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Alternator Information
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Alternator Information

The problem

Standard alternators are not designed to be good battery chargers; they are designed only to charge an engine start battery sufficiently to start the engine. Because of this inherent design problem associated with the standard regulator, a more advanced regulator is required which in effect converts the alternators from a constant voltage power supply to the latest 4-step constant current battery charger (see battery charger graphs). Because of this improvement in the alternator control system, these regulators dramatically enhance the alternator's charge rates by between 200 – 2000% depending on how poor the original system is.

The Sterling System is the only real time control system, which is in operation 100% of the time. This real time control ensures the high charge cycle is switched off when the batteries are full (regardless of battery bank size or state) and the high charge will automatically reset itself if after the charge has been completed and the output from the batteries exceeds the output from the alternator. Because this is real time-based, this monitoring and control is in operation all the time the engine is running.

The Sterling Regulator is designed to charge batteries as fast as possible and to their maximum capacity without damage to the batteries or alternators. Therefore, we opt for the constant current charging mode and not pulse charging which would double the charge time.

What to expect from an Advanced Regulator

  • Maintains maximum performance to alternator’s power curve within preset envelope supplied by battery manufacturers
  • Batteries charging 4 – 20 times faster
  • Enables 25 – 35% extra useful power to be stored in batteries. A conventional alternator will only charge the battery to a max of about 75% and the battery voltage drops to a useless voltage of about 40%, which means that out of 100 amps of battery capacity only about 35 amps are used. An advanced regulator will fully charge the battery giving an extra 25%, which increases the useful available power by about 70%
  • Battery plates kept free from sulphate damage resulting in longer battery life
  • Due to the built in safety features in the event of incorrect installation the unit will switch itself off
  • Reduces needless running hours on the main engine
  • Compensates for voltage drops due to long cable runs, amp meters, diodes and other general wiring associated problems
  • Automatically converts machine-sensed alternator to a permanent battery sensed alternator.

This advanced regulator is the easiest to fit, safest, most powerful and because it is an O.E.M product, the cost is low.

Safety first

The Sterling Advanced Regulator has full safety features to prevent damage to your system. In the event of incorrect installation or a fault developing on the boat or vehicle, the high voltage trip picks up high voltages at the batteries and the alternator and switches off the advanced regulator (the field circuit is disconnected totally from the control via an internal relay).

The Sterling Unit was the first to introduce parallel operation with the regulator, ensuring continuous alternator operation even in the event of a system failure.

Everyone in the power game recognises that the best battery charger you can buy is a 3 step constant current charger. These have superseded the old constant voltage chargers, The Sterling regulator converts your alternator from an old constant voltage alternator to a modern constant current battery sensed charging alternator.

The test

Using a standard 12V, 90 amp Bosch alternator fitted to our test bench and rotated at a constant speed, the following test was undertaken. 4 x 100 amp ''leisure'' batteries were used, they were split into 2 battery banks, one for engine start and three for domestic. The engine start battery was fully charged (to copy that in real life) and the 3 x domestic batteries were discharger until such time as one of our 1800 watt inverters tripped out on low voltage. (To make the test fair we linked 9 batteries together to make one larger battery bank then discharged them all to exactly the same level, then a random three batteries were selected and used for each test), the idea was to see how many amps could be replaced into a 300 amp battery bank which had been discharged to a level one would expect in real life (about 50 – 60% empty) in a 3 hour period and to display the results in as simple a way as possible to highlight the difference between all the different options and why an Advanced Regulator is a necessity not a gimmick.

Charge Improvement graph

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