Thursdays are usually maintenance day for the electrical power supply company in my area. So there was nearly a full day power cut. Luckily, I have a UPS so that sorts out the problem for 8-9 hours. The lead acid battery I use for my UPS is about 3-4 years old, and these being unsealed batteries they last long, really long if maintained properly.
In the past I have had one such battery last for a decade before requiring a replacement.
Unsealed lead acid batteries require two important maintenance activities:
Topping up distilled water every 6 months
Applying petroleum jelly / grease on the terminals to prevent corrosion
The distilled water topping up is done regularly because I buy the bottles in bulk, but I didn’t have the battery terminal grease to apply and had been procrastinating over buying it for quite some time.
Then disaster happened – the UPS started beeping low battery. I checked the voltage at the battery terminals when the UPS was under load, it was showing 12.4V. Then I checked the voltage at the end of wire after the lugs it was dropping to 9.8-10V in between. The cables and terminals had lot of deposit accumulated over the years, which I had cleaned recently after the UPS beeped last time which seemed to fix the issue temporarily. But yesterday it showed no signs of stopping. Additionally I observed the positive wire was quite warm which usually doesn’t happen otherwise. Time to do a permanent fix.
So I purchased new lugs, nuts and bolts, crimped them and installed after scraping off the corroded material collected on the terminals using sand paper. Beeping stopped. Then I applied Lithium NLGI 3 grease on it to prevent further corrosion. Making an event in my calendar to check this every 3-6 months. 😅