Originally Posted by btrayfors
I don't have any objectively verifiable evidence, but from "feeling" and from comments made by battery manufacturers who have collaborated in some of my research I believe there is reason to believe that charging the batteries as fast as they will accept current is good for them.
This may or may not be due to internal bubbling which could help avoid stratification of the electrolyte and, possibly, speed up the process of dislodging loose PbSO4 deposits on the plates.
Maybe MaineSail has a view on this.
I think having both types of charges available is often best. This can be especially true with thick plate deep cycle batteries where high charge current tends to build surface charges that don't penetrate the plates as effectively as a slow charge will.
The fast charge will "shake" things loose, limit stratification and with good voltage can help to minimize sulfation.
On the other side a good slow charge of a thick plate deep cycle battery is perhaps the best way to get it chuck full and push the charge deep into the plates. Mixing things like wind & solar with high amp charge sources can be a productive way to handle batteries..