Choose the commercial battery question that best matches yours
Which commercial battery do I need?
Match the vehicle, technology, Ah, CCA, size, layout and duty.
How does a 24V battery pair work?
Two matched 12V batteries normally operate as one 24V system.
The truck will not start
Check charge, connections, cranking, charging and external loads.
The batteries go flat overnight
Estimate hotel loads and check charge recovery and battery condition.
How should the batteries be charged?
Use a charger and voltage matched to the complete battery system.
How do I test a battery pair?
Charge the bank, then test and compare both batteries individually.
How should they be replaced?
Use matched batteries, lifting aids and the vehicle isolation procedure.
I think a battery is faulty
Charge and test the complete pair and rule out vehicle causes first.
Different commercial vehicles place very different demands on the battery
Vans and light commercial vehicles
Frequent starts, multi-drop work, refrigeration, tail lifts, telematics and urban driving can create greater cycling demand than ordinary car use.
Rigid trucks and distribution vehicles
Repeated stops, loading equipment, cab systems and limited continuous driving time can leave less opportunity to recover charge.
Tractor units and long-haul HGVs
Overnight lighting, refrigeration, television, parking heating, parking cooling and other hotel functions can deeply cycle the starting batteries.
Buses and coaches
Doors, lighting, ticketing, climate control, passenger systems and frequent stop-start operation require high endurance and dependable charge acceptance.
Agricultural and construction vehicles
Large engines, seasonal use, cold starting, dust, vibration and long periods standing all influence the required battery specification.
Plant, municipal and specialist equipment
Hydraulic systems, beacons, pumps, winches, controls and auxiliary equipment can demand both strong cranking and repeated cyclic performance.
Two similar trucks can need different technologies because one has basic starting duty while the other has hotel functions, end-of-frame mounting, tail-lift use or advanced energy management.
How a commercial 24V battery pair works
Many trucks and heavy commercial vehicles use two 12V batteries connected in series. The voltages add together to create a 24V system, while the Ah capacity remains the same as one battery.
Use matching batteries
Match brand range, model, technology, voltage, Ah, CCA, age, terminal layout and condition wherever possible.
Replace an aged or failed pair together
One new battery connected to one worn battery can charge and discharge unevenly. Treat the pair as one system unless the vehicle manufacturer and approved testing support another decision.
Test each battery individually
A 24V bank reading can hide one weak 12V battery. Fully charge the system, then compare both batteries using the correct test method.
Inspect the series link and earth paths
Loose, corroded or damaged interconnects can create voltage drop, heat and poor starting even when the batteries are serviceable.
Investigate voltage imbalance
A material difference between the two battery voltages or test results requires investigation of the batteries, connections and any unequal 12V loads.
Record the pair as one replacement
Keep both serial numbers, fitting date and test results together for maintenance, fleet records and warranty assessment.
A 12V tap can discharge one battery more heavily and create imbalance. Use an approved 24V-to-12V converter or the vehicle manufacturer's designated auxiliary supply.
How to select the correct commercial battery
Identify the exact vehicle and duty
Use the registration, VIN, make, model, year, engine and vehicle use. Include multi-drop, hotel loads, tail lift, refrigeration, agricultural or end-of-frame operation.
Confirm the system arrangement
Check whether it uses one 12V battery, two 12V batteries in series, multiple parallel strings, a separate hotel bank or an auxiliary battery.
Match the required technology
Confirm standard flooded, Super Heavy Duty, EFB, AGM, GEL or another specified technology. Do not downgrade an advanced commercial application to a basic starter battery.
Match Ah and CCA
Capacity at the stated rate supports reserve and hotel loads; CCA supports cold starting. Both must meet the approved vehicle specification.
Check length, width and total height
Large commercial cases can look similar while differing in height, lid design, terminal clearance, handles and mounting features.
Check terminal layout and terminal type
Confirm positive-terminal side, post size, threaded studs, cable orientation and whether the pair uses identical or opposite layouts.
Check hold-down, tray and restraint
The battery must be secured against vehicle movement and vibration. Match the base, frame, clamp and retaining bar.
Check vibration and installation position
Rear-chassis and end-of-frame batteries experience severe shock and vibration. Use the specified vibration class and an approved product for the installation position.
Check hotel and auxiliary loads
Parking coolers, heaters, fridges, lighting, television, telematics, tail lifts and refrigeration can require greater cycling and charge acceptance.
Check fitting and control-system requirements
Modern commercial vehicles may require isolation, diagnostic validation, battery monitoring or manufacturer-specific restart procedures after replacement.
