Forklift Battery Types

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Forklift Battery Types

Forklift Battery Types Oct. 14, 2023

Forklift Battery Types

Forklift batteries comes in all shapes, sizes, and types. So how will you know what types of batteries will best fit your needs? Below, we have listed out the types of batteries that are currently being used in the material handling industry, along with their pros and cons.  In addition to the types of batteries available, there are specific requirements for equipment such as weight amp hours and physical shape. But that’s a discussion for another time. 

Flooded Lead-Acid (Wet Cell)

The most common types of forklift batteries, Flooded Lead-Acid batteries or Wet Cell batteries are batteries containing charged plates suspended in a mixture of sulfuric acid and water. The battery works by suspending the electrolytes between 2 oppositely charged plates within the water and acid mixture. Evaporation occurs during the operating and charging process. As a result, Wet Cell batteries require more regular maintenance than other battery types to maintain top performance. This comes in the form of regularly adding water to the battery and regular cleaning, which means your business will require a specialized watering system and a trained person with extra safety equipment to ensure the correct level of water in the battery and provide maintenance for it.  

The main benefit of the Wet Cell battery is its price. The battery itself costs less compared to other types of batteries, allowing businesses to have multiple batteries per forklift. If your operation requires machines to work around the clock, then multiple batteries will allow one to be recharged or serviced while the forklift is still being used. 

There are a few negative aspects with Wet Cell batteries. First, you may need to purchase a special watering system, plus provide training and safety equipment for employees who will maintain the battery’s water levels. Wet Cell batteries also require regular maintenance and cleaning to keep the batteries working at optimal performance. One of the biggest negatives is the required long charging times and cool-down period prior to utilization. Typically, we recommend charging a battery for eight hours and then providing an eight-hour cooling period, leaving you with eight hours of operating time in a 24-hour period. Wet Cell batteries also need a special charging station where your team will physically remove the battery from the forklift and plug it into the charger. This means that you will need a charger for each concurrently charging battery. If you have multiple forklifts in operation, then you will need even more space for charging batteries and cooling them. 

With correct maintenance and charging procedure, most Wet Cell batteries will last up to five years or 1,500 charging cycles. 

Gel Cell Lead-Acid (Gel Cell)

Gel Cell Lead-Acid or just Gel Cell batteries require less maintenance than Wet Cell batteries. A gel battery is very similar to a traditional lead-acid battery, but it adds silica to the electrolyte mixture to create a gel like substance. This thickening of the electrolyte medium means that gel batteries can be installed in a variety of positions and don’t emit as many fumes. Since these batteries are sealed, they do not require a special watering system to keep the battery working.  

When charging your gel battery, you’ll want to plan on giving it extra time. Slow charging cycles are common with Gel Cell batteries, but you can’t walk away and leave it charging. Since the electrolyte medium is a gel instead of a liquid, you will need to take the battery off the charger as soon as charging is complete since leaving it on could cause voids with the electrolyte which is irreversible damage. 

One of the biggest complaints with Wet Cell batteries is that they are susceptible to extreme vibration and other impacts. Gel batteries have an advantage in this situation as it can absorb the impact and vibrations, making them great batteries for items such as four wheelers. 

Absorbed Glass Mat (AGM)

Absorbent Glass Mat or AGM batteries are another type of sealed lead acid battery. AGM batteries work when sulfuric acid is absorbed by a very fine fiberglass mat.  

AGM batteries do not require regular watering like flooded batteries. The mats themselves do not absorb and are not affected by the acidic electrolytes which allow them to work effectively without any maintenance and bring the benefit of working in a larger temperature range. The leading advantages of AGM batteries is that charging is up to five times faster than Wet Cell battery and the ability to deep cycle. 

The main trade-off for an AGM battery is its low life expectancy, and each charging cycle can harm the life and performance of the battery. Manufacturers recommend discharging only up to 50% of their capacity per charging cycle, allowing the battery to last up to 1,300 cycles. 

Lithium-Ion

Lithium-Ion batteries are a newer battery technology when it comes to forklifts. The pros of the lithium-ion battery are that it is relatively maintenance free because it is sealed and requires no watering or cleaning. It has a fast-charging time, requiring only 2-3 hours to fully charge with no cooldown period. You can also employ opportunity charging, which means you can plug them in during a break period for a quick charge. In fact, you can usually plug Lithium-Ion batteries straight into the wall outlet. Perhaps, most important is its increased expectancy of up to 3000 charging cycles. It does not expose your team to harmful substances such as sulfuric acid.  

