Batteries... Ok to leave in the boat over the winter?

[MOA_Chaser]

I have two batteries in the boat, a big DieHard AGM and a dual purpose lead-acid.

I normally take them out and put them in my garage over the winter and keep a trickle charger on them. I do have a Guest smart charger on the boat and it's always plugged in. My father said that they should be fine if the trickle charger is left on them all winter, even in 0°F weather.

Is this correct? It's a real pain to get the heavy batteries out, and I'd like to avoid it if I can.

 

[Julian]

@ChargerGuy might have a professional opinion....my thought is that as long as your Guest charger is a newish model with "smart" charging and it won't over charge them....I agree with your dad that they should be fine! My only caveat would be that the batteries themselves should be sealed marine batteries, otherwise you risk them venting into the boat or overflowing....if you have them in boxes (or trays)...this might not even matter....

 

[Gym]

I agree with @Julian. Car batteries are fine in the winter cold.

 

[jcyamaharider]

Mine are in the boat on a smart charger in 2 boxes. I have no worries beginning of next season that they will be prestine.

 

[Bruce]

I have two AGM batteries. I leave them in the boat in my garage with the smart charger connected.

One year I forgot to connect the trickle charger I was using at the time and I had to replace the battery in the spring.

 

[Murf'n'surf]

While batteries will last if stored in freezing temps, you are just subjecting them to a harsh environment which will shorten their life span. It's your call, any "savings" would be negligible but I would shelter them if it was my choice.

 

[MOA_Chaser]

The Guest charger is a newer computerized smart charger; I leave it on all summer. They are also both marine batteries.

I did some more reading and it seems like it's not a problem, and that storing them in cold temperatures actually decreases the discharge of the battery; as in how many people keep their alkaline batteries in the refrigerator. And that warm, year-round climates have shorter battery life spans than colder climates?

http://72.10.52.249/index.php?option=com_content&task=view&id=29&Itemid=1

Even though battery capacity at high temperatures is higher, battery life is shortened. Battery capacity is reduced by 50% at -22 degrees F - but battery LIFE increases by about 60%. Battery life is reduced at higher temperatures - for every 15 degrees F over 77, battery life is cut in half. This holds true for ANY type of Lead-Acid battery, whether sealed, gelled, AGM, industrial or whatever. This is actually not as bad as it seems, as the battery will tend to average out the good and bad times.

I think I'm gonna keep them in the boat but plugged in this year.

 

[txav8r]

Many of us store our boats indoors and that is a big difference, even in colder climates. But using a smart charger is smart. Because when it tests and sees a drop, it starts a slow charge, more of a test current than a charge, although it has a charge component. It warms the battery slowly to accept the charge, and then starts the trickle or more if needed. So even in the cold, it shouldn't be a big problem, however storing in a 70 degree room would be optimal. I don't store mine like that, and the barn may dip down to freezing or below when the temp outside is extreme. I have done this with my AGMs for years now and get good life from them. The lead acid needs to be vented more than the AGM. And covered tightly without much airflow keeps a pretty high level of oxidized gas in the boat. That gas is corrosive. However, if you use a Yamaha cover that has vents and is the fabric, it is breathable...the shipping cover is not. But keeping the batteries in the boat, maintained, over the winter is just fine.

 

[Island Jay]

This is a common question that I get asked frequently.
In short, I keep them in my heated basement. Subjecting batteries to freezing is just a bad idea, regardless of what charger you have it connected to.
A basic trickle charger on 24/7/months at a time is also a bad idea, especially with an AGM. AGM's do NOT like trickle charging, particularly when they need a true charge.
I would only connect a smart charger to the AGM and it is a better idea for the lead acid, too. Once charged it goes into a computer controlled trickle charge. If it was already topped off, that is an arguable point. But if I drop $300-$500 on an AGM, I would not go cheap on the charger.

Non smart chargers just sent out blind current. This causes boiling, explosive gasses escape, etc. The smart charger knows when to turn on/off. Regardless, I still only plug in my charger here and there for a day just to keep it topped off because I do not have any real venting in my basement. If I did, I would leave it plugged in all winter.

In case anyone asks, keeping your batteries on the cement floor will not magically kill them. If anything, a frozen cement floor causes damage because of the cold, in which case it is the cold causing damage. But if you have a a warm basement like me, the ground is fine.

Also someone mentioned that a car battery is OK in the freezing, so leaving your boat battery in the boat in the freezing cold should be ok. This is true except for one big difference. You are using your car daily, not giving the battery a change to truly freeze and kill it's life system. The moment you start your car, the battery is not only getting used, but charged. This is why it is ok to keep a freezing battery in a car, but in an unused boat. If you left your car in the freezing cold for months without starting it or running it, you would shorten the lifespan of the battery, if not killed it.