We have recently replaced our domestic bank of batteries. We now have 4 X 105 Ah Varta LFS105. These are Calcium/Calcium maintenance-free. The battery charging
is either shore power/generator through a Victron Multi 12/2500/120 inverter/charger, or a 75 amp alternator
controlled by a Balmar
MaxCharge 614 controller. At the moment, the absorption voltage on both systems is set to 14.4 Volts. Both charging
systems have temperature sensors and voltage sensors at the batteries for temperature and voltage compensation to limit gassing. Recent research
on the internet
indicates that Calcium/Calcium batteries can be charged at a significantly higher absorption voltage than Lead/Antimony batteries, whose maximum is 14.4 Volts. Queries to battery
dealerships and equipment
suppliers have produced advice that Calcium/Calcium batteries should indeed be charged at higher voltage than 14.4 Volts, but the advice has varied from a low of 14.7 Volts to a high of 16.0 Volts.
Indeed, as Lead/Antimony batteries have now been almost completely removed from the market to be replaced by Calcium/Calcium batteries, it is perhaps timely for most boat owners to be questioning whether the advice they have been given concerning charging voltages is still extant; persistent under-charging causes premature battery failure just as much as over-charging.
Of course there is the possibility that, because most charge controllers are set to a maximum of 14.4 Volts, battery manufacturers / distributors / salesmen are reluctant to advertize the use of higher charging voltages because then most boat owners would have to go out and buy new charge controllers.
I would like to point out that I am following the convention whereby the term "Calcium/Calcium" refers to batteries which have Calcium re-enforcement in both grids, rather than Lead/Calcium where one grid has calcium and the other could be Antimony, Selenium or even Silver.
Despite considerable research
, I have been unable to find a single
authoritative source on the subject. Should anyone have definitive information on the subject, I would be grateful for details of the source.