This convenience comes at a price, though, as lithium-ion batteries cost many times more than your typical Wet Cell battery. Also, lithium batteries are affected by the environmental temperatures in which the unit works.  Freezer applications and unheated warehouses, along with our new England weather, can have a negative effect.  

Conclusion

Hopefully, this will give you a better understanding of forklift battery types. Still have questions? Give us a call at (203) 239-5351 or contact us and we can recommend a forklift battery that will work for your industry. 

Lithium Ion vs Lead Acid Forklift Batteries

Did you know the very first commercial lithium-ion battery was used in 1991?

However, when it comes to forklifts lithium-ion batteries have only been around for 12 years.

Lead acid is the ole reliable, dating all the way back to the early 1920s.

While they are older than you, lead acid batteries have had loads of updates over the years and are still a very sound option for certain applications, as you’ll see below.

So let’s get right to it… 

What are Lead-Acid Forklift Batteries?

Lead-Acid forklift batteries are rechargeable batteries that have a high power-to-weight ratio and are sought after due to their lower cost. 

They are known as motive batteries, AKA the motor of the vehicle. 

What most people don’t think of is the sheer size and weight of lead-acid batteries. 

The common car battery weighs about 40 lbs on average but a forklift battery can be between 800 to 4,000 lbs. 

In total a forklift weighs 9,000 lbs on average. That is the equivalent of 5 average-sized buffalo. 

Despite this, one of the benefits of the lead-acid battery is actually its weight. 

Forklifts lift heavy objects  (sometimes as much as 36,000 lbs.) hundreds of feet high, so they need something to help balance the weight. 

In this case, the battery acts as a counterbalance and keeps the forklift from tipping over when lifting heavy loads. 

What are Lithium-Ion Forklift Batteries?

Lithium-Ion forklift batteries are rechargeable lithium and graphite batteries with a very high energy density, low discharge rate and no memory loss. 

While lithium is a much lighter material, these batteries still require either a bodybuilder or a machine to move, weighing between 500 to 2,500 lbs. 

This lighter battery means less weight that your forklift is carrying, so sometimes you’ll even see a metal plate to help provide additional weight to keep the forklift from tilting when carrying heavy loads. 

There are some pros and cons to each of these battery types, but we’ll look at the major areas to help you come to a conclusion on which is best for your application. 

In this 4 round heavy-weight fight we will look at maintenance, charging, energy usage and most important, upfront cost. 

Let’s have a clean and fair fight, Round one…. take it away Bruce Buffer!

Maintenance

Lead-Acid Batteries

To keep it short and simple — lead-acid batteries require more maintenance. 

Now the longer version is that lead-acid batteries require watering. 

Just like taking care of your garden you gotta do the same with these batteries. 

What happens is water fills the individual cells in your battery to provide a functional level of chemicals and electrolytes that will produce power.

Doesn’t sound too bad right? 

Wrong! 

Even if you run a one-shift application your batteries will probably need watered once a week or at the very least bi-weekly. And this requires special equipment and the right level of care, because you water too much or too little and you’ll damage your battery.

So typically this labor will be performed by a material handling company/forklift dealer at an hourly rate. 

Other maintenance steps to take are: 

  • Service semi-annually to control acid and corrosion
  • Inspect for any defects
  • Keep electrolyte level above separator protectors
  • Keep the vent caps on tight

Lithium-Ion Batteries

Almost none. Lithium-ion batteries save you thousands because they do not require the most expensive maintenance piece… watering. 

However, there are a few things you should make sure to check on every so often. These are listed below. 

  • Check wear plugs & cables
  • Monitor charger for fault conditions
  • Make sure your software is up to date
  • Keep your batteries at room temperature
  • Allow partial discharges and avoid letting the battery die, it is best to charge when you’re around 15-25% of battery left
  • Keep away from moisture

Round 1 Winner: Lithium-Ion

Charging

Lead-Acid Batteries

If you take great care of your battery you will get about 1,500 charge cycles. Let me repeat that… GREAT CARE.

This equates to about 5 years if you charge the battery once per day. 

Of course, this is the over optimistic side because who doesn’t appreciate a half glass full person in your corner? 

But, if we are going to be more realistic, you should expect about 3.5 years of life. 

That isn’t too bad, but the problem arises when you have a 2 or 3-shift application.

In these cases you will need at least two batteries per truck because charge time will take 8 hours and then you will need a cool down time of 8 hours as well. 

You can get a better picture in the chart below. 

LEAD-ACIDLITHIUM-IONUse Time8 Hours8 HoursCharge Time8 Hours1-4 HoursCool Time8 Hours0 HoursTotal Time Needed Before Use16 Hours1-4 Hours

Lithium-Ion Batteries

As you can see above lithium-ion can be 4-16x more effective when it comes to charging production. 