Standard, SHD, EFB, AGM or GEL commercial batteries?
| Technology or duty | Typical application | What to check |
|---|---|---|
| Standard / SLI / HD | Vehicles with conventional starting duty and limited electrical consumption while the engine is stopped. | Approved Ah, CCA, endurance, dimensions and vibration rating. Do not use for intensive hotel or deep-cycling duty. |
| Super Heavy Duty | Large engines, cold starting, rough roads, agricultural and construction vehicles requiring robust starting performance. | Cranking requirement, vibration class, cycle endurance and exact fitment. |
| EFB commercial | Long-haul, multi-drop, urban delivery, hotel functions, rear-chassis mounting and power-hungry equipment. | EFB-compatible charging, high charge acceptance, cycling, vibration rating and end-of-frame approval. |
| AGM commercial | Highest electrical demands, frequent partial-state-of-charge operation, parking coolers, heaters and intensive hotel loads. | AGM charging strategy, temperature, installation approval, vibration, cycle duty and battery monitoring. |
| GEL commercial | Specialist extreme-cycling and deep-discharge commercial applications where the vehicle manufacturer specifies GEL. | GEL-specific charge profile, approved starting capability, system design and exact vehicle fitment. |
Higher-duty technology may be required when:
- The driver sleeps in the cab with electrical consumers running.
- The vehicle has a parking cooler or auxiliary heater.
- It performs frequent multi-drop starts.
- Tail lifts, refrigeration or specialist equipment operate regularly.
- The batteries are mounted at the rear or end of frame.
- The vehicle spends much of its time at partial state of charge.
Do not select from price alone because:
- A basic battery may start the truck initially but fail under cycling.
- Wrong technology can reduce charge acceptance.
- Insufficient vibration resistance can cause premature damage.
- Low usable reserve can leave the vehicle unable to start after rest.
- Incorrect application can invalidate a warranty claim.
Batteries positioned near the rear axle experience severe multi-axis vibration. Use only batteries approved for the vehicle's mounting position and required vibration class.
Popular commercial and HGV battery codes are not interchangeable
UK part references are useful for cross-checking the case and specification family, but the full vehicle application must still be confirmed.
Common heavy-commercial reference family. Check full dimensions, Ah, CCA, layout and terminal arrangement.
Common HGV reference family. Do not assume it can replace a 625 or 629 without full fitment data.
Common HGV reference family often used in high-capacity applications. Confirm technology and pair requirements.
Commercial reference family. Check case, polarity, hold-down, Ah and CCA before ordering.
Commercial reference family with its own layout and specification. It is not interchangeable by number similarity.
Common commercial reference family. Confirm exact vehicle and whether one or two batteries are fitted.
Common commercial reference family with different polarity or fitment from related codes. Perform a physical comparison.
A familiar UK code does not confirm the technology, endurance, terminal layout or vehicle duty. Compare the battery label, dimensions and vehicle application before ordering a pair.
Why batteries can be flat after an overnight rest
Cab and auxiliary equipment can remove a substantial amount of energy while the engine is stopped. The batteries then need enough reserve to start the engine and enough charge acceptance to recover during the next driving period.
Parking cooler or climate system
Can be one of the largest stationary electrical loads.
Auxiliary heater
Uses battery power for controls, pumps and fans even when fuel provides the heat.
Fridge and refrigeration controls
Operate for long periods and can continue cycling overnight.
Television and entertainment
Inverters and entertainment systems add conversion losses and standby consumption.
Cab and work lighting
Multiple interior, marker and work lights can create a significant combined load.
Telematics and communications
Trackers, routers, radios and fleet systems often remain powered continuously.
Tail lift or hydraulic equipment
Short-duration operation can draw very high current and needs adequate recharge time.
Inverter-powered appliances
Kettles and other heating appliances can create extremely high DC current.
Estimate how many amp-hours stationary loads may remove
This is a simple planning tool—not a battery selection, warranty or electrical-design calculation.
Enter the figures above and calculate.
Real performance depends on temperature, battery age, technology, usable depth of discharge, inverter efficiency, current peaks, charging-system recovery and the reserve needed for cold starting. Do not plan to consume the full nominal Ah.
For example, an average 180W load for nine hours on a 24V system represents about 67.5Ah before allowing for losses. That is a substantial part of a nominal 180Ah starting bank.
What to check when a truck or commercial vehicle will not start
Do not charge or boost a battery that is cracked, leaking, swollen, frozen, unusually hot or producing a strong smell.
Turn off cab equipment, inverters, refrigeration controls, lighting and accessories where it is safe to do so.
Check posts, cable lugs, series link, master isolator, starter cable, earth straps, restraint and visible damage.
