Multiple Smaller Batts VS Fewer Larger batts?

Re: Multiple Smaller Batts VS Fewer Larger batts?

The idea behind equalization is that not all cells in a battery bank perform identically. Some cells may be at 100% capacity and other cells may be at 80% state of charge.

There are two problems with unbalanced cells... First is that if you deep cycle a battery, the low cells will hit zero volts first, and if taken deep enough, actually reverse voltage and begin to "reverse charge"--pretty much destroying the cell/battery.

The second is that sulfates begin to harden if the cell is kept below 75% state of charge for days or weeks at a time... If you have your battery at 90% state of charge and one or more cells at 20% lower charge level--those cells may begin to sulfate and ruin the battery AH capacity over time.

When you equalize a battery bank--You are effectively overcharging most of the series connected cells to get charging current into those few cells that are at 80% state of charge. Yes, you are overcharging the "good cells" (overcharging is hard on cells too) to get enough current into the "low cells" to bring them up to 100% state of charge too.

Equalization is not needed for a group of parallel connected cells as they all see the same charging voltage (although, "equalization" to cause gas formation is used to "mix" the electrolyte in the battery banks too--if you have "tall batteries", they tend to "stratify" the acid--dense acid at bottom of cell, light mostly water at top of cell--so even parallel connected cells can use equalization to mix too). However, since nobody has a 2 volt battery bank, we always have series cells in any useful bank (12-48 volt is 6-24 cells in series)--so we all have to deal with equalization (couple times a year to once a month or so is typical recommendation. Usually only equalize if cells measure unbalanced voltage of 0.030 volts or specific gravity out by 0.030 or more).

-Bill