But, what about degradation?

You can put a checkmark next to lithium-ion on this one as well. 

Lithium-ion batteries generally last about 2,000 – 3,000 cycles.  Which is almost double of what you can expect with a lead-acid battery. 

This point goes to lithium-ion. 

Round 2 Winner: Lithium-Ion

Energy Usage

Wouldn’t you like to save money on your monthly electric bill? 

Well that’s what we’re looking at here, finding the battery that is more efficient *cough, cough* cheaper on utilities.

Lead-Acid Batteries

According to the always trustworthy Wikipedia, the energy density of a lead acid battery is 80-90 Wh/L with a specific energy of 35-40 Wh/kg.

All that seems confusing, but all it means is the measure of how much energy is stored in the battery.

Another fun fact for you, lead-acid batteries are not good at keeping their energy. They lose amps while moving, charging, lifting and idling. 

Meaning, as a shift carries on the forklift will become weaker and weaker as the battery level goes down, so you might be able to lift 3,500 lbs 186″ at the beginning of a shift but at hour 4 you might only be able to lift 2,600 lbs 186″. 

Lithium-Ion Batteries

The energy density of a lithium-ion battery is 100-265 Wh/kg.

That is 3-6 times stronger than lead-acid. 

The other big kicker here, lithium-ion batteries keep a constant voltage level during their discharge cycle. This can equal 50% savings in energy compared to lead-acid. 

One final point to add is that charging a lithium-ion battery can be done without removing the battery from the forklift. 

Unlike the lead-acid batteries, lithium-ion gives users the chance to use opportunity charging between shifts or even during break time. 

This is a huge advantage because now you do not need a second battery and your charging space will be just that, a charging space.

Typically with lead-acid you will need a space dedicated for storing your extra batteries while they charge.

This is a major advantage because now you can take that dedicated charging space and restructure it to be additional storage space. 

Round 3 Winner: Lithium-Ion

Upfront Cost

Lead-Acid Batteries

Lead-acid batteries will cost you about $5,000-12,000 brand new depending on your size and specs. 

The articles below are detailed on electric forklifts (class 1), reach trucks and order pickers (class 2) and pallet jacks, pallet stackers and tow tractors (class 3) and go into a little further detail on the battery costs for each model type. I wrote them so I promise you they aren’t too awful. 

Lithium-Ion Batteries

On average you can expect to spend $17,000-25,000 on a lithium-ion forklift battery. 

Now, before you completely write of lithium, consider the added perks from above and make sure to look at the final conclusion below. 

Round 4 Winner: Lead-Acid

Conclusion

The easy answer is lithium-ion is the better, more reliable, more efficient, and bigger bang for your buck option. 

However, this is only an obvious choice if you are running a 2-3 shift application with a few forklifts. 

If you have a warehouse with only a couple of forklifts and pallet jacks that are not used around the clock then you may be better off using lead-acid. 

Lithium-ion batteries take the W when it comes to maintenance, charge rate, charging capacity, degradation, lifespan, safety and overall ROI. However, lead-acid batteries are much cheaper and if they are only used intermittently, then they are probably the better option for you. 

When to Add Water to a Forklift Battery?

The best time to water your batteries is right before a shift, after the batteries have had time to cool down.

How Long do Forklift Batteries Last?

Lead-acid batteries will last 1,500 charging hours if maintained well. Lithium-ion batteries will last 2,000 to 3,000 charging hours. 

Do Propane Forklifts Have Batteries?

Yes, propane forklifts have batteries. However, unlike electric forklifts the purpose of the battery on propane forklifts is not to produce power, it is to help start the forklift.

How Much Does a Forklift Battery Weigh?

A forklift battery weighs between 800 to 4,000 lbs. depending on the type (lithium-ion vs lead-acid) and size (24V, 36V, 48V).

Forklift Battery [2022 Buyer's Guide] See The 6 Best Types


There are plenty of companies offering industrial batteries for forklifts. Aside from checking the voltage, how are you supposed to know which will be most suitable for your forklift operations?

For what seems to be a simple decision, there's a surprising level of specificity depending on your precise requirements. Between the pros and cons of lead-acid vs. lithium-ion batteries, cost vs. capacity, different charging systems, and the slight variations between brands, there are a lot of important factors to consider.

If you want to understand the options and ensure a suitable purchase, read on.


The 6 Types of Forklift Batteries


Forklift Battery Voltage

Electric forklifts come in a range of sizes and lifting capacities, based on the specific material handling tasks they're designed for. Unsurprisingly, their batteries also vary significantly due to differences in customers' energy requirements.

