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48 Volt Battery Backup The battery backup is designed to maintain a fully loaded xPM for a minimum of 20 minutes. It will shutdown when the voltage reaches 38 volts to prevent the power supply from going out of regulation and an alarm will be generated. Rechargeable batteries will lose their full charging capabilities over time and will need to be tested and replaced when they fall below 60 percent of their original capacity. The battery backup has been designed to operate in standby (float) service for approximately five years. The five years is based on the battery being kept at 20C (68F) and the float charge voltage being maintained between 2.25 and 2.30 volts per cell. This includes the battery being fully discharged once every three months. No battery should be left in service over five years, and if no maintenance is done it should be replaced every three years. The service life is directly affected by the number of discharges, the depth of discharge, ambient temperature, and the charging voltage. The expected service life can be shorted by 20% for each 10C that the ambient is above 20C. The batteries should never be left in a discharged state. This allows sulfating to occur which will increase the internal resistance of the battery and lower its capacity. The self-discharge rate is about 3% per month at an ambient of 20C. The self discharge rate doubles for each 10C in ambient above 20C. The discharged voltage of the battery should never go below 1.30 volts to maintain the best battery life. With this in mind it is recommended to periodically load test the batteries to ensure they have sufficient capacity to maintain the system during a power outage. Tests should be done on an annual basis and more frequently as they become older and begin to lose capacity. The load test is recommended off-process if possible as there will be no battery backup available while performing the test and recharging of the battery pack can take up to 16 hours. Having a spare available to swap, especially if doing on process, is a wise option leading to minimal time without battery backup and allowing the tested battery to be recharged on a bench outside the system for future swap with the next test. If regular maintenance is not performed the recommendation is to change at least every three years rather than every five. Power Supplies The power supply is the heart of the xPM power system and the recommendation is for a redundant power supply configuration having each power supply fed by its own dedicated power source. Honeywell has introduced the next generation power supply for this family which increases the robustness of the power system.Even with redundant power supplies, one must be careful when changing out a failed power supply. This is to minimize disturbance of the environment and to reduce the introduction of particles into the area around and near the power supplies. Those particles can be pulled through the airflow of the working power supply and result in the second power supply failing. For this reason, Honeywell does not recommend replacing a working power supply on-process (other than the black-colored version). However, power supplies do not last forever and you should consider upgrading older power supplies, or prepare to do so, when the opportunities arise. The recommendation for changing out the power supplies is every ten years and this replacement should be included during a scheduled down time if possible. The power supply replacement procedure listed in the Honeywell xPM Service manual should be followed at all times. Recommend Change of Original Black Power Supplies In October of 1996 Honeywell issued a customer priority notification (PN #1986) about a possible over-voltage issue with the blackcolored (51109456-200) power supplies that were sold from 1988 through 1994. The Honeywell recommendation was to change out those black power supplies with the new silver version. Honeywell still recommends and strongly suggest that these black power supplies be replaced with the current power supply under part number 51198651-100 regardless of when they were put into service. Silver Power Supplies There have been three part number versions of the silver power supplies. The first (51109684-100/300) was sold from 1993 through 1997. The second (51198947-100) sold from 1997 through today. The next generation power supply was released in early 2009 and was introduced initially through the power system maintenance upgrade kit. If a site is running the original silver version they have now been in service for over 10 years and sites should consider the need to replace before they are forced to do so by failure of the power supply. Note that there is always risk involved when powering down equipment and possible issues when the equipment is powered back up. As stated previously, it is recommended to change these out off-process if possible. Replacements on- process should be done only when a power supply fails and replacement is then required immediately.

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