This is the ultimate forklift battery guide.

This guide contains an in-depth analysis of forklift batteries.

In it, you’ll learn:

  • The different types, voltages, sizes, and weights of forklift batteries
  • The average prices of different forklift batteries
  • How to properly charge a forklift battery
  • Maintenance tips for keeping your forklift batteries healthy

Let’s dive in!

Forklift Battery Types

Generally, electric forklifts are powered by one of two types of forklift batteries:

  • Lead-acid
  • Lithium-ion

We’ll cover each below.

Lead-Acid Batteries

Also called “wet cell batteries,” lead-acid forklift batteries are the most common on the market.

A Foxtron ES lead-acid forklift battery
A Foxtron model ES lead-acid forklift battery

Components of lead-acid batteries include:

  • Battery case
  • Cells
  • Bars
  • Plates of lead dioxide
  • Cables
  • A mixture of water and sulfuric acid

These batteries generate electricity through an electrochemical reaction between lead plates and a mixture of sulphuric acid and water.

Lead-acid forklift batteries generally last between 1,000 and 1,500 cycles.

That equals about 3 to 5 years with over 300 workdays per year.

Lithium-Ion Batteries

Lithium-ion forklift batteries are gaining popularity partly because they offer many benefits compared to lead-acid batteries, such as:

Sealed cells to eliminate leaks

Short charging period

No water maintenance

Environmental friendliness

The components of lithium-ion batteries are a cathode, electrolyte (lithium), separator, anode, and two current collectors (positive and negative).

A Toyota forklift with a lithium-ion battery
A lithium-ion battery powering a Toyota electric forklift

Lithium-ion batteries have many different chemistries for energy production.

But the most popular one for forklifts is lithium iron phosphate.

In this process, while the battery is discharging electrolyte liquid, positively charged lithium-ions are carried from the anode to the cathode to generate power.

This process is reversed when the battery is being charged.

If maintained well, a lithium-ion forklift battery will last between 2,000 and 3,000 cycles.

That equals about 7 to 10 years of 300 workdays per year.

Forklift Battery Voltages

Forklift batteries come in different voltages.

Usually, the voltage depends on the size of your equipment.

But some equipment requires specific voltages to operate.

You should always confirm the voltage that your forklift can handle.

That’s because a wrong voltage can cause significant damage to the equipment.

If you’re not sure, it’s best to consult the lift truck data plate or owner’s manual.

A Toyota forklift data plate with the truck voltage (36 volts) outlined
A forklift’s data plate should list the required voltage

Typically, the common voltages for forklift batteries include:

12 Volts: Designed for small and light lift equipment such as powered pallet jacks

24 Volts: Ideal for smaller electric lift equipment such as center riders, end riders, walkie stackers, and electric walkie pallet jacks

36 Volts: Designed and ideal for mid-size electric lift trucks such as narrow aisle forklifts and 3-wheelers

48 Volts: Designed for larger lift machines such as 4-wheel counterbalanced forklifts

80 Volts: Used for large material handling such as pneumatic counterbalanced forklifts

Forklift Battery Sizes

There are hundreds of different forklift battery sizes, depending on your lift truck’s size, brand, make, and model.

In general, the larger the forklift you operate, the larger the battery size.

Often, you can find the size displayed on the battery’s nameplate.

A forklift battery nameplate with the model number outlined
The model of this battery is displayed vertically on the nameplate

If that is missing, however, you can check the cell connectors nearest to the positive terminal.

There, you can find the model number, serial number, and weight stamped.

A battery intercell connector with the model, amp hours, and serial number outlined
Check the cell connectors nearest to the positive terminal for the model number, serial number, and weight

The model number is ultimately what will tell you the size of the battery.

For example, take the model 18-85-17, where:

  • The first number indicates the number of cells. It also doubles as an indication of the voltage, since each cell is 2 volts. Therefore, an 18-cell battery is 36 volts
  • The second number represents the plate design capacity
  • The third number shows the number of plates in each cell. Uniquely, this number is always odd

You can quickly tell the size of the battery by looking at the plates per cell.

