Forklift Battery Charger Selection Guide
With so many forklift battery charger manufacturers in the market, how can a savvy warehouse manager or purchasing agent know which charger is best for their company’s operation?
Below, Warehouse IQ has provided a simple guide to selecting the best forklift battery charger and power solutions for your operation.
Shift Work – How Many Hours Does Your Lift Truck Work?
How many shifts are your electric forklifts working? If your answer is one shift, then the usual combination for electric forklifts is:
- 1 lift truck
- 1 battery
- 1 charger
A shift is defined as 8 hours of paid work for a forklift operator. In that time, a forklift will typically work 5-6 pedal hours. That means the lift truck is running its motor (lifting, lowering, or traveling) for 5 or 6 of the 8 hours.
Single Shift Operation Battery Charger Recommendations
The recommended charger for this type of operation is a Conventional Overnight Charger. This means purchasing a lift truck, a battery, and a single dedicated conventional charger.
Conventional Overnight Battery Charger
A conventional overnight forklift battery charger recharges a battery over 8 full hours. The start rate of the charger is typically between 15% to 20%. This means the charger restores 15% to 20% of the battery’s total rated ampere hours (energy) back into the battery within the first hour.
What does start rate mean? Imagine filling a large forklift battery-sized bucket with a standard-sized garden hose. The hose delivers enough water in the first hour to fill 15% to 20% of the bucket. So, the start rate of the hose is 15-20%.
Does that mean the battery will be fully charged in 5 hours with a 20% start rate? Yes and no. While the battery would be fully charged in 5 hours if the charger maintained a 20% rate, chargers are designed to reduce the amount of charge over time. The battery charges more rapidly at the start and slows toward the end, which is why it takes 8 hours to fully charge with a conventional overnight charger.
Types of Conventional Forklift Battery Chargers
There are several types of conventional (overnight) chargers for lift truck batteries, including:
- FerroResonant
- SCR
- HF Conventional Charger
Multiple Shift Forklift Battery Charger Recommendations
If you operate multiple shifts, you are likely considering higher-output chargers. You might use the following configuration:
- 1 lift truck
- 2 batteries
- 1 charger
- 1 battery changer
or
- 1 lift truck
- 1 battery
- 1 high-output opportunity or fast charger
Cost of Conventional vs. Opportunity Chargers in a Two-Shift Operation
If you operate more than one shift, consider the following battery charger infrastructure costs carefully:
(1) 18-125-13, 750 36 AH volt battery = $5,500 x (2) = $11,000 for two batteries
plus
(1) conventional overnight charger = $2,000
plus
(1) battery changer mounted to a pallet truck = $10,000
Total: $13,000 for power, plus a battery changer.
Compare that to:
(1) 18-125-13, 750 36 AH volt battery = $5,500
plus
(1) Opportunity charger = $4,000
Total: $9,500 for power.
That can be a $3,500 savings.
The True Cost of Opportunity Charging
Be cautious. It may seem like you’re saving the cost of a whole battery by using high-output opportunity chargers, but here’s why you’re not:
The Average Life of a Forklift Battery
When operating a forklift on a battery, you’re continuously taking ampere hours (amps) out of the battery and then recharging it until the battery eventually wears out. Let’s break it down:
A standard 750 AH battery has 600 usable amps (80% of the rated capacity). A standard battery warranty covers 1,500 cycles, which equates to:
(1) 750 AH x 80% = 600 AH x 1,500 = 900,000 total amps over its lifespan.
At 600 AH per day, the battery will last for 6 years.
If you use opportunity charging to replace 25% of the amps during breaks (2 x 15 minutes plus a 30-minute meal break across two shifts), you’ll get 62% more shift life, amounting to 975 amps per day. However, the battery life will also reduce at the same rate.
Fast Charge Forklift Battery Chargers
If you need more than 13 shift hours, you’ll require a higher output charger with a 50% start rate. A 750 AH battery will receive 375 amps per hour, providing a full 1,350 AH daily, which gives you 18 hours of available energy or 2.25 shifts.
If you use 1,350 amps daily, your battery will likely last only 2.66 years.
Differences Between Standard Charging, Opportunity Charging, and Fast Charging
These are the differences between standard overnight charging, opportunity charging, and fast charging. The start rate of the charger determines how quickly amps are restored to the battery. The number of hours your lift truck operates and the number of shifts will help you decide which method is best for your operation.
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