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Standard User Pheasant
(eat-sleep-adslguide) Thu 14-Nov-24 18:27:49
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Backup batteries (incl. strange and weird...)


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In the past few weeks, like buses that all come at once, I've come across more than what I'd think is my fair share of backup battery replacements. So I thought I'd share (in a tech nerdy way) some of them:

Xerox WorkCentre - backup battery installed on DIMM. This was definitely a new style on me. Was pretty easy to replace, as it clips onto the DIMM piggy-back style.

Lexmark X792 - this is a very tiny (under 7mm across) wristwatch sized - see for scale on board, ML621 lithium-manganese-dioxide coin cell. This one is apparently rechargeable! But the board was dead anyway.

Synology NAS - last nights rescue effort involved a standard CR2032 lithium-manganese-dioxide (non-rechargeable) button cell from the mobo in a DS1817+ Synology NAS - see the replacement cell. The original 2032 (bad one) had me fooled. Firstly resulting in complete dead, lights off, non-starting unit which I genuinely thought was a power supply fault (until @TinyMongomery wisely suggested I actually check the power supply. D'oh too logical!) Secondly checking the cell with a digital multimeter, thinking it wasn't drained/faulty as it was over 3V with open circuit.

My lessons learnt:
1. CMOS battery fails can disguise themselves in mysterious ways
2. If you rarely shutdown your devices, be prepared if they don't come back to life when re-powered or behave oddly.
3. Always test a coin cell battery with a small load in place. Open circuit testing with a DMM is otherwise not a reliable indicator of good health.
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