The good news is that our battery-backup sump pump worked.
The bad news is that our sump pump died.
Post-failure analysis revealed that the start capacitor for the pump had a crack in it, evidence of age and/or overheating.
Funny thing about those electrolytic capacitors; they are the component most likely to fail in electronics like pumps (sump and HVAC and fans) and LED lighting.This particular unit, according to Cheryl's research, was purchased a scant 4 years ago. This is far too short a lifetime for a sump pump which hasn't actually been run much. But the first sump pump in the house -- which was installed by the contractors -- only lasted six months. The next one lasted ten years. So they are very inconsistent.
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I got up early on Saturday morning to make Cheryl's coffee and first noticed that the back deck had water standing so I knew there had been substantial rain the night before. And then I heard what sounded like an airplane passing overhead -- except it didn't fade away. And the floor was rumbling. And then I realized that it wasn't an airplane, it was the sump pump, and it didn't sound right. It sounding ... different. So I immediately panicked, not because of the thought of water rising in the basement, but rather the fact that I couldn't just rush down into the basement to check it because first it was necessary to notify the renters downstairs so I wouldn't presume upon their privacy.
So I sent a text to Mary and (luckily!) she responded quickly and positively, and down I went to the mechanical room.
The floor was wet but only near the backup battery, which was odd. And the backup pump was kicking on about every 30 seconds. It was impossible to tell how long the pump had been running but the meter on the battery indicated that the voltage was dropping down to about 8 volts instead of the normal 12, so it was obvious that it had been running quite a while.
Having no idea how much longer it would keep going, I rushed over to the hardware store and bought a new pump and brought it back home and pulled the "pump assembly" (containing both the primary and backup pumps) and disconnected the old primary and installed the new one and then dropped the pumps assembly back into the sump and plugged it all in and -- it worked!
Taking the old one back into the garage, I tore it down, being careful to do it inside a plastic tub (because the pump is full of mineral oil) and found the cracked capacitor. Because I just have to know.