Joe,
It is my understanding that sulfation, the formation of crystalized lead sulfate on the battery plates, occurs when the battery is not fully charged. Since L/A batteries self discharge at the rate of about 4 to 6% per month, a fully charged battery left isolated can begin to lightly sulfate within a week or two. Sulfation of a more deeply discharged battery will begin in a little as 48 hours. This points to the importance of recharging as soon as possible after any considerable usage. For the maintenance of charged batteries, either type of trickle charger, pulse or constant, should be enough to reduce the sulfation rate to the practical minimum.
For non-sealed batteries, trickle chargers do keep the battery warmer. this is beneficial in freezing conditions, but in more temperate locations, any charging will accelerate the evaporation of the acid solution. This requires more diligence in keeping the batteries topped up with distilled water. This is a known requirement for batteries that are being cycled consistently, but also needs to be included for batteries stored for longer periods.
Fair winds,
Eric
PS. Now that I've said all this, I need to go to the garage and charge and de-sulfate the spare deep cycle battery that is stored out there.
--- In electricboats@
>
> Yes, have that graph (I think the left arrow s/b pointing at the 10%
> number). See that if the graph were continued to the ordinate it would
> asymptotically approach infinity, meaning that for very low DOD it doesn't
> matter how many cycles a battery undergoes.
>
> Thus, it perhaps doesn't matter if the battery is retained on float charge
> vs. getting recharged periodically from a very low DOD.
>
> Is sulphation an issue under constant float voltage conditions?
>
> JoeS.
>
> > From: Eric <ewdysar@...
> > Reply-To: <electricboats@
> > Date: Fri, 01 Jan 2010 21:25:36 -0000
> > To: <electricboats@
> > Subject: [Electric Boats] Re: AGM Battery: To Float Or Not To Float
> >
> > Joe,
> >
> > Keep in mind that the number of cycles is dependent on the depth of discharge
> > of that cycle. With lead acid batteries, a deep cycle battery may have a
> > lifespan of more than 10,000 cycles with a shallow (5%) DOD, but only some
> > hundreds of cycles of life at deeper levels (>70% DOD). I'm not sure that a
> > constant trickle charge ages the battery any slower than repeated cycles of
> > less than 1% DOD.
> >
> > A file was posted to this group just over a week ago named "batteryLIFE.
> > that illustrates this concept graphically.
> >
> > Fair winds,
> > Eric
> >
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