Post by Telemachus on Nov 1, 2016 14:10:19 GMT
Out of interest this is what the well respected BatteryFAQ website has to say about Absorb and Float
"9.1.2. The ABSORPTION stage is where the charger voltage, depending on the battery type, is constant between 14.1 VDC and 14.8 VDC at 80° F (26.7° C) and the current decreases until the battery is fully charged, which is typically the last 20% of the recharge. For wet batteries, gassing (making a bubbling sound) usually starts at 80% to 90% of a full charge and is normal. A full charge typically occurs when the charging current drops off to 2% (C/50) or less of the AH capacity of the battery and each cell of a wet battery is moderately gassing equally. For example, end current for a 50 AH (C/20) battery is approximately 1.0 amp (1000 milliamps) or less. If the battery will not "hold" a charge, the current does not drop after the estimated recharge time, and a wet battery is hot (above 125° F (51.5° C)), then the battery may have some permanent sulfation. (Please refer to Section 16 for more information about sulfation and how to remove it.) Manual two-stage chargers that have a bulk and absorption stage must be turned off when the battery is fully charged to prevent overcharging.
9.1.3. The optional FLOAT stage is where the charge voltage, depending on the battery type, is reduced to between 13.0 VDC and 13.8 VDC at 80° F (26.7° C), held constant. It can be used indefinitely to maintain a fully charged battery to overcome the natural self-discharge of the battery. The current is reduced to approximately 1% (C/100) or less. Three-stage "smart" chargers usually have the bulk, absorption and float stages. (Please refer to Section 13 for more information about storing batteries and continuous float charging.)"
I pretty much agree with all of that. Although where is says "The current is reduced..." I take it to mean as a result of the battery's demand, not the charger's max output. The important point is that float is not entered until after the battery is fully charged, and that float is a maintenance function.
"9.1.2. The ABSORPTION stage is where the charger voltage, depending on the battery type, is constant between 14.1 VDC and 14.8 VDC at 80° F (26.7° C) and the current decreases until the battery is fully charged, which is typically the last 20% of the recharge. For wet batteries, gassing (making a bubbling sound) usually starts at 80% to 90% of a full charge and is normal. A full charge typically occurs when the charging current drops off to 2% (C/50) or less of the AH capacity of the battery and each cell of a wet battery is moderately gassing equally. For example, end current for a 50 AH (C/20) battery is approximately 1.0 amp (1000 milliamps) or less. If the battery will not "hold" a charge, the current does not drop after the estimated recharge time, and a wet battery is hot (above 125° F (51.5° C)), then the battery may have some permanent sulfation. (Please refer to Section 16 for more information about sulfation and how to remove it.) Manual two-stage chargers that have a bulk and absorption stage must be turned off when the battery is fully charged to prevent overcharging.
9.1.3. The optional FLOAT stage is where the charge voltage, depending on the battery type, is reduced to between 13.0 VDC and 13.8 VDC at 80° F (26.7° C), held constant. It can be used indefinitely to maintain a fully charged battery to overcome the natural self-discharge of the battery. The current is reduced to approximately 1% (C/100) or less. Three-stage "smart" chargers usually have the bulk, absorption and float stages. (Please refer to Section 13 for more information about storing batteries and continuous float charging.)"
I pretty much agree with all of that. Although where is says "The current is reduced..." I take it to mean as a result of the battery's demand, not the charger's max output. The important point is that float is not entered until after the battery is fully charged, and that float is a maintenance function.