On 12 Jul 2009, at 09:58, Tony Brooks wrote:
> I am afraid that 14.4v is not as cut and dried as the chap implies.
> Some sealed cells (mainly gels)should not be charged at more than
> about 13.8 volts and some designs of AGM have similar voltage
> limitations. Sticking with ordinary wet lead acid batteries. 14.4
> volts is probably the optimum for efficient charging (that is
> maximising the conversion of lead sulphate to lead oxide and
> minimising wasting current in producing heat and splitting the
> water in to H & O). However the four hour figure is a pretty
> empirical one because on a "typical" system (whats typical?) 4
> hours is a figure that will ensure most systems are charged to
> between 80% & 90% of fully charged. The other 10 to 20% will take
> very much longer (say up to another 12 hours) and boosting the
> charging voltage may not help despite what the ammeter may be
> saying. It is very unlikely that a cruising boat can ever fully
> charge its batteries from the engine so they WILL gradually
> sulphate. AS you say, batteries are best looked at as consumables
> unless you can organise ,long term, low rate charging to deal with
> that last 10 to 20% fairly quickly after the discharge.
>
I should have made it clear in my earlier post that I was talking
about ordinary wet cells.
It's slowly getting easier to find places where we can overnight on a
shoreline, thus putting in around 12 hours more charge, but it's
still unlikely to be more than once every couple of months at best,
so not enough to hold off the sulphation.
Thanks for all the advice.
All the best
Bruce
Go steady, but keep going.
[Non-text portions of this message have been removed]
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