Pallet trucks and small three-wheeled forklifts tend to use a 24-volt battery (12 cells). They're relatively lightweight machines that don't need to move particularly fast or lift heavy loads, so these smaller batteries provide plenty of motive power.

A more typical warehouse-type forklift with lifting capacities from 3000-5000lbs will generally use either a 36 volt or 48-volt battery, depending on the maximum driving speed required and how often loads toward the heavier end of the range are to be lifted.

Meanwhile, heavy-duty forklifts aimed more at the construction industry will use a minimum of 80 volts, with many requiring a 96-volt battery and the very largest heavy industrial lifts going all the way up to 120 volts (60 cells).

If you want to calculate the voltage of a battery quickly and easily (where the stickers or other markings are obscured), simply multiply the number of cells by two. Each cell produces approximately 2V, although peak output can be higher when freshly charged.


Lead-Acid Forklift Batteries

Lead-acid batteries are the traditional standard technology for industrial battery solutions.

Each cell within the battery consists of alternating plates of lead dioxide and porous lead, submerged in an acidic electrolyte solution which causes an imbalance of electrons between the two plate types. This imbalance is what creates the voltage.

Maintenance and Watering

During operation, some of the water in the electrolyte is lost as oxygen and hydrogen gases. This means lead-acid batteries need to be checked at least once per 5 charging cycles (or weekly for most electric forklift operations) and the cells topped up with water to ensure the plates are fully covered. If this "watering" process is not carried out regularly, sulfates build up on exposed areas of the plates, resulting in a permanent reduction in capacity and output.

There are several types of watering systems available, depending on the battery design. Some of the best watering systems also have automatic shut-off valves to prevent accidental overfilling. Although perhaps tempting as a time-saving measure, it's very important never to water the cells whilst attached to the battery charger, as this can be highly dangerous.


Charging

If you're using electric forklifts for commercial material handling applications, a significant downside to this type of battery technology is the amount of downtime dedicated to charging.

Approximately 8 hours for a full charge, plus the time taken for the battery to cool as they get very hot during charging, means most of a day out of action. 

If your equipment is in heavy use, you'll need to purchase several batteries and swap them in and out for charging.

It is also unwise to perform "opportunistic" charging on lead-acid batteries i.e. charging them when convenient even if not depleted to at least around 40%. This causes damage which reduces the service life considerably.


Tubular Plate, AGM, and Gel-filled Batteries

In addition to the standard, flooded, flat-plate lead-acid batteries described above, there are several variations that produce electricity in a similar way but applying advanced technology to make a product potentially more suitable as a forklift battery.

A tubular plate battery is a system where the plate materials are combined and held within a tubular structure. This enables fast charging and reduces water loss, meaning less maintenance and longer service life.

Absorbed Glass Mat (AGM) batteries use mats between the plates which reabsorb oxygen and hydrogen. This results in a significant reduction in moisture loss and maintenance requirements. However, these are very expensive compared to other options.

Gel batteries use a similar electrolyte to flooded wet-cell batteries, but this is turned into a gel and placed in sealed cells (with a vent valve). These are sometimes called maintenance-free batteries because they do not need to be topped up. However, they still lose moisture over time and have a shorter service life than other lead-acid batteries as a result.

Flat-plate lead-acid forklift batteries will last around 3 years (around 1500 charging cycles) if cared for properly, whereas their albeit more expensive tubular-plate counterparts will keep going for 4-5 years under similar conditions.


Lithium-ion Forklift Batteries

The emergence of lithium-ion batteries, first developed in the late 1970s, provided a maintenance-free commercial alternative to lead-acid systems. A lithium-ion cell contains two lithium electrodes (an anode and a cathode) in an electrolyte, along with a "separator" preventing unwanted ion transfer within the cell. The end result is a sealed system that doesn't lose electrolyte fluid or require regular topping-up. Other advantages over traditional lead-acid batteries for material handling equipment include a higher capacity, faster charging times, longer service life, and reduced operator hazard as there are no unsealed chemical components.

However, they are significantly more expensive to buy in the first place. The other slight disadvantage, specifically for the forklift industry although it can be an advantage for many types of electric machinery, is these batteries tend to be smaller and lighter than lead-acid systems of a similar voltage. Most forklifts use the weight of the battery as part of their counterbalance system, whereby the weight of the forklift itself is distributed as far to the rear (away from the forks) as possible. This allows the lifting equipment to raise heavy loads without the truck tipping forward. Switching to a much lighter lithium-ion battery may require the use of additional ballast in the battery compartment to offset the reduced battery weight.

