Electric forklifts, also known as lift trucks, are workhorses for material handling, and they run on either lead-acid batteries or lithium-ion batteries. Regardless of type, forklift battery charging should be performed when the battery is down to 20 to 30 percent of capacity to lengthen the life of your electric forklift battery.
You can either charge the batteries directly in the forklift or remove and replace them. Although it sounds like a straightforward process, handling batteries, especially lead-acid ones, can be extremely dangerous, putting you at risk of burns from the sulfuric acid in the battery, exposure to toxic fumes, or other hazards. Batteries should therefore only be handled—carefully and skillfully—by a person who has sufficient training.
To keep you and your job site safe from hazards, this post offers a step-by-step process for charging forklift batteries properly and gives you ways to maintain your battery to extend its life.
How to Charge a Forklift Battery
A forklift runs on heavy-duty batteries that can perform for several years if you practice routine maintenance and proper care. If you do not already have experience handling forklift batteries, there are important steps to learn to work with them safely. It helps to follow a standard process, outlined here.
1. Park the Forklift in a Safe Charging Area
Every site that uses a forklift should have a safe charging station. Regardless of whether you plan to charge the battery in the forklift or take it out and charge it in a separate area, you must park your forklift, position it properly, use the parking brake, and turn off the forklift.
Any area where you’ll be charging forklift batteries should have good ventilation. An improperly ventilated charging area can lead to a build-up of hydrogen gas, which is highly dangerous. The charging area should also have proper fire protection and a way to flush out electrolyte if it spills during a battery change.
2. Wear Appropriate Protective Clothing
Handling a forklift battery exposes you to several risks that you can lessen through protective clothing. To lessen the risk of electrocution while charging, be sure you remove any metal jewelry. To guard yourself against acid splashes or corrosive burns from a lead-acid forklift battery, be sure you wear personal protective equipment (PPE), such as face shields, safety glasses, rubber gloves, and an apron. In case of an accident, be sure and have medical supplies, such as eyewash, and a fire extinguisher on hand.
3. Disconnect the Battery Cable from the Forklift
Open the seat to expose the battery and disconnect the battery cable from the forklift. This allows you to plug the forklift battery charger into the battery. Before doing so, ensure all the cables are in good condition and there is no visible damage. If needed, remove the battery from the forklift, taking proper precautions.
4. Connect the Charging Cable to the Battery
Connect the charger to the battery. Note that the battery amp hours—the amount of current a forklift’s battery can produce in an hour, which you’ll see on the data tag—should match the charging cable amp hours. The charger and the battery should also have the same output, measured in volts.
5. Charge the Battery for the Appropriate Duration
There are three ways to charge your batteries: through conventional charging, opportunity charging, and fast charging. These are all described in the following sections. Which method you choose will depend on factors including how much downtime the battery will have before it’s used again and what your priorities are in terms of battery lifespan.
Also, check when the manufacturer suggests that you equalize charge the battery—which means overcharging it to remove any build-up of sulfate.
Conventional charging takes the most time of the three methods. Keep this in mind if you’re using the forklift for multi-shift operations. In that case, you would need to switch out the battery with one that is already charged to avoid long delays.
- Charging timeline: Conventional charging takes about eight hours of charge time and eight hours of cooling time for a total of 16 hours.
- When to use this form of charging: This is the best option for maintaining the life and overall health of the battery when you have single-shift operations.
Opportunity charging works for both lead-acid and lithium-ion batteries but works best for lithium-ion. Be aware that although this method of charging is faster than conventional charging, it can harm the battery in the long run. It is, therefore, only recommended in certain circumstances, such as multiple or two-shift operations, where you can charge the battery during breaks.
- Charging timeline: Opportunity charging takes between 10 and 30 minutes (to charge up to 80 percent).
- When to use this form of charging: This is the best option for two-shift operations. Note that you’ll need to equalize the battery about once a week, depending on the manufacturer’s guidance.
Similar to opportunity charging, fast charging can actually cause even more wear or damage to the battery over time. Because it’s harder on the battery, it hurts the battery life. Consider carefully what your forklift battery life needs are before using this option.
- Charging timeline: Fast charging takes about 10 to 30 minutes to charge up to 80 percent.
- When to use this form of charging: This is the best option for three-shift operations, but keep in mind it is hard on the battery, and your battery likely needs an equalize charge once a week, depending on the manufacturer’s guidance.
6. Stop the Charge Once It Is Complete
Once your charge is complete, stop the charge, turn off the charger, unplug the charging cable, and plug the battery cable back into the forklift. You should let the battery cool if needed before you water it.
7. Add Water to the Battery as Needed
When the battery is charged and has cooled, you can remove the caps on the battery to check the water levels. This usually happens before the next shift. Add the appropriate water to each cell if needed without over- or underwatering.
8. Maintain the Battery to Improve Its Lifespan
Proper forklift battery maintenance helps to extend the lifetime of your battery. A forklift battery will typically last around 2,000 charge cycles. One charge cycle is about eight hours. You should charge a battery once it has reached a certain discharge level, typically 20 to 30 percent, to avoid damaging the battery.
- Follow the manufacturer’s recommendations on charge cycles: Never exceed the manufacturer’s charge cycle recommendation. The battery’s lifespan is based on the charge cycles and charging efficiently will lead to longer battery life.
- Equalize the battery according to the manufacturer’s recommendations: Note when the manufacturer recommends equalizing the battery, which means overcharging it to remove any sulfate build-up. This recommendation will depend on the charging method you use.
- Charge the battery correctly: It’s very important that you are meticulous about not under or overcharging the battery and follow the manufacturer’s recommendations. Specifically, always make sure to charge the battery at the appropriate discharge level to avoid damaging the battery.
- Don’t wait until the forklift shows low battery signs to charge: Slow starts, dim headlights, and the like are signs that the battery is getting low. Charge a battery once it hits the 20 to 30 percent range to avoid breakdowns or accidents if the forklift stops working.
Working with an industrial battery, such as those running forklifts, can expose you to certain dangers. However, proper training, careful attention to the charging procedure you follow, and the use of PPE can reduce potential hazards. Contact BigRentz for advice or for information on forklift rental options for your next project.