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Boost your Charging Abilities with a NZ made Smart Regulator!

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In my experience, the single best improvement you can make to your boats charging system is a smart regulator. There is one made here in NZ, which I did not know about. Here is some info, by Graeme Polley from smartregulator.co.nz;




“Smart Charging”


Back story


My professional background is in aeronautical engineering, but one of my passions is boating. After experiencing battery charging problems in my own launch and suffering the premature failure of many batteries, I started researching why.


I sent a battery back to the manufacturer here in New Zealand for warranty consideration. Only to be told that my batteries displayed signs of incorrect charging correctly as the plates were eaten away with “acid stratification”.  On quizzing the battery supplier he explained about the problems that arise from using automotive alternators in a marine vessel designed for heavy loads such as anchor winches and bow thrusters or running fridges etc.


This must be a well kept secret because alternators configured for cars seem to be extremely common in boats!


 I then started researching the solution: ‘smart’ voltage regulators. But I found the cost prohibitive – Using true Kiwi ingenuity, my scientist son and I designed and built our own unit. It worked perfectly. Shortly after, friends with boats discovered what I’d made and I soon found myself making ones and twos for friends. Now I have over 200 units in the market place.

I have helped many people install a smart regulator and modify their alternators.

There is a common thread of issues that if you do nothing else but follow these simple points your charging system will be better off.


About batteries


Typically with automotive regulators the battery acid does not get enough charge and this leads to acid stratification, which is where the water separates to the top and the acid settles on the bottom and in a ‘pure’ acid form will attack the battery plates leading to premature battery failure.

For many years we only had the choice of lead acid batteries, today the choices are greater. Do not mix battery types as they each have different charging requirements.

The 50% rule states that deep cycle batteries should only be discharged to 50% available capacity.

Some people believe that if they fit more batteries they will have more capacity, however if your alternator or run time is insufficient you will never fully charge your battery bank.

You should only use start batteries for high loads for short periods and deep cycle batteries for low loads for long periods.

Connecting batteries in series, the amp hour capacity remains the same as a single battery however the voltage is doubled.

 Connecting batteries in parallel, the amp hour capacity is doubled and the voltage remains the same as a single battery.


About alternators


When the alternator was designed in the 60’s it provided a huge leap in technology and reliability over the generator. However electronic knowledge was limited and the designers worked on the theory that a car battery charged to about 70% of capacity which was acceptable.

Typical target values for internal regulators are between 13.8 and 14.2V, which is too low for the absorption stage and too high for the float stage. So you have the worst of both worlds; during motoring bursts the battery won’t fully charge, but long term it will overcharge, damaging the battery.


An alternator has a huge fan that draws air from the back to the front of the alternator for cooling. Imagine if this air was salt laden, this will cause internal corrosion. For some reason manufacturers do not offer full paint protection. Consider getting the internals painted in good quality paint to get longer life out of your alternator.


A lot of automotive alternators are fitted with larger pulleys to handle the typically higher engine rpm. In the marine environment we tend to run our engines slower, so we should fit smaller alternator pulleys. On yacht engines I fit a 50mm pulley and a launch can handle 55mm. This makes a huge difference to the output of the alternator. The amp rating on an alternator is specified at a given rpm, this is anything from 6,000 to 12,000 rpm, and most alternators do very little output from 2500 rpm.

To make matters worse, yacht engines tend to have smaller diameter crankshaft pulleys making the overall ratio smaller.


We strongly suggest that for alternators over 80 amp rating that you consider using a screw tensioned system rather than the traditional slide bracket tension system for belt tension. These were designed for smaller output alternators. (See photo)


A rule of thumb for alternator belt size is a follows;





Remember, for every 25 amps you will draw 1hp power of engine energy, so for a small engine of around 20hp fitting a 120 amp alternator will put too much load on your engine.


Charging regime


Charge voltage is probably the single most important factor in charging, as all other factors are related to it.

When the engine starts up, we would like the battery to charge as fast as possible. This is accomplished by setting a voltage target of ±14.6V (the actual depends on your specific battery type). Once the battery reaches this value, it is at approximately 80% of full charge capacity, and gassing occurs. This signals that the highest safe level of charging has been reached. We should not exceed this gassing voltage (or we could damage the battery), but neither should we go too far below it (or we will take longer than necessary to charge the battery). At this stage the battery will continue to accept or absorb charge at a gradually decreasing rate.

Since the charging rate tails off, we should choose some sensible point to stop the intense charging and switch to just maintaining or floating the battery at a charged state. We do this by reducing the voltage set point by 0.6V and it is vital for the long-term health of the battery.


A typical charging curve looks like this




Installation tips

We do not recommend using an

OFF – 1 – Both – 2 type battery switch, (as shown) this switch requires input from the skipper and if you forget to isolate your start battery you could run that flat overnight.



A better choice is individual battery switches

And remember NEVER turn OFF the battery switch with the engine running, it can blow up the alternator and/or the smart regulator.