Overall, lithium-ion batteries are generally considered superior to most types of lead-acid batteries as long as the purchase price isn't prohibitive and you are able to compensate for the reduction in weight.



Factors To Consider When Buying


Voltage and Capacity

It's vital to make sure the battery for your forklift provides the correct voltage. Some forklift models can be run on a range, depending on operational parameters (usually either 36 or 48 volts), but most are designed to accept batteries with one specific power rating. Check the forklift data plate or the relevant manual for your make, model, and year. Using a forklift with an underpowered battery will affect performance and may prevent operation altogether, whereas too powerful a battery can damage the drive motor and other key components.

The capacity of a forklift battery, usually measured in Amp-hours (Ah), relates to how long the battery is able to sustain a given current. The higher the battery capacity, the longer you can run your forklift (or other electric material handling equipment) on a single charge. The normal range for forklift batteries starts at around 100Ah and goes up to over 1000Ah. as long as your battery has the correct voltage and will physically fit into the battery compartment, the higher the capacity the better.


Battery Compartment Dimensions

On a forklift, the battery is contained within a box-shaped compartment of fixed dimensions. However, there is no fixed, standard size for batteries of a certain voltage or capacity. Before you buy a battery, you need to determine whether it will physically fit in the compartment.

Lithium-ion batteries tend to be smaller than lead-acid batteries (for a comparable voltage and capacity), so size shouldn't be an insurmountable problem if you are switching over in that direction. That said, it's important the battery fits snugly so it's not moving around and potentially getting damaged. If you are going to use a forklift battery that is significantly smaller than the dimensions of the compartment, make sure you use padding or an insert to ensure a secure fit.


Charging Time

The downtime your equipment has to spend on charge between uses impacts productivity. Ideally, you want a forklift battery that runs for as long as possible on a single charge but spends as little time as possible at the charging station. This is mostly relevant if you are running a 24-hour operation with operators on shifts. If your site or warehouse is only open during office hours, there's plenty of time to charge your lift batteries overnight.

The charging time for a forklift battery is a function of the battery charger used as well as the battery 3itself. Different chargers can be single or three-phase and have different charging rates (in Ah). Some also have a "fast-charge" option.

However, it's not so simple as "the faster the better". Using a charger that doesn't match the recommended rate for the battery contributes to sulfation and battery degradation, especially in lead-acid batteries. This ends up costing you significantly, both for battery maintenance and by replacing the battery sooner than if you'd used an appropriate charger.

Lithium-ion batteries tend to have much faster charging times overall and are the better option if fast turnarounds between shifts are required. The other advantage here is many lead-acid batteries require a "cooling off" period after charging. Typically, even with a good brand of charger, a lead-acid battery will require 8 hours for a full charge, and another 8 for cooldown. This means they spend a lot of time out of operation and a customer choosing this type for commercial operations with regular forklift usage may need to purchase several batteries for each lift and rotate them.


Maintenance and Service Life

Most lead-acid forklift batteries for need regular maintenance, and specifically "watering" (the topping up of the electrolyte fluid to avoid undue damage to the electrode plates). This extra task takes time out of their operating schedule and must be dedicated to a suitably trained staff member.

For this reason, some commercial battery manufacturers offer one or more types of maintenance-free batteries. The downsides of these are they are either significantly more expensive than standard wet-cell sort or have a much shorter service life. A typical lead-acid battery will last approximately 1500+ charging cycles, whereas a sealed, gel-filled battery may only be good for around 700. AGM batteries often last even less.

Lithium-ion batteries also generally withstand more charging cycles than their lead-acid counterparts (around 2000-3000). In addition, their greater capacity is such that those from a quality brand will often support running a forklift for two whole shifts per charge. This means their effective service life tends to be even longer in real terms, whilst keeping your electric forklift running without interruptions for battery maintenance.

For more detailed information, see our forklift battery maintenance page. 

  


The Final Verdict

It's important to consider how your forklift will be used when choosing a battery. If you need fairly constant operation over full shifts, day in day out, lithium-ion batteries are going to be well worth the extra upfront cost. This type is also likely to work out cheaper for you in the long run, with less downtime for charging and maintenance and no need to purchase multiple batteries for the same piece of material handling equipment.

On the other hand, if your industry only requires you to use an electric forklift sporadically, with plenty of time for charging and maintenance in between, the cheaper lead-acid technology should be sufficient.


To see a complete breakdown of each part, see our parts of a forklift page.  





Tim Postlethwaite // Staff Writer

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