Originally Posted by
EarmarkMarine
Al,
For the link between the charger and the starting battery I think a standard 15amp marine switch is fine on the positive lead. This lead should be fused. If the switch doesn't get warm then you have no concerns. For the most part this would not be used. Its just a precaution if you have really run down the batteries and you want to protect your charger against an inordinate and temporary load. I have the same concerns in protecting the alternator in systems with massive stereos. In some cases we run cascading batteries that can manually be brought on or off-line in response to certain circumstances. Again, there is nothing like having a Stinger digital voltmeter wired directly to the two banks via a selector switch so you can get an accurate reading on each bank independently.
On a tangent, here is food for thought. We all know how the larger stereos can place a major demand on our batteries and charging system as a whole.
And, as voltage sags in reality your rated amplifier power also decreases by a pretty large margin. In our system designs we always place alot of emphasis on system efficiency in all phases including signal path, supply voltage plus woofer and amplifier efficiency. System tuning is also a very large factor and far more of an issue than most people realize. Consider that a fullrange Class D amplifier may be 60 percent more efficient than a Class AB amplifier. This means that the Class D converts 20 percent of incomming power to heat while a Class AB converts 50 percent to heat or 250 percent more waste... and even more efficiency is lost when bridged or run at lower impedances. Not to mention that the greater current draw creates an instantaeous voltage sag at the amplifier that can rob you of output power and dynamic range. I can't resist sharing this message in the middle of a charging system discussion.
David
Earmark Marine
Senior Member
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