The house batteries date from September 2011. We've gotten a hair over six years of service from batteries that are normally replaced every five years. They're not stone dead. See Sudden Death—Joys and Concerns for details of the last time they died.
They're not dead. But. They're barely charging. The engine battery is happily sitting at over 13V. The house batteries, on the other hand, keep slipping down to 12V or less. And when the solar panels raise the voltage enough to charge the engine battery, it's being drained by the house batteries. Not a good look.
I've got a little specific gravity tester. The acid seemed to register 1.10 (It's hard to read.) This means there's almost nothing in there but water. The sulphur is all bonded onto the lead. Which makes sense after six years.
Last time I replaced them, we were in the water. Moving each 62# battery off the boat was a series of awkward movements. Out of the engine room. Up the ladder. Out of the cockpit. Onto the dock.
We're on the hard, now. That means lowering the battery from the end of the mizzen boom using some kind of block-and-tackle. It certainly needs to be done ASAP so the pumps can keep the interior dry.
In 2013, I added these filler tubes to make it easier to top off the water. They're great. But. The batteries still age.
Now comes the hard choice: West Marine GC2 batteries or Trojan-brand? Theoretically, the WM is the same as the Trojan without the fancy maroon case. There is a minor difference: the WM is essentially the T105, and I've got T105Plus. The difference is 20 amp-hours times four batteries.
If I get the WM, I can have them delivered to the local store. To get the Trojan's, I may have to go to Stevens Battery Warehouse in Annapolis to pick them up. Not too difficult, really.