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George March 30th 06 07:37 AM

New battery voltage question
 
I bought a new 12V battery for the riding lawnmower.
Put it on the charger for a day and the voltage was 13.8 while on the
charger Removed from the charger and the voltage drops to 12.72.
The battery cables were disconnected.
Is this OK for a new battery?
Thanks

Mark D. Zacharias March 30th 06 12:34 PM

New battery voltage question
 
George wrote:
I bought a new 12V battery for the riding lawnmower.
Put it on the charger for a day and the voltage was 13.8 while on the
charger Removed from the charger and the voltage drops to 12.72.
The battery cables were disconnected.
Is this OK for a new battery?
Thanks



Actually, it's perfect for a new battery. Exactly what is supposed to
happen.


Mark Z.



default March 30th 06 10:52 PM

New battery voltage question
 
On Thu, 30 Mar 2006 06:37:22 GMT, George wrote:

I bought a new 12V battery for the riding lawnmower.
Put it on the charger for a day and the voltage was 13.8 while on the
charger Removed from the charger and the voltage drops to 12.72.
The battery cables were disconnected.
Is this OK for a new battery?
Thanks


Absolutely.

While on the charger the charger determines the terminal voltage. The
instant you take it off, it starts dropping (exponentially) until it
reaches its "resting" voltage.

I use 12.5 for a normal battery that has been resting for a day or so
as normal - but all batteries are a little different. A few tenths of
a volt may be normal.

You are good to go. If it is 12.00 volts after a good charge and a
day later, I'd worry about it
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JANA March 31st 06 02:55 AM

New battery voltage question
 
What you are getting is very ideal for the battery. The nominal voltage with
25% load capacity connected to the battery, it should be 12.5 Volts. The
tolerance can be about +- 0.35 Volts

The proper way to test a battery is to have a calibrated or known load on
it. Then it is possible to work out the internal resistance of the battery
to know if it is good or not. The rate of discharge for most gel cells is
that under load, they are considered discharged after they drop 10 to 12%
from their nominal voltage. To do all of this properly, you would need the
technical information for the battery.

From knowing the Ampere hours rating of the battery, and knowing the total
resistance of the load, it is possible to calculate the expected time for
the battery to discharge to 10% below the nominal. If the battery meets the
requirement or better, then it is considered to be in good condition.

In practice, a simple gel battery test would be to put a 12 Volt headlamp
across it, and at the same time take a voltage reading. If the battery can
keep roughly 12 Volts for a few minutes, then you know it should be working
okay.

--

JANA
_____


"George" wrote in message
...
I bought a new 12V battery for the riding lawnmower.
Put it on the charger for a day and the voltage was 13.8 while on the
charger Removed from the charger and the voltage drops to 12.72.
The battery cables were disconnected.
Is this OK for a new battery?
Thanks



ray13 March 31st 06 07:06 AM

New battery voltage question
 
Do yourself a favor, you got all that money invested in a riding mower
and you short change yourself with a cheap dollar store charger. Get a
Automatic charging charger that will charge the battery up fully, then
it goes into trickle charge once the battery is full charged.. A
battery that maintains a full charge will last a long long time
compared to a battery that gets over or under charged. Those are the
facts.


Rich256 March 31st 06 04:27 PM

New battery voltage question
 
George wrote:
I bought a new 12V battery for the riding lawnmower.
Put it on the charger for a day and the voltage was 13.8 while on the
charger Removed from the charger and the voltage drops to 12.72.
The battery cables were disconnected.
Is this OK for a new battery?
Thanks


For all you might want to know about batteries go to:

http://www.batteryfaq.org



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