What we tested

We tested standard batteries bought in the shop. We used only new, sealed package. The purpose was to compare the price with the quality. Our financial sources are limited so we can only test limited amount of batteries. Shall you need any other battery, just send us this battery and we will test it. Battery must be new and sealed in order to be fair to other marks. If send us a battery in the letter and we can not guarantee, that it was new, we make a note. If you do not like the tests of any our battery, just send us new one and we will re-test.

We asked some manufacturers to send us the samples to test. Many of them either did not answer or refused to send the batteries. We understand, that they feel how weak their batteries are in comparison with the others so that do not want to be tested.

We intend to test any type of batteries and accumulators, but we might need to have some special device. For example car accumulator needs to test apart of capacity also starting peak current which might go up to 600 Amperes. Testing such a current needs special device, so we must adjust all our equipment to these requirements.

How we tested

We used special device to test the batteries. Our device can make and record 4 tests per second. We record Voltage and Current at the same time and calculate the Power (VA), Capacity (Ah) and Energy (Wh).
The accuracy of the meter is 1% plus small additional measurement error given by the system. Moreover, there is significant decimal error, because the device measures only for 2 decimal places. That is why, the lower Voltage and Current we measure, the lower accuracy of measurement we got. Especially for very low currents (10-20mA) was the accuracy very low, but such a small currents did influence the whole measurement by more than 5%. To avoid any litigations, we declare the accuracy of the measurement on ±20%.
We found the significant problem to measure 9V batteries, where maximum discharging current is under 10mA. We had to set a special measurement chain from precise multi-meters to reach require preciseness. Moreover, the capacity of those batteries is time limited (couple of minutes) and battery need to refresh. That is why our measurement was cut to many short measurements.

Each battery was manufactured for special purpose. It is not the same use AA battery in digital camera or in wall clock. The difference is in the load (discharge Current). Some batteries are constructed to high current (lithium, alkaline) – they keep reasonable voltage to about 90% of their capacity. The others are constructed for slow discharge and their voltage goes down rapidly. This is why in certain cases we tested batteries with 2 different loads. The results with different loads (discharging currents) might be different.

The another question is to state, when battery is discharged. Which is the minimum Voltage, which is accepted by device. To be clear, we introduced 2 terms. Effective capacity and Total capacity. We define Effective capacity of battery as the capacity over certain effective Voltage of battery. For the measurement purposes we stated effective Voltage 0,8V (but it might be changed). Under this Voltage the device might not work, so you can not use the rest of capacity. Total Capacity of battery is measured, until Voltage decrease under 10% of effective voltage..

Discharge current

Each battery is constructed to certain Discharge current. That is why we tested the batteries in many cases with 2 discharge currents. The value of discharge current is only tentative and it dependes also on the Voltage of the battery and internal characteristics of the battery.

To measure Discharge currents we used 2 methods. Measurement with permanent resistance and measurement with permanent current. In case of permanent resistance we used standard resistors 2W or 5W. For the permanent discharge current we used small bulb. This bulb had the discharge current about 220mV in 1,2V. The lower Voltage gave the battery, this higher resistance of the bulb, which gave on very long characteristics very flat discharge Current. This is the characteristic feature of many devices.