Batteries go Dead

[wwaseleski]

On my 1995 Sea Ray 400 EC, the 2 batteries for the Starboard engine go dead after the boat is unplugged from the shore power for a week. I have every switch on the panel turned off, including the refrigerator. This is my first season owning this boat, it has been on shore power 95% of the time. What is causing this drain on the batteries?

 

[Island Time Buffalo]

Without more data I can only speculate. But right off the bat I'd say the batteries are just aging/dead. It could just be their age, but also Older chargers have a tendency to cook 'em quicker than the newer smart chargers, but in reality you only get a few years out of marine batteries. My average is about 4 years for a house bank.

But if they are strong coming off the shore power, it could also be a ground leak somewhere.

 

[Boater420]

What about a leaky bilge? Taking on any water causing the pumps to cycle? I'd have to say that's a long shot but coupled with some weak batteries it could be the cause.

Battery chargers often mask a dead or dying battery issues. To troubleshoot, I'd start with the batteries themselves. As mentioned above if they're old (4 years or more) I'd just junk them and get new. If they're new I'd check the water levels first as the battery chargers often boil them dry. Then load test the batteries.

If they pass the test then check the battery charger to see if it's charging them properly. If the charger is delivering the rated output then you know it's something else draining the batteries.

 

[wwaseleski]

I don't know the age of the batteries , I just purchased the boat this past April. One battery was stone dead, wouldn't take a charge. Sounds likely they all may be old and on their way out.

 

[Lazy Daze]

There's often a date code somewhere on the battery casing - sometimes burned in, sometimes a small sticker. For example, you might see "E8" - which would mean May '08. Now, this is for Deka batteries, but as far as I know, most companies use something similar. However, best thing to do is to pull the batteries and get them tested, as a first step. But the most common reason for your issue is a dead battery. IF they test OK, then an amp draw test would be next (although you could certainly do this first before lugging the batteries out).

 

[Bt Doctur]

battery chargers to batteries are like heroin to a human. Always charges you up but eventually does kill you.
When you go on vacation for 2 or 3 weeks do you plug your car into a charger????????????
So why do you think your batteries need to be constantly hooked up to a charger all the time.
A house battery on a charger, ok .It dosent affect you starting the motor.
Engine batteries ,never
Sitting at the dock , with ships lighting, radio, etc. of the house circuit, charger on.

 

[vanman59]

You should replace parallel batteries all at once, a weak battery will drain a good one. If you replaced one battery of a pair of batteries, they won't stay charged.

 

[JimT]

battery chargers to batteries are like heroin to a human. Always charges you up but eventually does kill you.
When you go on vacation for 2 or 3 weeks do you plug your car into a charger????????????
So why do you think your batteries need to be constantly hooked up to a charger all the time.
A house battery on a charger, ok .It dosent affect you starting the motor.
Engine batteries ,never
Sitting at the dock , with ships lighting, radio, etc. of the house circuit, charger on.

Not true with modern smart chargers. My boat is connected to shore power and charging (as needed) unless I'm out on the water.

My ZR1 is always on a battery tender when I'm not driving it.

 

[Creekwood]

Not true with modern smart chargers. My boat is connected to shore power and charging (as needed) unless I'm out on the water.

My ZR1 is always on a battery tender when I'm not driving it.

Smart chargers like Pronautics have a automatic desulfation cycle that helps extend the battery life too. My charger/converter is switched on the spring and off at the end of the season when the boat is winterized. I check the water levels every couple of weeks and before any long trips. I have never had to add much at all. A bit in the golf cart battery house bank but they get more charge cycle time.