Shore Power Charger
Very few 48V AC chargers were available in 2020. Fewer were suitable for marine use. A 48V charger was offerred by the battery supplier, Lithium Battery Power, but inaccuracies on the web page and warnings on the web page and the use of aligator connections did not inspire confidence. The auxilliary motor supplier, Electric Yacht, offerred two lines of charger, QuickCharge and Delta-Q IC1200. The QuickCharge line is based on a large transformer and has very limited programability with no mention of changing voltage threshholds. The Delta-Q line is programmable but only by a distributor and for a $150 fee. It is not custom programmed but rather one of a set of existing programs is selected by the distributor.
A 48V Delta-Q charger was purchased. This is their IC-1200 charger. Unfortunately charger setup for Delta-Q chargers is highly proprietary. If buying in the US, after purchase the charger must be programmed for a fee of $150 by Delta-Q's US distributor who in turn requires information beyond what is available from manufacturers spec sheets. None of this information is actually required to program the charger and if Delta-Q was not so secretive could be handled by many end-users, particularly ones with degrees in electrical engineering and over 30 years experience, like me.
After over a month of back and forth email some of the limitations of the programming service and the charger itself was revealed. Custom charging profiles are only created for OEMs (those purchasing at least hundreds of chargers). For consumers, a review of the charging requirements is done, actually a computer search of existing profiles, and an existing profile is selected. Then the charger can be shipped to the distributor to have that charge profile added to the charger and selected.
The 48V Delta-Q IC series chargers can only reach 58.8V. There are a limited number of charge profile numbers, apparently limited three decimal digits. Delta-Q wants a single mapping of charge profile number to actual charge profile hence the reluctance to create new profiles for end users. The charger itself can only hold a small number of profiles, about a dozen, creating the reason to return the charger to get "programmed". This is a bad design that has created a bad situation for users. Reserving a single charge profile number for "custom" might solve it but Delta-Q appears to see no reason to solve the problem.
The charge profile selected was one that set the absorbtion voltage to 58.8V, the highest voltage the Delta-Q IC series charger can support. Until 58.8V is reached the charger will provide 25A (6.25A for each of 4 strings in the 48V battery bank) at whatever voltage it can reach. After reaching 58.8V, the charger will cease charging if less than 3A (0.75A per string) charge is being absorbed. It will also stop charging after 12 hours. After the charger stops charging it has to be power cycled to start charging again.
Eventually I figured out how the charge program on the Delta-Q chargers gets set. The charger has to be shipped to a location on the west coast where they will pick an existing charge profile which is closest to the parameters you are asking for and install it and charge you $150 plus shipping for this service. Only for an OEM who would be buying at least hundreds of chargers would they create a new charge profile. The chargers themselves can only hold a limited number of profiles so the factory only loads a few common ones that cover some AGM batteries. This is a major drawback of the Delta-Q chargers.
In retrospect purchasing the Delta-Q charger was a mistake. More 48V chargers are now available. Waiting a few years for better chargers to become available didn't seem like an option at the time of purchase in 2020.