Bought one of the "newer" microprocessor controlled battery charger/maintainer/engine starter combo yesterday. Specifically the Schumacher xc75. Just wanted to hear some opinions on these versus regular battery chargers (i.e. older or more traditional).
The reason I am asking- I have it hooked up to a 75 group 660cca megatron II from interstate. I pulled the battery from my truck after a failed start, and found it had 10.67 volts. The battery is just 2 years old, however I believe I left some interior light(s) on the night before. Reading the manual it suggests a 12-23 hour charge for my battery at the lowest setting given the battery was at least 50% charged to begin with. (I'm not going anywhere anyway...) so I decided to give it a go. It has been on the charger for about 10 hours so far, and it has only charged 11%, according to the charger display.
Are there any real gains to be had from this type of computer controlled slow charge versus the trickle charge my old diehard used to give (in way less time)? I hear this charger also "de-sulfates" as it charges, any truth in that?

 

I have a similar charger & I love it. I use it for the blazers battery & the deep cycle batteries for my boat. Only issue I have with it is if the battery is totally dead, as in you left the headlights on all night, it won't detect the battery & then it won't start charging. The way I found around that is to hook up another battery via booster cables to trick it into seeing the dead battery. After a min remove the cable & it continues charging.
I hooked it up to a battery in one of the forklifts at work & it went into recondition mode, seemed to work well & the battery now accepts & holds charges.

It does seem to take longer than a typical charger but then again being a "smart charger" in auto mode it only gives what the battery is 'conditioned' to take for a charge.
I'm not sure on your model but it does make sense (in battery talk) to charge slow/optimally for the best conditioning & capacity for a battery.
An old school way of de-sulfating a battery & it can be somewhat dangerous is to take it outside protected from weather but a well ventilated area. Hook it up to a regular charger, set it to its highest charge & let it "boil" for a few hours. ALWAYS unplug the charger before disconnecting the battery in this case for sure, because of the gasses & explosion risk!!! Then set it to a trickle charge overnight. Google it to be sure of the steps.

 

Yeah I miss the old charger that would boil off batteries, I also used it for electrolysis several times for an HHO project. This new charger doesn't do that. It takes like 5 seconds to determine (like you said) what it is connected to, and then makes a decision on what type of charge to use. You can override it, but it still shuts down automatically. This particular model measures (I probed it with the Fluke) 4~7 volts on the low setting - on and off over the course of a few hours, and 16~17 volts constantly on the high.
I did however notice one problem in my initial testing, I have many (about 30) batteries from collecting various junk over the years, and it doesn't seem too keen at sensing 6V AGM batteries. I have about 6 of them, and on 4 of them it tries to use it's 12V mode. I am not sure if this is intentional or not, and it may actually take a couple of minutes to switch back to 6V. Either way, I just unhooked the battery and I was going to see if it holds the 13.4V that the charger brought it up too after 14 hours of charging.
Also, i did get an F02 error code from the charger -unable to desulfate- so I am not sure if my results will be the same as others.