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2016-08-24

Testing times, currently

Boat blog-unrelated shot of one of the two flight-capable Lancaster bombers left on Earth overflying National Yacht Club. It's important to lift one's eyes from the task occasionally.
A spate of work on the homefront meant that my battery bank was both unhooked to the DC side and off charger. Even with the installation of the galvanic isolator, I do not believe there's a compelling reason to leave the charger on unattended for a week, not when I have suspicions concerning the quality of the shore power setup.
Very much as seen in the above video, I checked out the specific gravity of each of the battery cells (18 in all in a six 6 VDC batttery bank). Initial readings were between 1.250 and 1.260, or "not bad", even uncorrected for temperature for my somewhat toasty vessel. The initial voltage was 12.47 VDC, "corner pos to corner neg", (recall that I am treating my house bank as one large 12 VDC battery), which was also indicative of pretty good health. The science of measuring battery state of charge and health (as judged by its ability to reach 100% of its rated capacity) is somewhat daunting and I claim no scientific expertise. I do think I now grasp enough to handle the basics, however.
Well, best hook this up then.
I then charged the bank until only a trickle of amps was being provided in the "float stage" from my charger. After an hour's rest (off charger completely), I registered 13.04 VDC. Measurement of each of the individual flooded cells gave SG readings of circa 1.275. All the batteries are therefore deemed fit. 
Behold the Skil 18 x 3 belt sander.I bought it (on sale, of course) to refinish red oak stair treads. Little did I know...
 I was, however, thinking that it had been a hot summer here and that my battery temperature monitor had frequently reported case temperatures of over 31C/88F. That in itself is no biggie, but I wanted to check the electrolyte levels nonetheless. So I thought I'd do a minor cosmetic job first.
Evidence that sloppy power washing will haunt one's decks.
This are the rather rudimentary aft-deck seats on Alchemy. We haven't paid attention to them, except to ponder at times how much of them we would likely cut out to put in propane tanks, liferaft valises and fender stowage or even some sort of dock box in which to put items like a barbeque while on passage. They've been neglected, but ultimately, it hasn't hurt them much, except aesthetically. The belt sander I purchased earlier in the summer to rehab some Victorian stairs at home made short work of the remaining bits of varnish, and a quarter-sheet palm sander did the rest. The result is either worthy of "nothing", or, in other words, just to let the bare wood "silver" naturally, or to give it a nice oiling. We'll see which Mrs. Alchemy opts for : coatings and stainings are more her department as I'm a grumpy incompetant when handed a brush.
Still needs some finalizing, but better than it was.
Back to the light of the charge brigade, I got a bright LED emergency torch and shone it down the fill holes of each cell on each battery. While, as would be expected from factory-fresh batteries, none showed exposed plates, I made an arbitrary call premised on imminent load cycling before the cool weather of fall and injected 10 ml of distilled water into each cell. This was enough to ensure the suggested 1/4" of electrolyte above all plates, but not so much that the level was particularly close to the underside of the vent caps.
Also, don't sweat into the batteries. It's an amateur move.
 Lastly, these vented caps need some vigourous thumb pressure to "click" back in. They are called "Water Miser vented caps" and, while better than just a pop bottle "solid" cap, they aren't the gold standard of a self-watering setup. Not sure if that's actually a good idea, however, as I would prefer just to have the habit of regular inspection and maintenance, much as looking at the end of a dipstick on a diesel can tell you more than just your oil level.
Click, and we are done.
A shout out to solar-power enthusiast"Handy Bob" for his role in suggesting these batteries, with which I am well-pleased.