For several years I have been impressed with this one:

https://www.amazon.com/Pulsetech-Xt...8-1&keywords=desulfating+charger#Ask

When it gets the battery fully charged,
the “trickle” cycle consumes 1 watt of power more than when the unit is on but no battery connected,
which is roughly 1/14.2 = 70 milliamps “Trickle Current”

It can charge two batteries in parallel.

I wish it had a 90% charged LED too, instead of individual LEDs for 75% and 100%,
or a 1-100% digital readout.