Batteries connected during the winter

craigswardmtb

So I had grande plans to charge the batteries every month to keep the batteries topped off during the long winter months. Well I haven't gotten down to the marina as often as I would have liked and when I showed up today with my generator, the batteries were dead. I was surprised as they were topped off a couple months ago. I fired up my Honda eu 2000 and charged them for a couple hours and I seem to have a good charge. So this raises a couple questions: 1. How long do you think it would take to fully charge two group 31 house batteries and two group 27 starting batteries? I think I have a xantrex 3 bank charger. Or whatever comes standard on a 2005 FV360. 2. What is typically hard wired to the batteries that would still drain them when the boat is on the hard and all circuit breakers and battery switches are in the off position? I did notice the helm clock was ticking, but I would think that the draw would be minimal? 3. There are two switched breakers on the port side of boat that I'm not sure what they do. They are located by the mounted bell on the backside of the port front seating. So between the the front and very rear seat. Any idea? Could there be other breakers in the engine compartment I may be missing? I'm just not sure why these 1 year old batteries are being drained what seems to be relatively quickly. Thoughts on what might be the draw on this 360?

Black_Diamond

A few things draw power all the time unless you can turn off the power to them: clock, GPS antenna & stereo. The Merc anti corrosion pulls power only in the water. A cold battery also has a reduced charge capacity over a warm one.

Dream_Inn

there are more things than you think that draw power.  If you don't completely disconnect or turn everything off, it's a matter of days before your battery will be dead.  CO detectors is one thing that adds as well.  The complete drain you did on your house batteries, I hate to say, will make them never be the same.  A complete drain is extremely **** them and they will never get that full charge again.  (this happened to me the first month I had my boat, I had some outdrive work done and it went on the hard, thinking I had everything off - ended up trading in two brand new batteries)

My thought is, if you don't leave some type of charger on, then just disconnect (takes maybe 5 minutes).

Capt Ron

I agree with DI... just throw those batteries away because they are toast... Parasite draws from many devices on board will drain the battery quite quicker than you think. All I do is remove the ground cables after the batteries are fully charged. When I return in the spring they are still up.

craigswardmtb

Bummer. Live and learn. The way my boat is shrink wrapped there is a main support on the hatch so getting in the engine bay is not possible. I'll have to think about this and assess my options.

BoatAway

i only have half the batteries you do, but i take them home with me as part of my winterization and charge them once a month until she goes back in the water. then they're always connected to shore power when docked.

i wouldn't go so far as throwing yours away just yet. keep them charged 'til the Spring (as above). Be extra careful once you get back out when the warm weather comes. Or have them tested (auto parts stores do it for free).

You might be OK.

Capt Ron

When a battery is fully discharged the acid will eat away the lead layers between the plates. The longer the battery is left in this state the more damage is done. Testing a battery will not always tell the truth, it's just a guideline. Not many people know that you can't test a deep cycle battery by putting a load tester across it... the battery is designed not to drain quickly so tests will show incorrect results. Deep cycle batteries will lose their capacity as they age. For example, every third year I replace my deep cycles batteries because at the end of the second season they cannot deliver the same capacity as when they are new. If you anchor out a lot you will notice the deep cycle batteries will drain out overnight with just a few loads when the previous year they were still up. If you neglect to change them in the third season they won't last all night at all. I used to take all my batteries home and charge them monthly. The batteries didn't last any longer so what I do now is fully charge them in the fall and then disconnect the grounds. In the spring the batteries were still up to 100%. The cranking batteries I just change when they need it (slow crank and etc). I just changed my cranking batteries last season because one of them was cranking slower than the other. Also they had a date stamp of 06 which meant they were seven years old.. One thing about boating, find yourself a good dealership where you can get batteries for a reasonable price because you will be buying batteries every three years for sure.

Dream_Inn

Capt Ron, I do agree with most said, but I do have luck with my house batteries lasting 5 years typically (I've done it a few times now). I'm sure they are a bit weaker the last year or so, but with a couple of them in parallel, it's still ok. I do agree that the first sign that I cannot make it thru the night on the house, out they go. Now, starting batteries, I take them till they show their weakness. This is because I always have the other on emergency switch to start. I try to keep my starter batteries bought a year or two apart for that reason. 7 years is really good! I had never thought about the testing for deep cycle, but it makes sense. Thanks.