Thus, an 18-85-17 is a smaller battery than an 18-85-29.

Forklift Battery Weights

You might be wondering: How much does a forklift battery weigh?

Overall, forklift batteries can weigh anywhere from 600 lbs. to 5,000 lbs. or more for the biggest electric lift trucks.

The weight of forklift batteries is important because they serve two purposes:

  1. To power the lift truck
  2. To act as a counterbalance for the forklift’s stability during operation

Consequently, the bigger the forklift, the more the battery will weigh.

So installing a heavier or lighter battery than what the manufacturer recommends could create a safety hazard because of counterbalance issues.

You can avoid this by checking the forklift data plate, which lists the weight range requirement.

A Toyota forklift data plate with the battery weight requirements outlined
Your lift truck’s data plate should specify the minimum/maximum battery weight

Forklift Battery Prices

Forklift batteries can vary widely in price, depending on the model and manufacturer.

But in general, a lead-acid forklift battery costs between $2,000 and $9,000 or more.

Here are the average prices for the most common lead-acid forklift battery models:

6-85-11 = $1,200

12-85-13 = $2,500

12-125-13 = $3,300

18-85-17 = $4,800

18-85-33 = $9,200

18-125-13 = $4,300

24-85-17 = $6,200

24-85-27 = $10,500

40-125-11 = $7,600

** These prices are only rough averages

Lithium-ion batteries can be more than twice as expensive as lead-acid batteries, but they also offer higher rewards.

Forklift Battery Safety

Forklift batteries can be dangerous to work with.

Some of the hazards include:

Crushing: Heavy forklift battery weight exposes operators to crushing hazards, which can lead to significant physical injuries

Shocks: Stored electricity in forklift battery cells can short circuit and shock an operator upon touch

Chemical burns: Acid-filled batteries can leak and cause serious chemical burns if the sulfuric acid comes to contact with the skin

Explosions: During the battery charging process, forklift batteries emit flammable hydrogen gas. This gas can cause flames or explosions if allowed to build to excessive levels

Temperature burns: High operating temperatures can expose operators to burn hazards

Corrosion: Sulfuric acid is corrosive and can cause floor and equipment corrosion if it splashes out of the battery

OSHA recommends the following safety practices to keep safe when working with batteries:

  • Wear the right personal protective equipment (hard hats, gloves, apron, face shield or goggles, safety footwear, and other PPE)
  • Ensure you keep battery covers open for proper heat dispersal during charging
  • Keep the charging area well ventilated
  • Keep clear of the forklift battery while it’s being moved or lifted
  • Remove all metal jewelry before entering the charging area. This includes anything metallic, from tools to earrings
  • Do not lay metallic items on the top of an uncovered battery to prevent sparking and electric shock
  • Check water and electrolyte levels before beginning charging, but never add water. Only add water after charging is complete
  • Never add electrolyte - only add water. Contact a forklift battery professional if acid needs to be added
  • Take active precautions with flammable materials
  • When attaching charging clamps, start by connecting the positive clamp to the positive terminal. Then connect the negative clamp to the negative terminal
  • Keep the charger unplugged and turned off while attaching or detaching the battery’s clamp connections
  • If the battery heats up or if fluid starts leaking from the vents, turn off the charger and restart the process at a lower rate of charge
  • Ensure you record water levels in a designated battery service log
  • If you have to wash batteries, use the right cleaning solution and washing equipment. Only wash batteries in a contained space
  • Don’t rinse battery water down the drain. Battery wash water is hazardous

Forklift Battery Charging

When it comes to charging a forklift battery, here are the important things you must consider:

  • The type of forklift battery
  • The charging method
  • The optimal charging time of the battery
  • The battery charging station requirements

Depending on the type of battery you have and how many shifts it works, you can use two different forklift battery charging methods: Conventional charging or opportunity charging.

We’ll cover each below.

Conventional Charging

Conventional charging is the normal way of charging a battery.

It is popular with lead-acid batteries and works best if you’re running a one-shift operation.

A Foxtron conventional charger
A Foxtron conventional charger

With this method, you charge the battery at the end of a shift and resume use when the battery is fully charged.

