Winches for every use, a microwave, entertainment system and a myriad of navaids is not uncommon even onboard 32 footers.

However, all too often the electrical infrastructure cannot cope.

Gone are the days of using a couple of "heavy duty truck batteries" and an automotive battery charger. These days, owners want to run everything - and more - and concentrate on their leisure time. Today's owners simply won't put up with dim lights and warm beer!

Currently, owners generally end up retro-fitting battery management products to overcome difficulties that the yacht builder should have foreseen.

Larger battery banks, alternator controllers and shore power systems are big sellers amongst retro-fit specialists. Many thousands of pounds are spent on such equipment but many boatbuilders won't believe that owners will spend money on electrical upgrades.

A wide range of battery management products exists, including alternator controllers, battery chargers, monitors, etc.

However, various recent new developments are likely to make a major impact on the marine industry.

Split charging devices Boats with multiple battery banks and charging sources need to split charge to the various battery banks on board.

Up until now only two methods have been available - split charge diodes or relays.

Each charging source - alternator, charger, wind generator - would need its own diode/relay.

Ever increasing domestic battery bank capacities mean that blocking diodes are rapidly becoming inappropriate for many electrical systems - especially when coupled with charging systems that introduce higher voltages.

Take a typical scenario - a yacht returns to the marina after a long sail. The engine battery is full while the 500AH domestic battery bank is flat.

Once plugged into shore power, the charger starts to replenish the domestic battery. During the "bulk" charge mode, voltage is increased for five hours at 14.8V with a blocking diode distributing power to the engine and domestic battery banks.

While the domestic battery charges happily at 14.8V, the engine battery only needed a "float" voltage of 13.5V.

Result: Engine battery is subjected to the same 14.8V over five hours and after a few weekends of the same, it boils dry.

Another issue with blocking diodes is that they can introduce voltage drop - making fitting of an alternator controller essential. However, a number of manufacturers produce "electronic" diodes that have zero voltage drop.

Split charge relays prevent "force feeding" of engine batteries but require a signal to switch on - usually the D+ terminal on the alternator (once the engine is running, this terminal becomes positive).

However, each charging source needs its own relay and switch on signal.

New technology is now available that overcomes the disadvantages of both methods. Known as battery combiners, voltage sensitive relays and pathmakers these devices are complete split charge management systems.

In a twin battery bank system, the combiner is connected across both batteries. Once it senses that either battery is being charged (by voltage rising), it will parallel both battery banks together.

Once voltage drops below a pre-set level, it un-parallels them. Combiners are generally available for two, three and four-bank systems and can handle an infinite number of charging sources.

Benefits include simplified larger electrical systems, resulting in lower installation costs for builders. Owners also like them as they can pile on charging sources without worrying about splitting up the charge.

"Smart" alternators Last month's electrical article outlined how automotive innovations are affecting marine electrics. Here's another one - the OEM "smart" alternator.

Thanks to European Vehicle Emission Legislation, engine manufacturers have tied alternator operation into vehicle engine management systems.

This allows the management system to cut out alternators when maximum power is needed for moving the vehicle, such as when driving uphill.

The same could happen when a boat is accelerating to get on the plane.

These alternators are bound to find their way into the marine industry.

Bosch, Valeo and Autocraft already supply such alternators. They differ by having a microprocessorcontrolled, built in regulator.

Apart from a B+ (positive output) terminal, they feature only a computer style data plug. No D+ terminal exists and bypassing or piggybacking onto the brushes interferes with the engine management system.

This spells bad news for retrofitting alternator charge controllers - a thriving niche industry within both the marine and automotive markets.

This change is also likely to affect split charging systems.

As these alternators do not have D+ connections, you cannot drive a split charge relay from them, which means a voltage-sensitive relay, or zero loss diode, is needed instead.

Power factor corrected battery chargers When CE marking was imposed on the British marine industry, we all invested huge resources to ensure that products and installations conformed.

The marine electrical market was no exception:

Electromagnetic Compatibility and Low Voltage Directives were major hurdles.

The latest barrier preventing battery charger manufacturers getting on with their jobs is a new directive relating to Power Factor Correction (PFC for short).

PFC is an extremely complex subject, but one which has major bearing on the market.

Basically PFC is concerned with how an AC powered appliance draws its current.

In the case of battery chargers: a PFC charger will draw power evenly and smoothly throughout each mains cycle. Non PFC chargers draw nothing for, say, half a cycle and then take an enormous spike.

The effect is that generator windings, circuit breakers and isolation transformers overheat or trip out faster.

These current draw spikes cannot be measured on a standard multimeter as they show only average readings.

The largest benefit of PFC chargers is that they are much more efficient - you can use a larger charger for the given generator/shore power capacity - a must for boats with ever increasing battery bank capacities.

All battery chargers have to have full Power Factor Correction. Currently only two or three manufacturers have full PFC on some of their chargers.

Deadline for the new CE mark was January 1, 2001. . ? Inspectors are currently focusing their attention on mass market domestic goods? DC to AC inverters DC to AC power inverters simply and silently convert 12 or 24V DC battery power to 230V AC mains electricity.

New inverters are compact, lightweight and extremely efficient. In fact, running standard 230V domestic equipment from an inverter uses considerably less power than DC equivalents.

This goes for most televisions, microwaves and some fridge compressors.

Until now AC generators and inverters have been separate devices, mainly because higher loads - electric galleys, aircon, etc - simply pull too much current from a battery bank.

However, many boats are fitted with both so that, at night, TV's and videos can be run silently.

Until now generators had to be rated for the maximum surge load they would run. A 5kW aircon set surges at 10kW, therefore a 10kW generator would be the minimum needed. However, new inverters from Trace and Victron have "generator support".

Generator support (GS) inverters are based on combi technology - a battery charger and inverter - with changeover switch - in one box.

When mains is available from the shore/generator it acts as a three stage battery charger.

When the AC power disappears (shore power disconnected/ generator shutdown), the unit automatically switches over and becomes an inverter.

GS units also feature additional circuitry that allow them to monitor the AC system. When it senses that the generator (or shore power) is becoming overloaded, the unit will switch on its inverter to boost up the AC system.

This means that a smaller AC generator/shore power supply can be used to run airconditioning or electric galleys.

A typical scenario could be on board a boat with a 5kW aircon set that surges at 10kW, 5kW generator and GS inverter.

At anchor, the owner switches on the generator. The GS unit starts to charge the batteries from the AC supply.

The owner then switches on the aircon. Instantaneously the GS unit switches to inverter mode and synchronises up with the generator to provide the 10kW surge needed.

Once the aircon is running, the GS unit reverts back to charging the batteries.

Cute - especially when you can half the size, weight and cost of the AC generator.

GS technology sounds extremely complicated. But tangles of sense wire and battery cable won't happen.

Because the unit is inserted within the AC system all sensing and switching is taken care of inside the unit's own case.

Where boatbuilders need to maximise space for accommodation and reduce building costs, the GS style inverters are sure to be a great success.