Vol 37 | Num 17 | Aug 22, 2012
Article by Pat Schrawder
HELPING TO KEEP YOUR 12 VOLT SYSTEM WORKING PROPERLY
One the most prevalent sources of problems with electronics is improper supply voltage. A properly functioning 12-volt ship’s system actually provides 13.6 volts. Most equipment manufactured today requires 12 volts minimum. If you ship’s batteries are not supplying the correct voltage, equipment will not work correctly and, if over-supplied with voltage, as sometimes occurs when you crank your engines and your alternator charges maximum, it can actually damage your equipment. Fortunately, there are a number of items on the market designed to help with these problems. Let’s look at just a few:
The abrupt DC system voltage drop that accompanies engine starting can
cause microprocessor-driven communication and navigation electronics to “dump” programmed memory. The Voltage Starting Protector Device is an item that attempts to solve this problem by providing supplemental voltage to your electronics while the engine is cranked. It contains a rechargeable battery, which is switched on-line to electronics when the starter switch or solenoid is engaged. When the engine is running, the device goes off-line and your alternator recharges the internal battery. It works very similarly to a battery back-up device that is commonly used to protect office computers and cash registers during power outages.
Marine communication and navigation electronics such as programmable data transceivers, GPS and other microprocessor-controlled devices also require clean and steady DC input power. Their sensitive circuitry is highly vulnerable, not only to voltage drop from engine start, but also noise and line spikes from alternators and motors, as well as conducted noise from various other electronic devices. There is a Power Conditioner that helps to correct this problem. It absorbs line "spikes", filters out electrical interference and provides supplemental voltage/battery back up for several minutes.
Insufficient charging of one or more batteries can also be a problem. Battery isolators allow charging multiple batteries automatically from one or two alternators, and prevent discharge or "dumping" of one battery into another. Each battery is charged according to its need without overcharging.
Discharging batteries beyond a critical low voltage can damage the batteries and/or load, and require a longer recharge interval. A low voltage disconnect prevents this condition. It is installed in-line between the battery and the load. The unit continually monitors battery voltage and if it falls below a preset voltage threshold, the load is automatically disconnected. When batteries are recharged past another pre-set voltage, the load is reconnected. Connect and disconnect points are user adjustable.
So what if your batteries are going bad and you don’t know it. Well, there is something for that as well. At least one manufacturer makes a device known as a Digital Battery Analyzer. It performs a complete analysis of battery condition in mere seconds, then displays conclusive data on a large LCD readout.
According to the manufacturer, it analyzes 12 and 6-volt lead-acid batteries of all types with ratings from 100-1400 CCA. It provides information on battery voltage, battery condition and available battery power. This gives you empirical data to assure your customers that their batteries are fine, or to support your recommendation that they be replaced by using a sophisticated test algorithm that measures battery cell conductance, which is affected by sulfation or loss of active material. This test has proven to be an accurate indicator of cranking ability, standby energy capacity and general state of health, regardless of state of charge. The test produces no heat, is completely harmless to the battery cells and causes no significant discharge.
In addition to these very helpful devices, the wise boater will not forget to periodically check all connections on the batteries, fuse holders and circuit panels for any corrosion or loose connections. Having the proper battery voltage will not help if these other factors prevent proper delivery of current.
Pat and her husband, Larry are owners of L&L Marine Electronics in West Ocean City.