These settings work great for batteries that haven’t been sulfated at all.  Newer and well-treated batteries will charge and receive their near-rated charge levels with that type of charge regime.  However, overheat the batteries, dry them out or leave them without recharging for long enough and sulfation happens.  After that, the batteries will not charge fully and may not accept charge at all without radically changing the charge profile.

Sometimes this means applying up to 100vDC to a 12v battery just to get some current to flow, then carefully monitoring for voltage, current, heat, smell.  Once current starts flowing, the voltage drops quickly, however it doesn’t drop into the usual “rising voltage with charge current” curve.  Rather, the voltage “drops with charge current” over time.  And this makes sense because you’re dealing with a battery that has developed high internal resistance and as it warms up and recombines sulfated material, the internal resistance keeps dropping.  Charge algorithms are not designed to deal with this as far as I understand.  Maybe the only ones that come close are ones that have a high freq/high volt “pulsed” mode for desulfating.  But even then, in my experience, once a battery gets into this state, it seems they never get back into the usual charge curve.  And so these chargers/maintainers really don’t help and indeed do the wrong thing.  And that’s too bad, because the only way to keep these batteries healthy and alive is quite a bit of manual work and close observation to avoid dangerous overcharge/overtemp situations.  The alternative is to accept drastically low capacity or to throw the batteries out.

Anyway, enough on this I suppose.  Ditch lead-acid and you won’t have to deal with this anymore J .

-MT