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-   -   Battery life? Winter storage? (http://www.sailnet.com/forums/gear-maintenance/49338-battery-life-winter-storage.html)

saltypat 11-30-2008 10:12 PM

Battery life? Winter storage?
 
Looking for some words of wisdom from the Sailnet gurus!

The boat is on the hard for the winter (MD), and I have a few battery questions. We have an Endeavour 33 which we took possession of in June of 2007. Three new batteries were put on at that time (came from West Marine, "maint free"). They have worked well. For the winter I was told I could leave them aboard, and just detach the neg. What does that accomplish?

Also, how many years does the average marine battery last? I am wondering if I need to replace them in the near future.

For your info, the winter of 07-08 I left the boat in the slip and the shore power connected (kkep the batteries charged, etc.)

Thanks for the help, Saltypat

sailingdog 11-30-2008 10:24 PM

If the batteries are fully-charged, then they should probably do fine. The question is whether they're AGM, GEL or "maintenance free" wet-cell batteries. If they're wet-cell batteries, then they will probably need to be re-charged occasionally while the boat is on the hard.

Detaching the negative means that there won't be anything using the battery, discharging it. However, all rechargeable batteries self-discharge to some degree, with wet-cell batteries having the highest self-discharge rate of the three commonly used lead-acid types.

As for how long the batteries will last, really depends on how well they're treated. Most are killed by neglect far sooner than they would ever die.

camaraderie 11-30-2008 11:39 PM

Yup...beware of "maintenance free" sealed LIQUID batteries. They will absolutely need to be charged during the winter at least once every couple of months to a full charge.
Genuine AGM's or GELS can be fully charged and then left all winter though it would not hurt to check their state of charge once every couple of months with a voltmeter. You should not let it get below a 12.25 V reading.

I also question the wisdom of disconnecting the negative cable. All too often a leak can develope or water can enter from the mast or ice/debris and rain can clog the cockpit drains and make them over flow into the cabin. I would always want a working bilge pump even on the hard. Not nice to find a flooded cabin in the spring.

sailingdog 12-01-2008 07:53 AM

Cam's got a good point about having a working bilge pump aboard. However, leaving a working bilge pump aboard means you have to check and charge the batteries more often... however, you have to balance that versus having a flooded cabin come springtime. :)

Bene505 12-01-2008 09:06 AM

A small solar panel goes a long way to maintaining the battery's charge over the winter. Even with a bilge pump connected.

There are flexible panels that you can put just about anywhere. Or get a rigid panel so you can permanently install it eventually. Then it'll serve you in the summer too. Hey, the winter is a great time to install it, for perhaps the same amount of effort as checking (and worrying about) your batteries all winter.

Note that with a small solar panel you'll only need a diode to connect it to your battery bank; you won't need a charge controller.

wchevron 12-01-2008 04:20 PM

Quote:

Originally Posted by camaraderie (Post 409576)
I also question the wisdom of disconnecting the negative cable. All too often a leak can develope or water can enter from the mast or ice/debris and rain can clog the cockpit drains and make them over flow into the cabin. I would always want a working bilge pump even on the hard. Not nice to find a flooded cabin in the spring.

one of the boats, on the hard, in my marina last winter ended up flooding out. the cockpit scupper hoses had rotted out. whenever it rained more water would fill the cabin. the owner came back from florida in the spring and found about 16" of water in the cabin. the insurance co. ended up totaling the boat since part of the engine was under water.

Kiskadee 12-03-2008 03:18 AM

Cool dry storage
 
If you leave them aboard you'll need an occasional recharge to keep them above 12.6 volts. There's little chance of freezing the battery if it's maintained above 75%. I'm not sure about the need to remove the negative lead, but it could lessen the potential of a short circuit in any part of the electrical system causing a fire.
A battery will slowly bleed it's charge if left on board. Temperature changes over the winter will allow a thin film of condensation to form on the battery case. This condensation will conduct a small trickle of current between the battery posts. Every month or two you'll need to top up the charge.
If possible, consider removing the battery and storing it at home in a dry cool spot. Never leave it on a cement floor as the cool cement will allow the same layer of condensation to form from minor air temperature changes. Even a small piece of plywood will insulate a battery from the cement.

