roger
New Member
Posts: 2 
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Post by roger on May 22, 2016 4:43:41 GMT -8
Hi, looking for help with understanding the MT-5 Tracer Meter SOC % value; it does not seem to be correct.
System: 12Volt, 4-100 Watt Renogy panels, MPPT 40A Renogy controller, 2-110AH AGM (UB121100) in parallel, 1000W Renogy pure sine inverter.
The battery voltage is reading 12.7-12.8 volts but the SOC % is showing 50%. However, 12.1 volt should correspond to 50% SOC.
I am concerned the charge controller will send excessive current to the batteries if it thinks they are at an incorrect, low, SOC.
Thanks!
Roger
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Post by Admin on May 24, 2016 14:18:46 GMT -8
Hello Roger,
The SOC% is based on the battery voltage and is not the actual capacity of your battery bank. According to the controller a fully charged battery would be when you are in float which is 13.8 volts any other voltage will read less than 100% SOC. One thing you might notice is right before sunset the controller will display 100% and 13.8 volts but as soon as the sunsets the SOC will drop to 40-50%. This happens because the controller uses voltage the judge SOC%.
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Post by spiderbob on May 30, 2016 22:54:39 GMT -8
There are additional problems in using voltage to gauge SOC, anything on (using the battery power, even just one 12v reading lamp) will effect voltage and thereby giving you a false reading. To get a true reading you would have to let your batteries sit, disconnected for at least 6+ hours and preferably twenty four hours, and then get a reading. The batteries need to be rested, now we all know that does not happen, so the reading is an estimate or actually a guess of what you may have. A good battery monitor is an important investment to make if you want to get proper settings and maintenance. Additionally, a real battery monitor works by measuring the current flowing into and out of our battery via a very accurate shunt. They are not cheap, but either are good batteries.
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roger
New Member
Posts: 2
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Post by roger on Jun 5, 2016 4:50:11 GMT -8
Thanks to both Admin & Spiderbob. That helps me to understand this newly acquired technology.
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