So I have new AGMs in hand from atbatt (the one linked in my May 1 post). Should I just charge them to to 27V together? Or are there other considerations?
MI wife tends to mow until the thing is whisper quiet and the voltage is below 24V. I have the impression the PbSO4 cells should be no less thatn 50% SOC to ensure good liife. How can I limit SOD? Should I limit it? Thanks! mike On Thu, May 1, 2014 at 3:49 PM, Michael Ross <[email protected]> wrote: > Roger, > > Thanks for the answer. The metric is what I made up as a way to compare > the items on the website, but it takes into consideration what I have heard > on this list. I (despite what folks might think from my constant poking > about) actually prefer to follow advice I am given. The Enersys/Genesis > cells look like a good bargain in #/lb and $/Ah and number and strength of > recommendations. > > *#1 13lb* $3.46/lb @ $45 17.2 Ah *$2.62/Ah* > > http://www.atbatt.com/genesis-np18-12-12v-172ah-sealed-lead-acid-battery-with-nb-terminal.asp?cr_brand=BB&cr_product=BP17-12#specifications > > On Thu, May 1, 2014 at 2:30 PM, Roger Stockton <[email protected]> > wrote: > >> Michael Ross wrote: >> >> > When you say lead is the fuel - how does that work? I wouldn't have >> > expected it unless it means the grids (my word for whatever they are >> > called. plates?) are bigger... >> > >> > I guess you could make the grids heavier better life in severe >> conditions. >> > How do you know the extra weight is in grid area and not structure? >> > >> > Or do I have the wrong idea altogether? >> >> You have the right idea. Lead is the main active ingredient in the >> battery, and it is quite dense, so it is a reasonable approximation to >> state that the heavier a lead-acid battery, the greater its actual capacity >> is likely to be. >> >> But, as you say, even if the battery is heavier, you don't know if the >> extra weight means more active material (e.g. paste) or beefier grids (the >> lead structure of the plates that supports the paste) or beefier internal >> interconnections. >> >> Beefier grids or internal connections can both contribute to a more >> robust or longer-lived battery, so this doesn't contradict the "heavier is >> better" philosophy. >> >> I think David makes a good suggestion, which is to dig up specs on the >> particular batteries you are considering and compare their capacities at >> the discharge rate that you will operate them at. The 20hr rate is >> meaningless for a mower that will likely deplete the batteries in about >> 1hr, and different makes handle high rate discharge quite differently. >> Also, as David notes, different manufacturers may state their battery's >> rated capacity at different discharge rates; e.g. Hawker/Enersys often >> states the rated capacity at the 10h rate while others may use the 20h rate. >> >> Note also that the weight metric really does not mean to shop by the best >> $/lb value, but rather that for two batteries of the same physical size or >> same rated capacity, the heavier of the two is likely to deliver greater >> actual capacity and/or provide greater service life. >> >> One caveat I would offer is that I think especially for AGMs there is >> more to the story than simply weight. With sealed batteries (AGM/gel), one >> of the keys to long service life is avoiding venting since this corresponds >> to (generally) irreversible loss of electrolyte. This is where a quality >> brand can impact the outcome of your buying decision. The manufacturing >> quality can affect the performance of the pressure relief valves that allow >> the cells to vent in a controlled manner. It is not unusual for Chinese >> AGMs with lower quality control to have vents that open at lower than >> desirable pressures and/or open at pressures that vary from cell to cell. >> >> Good luck! ;^> >> >> Roger. >> >> _______________________________________________ >> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub >> http://lists.evdl.org/listinfo.cgi/ev-evdl.org >> For EV drag racing discussion, please use NEDRA ( >> http://groups.yahoo.com/group/NEDRA) >> >> > > > -- > Put this question to yourself: should I use everyone else to attain > happiness, or should I help others gain happiness? > *Dalai Lama * > > Tell me what it is you plan to do > With your one wild and precious life? > Mary Oliver, "The summer day." > > To invent, you need a good imagination and a pile of junk. > Thomas A. Edison > <http://www.brainyquote.com/quotes/quotes/t/thomasaed125362.html> > > A public-opinion poll is no substitute for thought. > *Warren Buffet* > > Michael E. Ross > (919) 550-2430 Land > (919) 576-0824 <https://www.google.com/voice/b/0?pli=1#phones> Google > Phone > (919) 631-1451 Cell > (919) 513-0418 Desk > > [email protected] > <[email protected]> > > > -- Put this question to yourself: should I use everyone else to attain happiness, or should I help others gain happiness? *Dalai Lama * Tell me what it is you plan to do With your one wild and precious life? Mary Oliver, "The summer day." To invent, you need a good imagination and a pile of junk. Thomas A. Edison <http://www.brainyquote.com/quotes/quotes/t/thomasaed125362.html> A public-opinion poll is no substitute for thought. *Warren Buffet* Michael E. Ross (919) 550-2430 Land (919) 576-0824 <https://www.google.com/voice/b/0?pli=1#phones> Google Phone (919) 631-1451 Cell (919) 513-0418 Desk [email protected] <[email protected]> -------------- next part -------------- An HTML attachment was scrubbed... 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