Why didn't starter lithium batteries replace lead-acid batteries?

What is a car starter battery

starter lithium battery (formal name should be starting lithium ion battery) A lithium ion battery specially used for starting, lighting, ignition (abbreviated SLI) and power supply of vehicles, ships and aircraft, and is a complete replacement for starting lead-acid batteries Taste.

With the rapid development of lithium batteries in recent years, it has become a trend to replace lead-acid batteries with them. Naturally, people have thought of starting lithium batteries, thinking that this is a good idea. There are too many advantages of acid batteries, so many lithium battery manufacturers have tried one after another, and have invested heavily in research and development and testing. However, the result was a failure, and the enthusiastic lithium battery manufacturers ended in failure in research and development. Today, except for Mercedes-Benz, BMW and other high-end cars that have 48V start-stop lithium batteries and a small number of domestic vehicles, and some immature motorcycle starter lithium batteries, other fields have hardly used starter lithium batteries.

Why can't starter lithium batteries replace lead-acid batteries on a large scale?

There's more than one reason, but price is definitely the main reason.

Lead can be recycled. The world does not need to mine much new lead metal every year. It can be said that the cost of lead is the cost of recovery. Five years ago, the price of lead was higher than it is now, and in five years, our price has almost doubled, but the price of lead has fallen! The cost of lithium batteries has also continued to decline in recent years, but no matter how much it is reduced, in terms of Wh cost, it is three or four times or higher than that of lead-acid batteries.

The reason why the cost of lithium batteries is higher than that of lead-acid batteries is not only because the raw materials contain precious metals and there are many kinds, but the production process of lithium batteries is complicated and difficult, which is also one of the factors that increase the cost. In addition, lithium batteries must have a protection board or BMS (battery management system), which is not available in lead-acid batteries, and also increases a lot of cost. In addition, the assembly process of lithium batteries is far more complicated than that of lead-acid batteries. All of these have pushed up the cost of lithium batteries.

In addition to cost, the second major influencing factor is the safety characteristics of the lithium battery itself.

It is well known that lithium batteries are prone to explosion and fire. Therefore, when applying lithium batteries, lead-acid batteries are generally not replaced directly. Now, major lithium battery manufacturers continue to invest in this area, so the safety performance of lithium batteries is getting higher and higher.

The third influencing factor is the high and low temperature performance of lithium batteries.

Lithium batteries are not as high-temperature resistant as lead-acid batteries, so lithium batteries must be kept away from the engine. Lithium batteries can withstand high temperatures of 50 degrees, and lead-acid batteries can withstand high temperatures of 70 degrees. Lithium batteries can not withstand high temperatures next to the car engine as a starting battery. When used at high temperature, especially when the vehicle is often exposed to the sun, the danger still exists, and a good design is required. The low temperature performance of the lithium battery is also a problem. If the lithium battery does not take measures to start the vehicle at minus 20 degrees, there is a problem in starting the vehicle. This aspect is far inferior to the lead-acid battery. Of course, with the development of technology, the low-temperature performance of lithium batteries has improved rapidly. Now many lithium batteries can be discharged at minus 40 degrees. It may not take a few years. Low-temperature performance is no longer a limitation of the development of lithium batteries.

Another factor that everyone ignores is the impact of technology.

It is not easy to develop a good starter lithium battery. This difficulty is no less than that of electric vehicle power lithium batteries. Because, the problems existing in the lithium battery of electric vehicles are basically there in the starting lithium battery, but the large current required for starting the lithium battery and a series of problems caused by it are not present in the lithium battery of the electric vehicle. Therefore, it is very difficult and expensive to do a good job of starting the protection board or BMS of the lithium battery. Isn't the starting lithium battery already used in the BYD car? If you have disassembled their lithium batteries, you will find that their protection is not perfect, just barely used. Moreover, they are systematically designed for the whole vehicle, and there is a layer of protection for the lithium battery on the whole vehicle, but the protection of the lithium battery alone is not perfect. Therefore, this lithium battery can only be used for their car and cannot be used in other areas. This simplified design is also available on power tools, including some Bosch power tools. The battery protection board has only a few resistors on it, but the control board of the power tool has a built-in battery protection function, so the battery cannot be taken out alone. to use.

A fully qualified starter lithium battery BMS, as an automotive-grade application, should be second only to aerospace products in terms of research and development difficulty, so few people should be able to make it at present. The emergency starter power supply that everyone usually buys, as well as the motorcycle starter battery, etc., are basically unprotected from discharge. If you accidentally put it on zero volts, it will be damaged. When the positive and negative poles are short-circuited, you will be scared to death. Of course, some people will say that the lithium-ion battery of the motorcycle he bought has not been broken for a long time. That is because the motorcycle will be charged while driving, and this battery basically has no chance of over-discharging. And lithium iron phosphate batteries are really much safer, over-discharge or over-charge, or even leaking, in many cases nothing will happen. But as a perfection, BMS is really far from it.

It can be explained by this matter: if it is only a cost issue, the army will not consider it. The space for weapons such as tanks can be said to be an inch of land, and the lithium battery is so small, so why not replace the lithium battery? It must be that the technology and performance are not up to the requirements!

Why did the starter lithium battery not replace the lead-acid battery?

There are still many difficulties in starting lithium batteries for large-scale use, and its popularity is not an overnight thing. As a practitioner, I think starter lithium batteries can be used in some fields, which can solve the pain points in the past. Such as agricultural machinery and generators, these products do not need battery life, pure start, and they have a long idle time. If you use lead-acid batteries, forgetting maintenance may damage the batteries. When you really need to use them, you find that they are broken. Lithium batteries There is no such problem. However, the research and development and testing of lithium batteries are calculated on a year-by-year basis, and no results can be produced in three or five years. How many manufacturers can withstand such a long period of suffering?