Home Inverter Battery Holding High Voltage

T

timepass

Contributor
Home inverter battery setup was connected to mains supply as normal, & there was no power cut at all over the last 10++ days.
I randomly thought of checking the voltage on battery terminals, and surprisingly it turned out to be very high - 18.5 Volts.
I took it multiple times to be sure, & using 2 different voltmeters - at 7 AM, then at 7:30, then again at 8 AM. Each time it was showing 18.4 to 18.5 Volts when connected to mains supply which has been without any power cuts for last 10+ days.
AFAIK, the battery voltage (when charging) is at the most 14.5 to 15 volts, so the above reading got me thinking.

At 8:30 AM, I disconnected the inverter battery setup from the mains supply line, and took readings of battery voltage, including opening the tubular individual cells & their volt readings.
Here are the findings immediately after disconnect (8:30AM), and 3 hrs after disconnect (11:30 AM):
​

​
8:30 AM​
11:30 AM​
Total Voltage at Battery Terminals at the start of Check (Immediately Before opening cells)​
17.95​
15.6​
Cell1​
2.35+0.45=2.8​
2.1+0.6=2.7​
Cell2​
3.05​
2.74​
Cell3​
3.05​
2.3​
Cell4​
3.05​
2.8​
Cell5​
2.7​
2.7​
Cell6​
2.72​
2.72​
Total at Battery Terminals at the end of Check (Immediately after closing cells)​
16.22​
16.45​

Any inputs about:

A) Are such high voltages of 18V while connected to main supply, or of 16-17 V after disconnect, normal? Or is there a problem with battery?
B) If battery voltages appear normal, will inverter be a problem, or is there any issue to worry about?

Thanks
 
High battery voltage is typically a symptom of increased cell resistance.

I would suggest taking a reading of a AA cell to be sure your meter isn't the issue, then send the battery for inspection. Car battery vendors will offer a charging service, and they'll be able to tell you whether it's OK or not.

I also wouldn't use that battery anymore until its condition is verified.
 
timepass said:
Thanks.
Its NOT a "Car battery".
It is a home inverter battery. (Just to avoid any confusion).
Click to expand...
What he meant is car battery vendors almost always have high power charging systems available which can charge discharged inverter batteries from 0% charge.. Your inverter would not be able to do this for eg.
 
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Not normal. Mostly the battery need replacement. But as others mentioned, the charging guys will be able to confirm it. I had similar problem in the past, battery heating up, high voltage like this etc. Checked with an auto electrical guy and he confirmed that battery life is almost over.
 
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