I've gone 3 full days on 2 of my 3 batteries. At the end of the 3rd day, my co2 detector sounded an alarm letting me know that the batteries were dead/dying. I switch over to my other battery and started the engines to charge them.

I generally run TV, fridge, anchor light, phone charger, cabin lights.

 

There isn't really a correct answer to your question due to the variables..........How old are your batteries, what other 12V requirements did you have , how much stuff in the fridge, how many lights were on etc. Another point is to be careful what answers you get because every model boat is different. For example, I can stay indefinitely on the hook because I need to run thegenerator occasionally for the refrigerator as I don't have a dual voltage fridge. Someone with a smaller fridge than you has less amp draw.

Having qualified this enough, you may be nearing the end of the useful life of your batteries. Just because the batteries will crank the engines doesn't make them ok. One of the ways expereinced boaters tell about their batteries is by how long they last when anchored out. If yours won't stay up as long as you normally anchor, then it is time to look at replacing them.

Don't overlook the obvious stuff either....water level in the batteries, corrosion on the terminals, etc. Bear in mind that dead batteries will gas off hydrogen and it sets off CO detectors, so that may be a clue to what is going on.

Finally, your generator should be completely isolated from the other 12V systems on the boat so if you do run down the other batteries, the genset battery should still crank it.

 

Sounds like your batteries are "tired". Mine have always needed replaced after 2 to 2 1/2 seasons. I always did alot of overnighting and you should not see any problems with low batteries the next morning. Do you know how old your batteries are?

 

I am assuming the batteries are the original ones, that would make them 4 years old. The boat sat for one year without being run, I am pretty sure it was plugged into the dock power but not sure.

 

I agree with Frank completely, except, I don't believe our boats have a separate battery for the genset. I agree with jmunro123 that your batteries, if original, are very likely spent. My boat is one model year newer than yours and I replaced my batteries last fall. I put in 4 Optima Blue Top deep discharge batteries. They were about 10 times better than my old ones, and continue to be so.

 

I want to piggy back on this thread with a few questions of my own.

My batteries are about two years old and I have been experiencing similar results as you jmunro123. I can't get either battery to last more than a few hours on the hook anymore. But I have had them load tested and they both check out fine. I have also looked for any type of constant drain on them and there doesn't appear to be anything out of the normal.

My batteries are always on the charger when plugged into shore power and show around 13 volts when I start the motor so I know they are fully charged before leaving the dock. And my alternator works fine as well. The batteries are fully topped up with water as well. The only caveat is they are both starting batteries. Yesterday while on the hook for three hours with lights stereo and fridge running, the voltage level on the battery I was using dropped to 11 volts.

Because I never used to have this problem, obviously I want to try and understand what to do about it. Can batteries that check out after a load test still exhibit this short of a "usable" span?

:huh::huh:

 

Hampton wrote My boat is one model year newer than yours and I replaced my batteries last fall. I put in 4 Optima Blue Top deep discharge batteries.

We're still on our original batteries & we have an '05 also. When you added the "Blue Top", did you have to change anything ref the charger?

 

Negative. There is extensive discussion on the board about this. Here's the bottom line from my research:

Of the three basic types of batteries, wet-cell, AGM and gel, the first two are both lead-acid batteries of two different types of construction. The voltage requirements for the wet-cells for both charge and trickle are the highest of the three. The voltage req for the AGMs is less for both chg and trkl, but not by much. The gels require significantly less voltage for both functions.

Our dealer has been replacing wet cells with AGMs for years without adjustments to the chargers. I did. Mine are fine and there haven't been any issues in our area.

Note for those with newer chargers: Check your charger for a "AGM setting." If you're still concerned, get out the manual and check the specs on your charger, then compare to the battery's needs. I recommend Optima blue top deep discharge batteries. The way we take care of boat engines, heavy cranking amps is not as critical as protecting your batteries from overly draining them, and having the power to run your items for a long time.

 

Dave S,

I believe your symptoms are normal. You have starting batteries that are running refrigerators and other items. If you replace them, consider getting deep discharge batteries.