BHPian Jeroen recently shared some thoughts on testing car batteries in general. This thread is about standard 12V car batteries. There are many different types of batteries on the market, not referring to capacity, but rather battery construction and the underlying chemical principle. Most car batteries in India are sealed lead-acid batteries. In luxury cars, you can find AGM (absorbent glass mat) batteries. If you have a regular lead-acid battery, you may need to regularly check its condition and top it up with distilled water.
The most obvious way to check the battery’s condition is by connecting a simple voltmeter. Make sure the ignition is off and secure anything that may draw power from the battery. After turning off the engine, wait for 10-15 minutes before conducting the test. If you have just started the car and turned it off again, it’s better to wait a little longer.
In the case of modern cars, measuring battery voltage can be challenging. Modern cars disable various systems for the first 30-60 minutes. Especially within the first 10-15 minutes, there can be significant battery load. (For more information, see my thread on parasitic drain.)
Regardless of the exact battery type, the fundamental principle is that a fully charged battery should display around 12.6 volts. A value below 12.0 volts may indicate battery degradation.
It is also important to ensure clean battery contacts when connecting the meter. It’s a good idea to apply a layer of white petroleum jelly on the battery terminals and connectors. This prevents corrosion and damage while also affecting the accuracy of measurements.
Other methods include testing the State of Charge (SOC) and State of Health (SOH) of the battery. SOC represents the difference between a charged battery and a battery in use, under a known amount of charge delivered. It is expressed as a percentage of the available charge in the battery relative to the maximum charge it can deliver. SOH describes the difference between the tested battery and a new one, taking into account cell aging. It is expressed as a percentage of the battery’s capacity relative to the nominal value.
In summary, SOC provides information about the battery’s charge compared to a new one, while SOH informs about the rate of battery discharge. The lower the SOH, the faster the battery’s capacity is depleted.
If you are interested, take a look at this article that explains these concepts in more detail.
If you follow my thread on automotive DIY, you surely remember that in the past year, I had a few battery-related issues. Sometimes, the fault lay with the battery itself, while other times I had to replace the alternator, and currently, my Jaguar has a slight parasitic drain. I always had to rely on other people’s assistance to check the condition of my batteries, apart from the obvious voltmeter measurements. Because of this, I came across various battery testers. It proved difficult to find detailed information about what makes a good battery tester. I will come back to this later.
Since I often purchase items from Chinese websites like AliExpress and Temu, I frequently see ads related to “tools” in my Facebook and other platforms’ feeds. I noticed a small battery tester on the Temu website. It had a discounted price, from 150 euros to 25 euros. I simply couldn’t resist such an opportunity, so I immediately used my credit card!
The delivered package arrived within 10 days.
As you can see, it’s a very basic box. The instructions seem more elaborate than they actually are because they include text in 35 different languages. So, don’t expect too many details.
In theory, using it is very straightforward. Similar to a voltmeter, make sure you connect it to clean metal parts of the battery and that the battery is not being powered by any devices. If the battery is in charging mode, disconnect it.
You need to check several pieces of information about your battery, such as the type and CCA (Cold Case Crank). CCA measures the battery’s ability to start the engine in cold conditions. It tells how many amps a 12-volt battery can deliver for 30 seconds at a temperature of -17.8 degrees Celsius before the voltage drops to at least 7.2 volts per cell.
With the decrease in atmospheric temperature, the battery provides less starting power. However, as the atmospheric temperature drops, the engine requires more energy to start!
Finding information about your battery type can be a challenge. None of the six batteries in our car fleet had the mentioned battery type. I had to search for information about each battery online.
FAQ section based on the main topics and information presented in the article:
1. How to check the condition of a car battery?
The most obvious way to check the battery’s condition is by connecting a simple voltmeter. Make sure the ignition is off and secure anything that may draw power from the battery. After turning off the engine, wait for 10-15 minutes before conducting the test.
2. How to measure battery voltage in modern cars?
In the case of modern cars, measuring battery voltage can be challenging because various systems are disabled for the first 30-60 minutes. It is recommended to wait longer before conducting the test.
3. What voltage values indicate a fully charged battery?
The exact battery type may vary, but the fundamental principle is that a fully charged battery should display around 12.6 volts. A value below 12.0 volts may indicate battery degradation.
4. What are SOC and SOH of a battery?
SOC (State of Charge) represents the difference between a charged battery and a battery in use, expressed as a percentage of the available charge relative to the maximum charge. SOH (State of Health) describes the difference between the tested battery and a new one, taking into account cell aging, expressed as a percentage of the battery’s capacity relative to the nominal value.
5. What are the methods of testing SOC and SOH of a battery?
SOC can be measured by comparing the battery’s charge to that of a new battery. SOH can be assessed by analyzing the rate of battery discharge. The lower the SOH, the faster the battery’s capacity is depleted.
6. How to use a battery tester?
Connect the tester to clean metal parts of the battery and make sure the battery is not powered by any devices. Disconnect the battery if it is in charging mode. Check the information about your battery, such as type and CCA (Cold Case Crank).
7. Where to find information about the battery type?
Information about the battery type needs to be found online as it is often not available on the car battery.
Useful links:
– Occupational Health and Safety
– AGM Batteries – Guide
– Dead Battery Syndrome – How Car Batteries Work
The source of the article is from the blog agogs.sk