A low 24V reading needs further investigation of the two 12V batteries individually.
Use a 24V charger on the complete bank only where the vehicle and charger instructions permit it, or follow the approved individual-battery procedure.
Enter the correct technology, rating standard and labelled CCA for each battery.
Check starter current, voltage drop, alternator output, smart charging and cable resistance using the vehicle procedure.
Confirm the current draw after systems enter their normal sleep state and during intended overnight equipment use.
Rapid clicking
Often low voltage or a high-resistance connection, but test the starter circuit.
Slow cranking
Possible undercharge, aged batteries, cold conditions, starter demand or cable loss.
Starts after charge, flat next morning
Check hotel loads, parked drain, usable capacity and whether the bank fully recharges.
One battery repeatedly tests weaker
Inspect for imbalance, unequal 12V loads, connections and pair age before replacement.
Hot link cable or terminal
Stop using the vehicle and investigate resistance, looseness or excessive current.
Charging warning while driving
Follow the vehicle manual and obtain prompt charging-system diagnosis.
How to charge commercial batteries correctly
Confirm 12V or 24V
Match the charger to the complete system voltage and approved connection method. Never place a 12V charger across a 24V bank.
Confirm battery technology
Use the charger programme specified for flooded, EFB, AGM, GEL or another approved commercial technology.
Check the supported Ah range
Large commercial batteries need a charger capable of restoring their capacity within a practical time without exceeding the battery manufacturer's current limit.
Use approved charging points
Vehicles with battery sensors, isolators or remote terminals may require designated positive and earth connections.
Charge the pair as a balanced system
Follow the workshop procedure. When batteries are charged individually, use the same compatible programme and confirm both complete the charge.
Allow sufficient time
A deeply discharged 180Ah or 230Ah battery cannot be restored by a short boost. Let the automatic charging stages complete.
Ventilate and remove ignition sources
Lead-acid batteries can release hydrogen during charging. Keep the area ventilated and away from welding, grinding, flames and sparks.
Stop for heat, swelling or abnormal smell
Disconnect the charger safely and obtain specialist assessment.
This can create arcing and damaging voltage spikes. Test the charging system with suitable diagnostic equipment and the manufacturer's procedure.
Hotel loads can discharge the batteries deeply, while lights, refrigeration and other consumers continue using alternator output during driving. A worn or unsuitable battery may not recover enough charge before the next rest period.
How to test a commercial battery pair properly
Record the fitted specification
Note technology, Ah, CCA, rating standard, part number, installation position and pair age.
Inspect both batteries
Check case condition, restraint, terminals, series link, cables, earths and signs of heat or vibration damage.
Fully charge before a health decision
A low state of charge can produce an unreliable or recharge-and-retest result.
Measure the bank and each battery
A rested, fully charged pair of ordinary 12V lead-acid batteries is broadly around 25.4–25.6V as a 24V bank, but assess each 12V battery individually and use the product data.
Use identical tester settings
Select the correct flooded, EFB, AGM or GEL algorithm and enter the labelled CCA using its stated EN, SAE, DIN or other standard.
Compare the two results
Investigate a significant difference in measured performance, voltage, internal condition or charge acceptance.
Test cranking and voltage drop
Check the starter circuit, series link, positive cable and earth paths under load using vehicle-specific limits.
Test the complete charging strategy
Modern output can vary with engine speed, temperature, electrical demand and energy-management commands.
Measure hotel and parked current
Test after control modules enter their intended state and compare the current with the vehicle and fleet equipment specification.
Document the diagnosis
Keep printouts or readings for both batteries, the charging system and the vehicle loads for maintenance and warranty records.
This prevents a vehicle, connection or hotel-load problem from being misdiagnosed as two defective batteries.
Why commercial battery replacement needs careful planning
Battery weight
Large commercial batteries can weigh tens of kilograms. Use carrying handles only as intended and use mechanical handling or a two-person lift where required.
Isolation procedure
Follow the vehicle's master-isolator, ignition, telematics and power-support procedure before disconnecting the bank.
Disconnect earth first where specified
On a conventional negative-earth vehicle, the workshop procedure commonly disconnects the negative or earth connection first and reconnects it last.
Mark cables and battery positions
Photograph the pair and label the positive, negative, series link, auxiliary feeds and monitoring leads before removal.
Replace damaged links and lugs
A new battery pair will not correct overheated, corroded or high-resistance cables.
Use specified torque
Loose connections overheat; excessive force can damage posts and internal connections. Use the correct hardware and torque.
Secure the battery tray and restraint
Refit clamps, covers, heat shields, insulation and venting exactly as specified for vibration and crash safety.
