Two key battery parameters influence reliable engine starting: capacity and starting current or cold starting current. Capacity shows how much electricity a battery can store, while cold crank flow indicates how confidently a frozen engine can be started in cold weather. This article explains how manufacturers verify these characteristics on the assembly line. Tests were performed using professional equipment in the Kursk Battery Plant test laboratory. During the battery assessment, the performance of the Midtronics portable tester cs EXP1000 was also evaluated.
We verify the capacity
Capacity appears as nominal and reserve on the battery label. Nominal is measured in Amp Hours Ah, while Reserve is expressed in minutes. The PROS battery used in our tests has a nominal capacity of 60 Ah.
Russian standards regulate battery tests and methods, specifically GOST R 53165 2020. The tested battery must be new, with no more than 45 days since release, and it must be fully charged prior to testing.
For nominal capacity, batteries are submerged in a water bath kept at 25 plus or minus 2 degrees Celsius.
Batteries during nominal capacity tests are immersed in the water bath.
The test procedure requires discharging the battery with a direct current of 3 A down to a voltage of 10.50 V, with the discharge time closely monitored. Actual capacity is calculated using the formula FROMf = t ln
Where FROMf is the actual capacity in Ah, t is the discharge time in hours, and ln is the natural logarithm value of the discharge current in amperes.
The charge-discharge standard for electrical testing shows a set discharge current of 3.00 A, a discharge duration of 020:48:47, a voltage during discharge of 10.53 V, and a termination voltage of 10.50 V. The tested battery discharged for 20 hours 49 minutes, yielding an actual capacity of 62.45 Ah, exceeding the stated capacity.
Determining the current
After establishing the actual capacity, the batteries were fully charged again and stored for 24 hours in a climate chamber at minus 18 plus or minus 1 degree Celsius before testing the cold start current. This test followed European standard EN50342-1.
When removing the battery from the climate chamber and checking the temperature indicator, a green light denoted the set temperature and a red light showed the actual temperature.
Testing of a cooled battery involved discharging for 10 seconds at the current specified on the product label. For PROS this value is 640 A, with the voltage not allowed to drop below 7.5 V. The measured final voltage was 7.74 V at an actual discharge current of 657 A, and this test was deemed successful.
Midtronics tester underestimated the current reading by reporting 501 A in Europe at minus 18 C. After a short pause of ten seconds, the discharge continued at 384 A to reach a final voltage of 6.0 V. The overall duration exceeded the required minimum of 90 seconds.
A current setting of minus 30 degrees was used for a further test to simulate operation in cold climates. The discharge current was set at 533 A.
The discharge current reached 533 A during that test and the battery passed. In another instance the Midtronics device read only 420 A, and a misread temperature occurred, showing plus 3 degrees instead of minus 30 degrees. These discrepancies illustrate how surface temperature measurements can affect cold start calculations.
Assessing strength
How well does the PROS battery case endure severe frost The Kursk Battery Plant uses a frost resistant, shock resistant propylene copolymer for the case that withstands impacts at minus 50 degrees Celsius. It was extremely cold in the testing area, and the monoblock housing was subjected to impact tests.
Impact testing for the monoblock followed the installation requirements of GOST R 51977. The battery case endured four side impacts without cracking.
Power Test completed a winter battery test sequence. All declared characteristics of a standard production battery were confirmed. The PROS battery can be installed in a car and is ready to start the engine in winter conditions.
The critical equipment
At room temperature, the tester indicated a current of 667 A in European standards.
Midtronics testers are devices equipped with an infrared sensor to determine the surface temperature of the battery and to adjust power calculations based on that temperature.
At room temperature the tester delivered readings closest to the true cold start current. In cold conditions, however, the device tended to underestimate readings. The battery tested showed a cold start current of 657 A at minus 18 C, while the device read lower values, with larger errors at minus 30 C. This discrepancy is likely related to surface temperature measurements and subsequent effects on the calculated cold crank current. A photo shows the electrolyte temperature at minus 30 C while the device indicates a surface temperature of only plus 3 C.
Practical results indicate that such devices work well indoors at typical room temperatures. In cold environments the internal algorithm recalculates the current and can give underestimated results. Outdoor use for winter tests with portable testers is not recommended. Serious battery testing should rely on professional equipment.
Note: this article summarizes tests conducted by the Kursk Battery Plant and references standard testing protocols with appropriate attributions.