No car is safe per se, because on average more than 30k Americans die each year due to car-related reasons. Cars are heavy, powerful, full of flammable liquids, and are sometimes moving at extremely high speeds, all of this makes them dangerous, no matter the powertrain option.
On the other hand, EVs are not filled with flammable liquids which makes them safer from that perspective, but EVs carry energy-dense lithium-ion batteries which are flammable and can even explode occasionally.
Hybrids are a mixture between regular gasoline or diesel-powered vehicles and EVs, this means that the potential safety concerns are even greater. Thankfully, lots of modern-day hybrid vehicles use nickel-metal-hydride batteries which are safer than lithium-ion batteries, but not as power-dense nor efficient.
It’s safe to say that jury is still out on this question as there is no sufficient data that can safely prove why and how do batteries ignite and/or explode. Whatever it may be, there are loads of safety precautions these days that are designed to stop batteries from exploding.
Nickel-metal-hydride batteries (NiMH) – Most common hybrid battery type
Nowadays the vast majority of hybrids still use nickel-metal-hydride batteries which are safer than lithium-ion batteries but are way less power-dense and power efficient. These batteries use hydrogen to store electric energy, and they also use titanium to properly secure the hydrogen ions.
NiMH batteries have been around for quite some time now, and as such, they are cheap and easy to come by. They offer around 4 to 5 miles per Kwh and are way better when compared to acid lead batteries which are also used in many cars today.
NiMH batteries can be easily recharged and depleted, but they are nowhere near as efficient and power-dense as lithium-ion batteries. As far as safety is concerned, NiMH batteries are indeed more stable and less likely to catch fire or explode.
The reason behind this is the fact that NiMH batteries are less power-dense, and there is a lot less active material inside each cell. However, NiMH batteries are harmful to the environment, and they should be disposed of according to the manufacturer.
Lithium-Ion batteries (Li-Ion) – Stronger, better, faster, lighter, and deadlier
Li-Ion batteries are simply better when compared to NiMH or lead-acid batteries because they are way more efficient, more powerful, smaller, lighter, and all-around faster to charge. Li-Ion batteries are made out of highly reactive lithium and carbon, as such they are capable of storing way more energy.
However, Li-Ion batteries are far from perfect. They cost a lot of money, and some EVs and hybrids use battery packs which cost tens of thousands of dollars to replace. Such prices are a huge deterrent for many people wanting to make a transition towards EVs, but as time goes on, these prices should drop.
It is also important to note that Lithium-Ion batteries are primarily made for smaller devices, and as such, larger Li-Ion batteries are not as efficient nor superior. Larger Li-Ion batteries are also flammable and prone to exploding, and that’s the truth.
Even though such instances happen fairly rarely, and there are lots of precautionary measures out there made to ensure that a Li-Ion battery does not catch fire, but Li-Ion batteries do sometimes catch fire, and when they do, it is really hard to extinguish that fire.
Overal safety of hybrid cars – Safer for the driver, more dangerous for everyone else
Batteries and powertrain components are indeed a vital part of overall car safety, but they are not the only components that have to be constructed in a certain way. Hybrid and EV cars are inherently heavier, sometimes a hybrid variant can weigh as much as 500 pounds more than a regular gasoline variant.
As such, this added weight contributes to overall safety because a heavier car is bound to be safer when crashed with a lightweight car. The IIHS estimates that hybrids car accidents are 25% less likely to seriously injure the driver, but as far as pedestrians are concerned, it’s the other way around.
One of the greatest issues with EV and hybrid cars is the lack of noise when they are solely using the electric engine. Nowadays, almost all hybrid cars have to emit some kind of noise to pass homologation for most markets.
Can you completely discharge a hybrid lithium-ion battery?
In theory, Li-Ion batteries can be discharged completely, but that’s not something you’d ever want to do because the copper inside the battery can dissolve into the electrolytes. If you do completely discharge your battery, you are like going to experience a severe drop in battery health.
Sometimes this can even require you to completely replace the entire battery, and that can set you back a few thousand dollars. Granted, most newer hybrid car batteries are almost impossible to fully discharge.
How long does a hybrid battery last?
Another great issue with Li-Ion batteries is that they don’t last forever, to be exact, most car Li-Ion batteries last up to 100-150k miles. After this, you are bound to replace the battery, and that can cost a considerable amount of money.
On the other hand, a nickel-metal-hydride battery can sometimes last as much as 355k miles, and even when they do go bad, they are cheaper to buy because they are more common. Some Toyota Prius NiMH batteries can allegedly last even longer than that.
Are hydrogen cars better than hybrid cars?
Not many people know this but you can buy a full-on hydrogen car these days, and some people even reckon that a hydrogen car is the best clean alternative to gasoline and diesel. One of the main benefits of hydrogen cars is that they tend to give you higher mileage than electric cars.
Be that as it may, hydrogen is not perfect, and that’s probably the reason why hydrogen never came to be a mainstream choice of propulsion. A huge issue with hydrogen is the severe lack of efficiency and ease of use because there are virtually 0 hydrogen stations in most populated countries, and that’s partly because hydrogen storage is inherently inefficient.