What is a load plug and how can I test the battery with it?
Content
The value of the battery in the car can hardly be overestimated: it supplies the starter motor during engine start-up, as well as other electrical appliances, depending on the current operating mode. In order for the device to work for a long time and properly, it is advisable for the driver to monitor the state of the battery. A load plug is used to analyze the characteristics of the battery. It allows you not only to assess the charge level, but also the performance of the battery, simulating the start of the engine starter.
Description and working principle
A load plug is a device that is used to measure the charge in a battery. The charge is measured both under load and with an open circuit. This device can be easily found in any motorist store.
The idea behind the plug is that it puts a load on the battery to simulate starting the engine. That is, the battery operates in the same way as if it were supplying current to start the starter. The fact is that the battery can show a full charge, but not start the engine. A load fork can help figure out the cause. A simple model will be sufficient to test most batteries.
Testing is only necessary on a fully charged battery. The open circuit voltage is measured first. If the indicators correspond to 12,6V-12,7V and above, then measurements can be taken under load.
Defective batteries cannot withstand the load, although they may show a full charge. The load plug delivers a load that is twice the battery capacity. For example, the battery capacity is 60A * h, the load must correspond to 120A * h.
The state of charge of the battery can be assessed by the following indicators:
- 12,7V and more - the battery is fully charged;
- 12,6V - normal battery charge;
- 12,5V - satisfactory charge;
- below 12,5V - charging is required.
If, after connecting the load, the voltage begins to drop below 9V, this indicates serious problems with the battery.
Load fork device
The plug arrangement may differ depending on the model and options. But there are a few common elements:
- voltmeter (analog or digital);
- load resistor in the form of a spiral of resistance in the plug housing;
- one or two probes on the body (depending on the design);
- negative wire with crocodile clip.
In simple instruments, there are two probes on the plug body for measuring under load and open circuit voltage. An analog voltmeter is used, which shows the voltage with an arrow on the dial with divisions. More expensive models have an electronic voltmeter. In such devices, it is easier to read information and indicators are more accurate.
Different models of load forks have different characteristics and capabilities. They may differ in:
- measuring range of the voltmeter;
- measuring current strength;
- operating temperature;
- purpose (for acidic or alkaline).
Types of forks
In total, there are two types of battery load plugs:
- acidic;
- alkaline.
It is not recommended to use the same plug for testing different types of batteries. Alkaline and acidic batteries have different voltage ratings, so the load plug will show inaccurate readings.
What can you check?
Using the load plug, you can determine the following battery parameters (depending on the capabilities of a particular device):
- battery charge level;
- how long the battery retains its charge;
- identify the presence of closed plates;
- assess the condition of the battery and the degree of sulfation;
- battery life.
The load plug also allows you to measure the amperage in other electrical appliances. The main difference is the spiral of resistance. The resistance value of each coil is 0,1-0,2 ohms. One coil is rated for 100A. The number of coils must be suitable for the battery capacity. If less than 100A, then one is enough, if more - two.
Preparing the battery for testing with a load plug
Before testing, you need to perform a number of actions and meet the necessary conditions:
- Disconnect battery from vehicle electrical system. You can even test without removing the battery from the car.
- Before checking, at least 7-10 hours of battery idle time must pass. It is most convenient to take measurements in the morning, when the car has been parked overnight after the last trip.
- The ambient temperature and the temperature of the battery should be between 20-25 ° C. If the temperature is low, then bring the device into a warm room.
- The battery caps must be unscrewed before testing.
- Check the electrolyte level. Top up with distilled water if necessary.
- Clean battery terminals. The contacts must be dry and clean to avoid the occurrence of parasitic currents.
If all these conditions are met, then you can proceed to the check.
Testing the battery with a load plug
No load check
First, a no-load test is carried out to find out the battery condition and charge. That is, the measurement is made without resistance. The load spiral does not participate in the measurement.
The algorithm of actions is as follows:
- Unscrew one or two nuts to disconnect the drag coil. There can be two spirals.
- Connect the positive terminal to the positive circuit.
- Bring the negative probe to the negative terminal.
- Commit the result.
The charge level can be checked against the following table.
| Test result, V | 12,7-13,2 | 12,3-12,6 | 12,1-12,2 | 11,8-12 | 11,5-11,7 |
| Charge level | 100% | 75% | 50% | 25% | 0% |
Checking under load
Many drivers find stress testing damaging the battery. It's not like that at all. When all conditions are met, testing is completely safe for the battery.
If the battery showed 90% charge without load, then it is possible to carry out a test under load. To do this, you need to connect one or two resistance coils by tightening the corresponding bolts on the device body. The load coil can also be connected in another way, depending on the design features of the device. If the battery capacity is up to 100A * h, then one coil is enough, if more than XNUMXA * h, then both must be connected.
The algorithm of actions is as follows:
- The positive terminal from the device is connected to the positive terminal.
- Touch the minus probe to the minus terminal.
- Hold the contact for no more than five seconds, then disconnect the plug.
- View the result on a voltmeter.
Under load, the indicators will be different. The voltage on the voltmeter will sag and then should rise. An indicator of more than 9V is considered normal, but not lower. If the arrow drops below 9V during measurement, it means that the battery cannot withstand the load and its capacity drops sharply. Such a battery is already defective.
You can check the indicators according to the following table.
| Test result, V | 10 and more | 9,7 | 9 | 8,3-8,4 | 7,9 and less |
| Charge level | 100% | 75-80% | 50% | 25% | 0 |
The next check can be carried out only after 5-10 minutes. During this time, the battery must restore its original parameters. The resistance coil gets very hot during the measurement. Let it cool down. It is also not recommended to carry out frequent checks under load, as this puts a lot of stress on the battery.
There are many instruments on the market for measuring battery health. The simplest load plug Oreon HB-01 has a simple device and costs only about 600 rubles. This is usually sufficient. More expensive models like Oreon HB-3 have better performance, digital voltmeter and convenient control. The load plug allows you to get accurate data on the battery charge level, and most importantly, to know its performance under load. It is necessary to choose the right model of the device to obtain accurate indicators.
Questions and answers:
What voltage should be on the battery when testing with a load plug? A working battery without load should produce between 12.7 and 13.2 volts. If the plug shows a charge less than 12.6 V, then the battery needs to be charged or replaced.
How to check the battery charge correctly with the load plug? The positive probe of the plug (most often it is connected with a red wire) with the positive terminal of the battery. Accordingly, the negative (black wire) is connected to the negative terminal of the battery.
How to test a gel battery with a load plug? Testing a gel battery for cars is identical to testing any type of battery, including a serviceable lead acid battery.
How to determine the battery capacity? Battery capacity is measured by connecting a consumer and a voltmeter. The time it takes for the battery to discharge to 10.3 V is counted. Capacity = discharge time * per discharge current. The result is checked against the data on the battery sticker.
