Adverc split battery charging solutions and
Alternator Controllers - For better battery performance
 

Low battery performance poor charging, and limited availability of DC power. These battery problems are usually exacerbated by long periods of no charge followed by high demand for power such as starting and daily running. Overcharging or boiling the batteries is also a potential problem.  Car type alternators, as fitted to most marine engines are faced with many challenges and ultimately are ineffective.  Similarly single battery solutions for both starting the engine and use of services is an ineffective way of managing the demand of power on board.  A special solution is required which includes split batteries and a more efficient, intelligent charging system.

Whether you own a yacht or a powerboat, the challenges and requirements are the same.  Sailing boats use the engine less so need an efficient charging solution to maximise battery charging for the limited time the engine is running.  Motorboats tend to have more heavy duty electrical equipment such as, more powerful inverters, anchor windlass, and hydraulic operated systems such as gangways.

Efficient discharging
Splitting the batteries means one battery is dedicated to starting the engine, whilst the other feeds the services.  To charge the split batteries, they need to be connected to the alternator when the engine is running and disconnected from one another when the engine is not running.  Two methods are available, using relay or diode solutions. 

Efficient charging
For optimum charging efficiency, Adverc battery management creates a system with battery voltage sensing which overcomes voltage losses in the system such as long cables and split charge diodes.  Adverc also monitors the temperature and adjusts the charge rate accordingly.  This charges the batteries quickly, it does not allow overcharging to occur because it senses the charge and temperature around the batteries at all times.

Here is a more detailed, technical explanation.

An alternator controller solution will be available to ensure improved alternator performance with high integrity battery selection and charging.

Consider the battery on a sailboat.  It sits around for extended lengths of time, days, weeks or even months, unused, slowly discharging itself as all batteries do, then the owner arrives, fresh, full of enthusiasm and raring to go on an extended night trip.

The battery (or battery bank) may have to start the engine, run the fridge, the diesel heating system, the Nav lights, autopilot, stereo, Navtex, VHF, etc and the engine gets switched off after about 15 minutes once outside the marina entrance.  The next 12 hours are through the night sailing.  Little wonder that at 3am the engine has to be started to “save the situation”.  You will be very glad that you fitted a separate engine battery, but did you have the splitter switch in the right position to ensure it was charged or did you forget to split the batteries so that you have not run them all down together. You are then even more grateful to yourself for buying the small petrol generator to run the battery charger to charge the battery to start the engine, so the Nav lights come back on.

Motor boats are not necessarily exempt from battery problems either.  Whilst the engines run for longer and therefore the alternator(s) charge for longer, the amount of electrical power needed by a motor boat in its berth has crept up.  Examples are more intense interior lighting, some have two fridges,  maybe larger stereo’s, etc.  Motorboats tend to have more heavy duty electrical equipment such as, more powerful inverters, anchor windlass, and hydraulic operated systems such as gangways.  So whether you own a yacht or a powerboat, the challenges and requirements of battery charging and use of power are the same. 

Consider the battery in your car.  The engine runs, the battery gets charged for the whole journey, there’s little taken out of it as the engine starts easily and other than lights there are no fridges, etc to power.  The car may be run just about every day therefore the battery never self discharges.  This could be where we get our expectation of what our boat batteries should do.

Splitting the batteries and having one battery dedicated to the engine is recommended, either using a diode or a relay.  Diodes are good, there are no moving parts, they sit in circuit allowing charge from the alternator to go into both batteries and once the engine is off they don t allow one battery to pull down the other as charge can only flow on way through.  However they are semi conductors and are damaged by heat (hot engine rooms) and voltage spikes.  A simpler but effective method of split battery charging is to use a relay.  They are cheap and simple however the disadvantage is that with the use of a mechanical device the extra current required from the alternator field circuit to power the relay coil.  Heavy consumption from items like the windlass could draw large currents through the relay from the engine start battery due to the services battery being in too low state of charge.  This scenario in particular occurs when leaving an anchorage when the services battery is low and the windlass is operated.

When the batteries regularly run flat we tend to assume the answer is to throw more batteries at the problem. This is not the answer.

What we need to do is look at how we charge the existing ones.  First of all it is important to know that you only get to use about 50% of the available charge you can get the battery to take.  Therefore a 100 amp hour battery will only be charged to about 70% by a standard car alternator (those are the ones fitted to boat engines).  That gives us 70 amp hours, not 100 of which we actually only get to use 50% of that, i.e. 35 amp hours.  It can be seen that for a given battery we can only influence one thing, i.e. the amount of charge we can get into it.

Fifteen minutes of engine running is a drop in the ocean compared to what the battery really needs.  Couple with this some other facts such as you might have to remember to put the switch in the right position, the length of the leads from the alternator to the battery bank and you can see that you are achieving very little and you shouldn’t be surprised when the lights go dim.

What about a system that measures the voltage at the battery and not at the alternator output, this would overcome the losses in the cables, indeed you could put a diode splitter into the circuit instead of the switch and the diode losses are also catered for.  This way each battery bank takes whatever charge it needs and cannot be discharged by being connected to the other battery.  In other words you can have a dedicated engine start battery and a dedicated domestic battery, automatically charged and the domestics don’t discharge the engine battery.

To do this you need an alternator controller as the field windings of the alternator need to be controlled by a device other than the alternators inbuilt regulator.

With intelligent alternator controllers you can get even more benefits.  The alternator can be controlled in such a way so as to boost the charge into the batteries. i.e. we can get more than the 70% charge level mentioned earlier and we can achieve this over a shorter time period than with the standard alternator. Over 95% charge is achievable with good condition batteries and the intelligent part of the controller ensures that the batteries are never boiled.

This means more efficient charging of more than one battery to a higher charge level over a shorter period of time.  This increases the chances of getting the both the engine to start and the other electrical appliances running all night.

Intelligent alternator controllers are wired in such a way that if they fail then the original alternator regulator takes over.  Whilst you may be back to square one you are at least getting some charge rather than none at all.

BoatWide can supply and give support for the Adverc range of Intelligent Alternator Controllers.

They can be fitted to just about any alternator, 12v and 24v positive and negative earth systems and provide a superb level of service and peace of mind.  After fitting, batteries with charge level indicators begin to show “fully charged” status not seen since the battery was new.

We have supplied three options, first split battery charging using a relay being the most cost effective solution.  Then two other options which include splitting the batteries by your preferred method, solutions two and three include an Adverc controller system.

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