Charging Batteries Over the Winter

[jrcinnh]

Fully charged batteries won't freeze until -90F so if you keep them charged you can leave them on the boat. The risk is if something discharges them. Fully discharged they will freeze around 30F. I just take off the red cables and leave them till spring. They will self discharge but a good battery will still be at 80% in the spring. If I was really nervous, I'd stop by once in February and give them a charge.

BTW it's been a real long time since battery cases were porous enough to allow concrete to discharge the electrolyte through the bottom. Placing batteries on concrete is harmless to the battery. But if you overcharge them, spilled acid will stain the concrete.

 

[SeaBee3]

Thanks for all the good information. I've always taken the batteries out of the boat, stored them indoors, on wood, and topped off the charge prior to putting them back in the boat in the spring. Never had any battery problems but it does become somewhat a hassel to transport.
Speaking of batteries...
I need to replace my PWC (Polaris Virage) battery about once a year. I've been told it's due to all the vibration it is subjected to. Any suggestions?

 

[comsnark]

A built in charger is a good thing. My boat is ALWAYS plugged in when it is in the water.

When it is out of the water, I pull the batteries and bring them indoors. I can't imagine that letting them be in freezing weather is good for them. With them indoors, I put them on a battery charger once a month.

I can't tell you how my large SeaRay batteries do. . but my small cheap SailBoat battery is now starting to die after 6 full years. My jetski batteries seem to last 2-4 years. Not happy about how they have been lasting. Of course. . being on a jetski can't be helping

 

[Dave M.]

When it is out of the water, I pull the batteries and bring them indoors. I can't imagine that letting them be in freezing weather is good for them. With them indoors, I put them on a battery charger once a month.

I think letting them be in freezing weather IS good for them. Aging of batteries and self discharge is a chemical process, and the rate of many chemical processes is cut in half every time you reduce the temperature by 10 degrees C. Heat is the enemy of battery life. Well, one of them.:grin:

 

[rondds]

i still keep all my AA and AAA batteries in the fridge. but that's not freezing. 'round here, it gets real windy and get many a day btwn late dec and mid feb in the low 20s. and that water we pour into the batteries is distilled, which means pure, with nothing to lower the freezing point.

 

[comsnark]

Well. . we put distilled water into the battery, but it ain't pure once it's in there!!

You guys are giving me pause regarding how I winterize batteries. It is a minor hassle for me -> between my various water craft I have six batteries to deal with. I use two chargers just so I can get the charging work done in three days per month instead of six days per month.

All the marinas in my area pull the batteries (I am in the same neck of the woods as Rondds), and our winter low is around 0F.

 

[rondds]

the other thing to consider with many searays (if not all) is that there are two batteries in parallel, being charged by one bank of the charger. obviously, if the battery does not need charge the bank shuts off. but suppose the two in parallel are not holding a charge evenly. the charger will put out voltage to both batteries, possibly overcharging the "good" battery. couple this with the fact that, during the winter, with all systems shut down, there is no draw on the batteries at all. this could cause water "boil-out" and bigger problems.

if your batteries are in the house, there really is no need to keep the charge topped off during the winter. if each battery is healthy, it wont fully discharge in a 6 month period. maybe it'll drop a volt or two. then, you need to only charge it up ONE time in the spring, before re-installing.

it's no doubt a hassle lugging these batteries around, but, to prolong their lifespan and, more importantly, prevent unexpected failure during the season (that could really ruin your day), i'd take em home. (i've got 3 on the boat and a battery for my lawn tractor for a total of 4, and those series 31's are REALLY heavy).

 

[Dave M.]

This is from the Trojan (battery) web site:
"Can a battery freeze?
The only way that a battery can freeze is if it is left in a state of partial or complete discharged. As the state of charge in a battery decreases, the electrolyte becomes more like water and the freezing temperature increases. The freezing temperature of the electrolyte in a fully charged battery is -92.0 F. At a 40% state of charge, electrolyte will freeze if the temperature reaches approximately 16.0 F."

Your marina does not want to be financially responsible for any batteries that are old and contaminated, thus have a high rate of internal discharge and freeze. These could discharge themselves enough to freeze at 0 F or even higher. They can't know that condition of everyones batteries, so are obliged to play it safe, and charge for it.

 

[Henry Boyd]

My view is that taking the batteries out of the boat when it is up on stands, and transporting them to my home, hauling them to the basement and back again places a far greater risk to battery (as well as boat, car, clothing) destruction than leaving them charged and disconnected on the boat.

Another important tidbit, If you disconnect the battery(s), remove the drain plug...........

Henry

 

[Dave M.]

Another important tidbit, If you disconnect the battery(s), remove the drain plug...........

:smt017 OK, I have to confess you had me on this one. I just could not imagine what secret you knew that led you to this. :huh:

Then I realized it does rain in some parts of the world. Is that it?

 

[Gunn]

Re: battery storage

Is the Guest factory installed charger in my boat ok to leave charging all winter? The charger uses three stages to charge a battery. The final stage is described in the manual as follows:

"When the battery approaches full charge, the charger switches into its third charging stage, gradually reducing he current fed to the batteries to as low as 0.1 Amps. At the same time, it reduces the output voltage to a "Float" or "Ready" charging rate of approximately 13.3 VDC."

Yes, that is what a trickle charger does and you can leave it charging all winter. I have a charger like that on my motorcyle and for years it works well; I leave it plugged in year-round, since its not ridden all that much lately.

 

[sbw1]

Before I started buying boats that have all sorts of bells and whistles, I seldom plugged into shore power. I owned an 86 weekender that never got plugged in unless we went to a marina or cruised. That boat had the old fashion flooded cells that everyone expected to replace every three years. I routinely got 5 years on a set of batteries. That boat was stored cold inside a steel building. The batteries were always fresh in the spring. As soon as one battery started to fail, I replaced both. Other than keeping the water levels up, nothing else was done and it worked better than my friends' techniques which involved keeping chargers on and removing batteries for winter storage. A friend of mine in the marina business told me the key to long life is water levels and putting the boat away with a full charge. I think that was good advice because it worked for me so well. Charging technology has improved a great deal since 86 as have batteries. But we have lots more stuff on boats today so leavinng chargers on is recommended in many cases. But if you own a simple boat, this is not an issue to be overly concerned about.