How to test Ni-MH batteries and how to judge the quality of Ni-MH batteries?

The first step in the capacity test of Ni-MH batteries is to solve the test conditions of Ni-MH batteries, and the second step is to solve the test methods.

Nickel metal hydride battery capacity test is divided into two types: laboratory method and manual method. Laboratory methods of requirements is very strict, need special equipment, in addition, on the condition of preparation will strictly comply with the requirements of the IEC, such as temperature and humidity environment in battery choice, should see battery with phenolphthalein test to see if there is climbing alkali, leakage phenomenon, the anode cap around aglow phenomenon, if the sample is good battery before charging for the first time with 0.2 C discharge current to 1.0 V. And then to prepare the precision test equipment.

The next test is a key link in the specific surface area test. Specific surface area refers to the total area of unit mass material. On the testing methods, widely used at home and abroad BET adsorption theory for nickel metal hydride batteries BET specific surface area. Specific surface area measurement to use intelligent tester, ensure the consistency of the test result, then, on the basis of the specific surface area can use mathematical model to calculate the battery capacity.

Now have special battery testing equipment, which USES the BET adsorption theory, the device will automatically select the most appropriate voltage and current, and by a full charge and discharge model, based on discharge process data to calculate the real capacity of the battery, battery detector at the end of the battery test automation will be the important parameters, including battery capacity, shown on the instrument.

A, rechargeable battery

1, the charge rate (C - rate)

C is the Capacity of the first letter, used to represent the size of the battery charge and discharge current values.

Rechargeable batteries, for example, the rated capacity is 1100 MAH, namely, said in a 1100 MAH sustainable for 1 hour, 1 C discharge time, such as 200 ma (0.2 C) discharge time sustainable 5 hours, charging can also be calculated at the controls.

2, termination voltage (Cut – off discharge voltage)

The point at which the battery discharge, the voltage drop to the battery should not continue to discharge the minimum operating voltage value.

According to the different cell types and different discharge conditions, the requirement of the capacity and life of battery is different also, so regulation of the termination of the battery discharge voltage is not the same.

Teach you how to use the multimeter to judge the stand or fall of rechargeable batteries

3, open circuit voltage (Open circuit voltage OCV)

Battery discharge, known as the open circuit voltage potential difference between the poles.

Open circuit voltage of battery, will be in accordance with the positive and negative battery electrolyte materials and, if the battery positive and negative materials are exactly the same, so no matter how big is the volume of the battery, the geometric structure, the open circuit voltage are the same.

4, the depth of discharge (Depth of discharge DOD)

In the process of the battery, the battery emits the percentage of the capacity of its rated capacity, called the depth of discharge.

Discharge the discretion of the depth and secondary battery charge life has a deep relationship, the deeper the depth of discharge when the secondary battery, the charging life is short, so when use should try to avoid deep discharge.

5, over discharge (Over discharge)

If batteries are in the process of discharge, more than the battery discharging termination voltage value, continue to discharge, he may be the cause of the battery internal pressure increases, positive and negative active material of reversible damage, reduce battery capacity of the.

6, charging, Overcharge

Battery charging, in after reaching full state, if continue to charge, may cause the battery internal pressure rise, battery case, such as deformation, midnight battery performance will be significantly reduced and damage.

Teach you how to use the multimeter to judge the stand or fall of rechargeable batteries

7, the energy density (Energy density)

Cells release by average per unit volume or the quality of electric energy.

General under the same volume, Lithium ion batteries Energy density is 2.5 times that of the nickel cadmium battery is 1.8 times of nimh batteries, so under the condition of the battery capacity is equal, lithium ion batteries will be smaller than the volume of nickel cadmium, nickel metal hydride batteries, lighter in weight.

8, self discharge (Self discharge)

Battery used or in any conditions, due to various reasons, causes the power loss phenomenon.

If in a month to calculate, lithium ion battery self discharge is about 1% - 2%, nickel metal hydride battery self discharge about 3% - 5%.

9, charging cycle life (Cycle life)

Rechargeable batteries used in repeated charge and discharge, the capacity of battery capacity gradually decreases back to the initial 60% to 80%.

10, memory effect (Memory effect)

In the battery charge and discharge process, can produce many small bubbles on the battery plate, a long period of time, the bubbles will reduce the area of the battery plate, also indirectly affect the capacity of the battery.

The page contains the contents of the machine translation.