(ET) 12V charger recommendations

[Ken Olum <kdo cosmos phy tufts edu>]

I'm getting ready to replace the batteries in my 48V Electric Ox.
Currently I'm using UB121350 12V 135Ah AGM.  I started with a BattEQ
equalizer, which was great until it failed.  Then I used Rudman
regulators, which have not proven satisfactory.  I'm thinking to just
get 4 chargers and charge the batteries individually, rather than having
a BMS and a single charger.  Anyone have recommendations for
high-quality 12V plug-and-forget chargers for AGM batteries?  Isolation
is essential.  Temperature compensation would be nice.

Alternatively, someone could try to sell me on using lithium instead,
though the usual electric car advantage of light weight is no advantage
here.

Thanks.

                                        Ken