Many companies have no idea how much they are spending to charge a forklift battery. Costs are hidden, and difficult to calculate, until now. Use this online calculator to estimate the cost to charge batteries for forklifts.
Estimate the Cost to Charge your Electric Forklift Batteries – It is more than you think!
This calculator is provided to support your internal discussions about reducing operating costs in your warehouse. Please use this as an informal estimate only. Please consult with your accounting firm before making business decisions based on the information provided here.
The Data Points of Charging a Forklift Battery
Here are the key data points that will go into the calculation of the cost of charging a forklift battery.
Forklift battery voltage
Forklifts and lift trucks that fall into the category of PIT (powered industrial trucks) run on these voltages in North America:
- 24 volts
- 36 volts
- 48 volts
- 80 volts (rarely)
In Europe, forklift voltages are often 80 volts.
Ampere hour of the forklift battery
The ampere hour capacity, also known as the AH of a battery, describes the total capacity of the battery’s cells. The ampere hours capacity, AH, is found hidden in the model number of the battery. To find out what the AH is of a forklift’s battery, follow the red cable from the connector up to the battery and then remove the plastic cover. The battery model number will be listed there.
Sometimes, there is a sticker on the side of the forklift battery noting the ampere-hour capacity of the battery.
How to Calculate the Ampere-Hour Storage Capacity of a Forklift Battery
There is a lot of information available in the forklift battery model number. To calculate the energy storage capacity of a battery, take the middle number from the model number and times by the last number once you have subtracted 1 and divided it in half. Here is an example:
Model number: 18-125-15
15 – 1 / 2 = 7 x 125 = 875 ampere-hours (AH). Find out more and calculate the AH in your forklift battery.
The Efficiency of a Charger
The efficiency of a forklift charger is based on the Average Power Conversion Efficiency, which means the ratio of DC output power to AC input power. Said another way, it is the comparison of the AC kWh drawn from the wall versus the number of DC kWh that are delivered to the battery.
The Columbic Efficiency of a Forklift Battery
The efficiency of a battery to accept a charge is what is called Coulomb’s Law. The coulombic efficiency is the rate at which electrons transfer.
If you are charging a lithium-ion battery, use 99%. Otherwise, 85% is a good number to use for a lead-acid forklift battery. If you are fast charging the battery, decrease the efficiency (less that 85%). If the battery is newer and being charged in a cooled area, raise it to 90%. Remember, the ability of a battery to accept a charge will never be 100%, so you need to discount the energy being received into the battery. The older the forklift battery, the hotter it charges at, the faster you try to charge it, and the greater than 70% you complete the charge with, the lower your coulombic efficiency will be.
Peak Demand Charge
To understand the peak demand charges a business needs to pay, think of peak demand as the highest rate paid for the highest usage in any 15 minute period.
If you think you are paying only 10 cents per kW, but you are charging all your Lithium-ion batteries all at the same time when the team goes on break at 11 am, you can be certain your entire day will be charged at the peak demand rate you were paying at 11 am.
Commercial customers typically face demand charges ($/kW) based on their peak demand during each billing period. This peak demand is usually defined as the highest average electricity usage occurring within a defined time interval (often 15 minutes) during the billing period. For many commercial customers, demand charges can account for 30 to 70
percent of the total charges on a monthly electric bill. Demand charge rates vary considerably across utilities, locations, building sizes, and building types. Because peak
demand is based on how and when a customer uses electricity, even two customers that consume similar amounts of electricity and are billed under the same utility rate may incur vastly different demand charge expenses, depending on their peak demand.
So, if your normal rate is 10 cents per kWh, divide it by .3 in order to gross the amount up by 70%.
Enter the number of lift trucks (forklifts, pallet jacks, turret trucks)
A lift truck is the term we use to refer to PIT (powered industrial trucks). Count the number of units in your material handling fleet. This will impact the cost to charge forklift batteries.
The number of forklift batteries to charge
How many batteries do you have for your PIT fleet? Do you have only one battery per lift truck? Then this number is likely the same as the number you entered for lift trucks. If it is more, then you are likely changing batteries. If it is the same, you are likely opportunity-charging batteries. If you have a single shift, it is possible that you are simply parking your lift trucks and charging them.