Complete diagnostic validation
Restore isolation, check warning systems and perform any required battery registration, reset or commissioning process.
- Same part number and technology.
- Same voltage, Ah and CCA rating.
- Same manufacture or stock-age condition where possible.
- Correct polarity, terminal and case layout.
- Both adequately charged before installation.
- No transit damage, leakage or distorted terminals.
A 12V or 24V commercial system can deliver enough fault current to melt tools, cause severe burns and start a fire. Use eye protection and insulated tools.
Use the vehicle's approved commercial jump-start procedure
High-capacity 24V systems and multiple battery connections create far greater risk than a simple car jump-start. Use the designated jump points, correct voltage and suitable commercial booster or donor vehicle.
Match system voltage
Never connect a 12V booster across a 24V system or use a 24V source on a 12V vehicle.
Use approved jump points
The vehicle may provide remote terminals that protect battery sensors, isolators and electronic systems.
Use commercial-rated equipment
Leads, clamps and booster packs must be capable of the required voltage and cranking current.
Do not boost a damaged battery
Stop if a battery is frozen, leaking, swollen, hot or giving off a strong smell.
Avoid repeated long cranking
Excessive cranking can overheat the starter, cables and connections.
Recharge and diagnose afterwards
A successful boost does not restore the bank or explain the discharge.
Follow the vehicle manual or use professional roadside assistance. Incorrect connections can damage batteries, electronics and the donor equipment.
How to reduce commercial battery breakdowns and downtime
-
✓
Test every battery during planned maintenance
Record state of charge, state of health and the difference between paired batteries.
-
✓
Audit hotel and auxiliary loads
Measure what runs while parked and remove unnecessary standby consumption.
-
✓
Check alternator recovery
Confirm the batteries receive enough charging time and current after overnight or tail-lift use.
-
✓
Inspect trays, clamps and rear-chassis installations
Vibration damage, loose restraints and cable movement can cause premature failure.
-
✓
Keep case tops and terminals clean
Dirt, damp and corrosion can contribute to leakage current and high-resistance connections.
-
✓
Use only the approved maintenance procedure
Do not open maintenance-free batteries. For serviceable products, follow the manufacturer's electrolyte-check and topping-up instructions.
-
✓
Charge vehicles during long standstill
Use a compatible maintenance charger where the fleet procedure permits it.
-
✓
Track battery history by vehicle
Record fitting date, product code, pair serials, test results and repeated electrical faults.
When to stop work and seek professional help
Move away and call emergency services if there is an immediate fire or explosion risk.
Avoid contact, isolate the area and obtain specialist handling advice.
Stop using the system and investigate connection resistance or excessive current.
Stop charging. This can indicate overcharge, heat or internal damage.
Diagnose the complete charging, starting and load system before fitting another pair.
Charge and test both batteries and document the vehicle and charging-system findings.
Hotel loads, undercharging, electrical drain, vibration, sulphation, incorrect technology, unequal 12V loads and normal service life can all cause failure symptoms. A manufacturing fault must be confirmed through the applicable test process.
Read the Battery Warranty Guide →Commercial, truck and HGV battery FAQs
Why do trucks often use two 12V batteries?
Two 12V batteries connected in series create the 24V system used by many heavy commercial vehicles. Their voltages add together, while the Ah capacity remains the same as one battery.
Should both truck batteries be replaced together?
In a paired system, matched replacement is normally the most reliable approach when the pair is aged or one battery has failed. A new battery connected to a worn battery can become imbalanced. Follow the vehicle manufacturer's procedure and test both batteries before deciding.
Can I replace only the weak battery in a 24V pair?
Only where the vehicle manufacturer and approved diagnosis support it. The remaining battery must be genuinely healthy, closely matched and compatible. In most aged pairs, replacing only one risks poor balance and shortened life.
Can I mix different Ah batteries in a 24V system?
No. Use matching batteries of the same voltage, technology, Ah, CCA, model and age. Different batteries can charge and discharge unevenly.
Can I take 12V power from one battery in a 24V pair?
This can discharge one battery more heavily and create imbalance. Use an approved 24V-to-12V converter or the vehicle manufacturer's designated supply.
What voltage should a charged 24V truck battery system show?
Two rested, fully charged ordinary 12V lead-acid batteries are broadly around 25.4–25.6V as a pair. Technology, temperature and recent charging affect the reading. Test each 12V battery individually and do not use voltage alone as a health test.
Why are my truck batteries flat after an overnight stop?
Parking coolers, heaters, fridges, lighting, inverters, telematics and entertainment can remove substantial energy. Also check battery capacity, state of charge, charging-system recovery and unwanted current draw.
