Sorry but WRONG on both counts.
Originally Posted by ornery
Pardon me but a fully charged battery should be 13+ volts. ALSO put a DIGITAL volt meter on the battery and just watch for voltage leak. That is see if the voltage drops noticeably. If your battery isn't holding a charge you will see the volt meter dropping. Set the meter to at least 2 decimal places and see if the voltage drops.
1. a 100% fully charged battery is 12.7 volts. The 13+ volts you see immediatey after charging is called a surface charge and is entirely misleading...as even a badly damaged battery will read over 13. This is WHY I said to set the battery aside for 24 hours to allow the surface charge to disappate BEFORE taking a reading.
2. The same applies to your "leaky" voltage. Every single battery on earth will show leakyvoltage after charging as it slowly drops form 13.2+ V to 12.7 or 12.4 or whatever its' true state of charge is. Furthermore...this has no useful purpose in tracking down minor parasitic loads because they have nothing to do with the battery not holding a charge.
Don't believe me?? Here:
Source: Trojan BatteriesBattery Testing
Battery testing can be done in several ways. The most popular includes measurement of specific gravity, and battery voltage. Specific gravity applies to wet cells with removable caps, giving access to the electrolyte. To measure specific gravity, buy a temperature compensating hydrometer at an auto parts store or tool supply. To measure voltage, use a digital voltmeter in the DC voltage setting. The surface charge must be removed from a freshly charged battery before testing. A 12 hour lapse after charging qualifies, or you may remove the surface charge with a load (20 amps for 3 plus minutes).
State of Charge / Voltage/ Specific Gravity
/ 12V 6V
100% 12.7 6.3 1.265
75% 12.4 6.2 1.225
50% 12.2 6.1 1.190
25% 12.0 6.0 1.155 Discharged 11.9 6.0 1.120 Source: Battery Charging Tutorial | ChargingChargers.com
Finally...I'd note that I use 24 hours as a wait time instead of 12 because surface charge removal is temperature dependent... the colder...the slower. In northern climates you can often come back even two or more days later and still find the battery over 12.7 (or whatever its' true SOC is).
...a cheap $20 load tester from Harbor Freight can cut the wait down to about 3 minutes.
This shows an experiment done by a friend of mine on static state of charge and the need to let a battery rest...complete with pictures. Case closed..
Measuring A Lead Acid Battery State of Charge Photo Gallery by Compass Marine How To at pbase.com