Thanks for link.

From your experience how long does a good (NOT new) battery hold its
charge?

-----Original Message-----
From: 12VDC_Power@yahoogroups.com [mailto:12VDC_Power@yahoogroups.com]
On Behalf Of Steve Spence
Sent: Tuesday, August 05, 2008 10:00 AM
To: 12VDC_Power@yahoogroups.com
Subject: Re: [12VDC_Power] Re: Forklift battery questions....

From http://www.batterystuff.com/tutorial_battery.html#6:

6. Battery Testing can be done in more than one way. The most popular is
measurement of specific gravity and battery voltage. To measure specific
gravity buy a temperature compensating hydrometer and measure voltage,
use a digital D.C. Voltmeter. A good digital load tester may be a good
purchase if you need to test batteries sealed batteries.

You must first have the battery fully charged. The surface charge must
be removed before testing. If the battery has been sitting at least
several hours (I prefer at least 12 hours) you may begin testing. To
remove surface charge the battery must experience a load of 20 amps for
3 plus minutes. Turning on the headlights (high beam) will do the trick.

After turning off the lights you are ready to test the battery.

State of Charge Specific Gravity Voltage (12V 6V) 100% 1.265 12.7 6.3
*75% 1.225 12.4 6.2 50% 1.190 12.2 6.1 25% 1.155 12.0 6.0 Discharged
1.120 11.9 6.0

*Sulfation of Batteries starts when specific gravity falls below 1.225
or voltage measures less than 12.4 (12v Battery) or 6.2 (6 volt
battery). Sulfation hardens the battery plates reducing and eventually
destroying the ability of the battery to generate Volts and Amps.

Load testing is yet another way of testing a battery. Load test removes
amps from a battery much like starting an engine would. A load tester
can be purchased at most auto parts stores. Some battery companies label
their battery with the amp load for testing. This number is usually 1/2
of the CCA rating. For instance, a 500CCA battery would load test at 250
amps for 15 seconds. A load test can only be performed if the battery is
near or at full charge.

The results of your testing should be as follows:

Hydrometer readings should not vary more than .05 differences between
cells.

Digital Voltmeters should read as the voltage is shown in this document.

The sealed AGM and Gel-Cell battery voltage (full charged) will be
slightly higher in the 12.8 to 12.9 ranges. If you have voltage readings
in the 10.5 volts range on a charged battery, that indicates a shorted
cell.

If you have a maintenance free wet cell, the only ways to test are
voltmeter and load test. Most of the maintenance free batteries have a
built in hydrometer that tells you the condition of 1 cell of 6. You may
get a good reading from 1 cell but have a problem with other cells in
the battery.

When in doubt about battery testing, call the battery manufacturer. Many
batteries sold today have a toll free number to call for help.

Steve Spence
http://www.green-trust.org

Sign up for our newsletter at
http://www.green-trust.org/newsletter/

Charlie Xiong wrote:
>
>
> Glen,
>
> A novice question for you... If to test the quality of a battery - is
to
> charge and discharge the battery - how many volts should the battery
> read on an ohm metter? And how long should the charge last (for a good
> battery) - hours/days/weeks/months?
>
> Thanks,
> Charlie
>
>
> -----Original Message-----
> From: 12VDC_Power@yahoogroups.com
<mailto:12VDC_Power%40yahoogroups.com>
> [mailto:12VDC_Power@yahoogroups.com
<mailto:12VDC_Power%40yahoogroups.com>]
> On Behalf Of Glen
> Sent: Monday, August 04, 2008 6:22 PM
> To: 12VDC_Power@yahoogroups.com <mailto:12VDC_Power%40yahoogroups.com>
> Subject: Re: [12VDC_Power] Re: Forklift battery questions....
>
> ----- Original Message -----
> From: "roadhse2" <roadhse2@yahoo.com <mailto:roadhse2%40yahoo.com>>
> To: <12VDC_Power@yahoogroups.com
<mailto:12VDC_Power%40yahoogroups.com>>
> Sent: Monday, August 04, 2008 5:30 PM
> Subject: [12VDC_Power] Re: Forklift battery questions....
>
> >
> >
> >> But as a scrap battery, who's to say what condition it is in and
so
> how
> >> many
> >> amp hours it can provide now? Seems to me you'd have to do a few
> >> charge/discharge tests to figure out how close it is to rated
> capacity.
> >>
> >> - (a different) Glen
> >
> > Thanks, i bought it from a scrap dealer...i didnt say the battery
> itself
> > was scrap...it came
> > out of a running/operating forklift....at least it was until it ran
> off
> > the end of the loading
> > dock unattended and bent the mast etc. bad enough they scrapped it
> out...
> >
> > I guess i was wondering what is the norm for amp hour capacity
> > figures....a 6 hour rate or
> > a 20 hour one...
> <snip>
> > that OTHER Glen
>
> If the forklift dropped and hit hard enough to do that, it may also
have
>
> damaged the plates of the battery. A cracked or broken plate would
> reduce
> capacity, and shaking up gunk/knocking loose plate material probably
> doesn't
> help performance either. The closest thing to a standard is the 20
hour
>
> rate but the important number is the one that best matches your
specific
>
> application, which invariably isn't anything like the manufacturer's
> numbers. That's where the calculators I mentioned come in. You give
> them
> two times (such as the 6 and 20 hours) and corresponding amp hours,
and
> then
> they can give you the approximate times for whatever amp hours you
want,
> or
> how many amp hours you should get over whatever time you choose.
>
> But again, with a used battery, and especially an abused battery,
you're
>
> going to have to experiment, charging and discharging it a couple of
> times
> and measure its performance.
>
> - (a different) Glen
>
> ------------------------------------
>
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