Warning...long post ahead!
Originally Posted by PokerDealer
Yes, equalizing is for sulfation, some manufacturers recommend once a month, Trojan recommends "as needed"....
Let me put the bottom line at the top.
Keep your batteries watered and charged and if stored without use for a long period of time, discharge them a little and hit them with a boost charge level for a while to re-mix the electrolyte. Under charging is worse than over charging. If they need water frequently...SOMETHING IS WRONG!
Real equalization has a very specific purpose and de-sulfation is somewhat different. Each charger or converter vendor likes to mix the terms and refer to their "special sauce" in whatever way they want.
We all benefit from the growth in alternative energy here. That is where all these fancy microprocessor controlled converters and chargers come from. Sure we might have 2, 4 or 6 batteries, but solar and wind installations could have tens or even hundreds of units...and they never get jostled by bumps moving down the road!
There are really only a few things that we can do to manage and keep flooded lead acid batteries at their peak.
1) Check the electrolyte level and CHARGE THEM. This is by far the most important thing to do. Try not to use more than 50% of their rated capacity and if you go beyond that, get them charged back as quickly as possible. In the normal discharge cycle, sulfate will form on the lead plates and re-charging removes it. Deeper discharge will form actual sulfate crystals which are harder to dissolve with recharge. Remaining sulfate will permanently remove some of the battery's storage capacity.
2) The acid in the cells of fully charged batteries that sit for a period of time can "stratify" with higher specific gravity solution migrating to the bottom of the cell and lower specific gravity electrolyte forming at the top of the cell. This stratification can be worse when the cells are not used and the battery is totally stationary (like in solar and wind systems.) A stratified battery will show a high charge since the acid is even more concentrated at the bottom of the cells, but be unable to supply current for a long period since the top of the cells is really in water. Mixing the electrolyte is simple, just hit the cells with enough current to form hydrogen bubbles and the bubbles rising to the top will re-mix everything. Progressive Dynamics and others provide this function by going back to 14.5 volts every once in a while, even if the battery is fully charged. PD does it every 21 hours when the unit is in storage mode (13.2 volts.) Solar charge controllers tend to do this every 15 minutes or so for a much shorter time since, obviously, in 21 hours the sun may no longer be shining! The de-stratification cycle is short enough that it doesn't boil electrolyte but re-mixes the acid solution. Some vendors throw the "equalization" label on this function (along with de-stratification and de-sulfation) but it is too low a voltage and too short a time to actually be called equalization. This will no more cure the need for equalization than the 2 hour recharge cycle the last time you used significant battery capacity. But then...you may never need equalization anyway!
3) True equalization is called for "as needed," and is designed to get all cells to exactly the same state of charge. If you need it, it is indicated by measuring the specific gravity of each separate cell and comparing them all. Equalization hits cells with a very significant over voltage (Trojan recommends 15.5 volts) for a long enough time so that all cells equally charged and brought to the exactly the same specific gravity. Equalization is a tough process and most vendors do not quote a frequency. In fact, Trojan indicates to only do it on an "as needed" basis and as a manual process. Banks with parallel current paths will be more susceptible since some cells may be starved for discharge/charge cycles by alternate current paths of lower resistance. Some banks never need it and if they do it is a once or twice a year kind of thing.
Most modern battery chargers have 3 output levels, the highest to boost the battery back from discharge (14.3 to 14.6), a lower one to finish the charge and supply the 12 volt loads that are also attached(13.6 or so) (after all these are converters
and not just chargers!
and a low trickle level to keep everything up and overcome storage loss in the batteries (13.2.) Vendors will talk about de-sufation, equalization, de-stratification and bulk charge in a variety of ways. Automatic equalization (15.5 volts) for any significant length of time is not recommended as it boils away too much electrolyte.