jviss, yes, they are six 2.7(+ or-) volts wired in series with thick plates. Together, the batteries weight about 250 lbs. I like them, and I am shocked that I am having this trouble with them. The Canadian product is manufactured by Surrette batteries.
- How were these batteries commissioned?
- Were the cells confirmed to all be at the identical SOC before wiring them in series?
- What is your charge current as a % of Ah capacity?
- What is your absorption charge voltage?
- What is your float voltage?
- What is your absorption duration?
- Are you using temp compensated charge sources?
Rolls batteries in a PSOC application can be charged as high as 15.0V however they will consume more water at these voltages and if any cell imbalances are present some cells will be getting over-charged while others are getting under-charged.
If the cells were not properly commissioned it is very possible that one or more cells are being under charged/less water use while the others are being fed considerably higher voltages and consuming more water. Cell imbalances are a very common problem in series strings, especially in PSOC use with infrequent EQ's.. For example:
Resting Voltage - Total Bank Voltage Measures 12.56V
Cell #1 2.13V
Cell #2 2.09V
Cell #3 2.12V
Cell #4 1.96V
Cell #5 2.13V
Cell #6 2.13V
Charging Voltage - Charger See's 14.6V
Cell #1 2.47V @ 12V = 14.82V - High Water Use
Cell #2 2.43V @ 12V = 14.58V - Minimal Water Use
Cell #3 2.46V @ 12V = 14.76V - High Water Use
Cell #4 2.30V @ 12V = 13.80V - Under Charged/Minimal to No Water Use
Cell #5 2.47V @ 12V = 14.82V - High Water Use
Cell #6 2.47V @ 12V = 14.82V - High Water Use
Any time 2V or even 6V batteries, like your L-16's are installed they should ideally be parallel balanced or equalized then checked regularly for cell voltage or SG imbalances. The topic of series string imbalances is finally becoming more recognized, but it has been an issue for a long while. To commission series batteries, via parallel balancing, you would need a charger that can charge at 6V. For Rolls batteries I prefer to wire the 2V or 6V cells in parallel then charge at 2.4V per cell and allow current to decline to about 1% of Ah capacity. I then boost voltage to 2.58V until SG stops rising or all cells read the same SG. They are then un-wired from parallel and allowed to rest for two to three days and SG and open circuit voltages are checked again.
Unfortunately these commissioning procedures are rarely employed and we see destroyed banks due to cell imbalances, infrequent EQ's and too high or to low of a charge voltage due to these imbalances. Rolls, due to plate thickness, recommends a charge current of 10% of Ah capacity or .1C, though they now, as of 2016, allow up to .2C, where other flooded brands can be charged as hard as 25% - 30% of Ah capacity.