what do you do with batteries in the cold winter months? The marina where I am staying this winter recommend disconnecting batteries if they are left on board. They are big and heavy so I prefer to leave them on the boat but it seems to me to make sense to leave them connected so that the solar panel, when it can, recharge (or top up) over the cold months. I suspect that over the winter, temps here close to Lake Ontario can regularly drop below 0 deg C and more than a few times below 0 deg F.
Any opinions or thoughts on the best course of action?
HI Jim, The marina is correct, disconnect the batteries. Make sure they are fully charged, and, if they have caps, check the water level is correct. Charging during extrem cold can damage the batteries, Do disconnect them to make sure all loads are removed.
I remove our 4 batteries in the fall and store them at home. Easier to keep them charged up and, I think, better for the batteries, though I have no real evidence for that. If someone can convince me otherwise, I’d be happy to take a less laborious route.
David Young
Bay Cat, 30U #402
Traverse City / Suttons Bay, MI
I have been leaving my single 10-year old Deka dual-service battery connected to all systems (tho it sure cannot hurt to disconnect them fully …) and hooked up to a $70.00 Canadian Tire 5 watt solar charger. I do top them up with distilled water in the fall and they rarely need a top-up in the spring.
I am in Toronto and, sometimes, it gets cold as hell here. Removing batteries is a physically challenging/dangerous task to be avoided. Murder if you have a bad back and battery acid burns.
Bottom line - this little charger keeps my battery FULLY stoked up during the winter. I’d do/get a careful analysis of what kind of solar charge you’d require depending on your battery bank and go that route.
I was told that solar chargers work better on a cloudy day vs. bright sunshine ??!!!
This will be my 6th year of charging the battery in situ. Highly recommended.
Thanks all for the comment and observations.
I should have mentioned that my solar charger has a controller so that should prevent over-charging. Turning the isolator switch to off is effectively the same as disconnecting, isn’t it? The batteries themselves are sealed AGM, I believe (something to check) so I shouldn’t have to worry about adding water.
I don’t like carrying big heavy batteries either, but I believe storing them at home over the winter would be best. For a fee the marina will remove them and take them inside but I’m afraid to ask how much!
I also leave the batteries on board ( Four Trojan 6 volt House Bank and one 12v starter ). They are a bit more than heavy and contain a fair amount of acid. A solar panel keeps them topped off during the winters. Yes, storing them in a warm place for the winter is best, but this system has proven to be both practical and safe.
Some boats have the electric bilge pump wired directly to the batteries so it works with the main switch off. Some stereos have a wire directly to the batteries to keep the channel memory. And some installers will hook diesel heaters directly to the batteries so that a person can't shut the heater off while it is still hot.
I know this because that is how La Reina was wired when We got her.
Wet cell batteries self discharge faster than AGMs or Gels so if you have wet cell batteries make sure the water level is up, they are fully charged and then check the state of charge periodiccay during the winter. If they are left partially discharged for a period of time lead acid batteries will lose capacity. If they are deeply discharged they are at higher risk of freezing.
Many years ago I deeply discharged the battery in my car trying to start it in -40 degree temperatures. When I came back the next morning to try to start it I found the acid/water in the battery was frozen. The amazing thing is that I was able to get the car started by pushing it with a truck and the battery recovered without apparent problems.
The main issue with charging in cold weather is the voltages required are higher than used in warmer summer weather. Unless you reach these voltages you will under charge the batteries and possibly not charge them at all. As well the solar trickel chargers that do not require regulation may not generate enough amps to do anything, that is why the do not need regulation. Plus there is maybe 4 hours of peak sun in the northern lattitides as well as cloud cover, The solar panel will only be effective for maybe an aaverage of 2 to 3 hours a day.
For example from the from the Trojan Web site my T105’s
Discharge at 4% per week or 9 amps.
At 20 degrees F I need 15.75V vs 14.8
A Colman trickel charger drives .475 amps at 15V… it will not charge or maintian my 2 golf cart batteries and one start battery…
I remove the batteries and take them home. Ya they are heavy. But I know they are charged properly, and do not like the idea of running a charger all winter on a boat. In fact many yacht clubs and marinas forbid the practice due to fire concerns.
There are chargers that address the temp issue and I assume there are solar regulators that will do the same. The Trojan web site has a good deal of information regarding charging requirements.
I agree with others that the best thing would be to take them out of the boat and store them in a warm environment.However, leaving them on the boat works for me with the following precautions.
I absolutely make sure that they are fully charged up.
I disconnect all cables from the batteries.Don’t just turn off the battery switch. Nothing should be connected to the battery terminals.
As soon as the weather is good enough to start going onboard and working on the boat, I will hook things up again and plug in the charger. My smart charger has temperature compensation so in practice it is supposed to apply the correct charge voltage. (charger is also set to the correct battery type)
If I was going to leave the batteries unattended for more than a few months then I would make sure to have some way to periodically charge them.