To replace a battery with a short circuit, the diagnostics of which is described in this article on the Auto without a service station website, a new battery was purchased. The choice fell on FORSE 6ST-60A2N. It was the cheapest one at the local auto shop, with the correct polarity and declared capacity. Before installation on the car, a simple check of the new battery was performed. The result was not pleasing. Pay attention to the indicator - it is green, and it looks promising.
The task of testing a new battery is to evaluate whether the actual capacity matches the declared one. Since it's an inexpensive model, I didn't expect much from it. But even taking this into account, I was in for a strong disappointment. In fact, a completely new battery turned out to be almost unsuitable for use in a car.
I did everything according to the following plan:
- Checking the voltage at the battery terminals.
- Charging the battery.
- Measuring battery capacity.
- Checking the battery release date.
Note. To measure the voltage at the battery terminals and charge it, I used a device based on the RIDEN RD6006P module. The actual capacity was measured with a device already proven in practice based on the ATORCH DL24 module. Both modules are built into a homemade charge-discharge device. Before this, the device was tested several times on other batteries, and showed excellent results.
Checking the voltage at the battery terminals
Based on the voltage at the battery terminals without load, you can preliminary estimate the degree of charge. You can find how this is done in the article about charging calcium batteries in a car without a service station. It is best to use a multimeter or similar device to measure voltage.
I did not use a multimeter, since my homemade device has this function. I am not afraid to call the measurement accuracy precision. You can see the result in the photo below in the line labeled V-BAT. The device showed 12.65 volts, which, frankly, pleased me. This means that the battery is approximately 95% charged.
Note. Never buy a new battery with low terminal voltage. This indicates that it is either defective or has stood on the store shelf for too long without the attention of the seller. I have already discussed how to choose batteries wisely in this article.
Charging the battery
After measuring the voltage at the terminals, I always recommend charging a new battery. Do this regardless of what the multimeter shows. You will see this later. Read more about this in the article “Do I need to charge a new battery” on the Auto without a service station website.
I will charge this battery to a voltage of 14.4 V with a current of only 2 A. I will explain why not 6 A. It is recommended to charge lead-acid batteries of this type with a current that corresponds to 10% of the capacity. However, I don't yet know what the capacity of this battery is. And I don’t trust the inscriptions on labels for a long time. As it turned out later, this is exactly the case.
But this is the point, and I will not tire of repeating this in my works. Let's say you have an old battery with a declared capacity of 60 amp-hours (written on the label). In theory, it can be charged with a current of 6 A (10% of capacity). But the actual capacity of an old battery is always lower than declared. Sometimes 1.5-2 times. As a result, when you start from the inscription on the label, you charge your battery with a current exceeding that same 10%.
The photos below show the key points for charging a new battery.
The charge was stopped when, at a voltage of 14.4 V, the current dropped to 0.18 A, and did not decrease any further.
Measuring battery capacity
I will also check the capacity of the new battery with a small current. Only 2 A. In theory, the lower the charge current, the greater the capacity of any battery. I will discharge to a voltage of 10.5 V. You can see the initial settings of the device in the photo below. Here I deliberately violated one of the rules for measuring capacity - I did not allow the battery to settle after charging. Therefore, in the first minutes of the discharge the voltage was somewhat too high. But this does not significantly affect the result.
And the result is in front of you.
Sadly, the capacity of the new battery turned out to be only 42.7 ampere-hours. This is with the stated 60 Ah on the label.
This result immediately made me think that the purchased battery was very old and had been sitting in the store for a long time. Therefore, I proceeded to the next stage.
Checking the battery release date
Finding out the release date of this battery was not so easy. Batteries with this name are produced by several manufacturers, and they all encrypt the release date differently in a set of numbers on the case. I identified the manufacturer based on external features. I found a decoding code for this particular manufacturer on the Internet.
The following was stamped on the body.
It turned out that at the time of purchase the battery was only 3 months old. This is not bad at all. It would not be able to degrade from 60 A*h to 42 A*h in such a short time even in the most unfavorable conditions.
Note. There is no point in checking this instance with a load fork. But it is useful to know about this method of testing a new battery.
I consider measuring the battery capacity the most reliable method of assessing compliance with the declared parameters. As you can see, in this case the purchase was disappointing.
To finally make sure that the battery you bought is bad, you can check it with a load fork, measure (hydrometer vs refractometer) the density of the electrolyte and weigh it. By the way, I did not weigh this battery. But I moved quite a few of them, and from experience without scales I can understand that the manufacturer underweighted the lead in this battery.