A battery could last for five to ten years if properly maintained. Keep it charged, clean and dry. Batteries don't like to be quickly discharged or charged as excessive heat may cause internal plates to warp and touch. Prolonged cranking of a hard starting engine will shorten battery life. Charging a fully discharged battery with the engine will reduce it's life as the alternator will be hitting it with a lot of current for the full charge period.

When stored on the hard I don't need a bilge pump as I have two gabboard drain plugs. I'd rather allow the water to continually drain out than risk the high current draw of a frozen bilge pump.

xort 12-03-2008 07:17 AM

Fully charged batteries have a SG of 1.26 and freeze at -72 deg F
Half discharged batteries have a SG of 1.19 and freeze at -12 deg F

With no load on the battery, it will drop from full to half in about 250 days at 50 degrees ambient temp

Taken from "Boatowners Illustrated Electrical Handbook" Second Edition by Charlie Wing

You should have at least one good electrical reference book on hand.

Self Discharge is slowed by lower temperatures, that is why it's harder to start your car in the cold...the battery doesn't give up its power as easily.

The bigger question is 'do you have the proper charger for maintenance free batteries?' An old style ferro resonant charger will ruin that battery in a few years. A proper charging setup will enable at least 5 years and probably a lot more life for the battery. It's part of a system.

sailingdog 12-03-2008 07:29 AM

12.6 VDC is basically a fully charged battery or nearly so. The myth about leaving the battery on a cement or concrete floor is no longer valid. It was from the days when the battery casings were not waterproof and hasn't been applicable in a long, long time.

Quote:

A hundred years ago when battery cases were made of porous materials such as tar-lined wood boxes, so storing batteries on concrete floor would accelerate their discharge. Modern battery cases are made of polypropylene or hard rubber. These cases seal better, so external leakage-causing discharge is no longer a problem, provided the top of the battery is clean. Temperature stratification within very large batteries could accelerate their internal “leakage” or self-discharge if the battery is sitting on an extremely cold floor in a warm room or is installed in a submarine.
Hopefully, the batteries aren't being stored in a really warm room with a cold concrete floor, which would lead to greater self-discharge due to the temperature in any case....Also, most batteries used by small sailboat owners aren't large enough for temperature stratification to be an issue in any case. If the top of the battery is clean, it doesn't matter that condensation forms on it... relatively pure water, which is what condensation is, is a lousy electrical conductor. :)


Quote:

Originally Posted by Kiskadee (Post 410830)
If you leave them aboard you'll need an occasional recharge to keep them above 12.6 volts. There's little chance of freezing the battery if it's maintained above 75%. I'm not sure about the need to remove the negative lead, but it could lessen the potential of a short circuit in any part of the electrical system causing a fire.
A battery will slowly bleed it's charge if left on board. Temperature changes over the winter will allow a thin film of condensation to form on the battery case. This condensation will conduct a small trickle of current between the battery posts. Every month or two you'll need to top up the charge.
If possible, consider removing the battery and storing it at home in a dry cool spot. Never leave it on a cement floor as the cool cement will allow the same layer of condensation to form from minor air temperature changes. Even a small piece of plywood will insulate a battery from the cement.

A battery could last for five to ten years if properly maintained. Keep it charged, clean and dry. Batteries don't like to be quickly discharged or charged as excessive heat may cause internal plates to warp and touch. Prolonged cranking of a hard starting engine will shorten battery life. Charging a fully discharged battery with the engine will reduce it's life as the alternator will be hitting it with a lot of current for the full charge period.

When stored on the hard I don't need a bilge pump as I have two gabboard drain plugs. I'd rather allow the water to continually drain out than risk the high current draw of a frozen bilge pump.


WouldaShoulda 12-03-2008 09:02 AM

My battery is in my basement kept off the floor.

I'll charge it once mid off-season and again before I put it back on the boat.


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