Hi all,
I did a series of 10 succesive internal resistance measurements on three AAA NiMH batteries (two unknown brand and one Maha Imedion 800 mAh), all aged several years.
I first used my Opus BT-C2000 charger using the "Quick test" function. Batteries were left untouched in the charger, which I simply disconnected from mains between two measurements.
Here are the values I got (mOhm) :
Batt1: 849 / 895 / 906 / 939 / 904 / 88 (!) / 1044 / 1183 / 646
Batt2: 288 / 312 / 375 / 469 / 451 / 414 / 404 / 373 / 376 / 334
Batt3: 804 / 1016 / 1072 / 924 / 914 / 916 / 898 / 995 / 952 / 870
Even though I'm aware that IR measurements cannot be very accurate this way (from HKJ's remarks in his tests, and from a warning in the Opus manual), I'm suprised to see such a variation whereas I have not even removed the batteries from the charger between successive measurements.
Then I measured the same batteries with my Opus BT-C100. This time, the battery was put in the bottom of the battery compartment, and the negative contact was slid away from the battery between two successive measurements, in order to interrupt the contact. Resuts were:
Batt1: 777 / 1166 / 2166 / 973 / 1528 / 912
Batt2: 963 / 708 / 483 / 440 / 729 / 569
Batt3: 957 / 970 / 838 / 895 / 967 / 1224
Hence even worse discrepancies than with the BT-C2000.
I know such high values mean my batteries are no longer in good condition (except maybe Batt2 for low current uses), but I wonder how come I get so different results for the same battery.
Measuring a brand new Sony VTC6 18650 with my BT-C100, I get much more consistent values, like HKJ did in his test of this charger.
On the other hand, I have a Fluke DMM, can I use its ohmmeter function to test the internal resistance of batteries?
I did a series of 10 succesive internal resistance measurements on three AAA NiMH batteries (two unknown brand and one Maha Imedion 800 mAh), all aged several years.
I first used my Opus BT-C2000 charger using the "Quick test" function. Batteries were left untouched in the charger, which I simply disconnected from mains between two measurements.
Here are the values I got (mOhm) :
Batt1: 849 / 895 / 906 / 939 / 904 / 88 (!) / 1044 / 1183 / 646
Batt2: 288 / 312 / 375 / 469 / 451 / 414 / 404 / 373 / 376 / 334
Batt3: 804 / 1016 / 1072 / 924 / 914 / 916 / 898 / 995 / 952 / 870
Even though I'm aware that IR measurements cannot be very accurate this way (from HKJ's remarks in his tests, and from a warning in the Opus manual), I'm suprised to see such a variation whereas I have not even removed the batteries from the charger between successive measurements.
Then I measured the same batteries with my Opus BT-C100. This time, the battery was put in the bottom of the battery compartment, and the negative contact was slid away from the battery between two successive measurements, in order to interrupt the contact. Resuts were:
Batt1: 777 / 1166 / 2166 / 973 / 1528 / 912
Batt2: 963 / 708 / 483 / 440 / 729 / 569
Batt3: 957 / 970 / 838 / 895 / 967 / 1224
Hence even worse discrepancies than with the BT-C2000.
I know such high values mean my batteries are no longer in good condition (except maybe Batt2 for low current uses), but I wonder how come I get so different results for the same battery.
Measuring a brand new Sony VTC6 18650 with my BT-C100, I get much more consistent values, like HKJ did in his test of this charger.
On the other hand, I have a Fluke DMM, can I use its ohmmeter function to test the internal resistance of batteries?