Reduce automotive electrical faults with precision battery detection and sensing technology

One out of every five car failures is caused by batteries. In the next few years, this problem will become more and more serious with the popularity of telex, the launch/extinguish engine management and the hybridization of hybrid (electric/gas) technologies.

In order to reduce the fault, it is necessary to accurately detect the voltage, current and temperature of the battery, pre-process the result, calculate the state of charge and the operating state, send the result to the engine control unit (ECU), and control the charging function.

Hyundai was born in the early 20th century. The first car relied on manual starting, which required a lot of power and was at high risk. The car's "hand crank" caused many fatalities. In 1902, the first battery starter motor was successfully developed. By 1920, all cars had been electrically activated.

The dry battery was originally used and must be replaced when the power is exhausted. Soon after, the liquid battery (the old lead-acid battery) replaced the dry battery. The advantage of a lead-acid battery is that it can be charged while the engine is running.

In the last century, there was almost no change in lead-acid batteries, and the last major improvement was to seal them. What really changed was the need for it. Initially, the battery was only used to start the car, honk the horn and power the lights. Today, all electrical systems of a car are powered by it before ignition.

The proliferation of new electronic devices is more than just consumer electronics such as GPS and DVD players. Today, body electronics such as engine control units (ECUs), power windows and power seats are standard on many basic models. Index

The increased load at the level has had a serious impact, as evidenced by the increasing number of failures caused by electrical systems. According to ADAC and RAC statistics, almost 36% of all car failures are attributable to electrical faults. If this number is analyzed, it can be found that more than 50% of the faults are caused by this component of the lead-acid battery.

Assess the health of the battery

The following two key characteristics can reflect the health of lead-acid batteries:

(1) State of charge (SoC): The SoC indicates how much charge the battery can provide, expressed as a percentage of the battery's rated capacity (ie, the SoC of the new battery).

(2) Operating status (SoH): SoH indicates how much charge the battery can store.

charging

The state of charge indication is like the "fuel gauge" of the battery. There are many ways to calculate SoC, two of which are most commonly used: open circuit voltage measurement and coulomb measurement (also known as coulomb counting).

(1) Open circuit voltage (VOC) measurement method: There is a linear relationship between the open circuit voltage and its state of charge when the battery is unloaded. There are two basic limitations to this calculation: first, in order to calculate the SoC, the battery must be open and not connected to the load; second, the measurement is accurate only after a fairly long period of stability.

These limitations make the VOC method unsuitable for online computing SoCs. This method is usually used in an automobile repair shop where the battery is removed and a voltage meter can be used to measure the voltage between the positive and negative terminals of the battery.

(2) Coulomb assay: This method uses the coulomb count to obtain the integral of the current versus time to determine the SoC. With this method, the SoC can be calculated in real time even if the battery is under load. However, the error of the coulomb assay increases over time.

Generally, the open circuit voltage and the coulomb counting method are used to calculate the state of charge of the battery.