Should I be concerned about the house battery

LakePirate · #1 (**permalink**) 10-12-2010

Both batteries (a group 24 starter and 27 house) showed 100% charge on the meter before leaving the dock. After only about an hour and half of sailing with only the gauges on I went to start the motor with the switch on just the house battery and nothing. Ran down and switched to all and it fired right up. I know the group 27 isn't designed to be a starter battery but figured it would have enough to at least spin the motor a little. My question is since it didn't do anything should I be considering replacing the batteries?

night0wl · #2 (**permalink**) 10-12-2010

How much amperage does your starter draw to turn the engine over? Realistically, that size battery bank should have enough juice to do the deed...really, the type of battery form factor (a Group 24 or Group 27) isn't salient to the discussion.

The TYPE of battery, however, is. Are these Group 24 or Group 27 starting batteries....flooded deep cycle....AGMs....? How do you keep them charged when not in use? Also - a simple battery load test will reveal if the batteries are any good. I've had many batteries show strong voltage (12.8+ Volts) only to just fall to 10 V and lower (discharged) when the slightest load is put on them. That just means the battery is shot.

More info would be useful to diagnose your battery issue. But at a minimum, I would recommend a battery load test. Most auto repair stores will do this for you.

LakePirate · #3 (**permalink**) 10-12-2010

The 24 is a starter and the 27 is a deep cycle. I didn't have a volt meter with me but I'm guessing since the batteries are 3 years old it's time to replace.

Gene T · #4 (**permalink**) 10-12-2010

Have you checked the electrolite level?

Gene

mitiempo · #5 (**permalink**) 10-12-2010

You should be able to start a small gas or diesel engine (under 40 hp or so) with any group 27 battery in good condition. Even a deep cycle battery.

3 years isn't long for batteries if charged properly.

You say they showed 100% charged by the meter. What kind of meter?

Also if one battery is dead best to switch to the other battery, not to both. Combining a good with a dead battery can drain the good battery.

It sounds like the battery might be shot.

arf145 · #6 (**permalink**) 10-12-2010

I would guess that your meter is a volt meter. Batts can show 100% (or close to it) in terms of volts while being fairly dead in terms of capacity--as nightowl said.

DwayneSpeer · #7 (**permalink**) 10-12-2010

A volt meter will not tell you much of anything in terms of how good the battery is, just that it's charged.

CapnRon47 · #8 (**permalink**) 10-12-2010

LakePirate,
It may also depend on how the boat is wired. I have 4 house batteries but I cannot start the engine from them I have to either use the starter battery or have them all on both.

mitiempo · #9 (**permalink**) 10-12-2010

CapnRon
That makes no sense. If "both" selects the house batteries they must be connected to the post the start battery is not connected to, either 1 or 2.

sailingdog · #10 (**permalink**) 10-13-2010

What kind of meter are you using? IF it is just a voltmeter, it is USELESS for determining state of charge for the most part. For a voltmeter to give any reliable reading, the batteries have to be sit undisturbed, without loads or charging for a fairly significant period of time, usually 10+ hours, so that you're actually reading the true state of charge, rather than surface voltages from charging the batteries. A Hydrometer can show you the real SOC on a wetcell battery.

Do you have wet cell batteries? If so, when was the last time you checked the electrolyte levels in them. If the levels are low for any significant period of time, you can damage the plates and then the battery will lose significant amounts of capacity, although the voltage readings won't change much.

Also, how are you charging the batteries? Wet cell batteries like to be on a smart, three-stage charger. They also will self-discharge over time, faster with higher temperatures, so charging them on a regular basis is a good idea.

Quote:

Originally Posted by LakePirate

Both batteries (a group 24 starter and 27 house) showed 100% charge on the meter before leaving the dock. After only about an hour and half of sailing with only the gauges on I went to start the motor with the switch on just the house battery and nothing. Ran down and switched to all and it fired right up. I know the group 27 isn't designed to be a starter battery but figured it would have enough to at least spin the motor a little. My question is since it didn't do anything should I be considering replacing the batteries?