How to choose a Lithium-ion battery for Forklift application?
A Lithium-ion battery is much more expensive than Lead-acid battery
The average price for a lithium-ion forklift battery is roughly $17-20k (about 2-2.5x more than a similar lead-acid battery)
Why do we want to replace a cheap lead-acid battery by an expensive Lithium-ion battery?
We are probably told by Lithium-ion battery suppliers that Lithium-ion batteries have the following advantages over Lead-acid batteries:
- Dramatic cost savings
- A lower total cost of ownership
- Longer life span
- Safer operations
- Faster, more efficient charging
- No need for a battery room
- Less downtime
Can we pay less ?
Most of us as users are more concerned with the direct cost-saving rather than that indirect cost-saving such as operation cost, battery room cost.
There are 2 parameters battery which will affect its cost: (1) the effective capacity under high discharge current and (2) the life span.
(1) The effective capacity under high discharge current
A Lead-acid battery’s capacity is typically rated at 20 hours of discharge time or 0.05 C.
0.05C of a 100Ah Lead-acid battery means 5A constant discharge current and the battery will be fully discharged in 20 hours.
Forklift application demands very high discharge current ranged from 1C to 3C.
Lead-acid battery’s effective capacity at 1C is only 60% of the rated capacity, 100Ah Lead-acid battery will only have effectively 60Ah capacity. At 3C, the effective capacity can drop to 40% of the rated capacity. (use AGM as an example)
On the other hand, Lithium-ion batteries will have a very steady effective capacity even at a very high discharge current from 1C to 3C. https://everspring.net/?p=81.
Therefore, we can replace a 100 Ah Lead-acid battery with a 40 Ah Lithium-ion battery for the same performance.
(2) Cycle Life
The cycle life of Lead-acid batteries only has 400 cycles at 80% D.O.D. (use AGM as an example). Most of the Lithium-ion batteries have cycle life over 2,000 cycles at 80% D.O.D.
If one cycle of charge and discharge per day, the average cost per year of Lithium-ion battery will be 1/5 of the Lead-acid battery in the above case.
(1) Forklift application demands very high discharge current ranged from 1C to 3C
If the price is similar, choose the Lithium-ion battery which can handle high discharge capacity. A smaller Ah capacity Lithium-ion battery can be used to replace a larger Ah capacity Lead-acid battery.
(2) Unlike commercial vehicles, Forklifts are normally used for a very long time
If the price is similar, choose the Lithium-ion battery which has a longer cycle life, which means a lower cost per year.
The author has 30 years of experience in the Lithium-ion battery industry from the laptop application, electric vehicle, to large energy storage.
To learn more about Lithium-ion batteries, please visit everspring.net