As a suggestion, if you are running a start battery and a house battery, separate the two i.e. run separate bus bars and use a VSR (Voltage sensitive relay).

The VSR is installed between two batteries. In simple terms the VSR is a smart switch, when you first start your engine the alternator charge is directed to the start battery first. When this battery goes above 13.7 volts the VSR connects both batteries together. Both batteries are now charging. Alternately, when the system voltage drops back below 12.6 volts, i.e., no more charging, the relay opens and the batteries are separate. This means that following an overnight your start battery is at least 12.7 volts which is sufficient to start the engine regardless of the condition of the house battery.


Another advantage of BEP's VSR is that the house battery is completely isolated from the engine battery during the voltage-hungry starting procedure. This means that as long as all electronics are powered by the house battery (as they almost certainly will be), they will not be subject to damaging voltage spikes during start up.


More information can be found at the BEP website.


Ensure the earth leads to the alternator and starter are not used via the engine block. If there is any high resistance the earth trace will find itself tracking through your engine bearings and could cause arcing. For peace of mind run separate earth leads.


Make sure your engine has enough “belt” to drive the alternator you select.


Do not leave batteries discharged for extended periods of time.


Provide a means to cross-connect battery banks for emergency starting.


Voltage drop is the enemy, look to find the offending connections and fix them.


Automotive ‘in line’ ammeters are a huge voltage drop in your charging system. The best option is a ‘shunt’ type ammeter.



Smart regulators


Here in New Zealand we have the following brands available

Ample Power /CruzPro/ Sterling/Balmar, and my own unit ZM4


I would highly recommend that you invest in a smart regulator; it will greatly improve your charging system and longevity of batteries.


More information and some good download material at the Smartregulator website. Just click the advert!


Thanks for that Graeme, and he's also offering a discount for crew.org members - so don't forget to tell him you saw this on here!! :-)

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Hi everyone, I am not a regular poster but would like to add to this. I am currently in Fiji and coming home in 4 wks. Just replaced my batteries but thought I might have had a charging problem related to my batteries demise. I read this article as thought that the solution may be a new regulator and liked what this article said. Had a crew member returning briefly to NZ so contacted Graeme about possible replacement. He worked with me sugesting various things even including buying a replacement alternator in the USA rather than get him to supply it. As it turned out Don at Musket Cove was kind enough to double check things and it is likely to be a monitor calibrating problem rather than charging. Long story but will relate it if there is any interest. As it stands there is possibly no problem. Take home message for me is that full fielding an alternator will not necessarily result in full output of the alternator if the battery is three quarters full. Anyway the point of my story is that Graeme gave me the typical Kiwi service by email. Keen to help a person in a spot, not always looking at the bottom line, and was very knowledgeable. Will be buying a reg and alternator spare from him for the next Morning Cloud trip.

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Graeme's ZM4 is a great unit. They are currently working on a ZM5 which is going to be unbelievable in what it can regulate. It will be the central regulation unit for all charging equipment on the Boat. Plus it is going to be able to regulate charging for LiPo batteries, which will be an extremely cost effective method, because currently all lithium charging/regulating devices are expensive and make Lithium an expensive choice.
    I do have one concern in his comments though and that is in regards to the use of VSR's, or more precisely, House and Start Bank. Not Graeme's fault, it is the way these VSR's are advertised for use without explanation of hat can go wrong.
Although there are several different ways of connecting these things and I have issues with all of them.
While the way described by Graeme is the best of the options, there is a very important point to understand. Batteries of different sizes and/or different ages do not like being charged as one common bank. All Battery cells have an internal resistance. This resistance is different between Cells of different current capacities and it also alters with age. Any Cell that has least resistance (resistance heading toward a short) will draw more current. As the Cell draws more current, it's temperature rises. As the Temperature rises, the resistance of the cell decreases even further and then eventually that Cell is drawing the bulk of the current and starts to Boil the Cell. That Cell could be a series of Cells in a Battery of different size of another. So one battery, or bank could draw more of the charging current than another Battery/bank of different capacity.
The normal rule of thumb is that any battery in a Bank should not be replaced in said bank on it's own, if the age of the Bank is more than 12months of age. A new Battery will simply cause the Battery to take all the current and boil or at the least, take the bulk of the charge and not allow the other battery/batteries in the bank to fully charge. Eventually the other battery will act as an isolator and none of the bank will ever fully charge.
If all batteries, that is Start bank and House bank, are of the same age and size, then connecting them all is one by using a VSR is not so much of a concern initially. But after time, especially if charge conditions end up becoming different for each separate bank, those banks will change over time to be different again and one or the other bank will begin to draw more and more charge current, robbing charge current from the other bank and thus becoming more and more different  and around in ever increase circles we go.
No matter what way I view the use of these things, i still keep coming back to the use of a MOSFET controlled Charge splitter. Hardly any difference in cost re the Splitter or the VSR, simple in operation, no Voltage drop (this is the difference between Diode splitters and MOSFET splitters) offer complete isolation and each Bank charges with the current each requires no matter size or age of bank.

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