Hello all
I have a question relating to xhp150 battery pack, two of batteries in series have failed, and we have to replace them in pack. We need a protocoles of how to change these faulty batteries and repair battery pack?

 

It's not clear what you are looking for - an electrician / engineer would isolate then separate the batteries for replacement. Since there may be high voltages involved (over 50vDC) then your industry / client may require an approved Method Statement or similar to ensure the work is undertaken correctly and safely.

If they are old then you are recommended to replace all cells in the pack. If they are not old then I'd want to know reason for failure - your supplier should be able to help.

eg: https://www.everexceed.com/xhp-sintered-plate-range-nicd-battery_p88.html

 

Hello all
I have a question relating to xhp150 battery pack, two of batteries in series have failed, and we have to replace them in pack. We need a protocoles of how to change these faulty batteries and repair battery pack?

https://everexceed.en.made-in-china...Light-Power-Backup-Power-Station-Battery.html

 

Hey Sara,

Failed as in? What tests have you done to declare that they have failed? The Voltage has dropped to '0' or lesser than the other cells? How less? Is there any observable or pinhole type leakage from the cells ?

As a general rule of thumb, a battery string that has had or is ready to have 20% or more of the cells compromised should be considered for full replacement (see IEEE 450).

There are few parameters that should must be kept same while evaluation of battery replacement in the existing battery bank e.g. Same AH capacity, Same Internal Resistance, Same Cell Voltage, Same Charging or discharging rate etc.

• New cells placed into an older string will age faster, due to the higher float current draw and the float voltage variations in the string.
• Mixing different age cells in a string typically is not recommended as it compromises the whole string and requires closer string monitoring through the end of string life and potentially more equalization or single cell charging.

Our Experience:
During shutdown of one of our Gas turbines(It has a battery bank of 60 cells (4 cells per battery) installed as a means of Field flashing and Emergency Lube oil pump staring) as part of PM of its battery bank, a load test was carried out during which the battery charger was turned off and after 40 hours approximately, the overall voltage of the batteries dropped from 130V to 115V. At this point, a load bank was connected to the batteries. The test was performed for approximately 35 minutes. By the end of this time, 4 of the cell’s voltages had dropped even to 0V.

Out of 60 cells (15 batteries, 4 cells/battery), 4 cells were compromised as given below.

Battery	Cell No.	Voltage
8	2	0 V
15	2	0.6 V
9	3	0 V
9	4	0.6 V

After connecting the charger back and charging the battery bank, the voltages of these faulty cells returned to the normal values (2.000 V) and no significant voltage drop was seen afterwards. Another load test was performed to test the batteries. The emergency lube oil motor, 88QE is a DC motor which is used to safely shutdown the gas turbine in case of AC lube oil motor failure or a blackout. 88QE was started manually and the voltages across the battery cells were noted.

After consulting with OEM (SAFT) and referring to different case studies of battery banks failure, the major contributory factor came out was of aging. The life of battery bank specified by Manufacturer was 10 years but some of the cells. as specified, failed early because of different factors. The limiting factor in flooded batteries is usually the deterioration of the positive plates over the lifetime of the battery. It could be due to sulfation, grid failure, positive plate growth as it absorbs electrolyte, or some combination of such. These factors can be affected by, temperature, float voltage, storage length (duration of time the batteries were left open circuit), number of cycles, etc.

Regards,
Mutahir