Posted by =?TIS-620?B?4s3BIMGz1SC70bfgwS on November 28, 2009, 12:52 pm
> Very conveniently, the relationship between a battery's state
> of charge and its voltage is linear (10% per 0.10V) between about 90%
> (12.70V) and 20% (12.0V). However, when a battery has been on
> charge, even if its not fully charged, the voltage will be up
> around 13.8V. This will slowly drop to around 13.6V over the next
> few hours, but even if left overnight it shouldn't drop below
> 13.0V unless the battery was only partly charged or is on the way out.
Battery manufacturers would disagree slightly.
If you charge up a sealed AGM battery, you may read
14 ~ 15 volts when you first take it off the charger, but the resting
voltage will drop down to 12.8 volts and stay there in about half an
hour, assuming that the battery was in good condition and took a full
charge.
Posted by Bob on November 28, 2009, 4:30 pm
On Sat, 28 Nov 2009 09:52:20 -0800 (PST), âÍÁ Á³Õ »Ñ·àÁ ËØÁ
|>
|>> Very conveniently, the relationship between a battery's state
|>> of charge and its voltage is linear (10% per 0.10V) between about 90%
|>> (12.70V) and 20% (12.0V). However, when a battery has been on
|>> charge, even if its not fully charged, the voltage will be up
|>> around 13.8V. This will slowly drop to around 13.6V over the next
|>> few hours, but even if left overnight it shouldn't drop below
|>> 13.0V unless the battery was only partly charged or is on the way out.
|>
|>Battery manufacturers would disagree slightly.
|>
Yer sure right about that, it's a 3 ring circus of dis/informations all
over.
It may depend on were they were made, but I did use some Chinese
"AGMs" with a holding 13.6 volts 2 hours after charging but no load....it
started with about the same cca as a 12.8 "wet" sla battery.
|> If you charge up a sealed AGM battery, you may read
|>14 ~ 15 volts when you first take it off the charger, but the resting
|>voltage will drop down to 12.8 volts and stay there in about half an
|>hour, assuming that the battery was in good condition and took a full
|>charge.
This battery is on the vehicle circuit, and not a stand alone battery on a
table....right?....a GT9B-4 12v/8Ah wants a charge at 12.v, and the Majesty
Yamaha yp400ts manual considers 12.8v as a minimal voltage, but AGMs can go
down to 12.5v before needing a recharge.
I prefer using a Shumacher 4 stage smart charger with blinding LEDs,
and it equalise/bulk/absorb charges to 12.9v/%100 and then goes into a float
maintenance mode, and goes up to a possible 17v (stubborn batt) to maintain
at least a 13.2v for regular MF/Marine/DeepCycle, and 13.4v for agm/gel
status for a specified time.
The 12.9v full charge is referred as %90 by other chargers, most
chargers, all have a slightly different but very consistent preference.
.
This float *topping mode* is good if you have time/patience with a
passive/auto smartcharger....wereas an active/constant charger feeds the
battery what it is supposed to be with no time consuming battery queries.
Bob
Posted by =?UTF-8?B?4LmC4Lit4LihIOC4oeC4? on November 28, 2009, 5:20 pm
> |> If you charge up a sealed AGM battery, you may read
> |>14 ~ 15 volts when you first take it off the charger, but the resting
> |>voltage will drop down to 12.8 volts and stay there in about half an
> |>hour, assuming that the battery was in good condition and took a full
> |>charge.
> This battery is on the vehicle circuit, and not a stand alone battery on a
> table....right?....
No, that is the open circuit voltage while the battery is sitting on
the table half an hour after charging it.
The manufacturer's literature that comes in the box with the battery
tells exactly how to fill it with the supllied electrolyte and how
long to charge it and at what rate.
Then the literature says to measure the resting *open circuit* voltage
and specifies that 12.8 volts indicates a full charge for the AGM
battery.
If the manufacturer doesn't know the right information, who on earth
would know?
If I can't trust the manufacturer to give me correct information, then
I'm at their mercy...
The last two AGM batteries I've owned lasted 8 years without problem.
Posted by R. LaCasse on February 24, 2010, 1:03 am
On Sat, 28 Nov 2009 14:20:33 -0800 (PST), ??? ??? ????? ???
|>The manufacturer's literature that comes in the box with the battery
|>tells exactly how to fill it with the supllied electrolyte and how
|>long to charge it and at what rate.
|>
They cant be regular AGM, you can't fill a real AGM, they are
hermetically sealed with no vent caps, although some Chinese brands had (do
not remove) vent caps that worked pretty good. Once you open the vent caps,
there is a cell imbalance and a great loss of power.
Real AGMs are never filled with electrolyte, but some variants ARE.
|>
|>Then the literature says to measure the resting *open circuit* voltage
|>and specifies that 12.8 volts indicates a full charge for the AGM
|>battery.
A real AGM is about 13.00volts, and the regular "immortal" 12.9v
level being acceptable.
|>
|>If the manufacturer doesn't know the right information, who on earth
|>would know?
Usually, only an auto charger or "sense-0n-demand" type charger can
be correct as to what the battery can handle. I use an Schumacher sc1200 at
2amps/AGM/ full auto modes.....mostly.
|>
|>If I can't trust the manufacturer to give me correct information, then
|>I'm at their mercy...
Some won't admit they have an AGM config, since their battery
chargers don't top-up an AGM properly so they dick around with Yuasa
fumion/polimion/yumion wordings to confuse..somebody....Ztong calls them
AGM!
GS on the other hand calls all their GT*****/GT9B-4 ALL
AGM....GT=AGM, they finally admitted that in their 2007 catalogue status.
|>
|>The last two AGM batteries I've owned lasted 8 years without problem.
That is exceptionally good for an AGM..lemme guess ....left on
charge all night every night for 8 years....that would work, except for
street parking lot parkers like me with a 8amp battery.
--
National Association of Assault Research
Soul Yamaha Majesty400 2005, Grey, Night Rider!
http://*remove*tarbitch.balder.prohosting.com/scooter.html
http://*remove*pages.istar.ca/~vampire/YamyMajesty400.jpg
Bob
Posted by S'mee on December 1, 2009, 12:13 am
On Nov 28, 10:52 am, âÍÁ Á³Õ »Ñ·àÁ ËØÁ <macmi=
...@gmail.com> wrote:
> > Very conveniently, the relationship between a battery's state
> > of charge and its voltage is linear (10% per 0.10V) between about 90%
> > (12.70V) and 20% (12.0V). However, when a battery has been on
> > charge, even if its not fully charged, the voltage will be up
> > around 13.8V. This will slowly drop to around 13.6V over the next
> > few hours, but even if left overnight it shouldn't drop below
> > 13.0V unless the battery was only partly charged or is on the way out.
> Battery manufacturers would disagree slightly.
> If you charge up a sealed AGM battery, you may read
> 14 ~ 15 volts when you first take it off the charger, but the resting
> voltage will drop down to 12.8 volts and stay there in about half an
> hour, assuming that the battery was in good condition and took a full
> charge.
If you posted it it's either a LIE or you plagerized it...
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> of charge and its voltage is linear (10% per 0.10V) between about 90%
> (12.70V) and 20% (12.0V). However, when a battery has been on
> charge, even if its not fully charged, the voltage will be up
> around 13.8V. This will slowly drop to around 13.6V over the next
> few hours, but even if left overnight it shouldn't drop below
> 13.0V unless the battery was only partly charged or is on the way out.