By erratic charging....it would come on for a very short time, lights would get noticeably brighter, and when it went off the lights would dim. The battery would never charge to full, and was charging less and less..as measured by the 4 lights on my control station.
I have a separate battery charger that would always charge the battery back up where all 4 lights would lite.
As soon as I installed the PD converter the battery (Trojan) retained its full charge, and the lights have not dimmed since.
I also didn't mention all the troubleshooting I did with a volt meter in several different configurations before removing the 8955 converter...the key measurement was watching the converter trying to charge the battery (unsuccessfully).