"Gould 0738" wrote in message
...
This is the point I was trying to politely make to Gould. If you listen to
his story half the newbie boaters will be filing into West Marine to buy new
batteries when the ones they have are likely to be perfectly fine.

Eisboch

Your point is accurate, merely incomplete and also misleading if considered
without
taking important variables into account.

If that "newbie" owns a battery that cannot be charged to a point above 12.6
volts on a functional charger he darn well just might be in need of a new one.

A bad battery or a depleted battery may still read a high voltage when connected
to a charger, and even for a while after being removed. All your reading of
13.2 tells you is that your charger decided to go into float mode. This may be
a strong hint that the battery is fully charged, but it doesn't necessarily mean
that.


Do most boaters disconnect the battery from the boat, and set it on the dock
overnight, before evaluating the state of battery charge?

If you read the information I presented, you would know that a flooded battery
will settle most of the way rather quickly, and that the surface charge can be
removed by applying a load for a few minutes. Every boater should learn these
simple facts, it isn't rocket science.

If we are going to discuss
testing a battery and the results that should be expected, it makes sense to
frame that discussion around actual boating conditions.

What could be more of an "actual condition" than checking the state of charge
when you wake up after a night on the hook? Your scenario seems to be connected
to shore power. Further, if someone is interested in getting a reliable State
of Charge, they should use the methods described by all of the experts. It only
takes a few minutes to remove a surface charge; failure to do so gives a
meaningless answer.



What happens when the "surface charge"
bleeds off a battery that can only absorb 1.1 volts per cell? Probably drops
down close to 12 volts in fairly short order- a marginal level that all of us
will agree is getting rather weak.

I'm not sure what you mean by "absorb 1.1 volts" - batteries absorb Amps, not
Volts. But yes, if a battery is reading 12 Volts with no load, it is probably
either discharged or in poor health.


There's also a difference in the voltage one can expect if checking the
batteries on a trailer boat sitting in the backyard under a tarp vs a boat
that
is connected to shorepower. But in either case, at the moment when the battery
has absorbed a full and healthy charge or recharge it will
read 2.2 volts per cell. I don't disagree with a statement that later on it
may
read less.

This may be true with a given charge protocol, but it is not true in all cases.
Further, the opposite is not true at all: if you get a reading of 13.2 without
having any knowledge of the history, you can't say anything about the charge
state or the general health of the battery. This is the essential point in this
discussion. If a battery is discharged to 80%, and then you put it on a float
charger at 13.2, you won't add much (if anything) to the charge state, but
because of the surface charge you will get a reading of 13.2.

Anyone interested in learning about this should read the links I've provided, or
google on: "surface charge" battery