Originally Posted by FlyingCloud1937
Most house banks are going to be much larger then the start bank. So if you take a fully charged start bank, and a 1/2 discharged house bank. Next lets just say it take 6-8 hrs to completely charge the house bank. That's going to be at least 4 hrs of overcharge to the start bank.
Now how many hrs of over charge is going to accrue to the start bank over 30 days of cycling the house bank, how many hrs over 12 months is going to accrue?
Lloyd we were discussing an Echo Charger
which limits the voltage to an AUX battery to 14.4V. In my experience the start battery rarely see's 14.4V unless the house bank is seeing some where around 14.7-14.8V.
So what is "over charge" of a start battery? I guess the millions and millions of car and truck batteries, with no temp compensation, and deadly high charging
voltages should not be lasting us more than a few months based on the math above..?
If we take the suggestion that there is a potential for 4 hours of over charge, each event, at face value, when most boaters barely put 100 engine hours per year on what do we have? If we figured each event put 4 hours of over charge on that is still only 25 top up cycles or about 50 hours of charging at 14.4V+ per year.
My wife's Honda
pilot has a standard thin plate starting battery. It lasted from 2003 until June of 2011. That is eight years and 141,000 miles. Due to having a toddler and a badly located dome light switch that battery was killed to flat dead over 12 times and once sat that way for four days before being noticed and charged. Every time the battery came back and worked again.
At an average speed of 30 MPH that mileage equates to about 4700 engine hours of use at these deadly voltages. Her alternator is regulated to 14.4V and seeing as the battery is usually fully charged it sees 14.4V almost continuously. I don't know too many boaters who ever put 4700 hours on an engine unless fishing
commercially. These batteries are also never "maintained" like we do in boats. I never once checked it, never really cared, but I have checked the output voltage of the alt.
also backs their car starting batteries with a 100 month warranty with the first 36 months being 100% free replacement. It then prorates. Even at 75 months they are paying for 30% of your new battery. That is over 6 years at 14.4V+ and the manufacturer is still willing to pay for 30% of a new battery regardless of engine hours..
Even if we figure an average driver does 15k per year at 30 MPH avergae speed Honda, Die Hard and others are covering batteries that will survive 14.4V+ charging for 1500 hours of engine run time with a 100% free replacement warranty. For the average boater, sailor especially, that is 15 years of engine run time at 14.4V. Something to think about...
Sears even puts a 4 year free replacement warranty on their DieHard Platinum battery. Many cars are regulated to 14.2V or greater these days. The battery in my car lasted 121,000 miles at 14.4+ volts....
The idea that an Echo Charger
is going to kill a starting battery with a built in voltage limit of 14.4V, in short order, is just not a reasonable conclusion and not something I have ever experienced..