The downside of this method is that it decreases the amount of time the forklift operates, and subsequently its productivity.

But the upside is that conventional charging is the least damaging way to charge a lead-acid battery.

Opportunity Charging

Opportunity chargers use a higher power output to quickly charge a battery on an as-needed basis.

The need basis can be whenever there’s an opportune moment to charge the battery, such as when the forklift operator is on a lunch break.

Three different models of Foxtron opportunity chargers
Three different models of Foxtron opportunity chargers

Overall, opportunity charging works best for multi-shift operations.

That’s because you can quickly get charged without having to swap batteries.

Lithium-ion forklift batteries are best suited for opportunity charging because they don't need to be recharged to 100% battery capacity.

On the other hand, while you can opportunity charge lead-acid batteries, it’s less desirable.

The reason is that the higher power outputs from an opportunity charger can damage the battery and shorten its lifespan.

Forklift Battery Charging Area Requirements

Lead-acid batteries have specific battery charging area requirements that lithium-ion batteries do not.

This is because lead-acid batteries have the potential for safety hazards such as acid leaks and spills, venting explosive gases, and high temperatures.

A charging area for lead-acid forklift batteries, including ventilation hoods for exhausting hydrogen gas
Due to their risks, lead-acid forklift batteries require a separate charging area

Consequently, OSHA requires a blend of preventive measures and emergency equipment in all forklift battery charging areas.

OSHA states that:

“Charging a forklift battery produces highly flammable hydrogen gas. Clear instructions should be present for how to respond to any emergency such as acid spill or fire accurately.”

So, according to OSHA, the designated battery charging area must have the following safety requirements:

Fire extinguisher

Phone for communication in case of emergencies

Eyewash station (that supports at least 15 minutes of flow)

Readily available neutralization materials (such as soda ash or baking soda) to neutralize spilled acid

Ready access to water

Adequate ventilation to disperse flammable hydrogen gas

No smoking signs. Smoking in the charging area is prohibited to prevent accumulated hydrogen from exploding

Appropriate personal protective equipment. This should include goggles, hard hats, face shields, rubber aprons, rubber/neoprene gloves, and safety toe footwear

Adequate warning labels identifying hazards

Forklift Battery Charging Procedure

Forklift battery charging is done close to electricity and sulphuric acid.

So it should only be done by trained employees.

Once the battery is ready for charging, make sure you’re wearing protective gear before starting.

Then, follow the steps below to charge the battery:

  1. Safely park the truck in the charging station and apply the brakes

  2. Ensure the charger voltage matches the battery voltage

  3. Ensure that the charger is turned off before connecting the battery

  4. Ensure the charger cables are in good working condition

  5. Open the hood on the truck. This allows for easier venting of any gasses that are released

  6. Disconnect the battery connector from the truck

  7. Plug the battery connector into the charger’s connector

  8. Once connected, allow ample charging time. Lead-acid forklift batteries require a full eight-hour charge to distribute the acid throughout the battery properly

  9. Keep battery covers and hoods open for proper heat dispersal during charging

  10. To prevent boilovers, add distilled or deionized water after charging, preferably using a water gun. Do this only after the battery has cooled down

How Long Does it Take to Charge a Forklift Battery?

A lead-acid forklift battery requires 8-10 hours to charge fully if it was down to 30% capacity.

After charging, the battery should be allowed 8 hours to cool down.

The charge and use cycle for a lithium-ion battery is a 1-hour charge, 8 hours of use, and another 1-hour charge.

Additionally, lithium-ion batteries do not require a cooling period.

Forklift Battery Maintenance

Proper forklift battery maintenance plays a critical role in preserving the useful life span of your forklift battery.

A technician performing maintenance on a forklift battery
Keeping up on maintenance is the single best way to keep your batteries healthy and productive

Maintenance requirements depend on the type of battery you’re using and your work operations.

Lithium-ion batteries are sealed and require little to no maintenance.

On the other hand, lead-acid batteries require frequent maintenance to prevent degradation of the chemical process and preserve their operating capacity and lifespan.

