We are producing a redesigned version of the original dual voltage charge control / rectifier stage. This allows us to do a repair to all phase 1 and phase 2 battery chargers, and upgrade phase 2 chargers to dual voltage charge if required. The unit also includes the fan relay drive circuit, charge / display interface, and charger lock-out during engine start.
In addition the new board also features a system reset if the voltage falls low due to high load, the unit will recycle through charging service battery to 14.2 / 3 volts, then the engine batteries and finally return to float charge.

It is planned in 2008 to introduce a completely new transformer based mains battery charger to allow replacement of existing battery chargers, without compromising the systems operation.
The new charger will be 50% lighter, and feature a 5 stage charge sequence. The engine batteries are charged independently to a two stage cycle. All banks feature a pulsed maintenance phase, during which the battery charger will turn off the mains when not required, minimising mains power usage.
Fan relay control, charger / display interface, and charger lockout interface is included. Initially a 20 amp unit is planned, enclosed in a stainless steel case. It is intended to extend

Battery charger production relates back to a request by Sealine in 1983, to produce a charger that was better than the single voltage float charger then on the market. The object was to design a charger that would integrate with the switch panel / charging system. Providing power for the boat during the evening, then top up service and engine batteries over night, when demand was low, on a multi-stage format.

Production settled on a unit ( fig 1 ) that would provide a nominal 20 amp of power, for either battery charging or to power boat equipment. This was achieved by initially charging the service battery to 14.2 / 3 volt ( Westerly units were 15.2  volt see Westerly chargers ). At this point the engine batteries were put on charge and also charged to 14.2 / 3 volt,. Voltage now dropped to 13.6 volt float charge, to maintain a power supply, and avoid gassing the batteries. The system also meant  that the engine batteries were not subject to high voltage and gassing during the power supply / charge phase of the service batteries. There was no equalisation charge cycle built in, this was found to be not required ( normally falling to around 0.5 amp after 2 minutes ) due to the cycle, and charger / battery bank size. The value of 14.2 / 3 was selected to ensure an old lead acid battery would always reach a float charge trip voltage, and avoid any chance of extended gassing due to battery age. They were also fitted with a control interface, to run an extractor fan when on high charge rate to remove gas produced.

Following cost reductions introduced by Sealine in 1991, a single output float charger was introduced. This is identified by the black aluminium case ( fig 2 ) , early units were self colour, some dual voltage units were produced, spec as yellow cover identified by blue and brown interface cables. Units provided approximately 25 amp at 13.6 volt,. Boats built to this spec can be identified by the mains switch for charger on switch panel  being listed as “ shore support “, not “battery charger” as the dual voltage chargers. They included an engine start interface to drop out charger on engine startup.

1993 saw the introduction of a new dual voltage mains charger to replace the float only charger, and the float charger happily abandoned. They were made in two ratings, 25 amp ( PBO did an independent charger tests and rated it at 35 amp ) and a 55 amp unit for the 450 range. These units were also fitted with an extractor fan drive interface on high charge rate, to remove gas generated. They also included the starter motor interface, to drop out charger during engine start.