Join Date: Mar 2001
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Batteries going bad?
We've recently done a number of upgrades to the electrical system, including new panel and reconnecting some gear that came with the boat wen we bought her, but were never hooked up, i.e. a Heartlink10 monitor. We have 3 3-year-old group 27 batteries in the house bank. For those not familiar, he Heartlink uses a shunt on connected to the ground. All equipment that is connected to the house bank goes through that shunt so the monitor can measure the amp hours used. It measures the drain when devices are running and, when charging, it measures the amount of replenishment going on. It compares its measured usage with the amp hours you tell it that your bank has via configuration and displays the state of charge in a manner similar to a fuel gauge, e.g. half full. So when it says the bank is half full, what it means is that you have used half of the capacity it thinks the bank has.
Here's my question: After a weekend of cruising, the Heartlink says the bank is full, that I've hardly used any of its capacity, but when I check the voltage of the battery, it is below 12v, around 11.8v. When fully charged, the bank voltage reads close to 13v. I thought that when the voltage goes below 12, you're pretty well depleted. Does this mean that my batteries are unable to hold a full charge anymore, and are therefore running out of charge with very little usage? If so, does that mean they are nearing end of life? Any insight into how to read these various signs will be much appreciated.