The key activities in forklift battery maintenance include:

  • Proper charging
  • Watering
  • Equalizing
  • Washing

Let’s go through these items.

Charging

Proper forklift battery maintenance requires that you only charge at certain times and only to certain degrees.

Be sure to charge your lead-acid battery when it’s no less than 20% discharged.

A Toyota electric forklift on charge
Charge your battery once it’s reach 20% discharge and don’t remove it until charged 100%

And remember never to interrupt a charge cycle on lead-acid batteries and not to undercharge or overcharge it.

Instead, let the battery charge until the charger says it’s 100% complete.

For lithium-ion batteries, you can do opportunity charging.

Watering

Forklift battery watering is essential for maintaining optimum capacity and preventing premature failure.

Since lithium-ion batteries do not require watering, this section will be exclusively about lead-acid batteries.

In a lead-acid battery, water protects the battery’s active material.

A proper water level in a forklift battery cell
The water level should be slightly above the plate (in orange)

And if the water level drops too low, the active material dries out.

This in turn can permanently damage the forklift battery and shorten its useful life.

You might be wondering: How often should you water a forklift battery?

The answer is that you should water the battery every five to ten charging cycles.

That said, since every battery can be different, it’s best to check the manufacturer’s recommendations to be sure.

When it comes to the procedure for watering your batteries, there are a few things to keep in mind:

Use only distilled or deionized water to fill your batteries. Minerals in tap water can damage the battery and impair its performance

Never overfill a forklift battery with water. This can cause an overflow, which can spill sulfuric acid and lead to injury and a loss of battery capacity. Instead, only fill until the water level is just about the cell plate. This will leave enough space for the liquids inside the battery to expand when the battery is in use

Always top up water after a full charge or equalize charge (never before) and preferably after it has cooled down. This is when the battery’s water level is at its highest level, and you can see the level before topping it off

Equalizing

Equalization charging or “equalizing” for short is essentially a forced battery overcharge, which causes bubbling and gassing inside the cells.

Equalizing serves two purposes:

  1. Removing lead sulfate crystals from the battery plates before they harden
  2. Rebalancing the electrolyte concentration by reversing stratification

Stratification is when the water and acid separate.

When this happens, the acid becomes more concentrated at the bottom of the battery, reducing the battery’s capacity.

By causing bubbling and gassing in the cells, equalization reverses stratification by remixing the battery’s water-acid mixture.

An illustration of a stratified battery next to a normal battery
A normal battery on the left and a stratified battery on the right

Now, you’re probably wondering: How often should you equalize your batteries?

The answer is that equalizing frequency depends on your battery manufacturer and level of battery use.

It can range from once a month to once or twice a year.

When it comes to how to equalize a battery, keep in mind that you’ll need to use a battery charger that has an equalizing setting.

Not all forklift battery chargers offer this functionality.

The equalize button on a forklift charger outlined
Some battery chargers - like this one - have an equalize function. But not all chargers do

Once you have the appropriate charger, equalizing is pretty straightforward:

  1. Remove all battery loads

  2. Connect the charger to the battery

  3. Set the charger to the battery’s manufacturer-guided equalization charge level

  4. Switch on the charger, ensuring the electrolyte begins gassing and bubbling

  5. Measure and monitor the specific gravity of the cells. This will increase with charging

  6. Equalizing is complete when the specific gravity of the cells no longer increases

  7. Once done, replace any water lost during the equalizing once the battery has cooled

Washing

By washing forklift batteries and keeping them clean, you will promote work safety through:

  • Reducing workplace hazards from sulphuric acid
  • Extending the battery’s useful life by reducing exterior battery and lift truck corrosion from leaked acid
  • Improving the battery’s charge time by reducing electrolyte build-up on charging terminals

So how often should you wash your forklift batteries?

At least once per year, unless your batteries get dirty enough to warrant more frequent washing.

Conclusion

There you have it: The ultimate forklift battery guide.

Now, we’d like to hear from you.

Are you a forklift operator?

If so, what did you learn about forklift battery handling that we’ve discussed here?

Let us know in the comments section below!