Battery issues on my Sundancer

[Captain Jimbo]

I have had my two batteries for about five years without any issues until a couple days ago . I was out on the water and had stopped the engine for a few minutes then went to restart it and both batteries were nearly dead and neither could start it. I turned the control knob to both batteries setting and it started thank goodness! I then checked the batteries after charging them overnight and found battery 2 to charge up just fine but my battery 1 was dead. I then bought a new battery and replaced battery 1 but I had to move battery 2 out-of-the-way to get to battery 1 in the tight engine compartment. I then checked both batteries and they seem to be fine, then took the boat out on the water for about seven hours, upon return I checked battery 2 and it was completely dead. I’ve been running off the battery 1 all day and it still started right up after I stopped the engine. I am now charging again overnight and will check tomorrow morning, anybody have any ideas what the problem could be? Could the battery charger on the boat be defective ? Maybe the alternator isn’t charging the batteries ? Or did I not reconnect the batteries correctly ? Any comments would be appreciated , thanks !

 

[mquiet]

Sounds like a couple things need to be checked. When plugged in, use meter and verify that you are charging. Then disconnect and start boat and verify that the alt is charging the battery you have selected. Your symptoms sound like th battery is drawing down during use. I would also verify the alternator in line fuse is not popped. Mine have done that before and I was not charging while running. But you need to get a meter on it and see what is going on.

 

[Little Ducky]

If they were both 5 years old I'd consider yourself lucky and would have replaced both batteries at the same time.

If you run them in parallel (A and B on) the weak battery will draw down the new battery.

 

[Captain Jimbo]

Sounds like a couple things need to be checked. When plugged in, use meter and verify that you are charging. Then disconnect and start boat and verify that the alt is charging the battery you have selected. Your symptoms sound like th battery is drawing down during use. I would also verify the alternator in line fuse is not popped. Mine have done that before and I was not charging while running. But you need to get a meter on it and see what is going on.

 

[Captain Jimbo]

I found the problem ...I hadn’t totally tightened the lead to the positive terminal and that’s why it sounded like it was dead !!! Thanks both of you for your good comments ! I did by a second new battery and put it in anyway just so they will age the same .