Winter is coming -Battery Question?

[ImASonOfaSailor]

My 12v Marine battery is still in my boat, i have a solar panel to charge it, then it goes into a regulator. SO this will be my first winter with boat with a battery so Should i leave solar panel connected? or let battery do what ever it does? will the battery just die or does it stay the same?


What do you all do?

[Maine Sail]

If you can aim the panel at the prevailing sun angle for winter, and ensure it does not get occluded by snow, it happens, and your controller is a good quality controller with a float stage, then you'd be fine leaving it connected.

Often times when we get a storm that starts out as rain and then turns to snow the rain on the panel turns to ice and then the snow sticks to it. I have seen some panels with very steep winter angles full and loaded with snow due to this phenomenon. Usually it melts in a few days but I know more than one owner who's banks were killed despite being connected to solar due to this phenomenon. Some controllers draw more than other for "self power" and this is why disconnecting from the rest of the system, and its parasitic loads, is critical....

Some points:

#1 All system connections other than solar should be disconnected from the batteries. I find the NEG connections often easiest to disconnect. Only the controller should remain connected to the batteries.

#2 You will only be able to charge one bank of batteries unless you have a very low draw method of "combining" banks at charge voltages. If the panel becomes occluded you can drain your bank with an ACR or Echo charger, if it is occluded for long enough. If the panel is large enough it will recover the banks but if is "maintainer" size you'll likely never recover.

#3 Colder temps drastically slow the rate of self discharge and help prolong battery life. However you have LESS usable capacity in colder temps so that .3A parasitic draw effectively becomes much larger in colder temps. The batteries should be 100% charged before disconnecting them and this usually means less than 0.5% of Ah capacity in acceptance at 14.2V.

#4 I would advise a "top up" charge every six to eight weeks if you disconnect and let sit.. Usually only 4-8 hours is needed as the self discharge in colder temps is very low. This is more to get the electrolyte moving to prevent stratification. Be sure your charger can go into absorption first, and remain there for a few hours, to get the electrolyte moving..

[CaptTom]

Some people insist that removing batteries and putting them somewhere with a stable temperature, but NOT on concrete, is the only answer. I used to do that. Now I leave the batteries in and top them off by plugging in the charger about once a month.

If I had a solar charger, I'd leave the battery in and the charger on all winter. Just to be sure it's working, I'd check the battery with a float tester a few times.

Always be sure the battery is 100% charged before storing.

[billyruffn]

I left batteries (2 banks of 350 and 450 Ahrs and a 110 Ah start battery) connected to the 100 W solar panel all last winter. I checked them every month or so and found the voltage above 13 V on every visit. When I'd turn on the battery charger the amp draw would quickly drop which is a good indication that the solar panel was keeping the batteries well charged. I might add that the boat and panels were covered w/ 7 mil white shrink wrap and the solar panel still worked fine.

[ImASonOfaSailor]

well i have one battery, 1 15 watt solar panel and the boat is in my back yard so i can take snow, and Ice off if that happens. So i guess ill hook the solar up when i get a chance!

[smurphny]

Although it is a major PITA, I always remove all three HUGE batteries and take them home where I can keep them warm and charged. I don't want to have to worry about a solar panel failing and the batteries freezing. Of course it gets to -30 around here so it's probably more a concern than points south. If batteries freeze, they're ruined and expensive to replace. The other thing that is always a concern is having any potential source of ignition in an unattended boat. I am surprised that any boatyards even allow batteries to be on a boat all winter.

[pdqaltair]

Originally Posted by CaptTom

... but NOT on concrete, is the only answer. I used to do that....

This seems to be a hard myth to kill. Perhaps 50 years out 0f date.

From the Trogan battery site:
Storing a battery on concrete will discharge it quicker- Long ago, when battery cases were made out of natural rubber, this was true. Now, however, battery cases are made of polypropylene or other modern materials that allow a battery to be stored anywhere. A battery's rate of discharge is affected by its construction, its age, and the ambient temperature. The main issue with storing on concrete is that if the battery leaks, the concrete will be damaged.

From Optima site:
No, today's batteries use polypropylene plastic for the case material. They will not be affected. When possible, always store a battery in a cool, dry location.

[Flybyknight]

Originally Posted by Maine Sail

If you can aim the panel at the prevailing sun

17 degrees East of South.

[Maine Sail]

Originally Posted by smurphny

Although it is a major PITA, I always remove all three HUGE batteries and take them home where I can keep them warm and charged. I don't want to have to worry about a solar panel failing and the batteries freezing. Of course it gets to -30 around here so it's probably more a concern than points south. If batteries freeze, they're ruined and expensive to replace. The other thing that is always a concern is having any potential source of ignition in an unattended boat. I am surprised that any boatyards even allow batteries to be on a boat all winter.

A fully charge battery will not freeze until it's colder than -70F. I was born in Alaska and my folks were there for years, in Fairbanks, and they only had flooded batteries back then. Freezing batteries was not an issue but tires that went flop, flop and cracked steering wheels were when it hit -50 - -60F.. The batteries survived just fine but had less cranking amps so many cars had bigger batteries then they shipped with.

Keep in mind that in warmer temps the rate of self discharge & the chemical reaction rate/sulfation accelerates so keeping the batteries "warm" can have less benefit to storing them in a cooler location at your house. In cold temps sulfation is virtually non-existent and this is why ours have always been stored on-board every winter. Many boat yards require batteries to be "disconnected" from the vessel, if left on-board, as they should. They allow top up charging while you are there but generally disallow batteries to be left on-charge..

If leaving them on-board they need to be 100% disconnected and charged them to full...

[smurphny]

Originally Posted by Maine Sail

A fully charge battery will not freeze until it's colder than -70F. I was born in Alaska and my folks were there for years, in Fairbanks, and they only had flooded batteries back then. Freezing batteries was not an issue but tires that went flop, flop and cracked steering wheels were when it hit -50 - -60F.. The batteries survived just fine but had less cranking amps so many cars had bigger batteries then they shipped with.

Keep in mind that in warmer temps the rate of self discharge & the chemical reaction rate/sulfation accelerates so keeping the batteries "warm" can have less benefit to storing them in a cooler location at your house. In cold temps sulfation is virtually non-existent and this is why ours have always been stored on-board every winter. Many boat yards require batteries to be "disconnected" from the vessel, if left on-board, as they should. They allow top up charging while you are there but generally disallow batteries to be left on-charge..

If leaving them on-board they need to be 100% disconnected and charged them to full...

Absolutely right. Batteries don't freeze if kept charged. They do, however, lose charge more quickly when it's cold and I want to cover the boat and leave it all winter without having to check it on a regular basis. I don't plan on seeing the battery compartment until spring. The issue always in the back of my mind is that if there were ever a fire in the boatyard, no one could point the finger at me for a battery short being the cause. I also remove all signaling devices because if there were a fire, I would not want the guys in the FD having to deal with SOLAS flares going off.

I keep the batteries in my garage, where it is usually 40 degrees or so and occasionally put on a charge to keep them up to voltage. They are heavy sobs and I always dread disconnecting all the wires, ANL fuses, etc. and then getting them down the ladder and into the car.