If you've paid any attention to the weather report for North America, then you know it got REALLY COLD REALLY FAST the past two days.
One of the most horrific killers of batteries is dramatic temperature change or even freezing cold temperatures!
What a lot of people who live off-grid or who boondock (Dry-camp) Full-time often forget, is when it gets cold, you MUST increase the charge voltage to compensate for cold weather!
I get at least one phone call per day during the winter months from someone who wants to buy new batteries, when the fact is, their batteries are nearly fully-functional... They're just undercharged!
Repeated under-charging can lead to poor performance; leading to sulfation; leading to internal resistance; leading to your batteries' premature demise! (And UNDERCHARGING is not covered under warranty!)
So, save yourself some time and hassle -- as well as a few cold nights -- and trust this handy chart as a guideline for charging your batteries during cold weather.