36V or 48V 400 – 1,000Ah 1,500 – 4,000 lbs Warehouses, loading docks
Class II – Narrow Aisle 24V or 36V 600 – 1,200Ah 1,000 – 2,000 lbs Retail, distribution centers
Class III – Pallet Jacks/Walkies 24V 150 – 1,000Ah 400 – 1,200 lbs Ground-level stock movement
Capacity by Tonnage:
24V (1–1.5 ton): 165–300Ah – 4–5 hours runtime
48V (2–5 ton): 300–600Ah – 6–8 hours runtime (most popular)
72V/80V (5–8 ton): 500–700Ah – heavy-load operations
96V+ (8–15 ton): 700–1,000Ah – ports, yards, large cargo
Common Case Size Codes
Industrial batteries use standardized size codes. The format often indicates dimensions in inches or centimeters:
Size Code Dimensions (L×W×H) Typical Use
85-13 38.75″ × 19.88″ × 22.63″ (985×505×575mm) Mid-size forklifts
125-15 42.63″ × 21.88″ × 30.88″ (1,083×556×784mm) Larger Class I trucks
155-17 48.13″ × 23.88″ × 34.38″ (1,222×607×873mm) Heavy-duty applications
18-85-25 18cm × 85cm × 25cm Class I/II compartments
Example – 36V 1020Ah Battery (18-85-25):
Dimensions: 18cm (H) × 85cm (L) × 25cm (W)
Energy: 36.72 kWh
Runtime: 10+ hours in 4-ton forklifts
Ideal for: Toyota 8FGCU25, Yale ERP25
Brand-Specific Battery Size Examples
Toyota:
Model Voltage Ah Dimensions (L×W×H)
7FBEU15 36V 680 41.37″ × 31.06″ × 23″
7FBEU20 36V 935 50.68″ × 40.87″ × 22.75″
7FBH25 36V 1020 39.68″ × 31.75″ × 22.75″
Clark:
TM25: 36V, 625–735Ah, 24-cell configuration
S-Series Electric: 48V, 460Ah (lithium) or 625Ah (lead-acid)
WEP20 pallet truck: 24V, 230Ah lithium-ion
Crown:
RC3020-30: 36V, 625Ah, 38.08″ × 13.37″ × 30.56″
FC4040-55: 48V, 935Ah (dimensions vary)
General 48V Lead-Acid Example:
Dimensions: approx. 40″ × 25″ × 32″
Requires 2+ inches of clearance for cooling
Lithium-Ion vs. Lead-Acid Size Comparison
Feature Lead-Acid Lithium-Ion
Size Larger and heavier More compact (often half the size/weight)
Weight 800 – 6,000+ lbs 300 – 2,500 lbs
Maintenance Watering, equalization required Maintenance-free
Energy Efficiency 70–80% 95%+
Key Insight: A 48V 750Ah lithium pack can replace a 1,000Ah lead-acid unit while saving 40% weight. Lithium-ion offers 50% weight reduction (≈400kg vs. 800kg) and 3× faster charging compared to lead-acid.
How to Choose the Right Battery Size
Match voltage exactly – Mismatched voltage damages motors and controllers
Measure the battery compartment – Length, width, height, and terminal placement
Check minimum battery weight – The battery acts as counterweight; too light compromises stability
Select Ah capacity based on shift length:
Single shift: 300–600Ah
Double shift: 600–1,000Ah
Heavy continuous use: 700–1,200Ah
Verify connector type – Different brands use different connectors (e.g., Anderson SB175)
Confirm tray compatibility – Even a 1″ overhang can damage cables; never modify compartment rails
Summary
Forklift batteries are available in 24V, 36V, 48V, 72V, and 80V configurations with capacities from 100Ah to 1,200Ah. Physical dimensions vary by brand and model—a standard 48V lead-acid pack measures approximately 40″×25″×32″, while a 36V unit averages 30″×20″×30″. Lithium-ion batteries can be half the size and weight of equivalent lead-acid batteries. Always match voltage exactly, measure your compartment, and confirm minimum weight requirements before purchasing. For precise sizing, consult your forklift's data plate or contact the manufacturer with your model number.