I would do an equalizing charge and test the batteries individually. 100 AH at the 20 hour rate is like a constant 5 amperes for the whole 20 hours.

You can build a disconnect circuit that would disconnect the load when the battery reaches the low cell limit, and stop a counter that would display the elapsed time.

what I did was test the battery on another inverter and they didn't drop so rapidly like the other one..though not the same specs of inverter

 

Re post #20 You will not solve the problem by just talking about it. You need to do some measurments. You have been told wat to do to see if the inverter is drawing too much current with no load. You have just said (If I am undersatnding you correctly.) thet the % state of charge indicator goes from 60% to 100% within 10 minutes. You need to repeat this test while monitoring the charge current and battery voltage at say 1 minute intervals. It would also help if you gave more "big picture" information. Such as what is the application of this setup. Is the battery charging circuit part of what you are calling the inverter ? Are the batteries charged individualy from a 12 volt charger or are they charged in series from a 48 volt charger ? The more information you provide the more chance you have of getting a solution. The way you started your question by basicly saying I have something that is not working as I expect it to. What is wrong with it. Did you expect an answer like "change Q 14" that will solve the problem. The only fact you gave was that it was an inverter which may have been a few mW for a backlight on an LCD dispaly or it could have been a few megawatts supplying a factory.

Les.

 

what I did was test the battery on another inverter and they didn't drop so rapidly like the other one..though not the same specs of inverter

If you have a battery in a series of batteries that is defective, it will be detrimental to the whole string when charging and discharging.

Just because it lasted longer in another inverter doesn't mean anything. What was the load on that inverter as compared to the other one.

Do an equalizing charge on each individual battery. Then discharge the battery at the specified 20 hour rate while monitoring the battery voltage. Use a resistive load.

A bad battery will discharge to the low cell limit faster. If your charging with a constant current source, the defective battery will reach the specified voltage faster. Charge at the 0.1C level.

Search for battery University and become familiar with battery maintenance.

 

Ok..finally I finished monitoring and testing..it happened that the charging current was fluctuating seriously (10A-13A-5A-0A-9A-2A-16A) and also the lcd cicuitry was faulty.. worked on all that and the system is working perfectly..thank you all for your contribution

 

What could possibly be the problem?

you have to make sure all the battery in the battery bank are good, check each one for ''self discharge'' then change any one with fault, and your system will be okey, if your load/battery consumption calculation was done well.