Last week while I was traveling Leo wrote in with a good question about his boat's battery. His query came from a statement I made some ten years ago when I wrote the updated edition of the book shown here:
By the way, you can get your own copy of this book or any of my books by clicking on the Amazon.com link at the lower left side of this page. Once at the Amazon site, click on Minor Brotherton's name to get this book.
Ok, so now that I've made the shameless plug to try and sell some more books, back to Leo's good question.
Basically Leo wanted to know why I've said that it's not such a great idea to leave your batteries hooked up to a trickle charger all winter while they are out of service. Besides it being a waste of electricity, depending upon the charger design and its specific output characteristics you run the risk of just boiling the battery to death. His point to me was that the risk of boiling is low if the current and voltage outputs from the chargere are quite low. His concern is plate sulfation. I have written about that issue here and a review of several earlier posts is probably in order, so check these two out to get a feel for all of my thoughts on this topic:
OK, so here's my regimen for batteries. I now use one of the Pulsetech Extreme chargers in the fall and charge up both of my batteries to 100%. The Pulsetech approach takes care of any sulfation issues and I must reiterate that I've extended my battery life two-fold uing these chargers on a variety of my boat's over the last ten or twelve years.
Once the batteries are fully charged I disconnect I turn off my battery master switch. My parasitic loads add up to milliamps so I don't worry too much about them, but every boat is different so a mid-winter recharge is sometimes in order. alternatively, you can simply disconnect the batteries completely and leave them in place, but remember that any of your electronics that have memories needing power are going to have to be re-programmed in the spring.
The days of leaving batteries of any variety on charge all winter are way behind us.