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lorenzo-accaroli asked

Specific gravity VS CCGX voltage readings

Hi everyone, actually I have a TAB battery floaded lead acid battery (48V 24cells 775Ah(C5)). The fact is that... It's a couple of days that I check Sg of the cells in late afternoon when MPPTs chargers are in foat or even off status. Today I read 55V on CCGX but sg give is 1.25. My battery dealer told me some weeks ago that to have the voltage i have to add 0.84 to sg readings, so today 1.25+0,84= 2.09 V/cell, that gives 2,09x24=50,16V... 5V less than the reading on CCGX! why does it happens? I don't have BMV nor shunt. Inverter is off.

48v battery
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Alexandra answered ·

@Lorenzo Cavallo

Specific gravity readings can be affected by several factors like temperature and age. At some point in your maintenance you would have to draw off some of the fluid and replace it.

So as your batteries age and cycle, with sulphation the SG would not be as accurate.

If in doubt check with a good multimeter. Check your battery voltage and then the voltage at the mppt terminals.

The mppts are usually pretty decent with their voltage readings if they have been connected properly. At least I have had no issues

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