While I did a similar article on Lithium 3 ½ years ago, it is a good time to do an updated re-run as many people are still pretty novice in their knowledge of Lithium battery technology. I want to again thank our company President, Jun Hu, PhD in Electric Engineering, for providing the bulk of meat for this article.
There have been a few short articles in the Golf Car Trade publications about Lithium as well as companies advertising their use in Golf Cars and other electric vehicles. This article is designed to provide you with a basic knowledge level of the key types of Lithium-ion as well as the advantages and disadvantages of Lithium-ion vs. traditional lead acid batteries.
Here are some basic facts on Lithium-ion battery technology:
Lithium-ion Battery Types/Chemical Make-up Advantages and Disadvantages of Lithium-Ion
- Lithium is a highly reactive element, meaning that a lot of energy can be stored in its atomic bonds. This translates into a very high energy density for lithium-ion batteries. Here is a way to get a perspective on the energy density. A typical lithium-ion battery can store 150 watt-hours of electricity in 1 kilogram of battery. A NiMH (nickel-metal hydride) battery pack can store perhaps 100 watt-hours per kilogram, although 60 to 70 watt-hours might be more typical. A lead-acid battery can store only 25 watt-hours per kilogram. Using lead-acid technology, it takes 6 kilograms to store the same amount of energy that a 1 kilogram lithium-ion battery can handle.
- Higher voltage vs. lead acid. 3.7 volts vs. 2.0 volts
- Higher turnaround charge efficiency (97% vs. 75%)
- State of charge and state of health can be readily and remotely monitored
- Three to Four times battery life vs. lead acid batteries. On average 2,000+ charging cycles
- Much lighter weight of Lithium batteries provides more carrying capacity and range.
- No maintenance required vs. checking water levels and keeping corrosion of battery posts
- Flat Discharge curve. That means full power until the battery is near empty vs. lead acid batteries which begin to lose power when about 50% of capacity is used.
- More environmentally friendly than lead acid, AGM or Glass mat batteries.
- Self-discharge rate is very low (less than 3% per month). Allows for seasonal use vehicles to sit without concern of batteries completely discharging.
- Wider operating temperature. Lithium-ion batteries perform much better in extreme cold or heat compared to lead acid batteries.
- Cost is nearly 4 times higher than traditional lead acid batteries.
- They are sensitive to high temperatures. Heat causes lithium-ion battery packs to degrade much faster than they normally would. No different than lead acid batteries in a harsh environment, i.e. Arizona.
- If you completely discharge a lithium-ion battery, it is ruined.
- A lithium-ion battery pack must have an on-board computer (BMS or battery management system) to manage the battery. More on the BMS below.
- There is a small chance that, if a lithium-ion battery pack fails, in rare circumstances it can burst into flames
While some recent fire issues like Tesla has been experienced in the U.S. and in France, August of this year, millions of Lithium batteries are in use across the world with a very small percentage of issues reported.
The key to the safety of Lithium-ion is the battery management system or BMS. The BMS is the brain of the system. The BMS has many safety features built in including:
- Low voltage alarm cutoff
- High voltage alarm cutoff
- Cell balancing
- High temperature alarm cutoff
- High current alarm cutoff
- Ground fault detection alarm cutoff
To the right is a Lithium-ion battery pack undergoing testing at our STAR EV lab. Each cell is continuously monitored and is in constant communication with the BMS.
We hope that this article helps you speak with more knowledge and confidence when your customers ask about Lithium-ion batteries.
While the cost is still prohibitive for most Golf Car applications, we believe Lithium-ion battery use in our Golf Car and Commercial world will slowly gain momentum. Acquisition cost should drop some as usage in our industry continues to grow and more companies like Samsung enter the golf and EV Lithium battery market.
Let’s sell some EV’s!