Eric,
Thank you for the sulphation formation explanation and emphasizing the need
to recharge a depleted battery immediately. Having lived with "floodies" I
now only have AGMs onboard, located in otherwise useless near-inaccessible
locations. Would have preferred Gels (due to their ability to handle deep
discharges better), but my outboards' voltage regulators are set a bit too
high for them.
Incidentally, we should clarify our terminology and specifically use the
term "float charger" to define a properly voltage-regulated power source,
because the old-fashioned unregulated "trickle chargers" (simply a
transformer with rectifier) are notorious for murdering batteries.
JoeS.
> From: Eric <ewdysar@yahoo.
> Reply-To: <electricboats@
> Date: Sat, 02 Jan 2010 07:30:22 -0000
> To: <electricboats@
> Subject: [Electric Boats] Re: AGM Battery: To Float Or Not To Float
>
> 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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