Equalization, right

Just foggy enough to obscure the ice pans.

We had unusually warm weather earlier this week for February in Toronto, but a necessary spot of maintanance aboard went better at 10C than the -3C that is more usual at this time of year. Some welding and fabrication work will necessitate moving (and therefore disconnecting) the house bank a couple of metres forward into the saloon. At 55 kilos each (and there are six of the L-16 six-volt batteries to shift), this is a "non-trivial" task. I thought I'd give them not only a full charge, but an equalization. Here's some of the steps involved.

Readers of the above link, or the merely experienced, will notice that equalization is called for if trouble is suspected in the form of "tired" batteries as expressed via a historical review of amp-hour metering. While this is a complex subject, the analogy in the article of a car's fuel usage versus its remaining fuel supply is helpful, but I would add that a battery's range, in the form of useful amp-hour (Ah) capacity available, is an extension of that analogy. Just as a car can accumulating "junk", making it heavier and less efficient, so can a battery accumulate sulphation on its lead-antimony plates. This can be due to incomplete or rapid cycling of the charge, or other factors like damaged or corroded cabling or low electrolyte levels.The only way to know is to measure and evaluate against your particular battery bank's values, as seen in the first two illustrations here for mine.

The use of equal and robust cabling seems to have been a good idea.

I measured the specific gravity (SG) of all the individual batteries in the bank and corrected this value to an ambient temperature of 10C. All came in at 1.275, which suggested a full state of charge. This agreed with Victron's VEconfig monitoring software on my pilothouse computer. I logged all these figures for future use. Differences suggest different actions.

This was the "resting" voltage after about an hour off the charger. Again, it's suggestive of batteries in good nick, although a truer test would involve a longer rest off all DC loads, again, depending on ambient temperature. As I already knew the batteries had been pretty much babied in terms of watering, keeping the connections tight and keeping the discharges relatively low, I took it as given that all was basically well. Peering down the fill holes, however, I saw a slight lowering of the electrolyte, not enough to uncover the plates, but enough to merit a watering of 150 ml per battery. Th

The choice of skippers for house banks and ice cubes.

The Victron manual suggests, rather obliquely, I find, a way to manually enter equalization mode, which is a state of overcharge (15.5 VDC) sufficient to knock sulphation off the plates, via clicking the main switch on the front from "on" to "charger only" and back again. You are rewarded with blinking "bulk" and "absorption" LEDs, telling you your charger is cooking your batteries in a method (timed) calculated to have the desired effect. Well, I couldn't get this to work, and phoned the redoubtable Stefan at Ontario Battery Services to advise. He suggested, rather than developing a knack for the switch, I simply input the desired absorption stage voltage into the interface and then give it an hour. So I did. The electrolyte sizzled gently (bubbles of hydrogen are produced during th process) but did not noticeably heat the bank up; I have a temperature sensor to warn me of this, as well as fingers.

Saved as an "equalization profile": this software is pretty technical to use correctly, but is also easy to configure.

Did I actually need to equalize the house bank? That's debatable, which is why I didn't do it for hours on end. Equalization can erode the plates in time, so it's a trade-off between knocking the crud off and shortening the life. But this was the first equalization I did since installation and a general rule of thumb is "do this a couple of times a year", although a more shore-independent boat with a smaller house bank than ours of 1,185 Ah (@20 hour rate) might do so more frequently. People have to go to the dock for it. We won't although we will if it's logical or more convenient to do so. When I upside our alternator and tie in the solar panels, I should be able to equalize underway. But that's a topic for the future. Onwards to more welding.