My time is nearly up, so I need to put all our data in summary form. The following numbers refer to an actual operating population estimated at well over 600,000 cells and monoblocks.
We can summarize the capacity performance of 2V cells. You can interpret the “fail” as delivering capacity less than 80%, but note that the statistic is really opportunistic, and I don’t claim it to be a measure of the entire population.
For the pre-94 Group, the general outcome for AGM batteries was about 6 years, although there is one type expected to work into the next century. Many of the types of AGM batteries were subject to specific batch or design problems (leaks, deformed cases, etc) which inflates the “fail” figure, and most of the pre-94 AGM cells have been or are being replaced.
For gels, there are 7 year gel cells still operating which are expected to last a few more years.
For the post-94 group, the AGM cells expected and have given about 6 years, although 8-10+ years is expected for some types of batteries operating in controlled environments. Note that there were no gel cells in the post-94 group.
The experience is that is that the service-life of VRLA cells in the field has improved.
