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What is a Zero Volt Drop Intelligent Digital Alternator Distribution System?

This product uses a micro processor to monitor the multiple battery banks which are to be charged by an alternator, it ensures the batteries are all charged in conjunction with each other and prevents any back feed through the device in the event of high loads on one battery bank, the system also has the ability to disconnect the alternator and individual battery banks in the case of problems caused by the alternator or other power items in the system. It does all this and still offers only a max voltage drop of less that 0.01 volt, much less than any so called 0 volt drop mossfett / diode system. Many so called 0 volt drop systems simply do not come close the master volt battery mate is as high as 0.6 volts at full power ( where it counts ) while the Sterling is at 0.09 volts, a 600% performance improvement over the “Mastervolt” unit.

How does the unit function?

This unit on the surface looks like a simple device, however this is a very complex software control device with in excess on 1000 lines of code. Under normal operation the unit has a simple operating mode, however like all Sterling product being engineers we are not only concerned about normal operation conditions we like to build into our products as much safety and control as possible to both protect your electrical system and ensure the available power is directed to where it is required most but also ensuring that the engines battery is always charged.

What is the problem? Voltage drop across splitting systems (such as diodes) will cause poor performance with the charging of the batteries, however this can be compensated for by using things like advanced regulators or battery sensed alternators, however this in its self can cause problems with other batteries in the circuit, i.e. a over charge can take place, as explained in diagram.

All boats have at least two battery banks some have three. These tend to be the engine start battery, the domestic battery bank (please note that if you join three or four batteries together in your domestic battery bank it is still one battery), and the bow thruster battery. Having introduced 2 – 3 battery banks onto your boat, the problem then is how do you charge them from one alternator source (or two alternators which I will discuss later).

To understand what this product does we must first understand the problem.

Example 1 shows a typical split charge diode installation with a standard alternator with no advanced regulator or battery sensing reg. The test assumes the alt is a 60 amp alt, the diode is a 70 amp diode and there is average cable between the alt and the battery bank. The alternator voltage is assumed to be about 14.2 volts, however in real life this could vary from 13.9 to 14.8 volts depending on the manufacture and the internal regulator fitted to the unit. The important voltages to note on example 1 is the fact that the alt produces 14.2 at the alt but by the time it gets to the domestic battery it is only 12.8 volts, this is a appalling voltage and would result is you never charging your battery bank. However not that the engine battery is 13.6. (note this higher voltage, not a problem in this case but the phenomenon will cause the problem in later examples) this is because that at 60 amps the voltage drop across the diode to the domestic battery is 1 volt, however because the starter battery is almost full it is only drawing a few amps from the alt and so its voltage drop is only going to be about 0.4 amps (remember the voltage drop across a diode is not linear it is proportional to the current flow, i.e. the more current flow through a diode the greater the voltage drop). Conclusion in example 1 there is no danger to anything but there is an appalling low charge rate presented to the batteries.

Example 2 is replacing the standard reg with a battery sensed reg, this in effect says to the alternator, give me 14.2 volts at the domestic battery bank (or at the end of the battery sensed cable) regardless of what voltage the alternator has to produce to achieve this goal. This will improve the charger at the domestic battery a lot, i.e. you can see that the voltage will rise on the battery from 12.8 on example 1 to 14.2 on example 2. hover when the voltage is checked through the system and taking into account the voltage drops across the diodes, look at the engine battery voltage now, it is 15.2 v this voltage would rise even more if the cables were longer i.e. if you had 4 or 5 metres of cables then the voltage drop in the cables could be up to 1 volt, this would drive up the starter battery by another 1 volt etc etc. Conclusion the starter battery should be open lead acid type. In the short term this battery would simply gas a little, and regular maintaince would ensure the battery is OK. However with a sealed gel or agm this would gas and therefore destroy these batteries (so avoid gel, sealed and agm batteries on advanced charging systems).

Example 3 is the same pretty much the same as example 2 except a modern advanced regulator will push the batteries up to 14.8 and in some cases the new calcium calcium batteries could go as high as 15.4 volts. This simply adds another 0.6 volts onto example 2 with the same conclusions.

The solution: If the voltage drop across the splitting could be eliminated then the domestic and engine start batteries then there would be no excessive rise in voltage on the starter battery this way the gassing/high charge rate of the secondary would be the same as the domestic battery bank and so be under control. This would prevent excessive gassing taking place and causing excessive water loss in the starter battery. It also has many added features associated with this new technique

Other advantages to the Zero Volt Drop Intelligent Alternator Distribution System

  1. Distributes the most power to the battery bank which demands it.
  2. Isolates a battery bank when full and there is any attempt to back feed the power from the full battery bank to a lower battery bank.
  3. Isolates all full battery banks except the main load battery in the event of a massive load on any battery bank.
  4. Isolates the main alternator from all the batteries (the engine start battery is also isolated but a emergency internal circuit in the unit maintains a 1 amp emergency link with the alternator to try to save as much of the alternator internal workings as possible) in the event of a failure in the alternator's own regulator. This prevents the batteries from boiling.
  5. Isolates any battery bank which tries to back feed a high voltage from a different source. i.e. if there was a defective battery charger on one battery bank trying to back feed into another battery bank then the unit would disconnect that battery bank to save the others.
  6. L.E.D. display shows which channels are in use and which are not.
  7. Overload design, for example our unit, which is rated for a 150 amps, is actually continually rated for 240 amps with a overload of in excess of 1000 amps.
  8. Fail-safe: in the event of unit failure the engine start battery and alt remain connected, ensuring the safe running of the boat/vehicle. Prioritises the engine start battery charging over all othe battery bank outputs.

Competitors' products

Various other companies claim they have diode to the domestic battery is 1 volt, 0 volt split charge systems, however the so called transistors / battery is almost full it is only drawing a few amps mossfet,s splitters when under load are only about 50% better than the standard low cost diodes, where as the Sterling is 90% better, we actually have a 0.09 volt drop under full load conditions current flow, i.e. the more current flow through as opposed to 0.6 v which the Mastervolt product has , making our voltage drop. Conclusion in example 1, there product over 500% more effective. Plus we offer all the extra but there is an appalling low charge voltage functions as described above which the transistor/ mossfet,s products can only dream about.

Voltage drop across splitting system

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