Are Lithium Ion Batteries Really Dangerous?

In the wake of recent events such as the Samsung Note 7 fires , many people have begun to question whether or not Lithium Ion batteries are safe. In many cases, Lithium Ion batteries are actually much safer than most batteries that are commonly used, such as the Lithium Polymer battery:

Lithium Polymer Battery

  • Lithium Polymer Dangers

Over time, Li-Po batteries tend to puff up. This causes them to take up more space, and as a result they become more dangerous. This is not the case with Lithium Ion cells, which have a longer lifespan and can tolerate up to 500 charge-discharge cycles before needing to be replaced. Additionally, Lithium Ion cells are much  more durable. A common mistake is placing sharp objects (such as nails) next to a Lithium Polymer battery. The packs can be easily punctured due to their thin surface, causing them to catch on fire. Even a small puncture from a metal screw inside a battery case could short the battery pack and cause it to explode. The cylindrical shell of Lithium Ion batteries is much more durable, making it much less likely to be punctured during a crash. Furthermore, Li Ion cells have been consistently on the forefront of new increases in battery energy density. Since the success of Tesla motors, much more focus has been put into developing Lithium Ion cells with greater energy density.

Lithium Ion 18650 Cell Damaged

Pictured above is the metallic casing of a Li-Ion cell. The cell was accidentally bumped into a sharp surface, causing a dent. The aluminum surface protected the battery from being punctured. If this had been a Li-Po cell, the battery may have caught on fire.

  • Fake Lithium Ion Batteries

IMPORTANT NOTE: There are a few Lithium Ion cells similar to these that claim to have upwards of 5000-8000 Mah of capacity, but all of these batteries are Chinese ripoffs and should not be trusted.

Many sources on sites like ebay claim to have radical amounts of battery capacity inside their Lithium Ion cells. Despite how enticing it sounds to have a Li-Ion battery with “9000 MAH” of capacity, all of these batteries are fakes and incredibly dangerous to use. If we look at the top rated sellers for “18650 cells” on ebay, the first thing we see is this:

Fake Lithium Ion Cells Ebay

In reality,  many of these batteries have a capacity of less than 1000 mah. These cells are counterfeit batteries produced in China. In many cases, the cells are not checked for reliability. As a result, they are incredibly dangerous to use and they often overheat very easily. Many of the vaping explosions are often caused by critical failures in counterfeit batteries. If you see anyone advertising a battery over 3600 MAH, you should avoid purchasing their cells as they are most likely Chinese knockoffs. Almost all Lithium batteries (not just Lithium Ion) have counterfeit types. Oftentimes the low cost drags buyers in who are convinced they’re getting a good deal. There was an important documentary written about the issue of counterfeit batteries like these, which you can watch below:

Here’s a helpful graph from thebest18650batteries that shows the current MAH capacities for batteries from common manufacturers.

Best Lithium Ion Batteries


The best battery on the market, the NCR18650G, has a 3600 mah capacity. If an advertiser says their Lithium Ion has a capacity higher than this, than they should not be trusted.

It’s also important to note that the NCR18650G isn’t available yet in large quantities, but you can find limited supplies of them online (be warned: they aren’t cheap!). The best battery on the commercially available with a genuine capacity is the NCR18650GA, which has a capacity of 3500 mah:

NCR18650GA cells

The batteries used in Tesla models are very similar to the GA series. Like the GA series, they have a max discharge of 10A. The only difference is that Tesla Li-Ions are much more durable because they are intended for automotives.  They are also much cheaper because they are produced in such a large volume. As a result, they are also much safer — Tesla reported that only 1/10,000,000 cells end up defective.

Tesla Battery Module and Cells

Pictured above: Two Tesla cells, along with a Tesla battery module which holds 444 individual cells

Tesla cells like the ones above are available for purchase here.

DISCLAIMER: Like any battery, Lithium Ion batteries must be taken care of properly. Please see our guide on How to Care for your Lithium Ion Batteries for more information.