Newby needs definition for Equalization, float, absorb, bulk as related to batteries.

[AZFIREBALL]

Can anyone point me to the definitions for Equalization, float, absorb, bulk charge as related to solar batteries?

[Mike90250]

Solar PV batteries, car batteries, forklift batteries all take the same basics. Some of the voltage setpoints change half a volt or so, but nothing major. The battery manufacturer has the bottom line on how to treat their batteries.

The Battery FAQ has on this page http://jgdarden.com/batteryfaq/carfaq9.htm
the specific answers I believe .

[PNjunction]

That link has some great info. To go along with it, how about a loose light-hearted analogy for a CV Constant-Voltage charge ...

Consider being invited over to a holiday meal, and you are hungry (discharged).

At the start of the meal in the BULK stage, you are gobbling down food (current) as fast as it is brought to you. There are limitations to this stage, as eating too slowly means you will be at the table for days, or too fast and you barf on your host. These are the manufacturers limitations, typically for FLA batteries, C/12 minimum to C/8 maximum current. Too slow and you stratify. Too fast and you overcharge and vent.

As you eat, your terminal voltage rises. It will try to rise to equal whatever your charging source voltage is set at. To help you from blowing out a gut from overeating, a charge controller (belt) is used. Once the terminal voltage rises to closely meet the charge controller voltage setting, (your belt is now tight), yet you are still not totally full.

Enter the Absorb stage. With the belt preventing you from blowing a gut (the bulk voltage setting), you are still able to absorb a little bit of pie. You no longer gobble it down quickly, but now eat slower and smaller with each bite because of the belt/CC limitation. Once you have slowed down so much that you dread even one more bite, you are done. The important point here is that it is NOT the belt (CC) regulating your eating habits, but you, the battery itself! The belt is your only limitation, and is what forces you to eat slower. Without any restraint to signal to you to stop of your own accord, (no belt/CC at all or set to too high a voltage), you would just pop.

Float would be somewhat akin to snacking to compensate for parasitic drain, age etc after eating a full meal. Hours after the main meal, you notice that you are just a tad bit hungry yet again, so you snack with a much lower set voltage, again limiting how fast you are going to eat it.

EQualization is a forced *limited* overcharge in an attempt to balance out the cells. For example, a typical 12V battery has six 2-volt cells in series. Over time, or due to bad installation, some cells are fully charged, and others are not. When charging normally, the better cells are always slightly overcharged, and the bad ones never truly get a full charge. A forced EQ will purposely waste a little bit of the good cells in an attempt to bring the low ones up. Not all batteries can handle an EQ, like most AGM's, but there are a few exceptions.

Ok, after reading this I think I may have gone just a bit off the deep end. <grin>

[inetdog]

Ok, after reading this I think I may have gone just a bit off the deep end. <grin>

Equalization as applied to the production of pate de fois gras?

Just for grins, in the early days of production of NiCd batteries in sealed small cell configurations a US military lab took some 1AH NiCd D cells and subjected them to a "safe" .05C overcharge for several months. When tested at the end, they were perfectly functional 2AH cells. (The conservative design had some extra electrode material to help deal with recombination of gas produced during overcharging.)
This does not work for Lead-Acid chemistry!