What are truck hotel functions?
They are electrical comfort and work functions used while the engine is stopped, such as cab lighting, parking heating or cooling, refrigeration, television, fridges, charging and communications equipment.
What is an end-of-frame battery installation?
It places the batteries near the rear of the tractor chassis, often close to the drive axle. This exposes them to severe shock and multi-axis vibration, so an approved high-vibration battery is required.
What do commercial vibration ratings mean?
Commercial battery standards include vibration tests for different duty levels. The vehicle's mounting position and manufacturer specification determine the required class; do not assume every heavy-duty battery suits an end-of-frame location.
Do I need EFB or AGM truck batteries?
Use the vehicle-specific specification. EFB is commonly used for high energy demands, hotel loads and demanding mounting. AGM is used for the highest cycling, partial-state-of-charge and hotel-load requirements. Do not downgrade the technology.
Is a Super Heavy Duty battery the same as AGM?
No. Super Heavy Duty describes a commercial performance or range level, while AGM is a specific internal technology. Check the full product data rather than the range name alone.
Can I use a standard truck battery with a tail lift?
Only if the vehicle and tail-lift duty are within the approved specification. Frequent high-current tail-lift use can require greater cycling and charge acceptance than a basic starting battery provides.
Why does one battery in the pair get hot?
Stop using and charging the system. Possible causes include an internal fault, severe imbalance, loose connection, overcharging or unequal load. Both batteries and the complete electrical system need professional testing.
Why does one truck battery read lower than the other?
The pair may be imbalanced because one battery is weak, connections differ, a 12V accessory is connected to one side or the batteries have different age or condition. Fully charge, isolate as specified and test both individually.
Can I charge a 24V truck with a 12V charger?
Do not connect a 12V charger across the complete 24V bank. Use an approved 24V charger or the vehicle and charger manufacturer's procedure for charging each 12V battery individually.
How long does it take to charge a commercial battery?
It depends on Ah removed, charger output, battery technology, temperature and absorption time. Large 180Ah–240Ah batteries can require many hours after deep discharge. Let the approved automatic programme complete.
Can I test a truck battery with a car battery tester?
Only if the tester supports the commercial battery's technology, CCA range and rating standard. Test both 12V batteries individually and also test the 24V starting and charging system.
Does a higher CCA make a battery suitable for my truck?
Not by itself. Technology, Ah, vibration, endurance, cycle duty, dimensions, layout, hold-down and charging compatibility must all meet the vehicle specification.
What are common UK HGV battery codes?
Common reference families include 625, 627 and 629, while commercial applications also use references such as 655, 656, 663 and 664. These are not interchangeable; check the full specification and vehicle fitment.
Can I jump-start a 24V truck from a 12V vehicle?
No. Use the correct 24V commercial booster or approved donor system and the vehicle's designated jump points. Incorrect voltage or improvised connections can cause serious damage.
Why does a replacement pair go flat as well?
The underlying problem may be hotel loads, electrical drain, alternator or smart-charging faults, poor cables, unequal 12V tapping or insufficient driving time to recover charge.
Is a flat commercial battery covered by warranty?
Not simply because it is flat. Fully charge and test both batteries and check the vehicle, charging system, loads, installation and application. Discharge and completed service life are not automatically manufacturing faults.
How should commercial batteries be stored?
Store them fully charged, upright, cool, dry, clean and ventilated. Check voltage periodically and recharge with the correct programme before they remain undercharged.
Can I top up a commercial battery with water?
Only if the exact battery is designed to be serviceable and the manufacturer provides a topping-up procedure. Never open a maintenance-free, AGM, EFB, GEL or sealed product by assumption, and never add acid during routine maintenance.
How do I dispose of old truck batteries?
Do not place them in general waste. Use an authorised lead-acid battery recycling route. Local customers can contact Lucas Batteries UK about dropping off suitable used batteries.
Technical sources & review information
Last source check: 29 July 2026
Research basis: Primary manufacturer, regulator and equipment-maker guidance.
Editorial status: Prepared for final Lucas Batteries UK approval before publication.
- VARTA — Charge acceptance of truck batteries
- VARTA — Truck battery vibration and end-of-frame mounting
- GS Yuasa — Commercial and PSV battery applications
- UK HSE — Workshop battery-charging and handling safety
The exact battery datasheet and vehicle or equipment manufacturer's instructions take priority. External source pages and product specifications can change.
Match the vehicle, duty and battery pair before ordering
Browse the commercial range or send the registration, VIN, current battery codes, dimensions, system voltage and vehicle duty through our adaptive contact form.