Battery Discharging Problem

[Zameer]

I have 48 volt 600Ah (2×24=48 volt) battery bank, my hybird inverter set discharging limit at 42 volt after that when I check each 2 volt cell shows equal discharge voltage 1.8 but instead of one, it shows 0.9 voltage, now what can i do any one help me please.

[SunEagle]

To be clear about what you are saying is that you have a 48 volt system which is comprised of 2 x 24volt 12 cell batteries. The lower limit is set at 42 volts which should get you a ~ 21volts per battery or 1.75v per cell.

But you have measured and you get 1.8 volts on all but one where you get only 0.9 volts?

If that is correct I would say it is possible your volt meter may not be calibrated or the hybrid inverter is not working properly or that cell with the lower voltage is being stressed more than the other 11 cells or something completely different.

[Zameer]

I have 24 cell connected in series, this hybird system working best last 5 months but in this month when I feel that my battery storage reduced backup then I check this result ( every cell shows 1.8 volt except one it shows 0.9 volt ).

[Sunking]

It means your batteries are toast because they have not been charged up.

[SunEagle]

I have 24 cell connected in series, this hybird system working best last 5 months but in this month when I feel that my battery storage reduced backup then I check this result ( every cell shows 1.8 volt except one it shows 0.9 volt ).

It sounds like the inverter let the battery system get below a safe level at 42 volts and one cell went way too low at 0.9 volts. Since that cell is now "bad" the entire battery is probably no good.

You might be able to get a little more life out of your "system" but IMO I would replace it and change the charger to not go down to 42 volts but maybe something like 46 volts so each cell does not drop below 1.9 volts.

[Zameer]

It sounds like the inverter let the battery system get below a safe level at 42 volts and one cell went way too low at 0.9 volts. Since that cell is now "bad" the entire battery is probably no good.

You might be able to get a little more life out of your "system" but IMO I would replace it and change the charger to not go down to 42 volts but maybe something like 46 volts so each cell does not drop below 1.9 volts.

I don't understand, please to be clear what are you saying.

[SunEagle]

From what I have heard and read letting a battery voltage go too low can damage one or all of the cells. IMO letting the inverter set the voltage at 42v for a 48v system allowed the cells to go too low. 21v or 1.75v per cell is pretty low for a 24v 12cell battery and 0.9v is certainly way too low which probably killed the entire battery.

To be safe you probably should never let the battery go below 1.9v per cell or 22.8volt for a 24v battery.

If your battery manufacturer says you can do that then maybe they just want to sell you more batteries.

[jflorey2]

I have 48 volt 600Ah (2×24=48 volt) battery bank, my hybird inverter set discharging limit at 42 volt after that when I check each 2 volt cell shows equal discharge voltage 1.8 but instead of one, it shows 0.9 voltage, now what can i do any one help me please.

Sounds like you will have to replace your battery bank. To avoid problems in the future, increase your LVD setting. The Outback GVFX series hybrid inverter does not allow discharge-to-grid below 48 volts to avoid this problem, but when off-grid it is allowed to go lower. (Depending on LVD)