Dead battery

[BobM]

Upon boarding my boat this spring I found battery 2 dead. I also found the battery switch left on, so I presumed that I left a light on and killed it. I plugged the boat into AC and charged the battery. All seemed fine, but a week later the battery was dead. I know for a fact that the battery switch was off and that the bilge pump was switched off. The other odd thing is that the stereo was dead, not a big deal, as I planned to replace it, but it was nearly new.

So...since there was no problem last fall...should I presume the battery is gone? It is weird, there is a meter on the boat and it took a charge, but wouldn't hold it. Battery 1 is fine by the way. Both batteries were new in 2007. Seems like being discharged and cold might have sulfated the batter. I usually disconnect batteries and take them home, but was sick last fall and decided to risk leaving them on board.

Thanks in advance,

Bob

 

[Don S/V ILLusion]

Bob
Lots of folks replace the batteries which cures the problem only to find out later that simply cleaning all the connections which they inadvertently do when changing out the batteries would have solved the problem.
This isn't to say your desc fits that scenario exactly but the moral of the story is to always check the batteries at a min with a hydrometer or preferably have them load-tested before incurring a needless expense.

If the batteries were already weakened and further depleted entirely, you may have killed them but the above is always worth the time to make an informed decision.

 

[Rich Stidger]

The fact that you inadvertently left battery #2 on means that there was probably a small load on the battery - like maybe the keep-alive circuit in the stereo - and the battery just plain discharged to zero.

Having a battery completely discharged for any length of time promotes sulfation which is a death sentence for a flooded wet battery.

Since you have already attempted a recharge and found that it won't hold a charge, I would just replace the battery.

Your stereo is another issue. You should check for bad connections so that you don't have another non-operating stereo after you replace it.

 

[Stu Jackson]

Didgya ever check the fluids in the batteries???

 

[javaprog]

You can get the battery load tested at an auto parts store. They will probably do it for free.

Look for an inline fuse for the stereo.

 

[BobM]

Checked the fluids, they are fine in all cells. Put a voltmeter on the battery and it was 7.7V. I will pull it and take it to be tested. Fuse hunt for the stereo soon.

Bob

 

[Don S/V ILLusion]

Checked the fluids, they are fine in all cells. Put a voltmeter on the battery and it was 7.7V. I will pull it and take it to be tested. Fuse hunt for the stereo soon.

Bob

Don't bother Bob - save yourself the $$$ of having it tested and just collect the $5 for the core

 

[BobM]

Thanks Don...I guessed as much.

I tried to revive an older Seaworthy deep cycle I had around but I think it is done too. I will start a new thread about batteries.

 

[sailingdog]

Most lead-acid batteries self-discharge, and if left stored, uncharged for a long period of time, the batteries, especially wet cell batteries, will sulphate and die. A good way to prevent this is to use a small solar panel as a maintainer... Depending on how large your battery bank is, and where you're located, a 5-25 watt panel will often do the trick. I've written about this in my Solar Power on Boats blog entry.