Smart Alternator Regulator FAQS

CruzPro Ltd.
207 Whau Valley Road
Whangarei 0112
New Zealand
Tel: 64-9-459-1922

Internet: http://www.cruzpro.com

Performance Charging With Smart Alternator Regulators

It's a known fact that rum and coke tastes better when you don't have to listen to your engine running at the same time. We show you how to minimize engine run-time by turbo-charging your alternator with a high performance multi-step Smart Alternator Regulator (SAR).

Fixed voltage regulators are inexpensive to manufacture but are a poor trade-off between cost and performance for the boat owner. The initial savings are soon offset by the requirement to run the engine longer to achieve the same charge, battery life, noise, heat and smell generated by the engine. A fixed voltage regulator will also overcharge your batteries on longer runs - reducing their life and requiring more frequent top-ups of water.

Today's SARs enable you to safely fast charge your boat batteries thereby greatly reducing engine run time. Obviously, fewer hours of engine running saves wear and tear, fuel, and leaves more undisturbed time to enjoy the many wonders offered by New Zealand cruising. Your neighbors will also appreciate the extra quiet time.

The SAR is a multi-step charge controller that commands maximum safe output from your alternator while monitoring battery voltage and temperature. The SAR will deliver the bulk of the battery charge at maximum alternator output allowing battery voltage to rise until the "absorption voltage" has been reached. The SAR then lowers the alternator output to maintain a constant battery voltage at the absorption point. The absorption voltage is maintained for a period of time dependent upon several factors and then the SAR cuts back the battery voltage to a safe "float" voltage. Some SARs will also enable you to desulfate your battery plates by enabling an "equalization cycle". During equalization the SAR slowly raises battery voltage to an equalization level while limiting the charge current to about 4-6% of your battery's amp-hour capacity. This safely dissolves the sulfates that form on the battery plates during discharge and extends battery life.

The correct absorption, float and equalization voltages are dependent upon temperature and battery chemistry. The higher the temperature the lower values of absorption, float and equalization voltages that must be used to optimize battery life. For this reason sensors are used by SARs to monitor battery temperature and adjust the voltages accordingly. SARs will also have some switches on them to tell them what type of battery you are using and further adjust the charging voltages accordingly. Your fixed voltage regulator knows nothing about battery temperature and will almost always be charging to the wrong value.

During the bulk delivery phase the SAR will command the alternator to deliver maximum output continuously until the absorption voltage is reached. While many modern alternators can do so, some alternators are not rated to deliver full output continuously and can be damaged by excessive heat. For this reason the CruzPro SAR-20 can be told whether your alternator is "hot" rated or not and will automatically cut back the output of a non hot-rated alternator to a safe level after a while.

With today's heavy loads being demanded by the electrical and electronic conveniences found on many boats it's becoming more common for a second alternator to be fitted to the engine. If you're shopping for a SAR, try to find one (like our SAR-20) that has enough grunt to drive a second alternator field winding. Most alternators require about 3-4 amps excitation to their field winding in order to deliver maximum output so look for a SAR that can deliver 6-8 amps or more.

Another handy feature that some SARs offer is a trouble-shooting light that tells you what it's doing. The light will blink in various combinations to tell you what stage the SAR is in (bulk, absorption, float, equalization). SARs are available for both 12 and 24 volt alternators and some can be switched to handle either. Most (not all) SARs require that you have a P type alternator with an external regulator. If you have an N type alternator, or an alternator with a built-in voltage regulator it may need to be modified by a competent electrical installer to be compatible with a SAR.