Lee, you have given me a lot to think about and act on. I have put your messages in a folder and will refer to them when I get back on the boat.
Thank you! Norm S/V Bandersnatch Lying Julington Creek 30 07.695N 081 38.484W > [Original Message] > From: LA Licata <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]> > Date: 11/25/2008 1:37:26 PM > Subject: Re: [Liveaboard] Submarine Battery Discharges > > Norm, > > I think I mislead you. > > I do agree with Home Power that frequent undercharging will kill any > battery bank. > > What i did was charge the battery until it is full (normal battery > current would drop to less than 5 amps and stay reasonably > steady....) and then not even think of recharging the bank until it > is below 75% capacity.... and then back up to 100%.... If one looked > into the cells when the battery is at 100%, if you see a few small > bubbles appearing, then you are at 100%. Time to stop. Just need to > do this once or twice a year to verify that what your meters are > telling you is what you think is happening. I use a mirror to watch > the bubbles, with eye protection. Takes minutes to do so was not a PITA. > > As for frequent equalizations, I think twice a year is enough.... You > know you have it right when calculated capacity stays at about 100% > or so for many many cycles.... > > I will admit that I would consider increasing the number of > equalizations if capacity was to drop, but only after checking inter- > cell connectors, water level, specific gravity, performing a > cleaning, etc etc etc. But my experience is that you know when end of > life is reached when you done all of the above right, your bank has > lasted well beyond what everyone's does, and then one day, it just > seems to act exhausted.... > > Then, end of life has been reached.... > > Lee > > PS: I believe there was a 5% allowance for jumpered cells, more with > the battery manufacturer's permission.... > > never invoked either limit... > > Lee > > PPS: 210 cells gives one about a 460 VDC battery bank, give or take a > little > > > On Nov 25, 2008, at 2015, Norm of Bandersnatch wrote: > > Great info Lee.. > > So I take it the sub battery was 220-240 VDC, so jumping one sell > would be > only a 1% drop. > > This is the first I have heard of not charging the battery if it was > discharged to less than 75% of the AH capacity. Everything I have read > says that the "fuller" you keep the battery (without overcharging) the > better. > > Home Power has often said the Number One cause of early failure of house > batteries is chronic undercharging, and the Number Two cause was > overcharging. But they do recommend more frequent equalization, like > every > two to six weeks, the deeper the discharges the more often the > equalization. > > Thanks again for the great info on battery care. I will study your > input > when I get back to the boat and follow it. My AH meter is supposed to > automatically compute charge efficiency and compensate but I have found > that even when it says the battery is charged the hydrometer tells a > different story. I will look into the problem > > I will also seriously consider separate cells the next time I change > out my > house batteries. Do you recall how many jumpered cells you had in the > course of the battery's life? > > > Norm > S/V Bandersnatch > Lying Julington Creek > 30 07.695N 081 38.484W > > > > > [Original Message] > > From: LA Licata <[EMAIL PROTECTED]> > > To: <liveaboard@liveaboardnow.org> > > Cc: Norm of Bandersnatch <[EMAIL PROTECTED]> > > Date: 11/25/2008 10:25:20 AM > > Subject: Re: [Liveaboard] Submarine Battery Discharges > > > > Norm, > > > > The number of cells we had is hazy, but I think somewhere around > > 210-220 seems to stick in my mind. > > > > Reactor accident analysis determined what actions were required to > > render the reactor safe under all designed accident scenarios. There > > had to be enough electricity in the bank to provide the power > > necessary to meet these accident scenarios. Plus some. > > > > So, one can assume that the battery capacity was designed to meet > > these requirements throughout the battery bank's designed life (as > > measured in cycles and years) before replacement was warranted. So, > > to keep it all simple, as long as the bank met these design accident > > requirements, it was good to go. So, in theory, we were testing to > > the battery spec, in a round about sort of way.. > > > > Our AH meters had a calibration capability and meter adjustment was > > possible. You could do the same. Turn on a known unwavering DC load > > (like a string of DC lights that are all the same wattage) for a > > pe riod of time that allows battery voltage to drop something like > > 0.2-0.3 VDC and then stop the discharge and compare what was read vs > > what was recorded. If there is no adjustment possible, than a scaling > > factor can be calculated. > > > > Do this over two different voltage ranges if you really are bored. > > Should be little difference. > > > > Or, use your calibrated hydrometer to determine 100 % full and > > something less (maybe 60% or so?) and then using the capacity figure > > of your cells, see if amps out calculated is close to indicated. > > > > Re-perform test if after equalization, the reading appear to be > > different from the last time.... > > > > As for how we got so many years out of these cells, we had low > > pressure air agitation to keep the electrolyte mixed, temperature and > > humidity controlled battery compartment, a team of sailors who > > cleaned the place, measured carefully, checked inter cell connection > > torques, etc etc etc. > > > > On my last boat, i had Interstate 4Ds (3 of them) as my house bank > > and 2 group 31's for the engine starting bank. When i installed the > > 4Ds, i filled them with distilled water and electrolyte solution and > > charged them per Interstate's directions on a bench. Then, installed, > > and used distilled water to keep them full (checking bi-weekly in > > July and august, monthly otherwise), posts clean, connections tight, > > and batteries strapped down so no movement was possible. Never > > discharged below 50% and never recharged if the indicated capacity > > was above 75%. Equalized at the beginning and end of the season, and > > measured and recorded each cell's specific gravity with a hydrometer > > that I had just checked at the local battery shop for accuracy. At > > year one, battery capacity was just over 100%. When i sold the boat 4 > > years later, battery capacity was ~104 % with 134+ cycles on the > > bank.... Go figure... > > > > In the battery bank I want for my trawler, I am asking for 2.2 VDC > > cells. The inverter has a DC input range of something above 19 VDC so > > if I do end up with a bad cell or two, I could jumper and live that > > way until I could arrange for a replacement..... > > > > Lee > > > > > > On Nov 22, 2008, at 1548, Norm of Bandersnatch wrote: > > > > Lee, > > > > Thank you for the great information about the submarine batteries. It > > correlates well with the information I have read in Home Power > > magazine...... > > > _______________________________________________ Liveaboard mailing list Liveaboard@liveaboardnow.org To adjust your membership settings over the web http://www.liveaboardnow.org/mailman/listinfo/liveaboard To subscribe send an email to [EMAIL PROTECTED] To unsubscribe send an email to [EMAIL PROTECTED] The archives are at http://www.liveaboardnow.org/pipermail/liveaboard/ To search the archives http://www.mail-archive.com/liveaboard@liveaboardnow.org The Mailman Users Guide can be found here http://www.gnu.org/software/mailman/mailman-member/index.html
