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Greetings,
I tested 2 Golf cart batteries (230 AH). The batteries are 3 years old. Were used for 2 months during an emergency. On a solar system with an amp counter meter. Where never were exposed to DOD of 20% during that time. After the 2 months they were connected to a RV converter (13.4 VDC 20 amps max) 24/7. The converter is working fine (good brand). Regular maintenance was performed (distilled water and hydrometer checks). They test fine (voltage & hydrometer). After the 2 months were used 4 or 5 times to a DOD of no more than 30%.
Because I’m currently learning about electronics, and would like to learn about power supplies, I bought a programmable DC load to test power supplies. I has a battery test function. Performed the test one a time. Disconnected the batteries from the RV converter and let them rest for 12 hours. Rest voltages were 6.481 & 6.471. Because I was expecting that the batteries were in a good condition, I performed a 5 hours tests on the first battery. The specs for the batteries for 5 hours are 174 amps. So, I calculated that the amps for the test should be (174/5) 34.8. Programed the DC load to stop the test at 5.25 (is a 6v battery, the equivalent of 10.5v in a 12v battery). The battery only provided 13.1591 ah. Only 7.5% of 174 ah.
Because of that decided to perform a 20-hour test on the second. The battery is rated 230 ah at 20 hours. So, I calculated that the proper current should be (230/20) 11.5 amps. When the test ended the battery provided 50.7910 ah. That’s only 22% of 230 ah. I know that, because were I live, temps average 85F, the battery life would be cut to half. But was kinda surprised that the batteries tested that low.
I first though that my mistake was ending at 5.25v (10.5 for 12v) under load. If I let the battery rest for a couple of minutes, I can get 1 or 2 additional ah before reaching 5.25 again. But discharging the battery to 5.25 open circuit voltage does not makes sense, because in real life inverters stop working around 5.25 (10.5@12, 21@24 & 42@48).
If I performed the test correctly that means that these batteries are dead in only 3 years. Doing mostly nothing while kept charged and maintained (distilled water at proper level). Wow.
I tested 2 Golf cart batteries (230 AH). The batteries are 3 years old. Were used for 2 months during an emergency. On a solar system with an amp counter meter. Where never were exposed to DOD of 20% during that time. After the 2 months they were connected to a RV converter (13.4 VDC 20 amps max) 24/7. The converter is working fine (good brand). Regular maintenance was performed (distilled water and hydrometer checks). They test fine (voltage & hydrometer). After the 2 months were used 4 or 5 times to a DOD of no more than 30%.
Because I’m currently learning about electronics, and would like to learn about power supplies, I bought a programmable DC load to test power supplies. I has a battery test function. Performed the test one a time. Disconnected the batteries from the RV converter and let them rest for 12 hours. Rest voltages were 6.481 & 6.471. Because I was expecting that the batteries were in a good condition, I performed a 5 hours tests on the first battery. The specs for the batteries for 5 hours are 174 amps. So, I calculated that the amps for the test should be (174/5) 34.8. Programed the DC load to stop the test at 5.25 (is a 6v battery, the equivalent of 10.5v in a 12v battery). The battery only provided 13.1591 ah. Only 7.5% of 174 ah.
Because of that decided to perform a 20-hour test on the second. The battery is rated 230 ah at 20 hours. So, I calculated that the proper current should be (230/20) 11.5 amps. When the test ended the battery provided 50.7910 ah. That’s only 22% of 230 ah. I know that, because were I live, temps average 85F, the battery life would be cut to half. But was kinda surprised that the batteries tested that low.
I first though that my mistake was ending at 5.25v (10.5 for 12v) under load. If I let the battery rest for a couple of minutes, I can get 1 or 2 additional ah before reaching 5.25 again. But discharging the battery to 5.25 open circuit voltage does not makes sense, because in real life inverters stop working around 5.25 (10.5@12, 21@24 & 42@48).
If I performed the test correctly that means that these batteries are dead in only 3 years. Doing mostly nothing while kept charged and maintained (distilled water at proper level). Wow.
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