TAB EFB 70Ah 700A Independent Battery Test
his battery is recommended for cars with start-stop system. TAB is battery factory from Slovenia in Europe. Parameters of this battery according to the label: Capacity 70Ah, Starting current 760 amps according to the EN standard.
The battery is in L3 housing and is also maintenance-free, which means that water can not be topped up.
I bought this battery in a regular store with the following parameters; Weight 19,220 grams, Voltage12.58, Estimated inrush current of 807 amps, soc 91%, soh 100% this parameter should be interpreted as a degree of efficiency, internal resistance 3.8 mil Ohm.
I charged this battery using the russian rectifier Kulon. I have set the following limits; Voltage limit is 16 volts, Maximum current is limited to 15 amps, Charging time is 24 hours
After recharging, the weight of the battery drops by 4 grams to 19 216 grams, and after a 3-day break the battery has the following electrical parameters; voltage 12.74 volts
rated inrush current 798 amps, soc 100%, soh 100%, internal resistance of 3.8 milli ohms.
Reserve capacity test.
The external temperature of the battery is 14 degrees Celsius. The battery is loaded with 25 amps until the terminal voltage reach 10.5 volts. The tester counts the discharge time,
takes into account temperatures, capacity and the peukert factor. The result of this discharge is a time expressed in minutes. In this test it is 120 minutes. Converting this result to ampere hours, we can estimate its capacity at 78Ah in the en c20 standard.
The battery has been discharged by 100% of its capacity and Now the battery must be charged in my standards; maximum voltage is limited to 16 volts, maximum current is limited to 15 amps, and time is limited to 24 hours.
After the second charging, the weight of the battery drops by another 2 grams to 19,214 grams. After another 3-day break, the battery has the following parameters: voltage 13.0 volts, rated inrush current 837 amps, soc 100%, soh 100%, internal resistance of 3.7 milli ohms.
The most interesting part of the test, which is freezing
I put the battery in this condition in the freezer for 24 hours. After 24 hours of freezing, the external temperature of the battery is minus 25 degrees Celsius and the electrical parameters are as follows: voltage 12.85 volts, estimated inrush current 416 amps, soc 100%, soh 72%, internal resistance 7.4 milli ohms.
Immediately after removing from the freezer, the battery loaded with a current of 25 amps can withstand such a load for only 1 minute but if we waiting 1 hour more, the discharge time to 10.5 volts is already 66 minutes, and converting it into amero hours, taking into account all factors, we will get a 52Ah capacity according to the EN C20 standard.
Some construction details
Grid Type: Positive made in technology Expandyd metala, Negative made in technology Concasted
Grid Alloy for (pos and neg) grid is Ca/Ca