Hi Matt -
The only thing that matters in selecting the firmware is the ID#. Are you absolutely certain that your unit is 18 and not 17? The matrix in the article from the Firmware Upgrade Wizard is assuming that if your unit has UPS FW less than 8.0, it is an ID17 unit.
Our recommendation for upgrading UPS FW is to use the Firmware Upgrade Wizard (via Serial) if at all possible. It includes additional system checks that are not possible when using the Network Management Card. Furthermore, on an older UPS that is out of warranty I probably wouldn't upgrade the firmware unless you are experiencing an issue of some sort. If the unit is not performing as expected, then by all means upgrade the FW, but beyond that I tend to take an "If it ain't broke, don't fix it" approach. You can use the Network Interface for the UPS while you are awaiting batteries, but I would not upgrade the firmware until you have new batteries installed in the unit.
We have release notes for many of the images, but not all. All new releases moving forwards will have release notes attached. For the FW revs that have release notes you will find them bundled with the .enc files. For UPS ID 18 image the changes are as follows:
Release Notes (UPS09.4):
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1. SmartSlot card information displayed on the LCD is cleared when new card is hot-swapped
2. Updated LCD message in Japanese when canceling sleep.
3. Improved robustness of serial port communications to avoid errant serial port characters from causing delayed UPS operations.
4. LCD display operation with Legacy Communication Card (AP9620) improved to eliminate LCD display of items that are inaccessible when AP9620 is used.
5. Improved reliability of native USB operation command DelayBeforeShutdown and switched outlet control.
This improves compatibility with Custom software applications, and native OS shutdown agents.
6. Improved the cancelling of a UPS output programmed-off duration (sleep).
7. Improved programmed-off duration (sleep) response to power outage.
Release Notes (UPS09.3):
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1. Changed display of fw versions on LCD to be only the single important version number.
2. Improved self-test logging for PCBE / NMC.
3. Changed data reporting for future card support.
4. Eliminated occasional false alarm when AC restored shortly after end of battery discharge.
5. Corrected initialization of SOG status change cause variable to repair NMC logs after firmware upate.
6. Simple Signal logic changes for Interface expander 2 support
7. Simple Signal logic improvements to cover cases when SOG are off.
8. Added support for OEM customer.
9. Added factory debug capability for USB.
10. Add compatibility for IE-2 card.
11. Repaired an occasional math error in the battery replacement date algorithm that resulted in incorrect dates.
12. SOG loadshedding improved operation for canceled load shedding operations.
13. Adjustment of thresholds for AVR fault detection to increase reliability.
14. Corrected efficiency display in Japanese.
15 Increased upper end of allowed limits for Minimum Return Runtime, and Load Shed Runtime Remaining to match other Smart-UPS
