Stu, thank you for starting a new thread with your post. It seemed too good to bury in our carbon monoxide/propane gas/battery gas/???? discussion.
I am a dunce when it comes to batteries and electricity. Can you help by answering some questions that arise for me on reading your post. [Later added note: Stu, on searching, I see that you have written elsewhere at this site about batteries and electrical issues. I am following up those posts now so please don't think you should write anything in answer to my questions here that you have written elsewhere. M]
You wrote: In all of our years with
Aquavite and in earlier boats [celebrating our 25th year of sailing on SF Bay this past weekend], we never left our boats plugged in, and none of 'em sank! The reason is basic: we just do not know how poorly wired our neighbors' boats may be. Stray electrical can come from a bad dock wiring design or installation [not in our marina, though] or from poorly wired other boats even to a good marina system. We intend to have the zincs continue to do their work and not spend money on a new shaft or propeller if we can help it.
Question: Will you explain how having your own boat "plugged in" relates negatively (bad pun) to other boats' wiring, bad dock wiring, zincs doing their work.
You wrote: That said, I've learned a lot recently from John Nixon, a frequent contributor to this Message Board. Once I [
finally] installed our Link 2000, I learned two very important things: 1) my "energy budget" done in my head for the past ten years was pretty much right spot on (see:
http://c34.org/bbs/index.php/topic,3976.0.html); 2) my estimate of input TO the house bank FROM the various charging sources was NOT very good because I hadn't taken into account the acceptance rate of the batteries and the tapering off of the charging amperage even with a smart regulator and a smart three stage Freedom 15 inverter charger.
Question: are there generally just two charging sources: the [whatever it is - generator?] on the engine and the 110 volt charger?
You wrote: In discussions by email with John, as a result of what I term "Fridge Follies," wherein I was doing detective work on why our fridge would not restart during the second night at anchor, I learned two things: 1) equalize your batteries regularly to avoid diminished performance [assuming your batteries are wet cells and your manufacturer says it's OK to do so];
Comment: I would ask about equalizing wet cell batteries but will hold off until after searching this website for postings on the subject. At this point, I have no idea of how to do it. If there isn't another thread dealing with this topic, I would be interested in knowing from you here how one goes about doing it.
You wrote: 2) John provided this:
"Leaving lead acid batteries on float charge 24/7 will reduce the useful life of the batteries by as much as 35 to 40% compared to cycle charging, which by definition is to charge them only when they need recharging, then leave them alone. The continuous float charge results in accelerated positive grid corrosion, which has the effect of turning the positive plates in the battery into mush: a soft, expanded material that produces increased internal resistance and decreased deep cycle capacity. I only use cycle charging on my boats now, but I will leave them overnight or maybe for a day or 2 with the charger on just to make sure that they get fully recharged."I noted that in order to do so, I'd start a program of plugging into shorepower to top off the batteries once I got back to the slip before I left. He added:
"I doubt that an extra 30 minutes with the charger on when you get back to the dock is going to get your batteries fully recharged: that last 5% or so takes a long time, even with the very low internal resistance of AGM batteries like I have on our boat. If you are adverse to leaving the charger on all the time when you are away from the boat ( which I support completely, but not for the reason you might think...), a good simple way to give the charger time to do its work is to put it on a cheap/inexpensive 24 hr time switch with the ON peg pulled out. Just set it to run for 24 hours when you leave the boat: manually start it with the timer set just after the OFF pin, and it will dutifully turn itself off after a good 24 hour charge. In most cases, that will generally make sure that you have reached that 100% charge that the batteries need to not begin loosing capacity due to sulfation. Comment: On Hali we have four owners. Different owners use the boat quite a lot...at least for short day cruises. As a practical matter, we probably are less concerned about a 35-40% reduction in service life of the batteries than we are in knowing that the batteries are charged up whenever anyone comes to the boat and in having dead simple procedures that everyone can follow (like plugging in shore power when we leave the boat). We will need to think whether there is a dead simple procedure for cycle charging that would avoid our "plug her in" policy which results in continuous float charging.
You wrote (or quoted, not sure which on this part): So, for many reasons, it's important to both keep your batteries fully charged, avoid keeping them plugged in 24/7 on float, and take care of them. I am constantly amazed at the number of plugged in boats that NEVER GET USED. Whenever the owner comes down to the boat, there are going to be a bunch of things that don't work, most importantly their electrical systems.
Question: Did John have another reason - it is not clear to me that he stated it although he seems to have hinted at it - for avoiding leaving the battery charger plugged in 24/7?
You wrote: The fridge works much better now after the equalization, which I intend to do more regularly now that I know. The voltage used to drop to 12V whenever the fridge started running. After the equalization the voltage remains high and only slowly tapers off after fridge run time and during the off cycle of the fridge, the voltage actually rises a bit.
Question: Hali has a selectable battery "tester" for each of the two house batteries, at the panel. Each gives a voltage read-out only, on an analogue meter. At what "tested" voltage would you conclude that continued use of a battery is not good for equipment aboard the boat (or that for other reasons the battery should not be used)?"
Many thanks.