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I have a Cobalt R7 that has 2 Interstate batteries and I have always removed them before storing the boat for winter. I store the boat in a heated warehouse and am curious if it would be ok to leave the batteries connected in the boat for the winter? My concern would be that they loose their charge over winter or may go bad. Your thoughts or experiences would be appreciated.

You don’t need to pull them but I would keep a small battery maintainer on them. (Or make sure they’re fully charged before storage and completely disconnect).

Do you think they would be ok without the maintainer? The warehouse has 50+ boats/RV's and they will not allow everyone to be plugged in. I could put a charger on them before putting the boat in the water in the spring.

For longest life you should have them on a float (maintainer) charger in the off season.

I store my boat Dec-Mar and for the batteries, I just make sure the water is topped off and they are fully charged. I don't unhook them, just turn the battery switch off. Never an issue, at least never showed up in April with a dead battery - if you could hook a trickle charger up that would be best, but in most storage facilities that is just not possible.

We leave ours in as we can boat year-round, but I would probably pull them and take them home if they arent going to be used for a few months.

I am leary of leaving mine on an unattended charger. Being in the garage, I am afraid they could trip the GFI, shutting off the sprinklers and killing my cactuses.

I would pull the batteries if it were me. This gives you a chance to recharge them at home and keep them charged until springtime. My storage facility, like yours, is not set up to where I can plug a charger into a receptacle.

Longer version that I posted on another thread.
viewtopic.php?p=104205&hilit=BatteryMinder#p104205

Batteries actually self discharge less the colder it is. A fully charged battery won't freeze until -80°F so as long as the battery is fully charged, it is fine.

I have two boats. The Cobalt has an onboard charger that I leave plugged in while it sits in a garage that sits at around 50°F. I am MANY miles away from the boat so I just leave it plugged in 24 hours a day. My pontoon boat sits in a storage yard so I take the batteries home with me becuase of possible theft. I charge them up occasionally when they drop a couple tenths of a volt. All my batteries are AGM so they self discharge less than a regular flooded lead acid battery.

BTW...you don't want a trickle charger for long term storage. You need a charger that will actually float the batteries. Definition of a trickle charger is that it has a constant small current that gets input into the battery. You do NOT want that with a lead acid battery.

FLCErik wrote: Tue Sep 20, 2022 10:56 am I have a Cobalt R7 that has 2 Interstate batteries and I have always removed them before storing the boat for winter. I store the boat in a heated warehouse and am curious if it would be ok to leave the batteries connected in the boat for the winter? My concern would be that they loose their charge over winter or may go bad. Your thoughts or experiences would be appreciated.

In late 2019, our dealer closed our boat after doing some new boat maintenance. They just turned the battery switch off. We've been doing the same and have never had a problem with dead batteries. Still using the Interstate batteries that came with the boat. In north central Arkansas, there's probably 30-60 days each winter where temp is below freezing.

I store mine in a hi-dry and you can't plug them in, my batteries last 7 years or so? Just shut them off for winter.

I must be missing something. My Mercathode system will kill my battery in a few weeks. Nothing wrong, that's just how it works. It's wired to be one of the two loads that stay powered with the battery switch in off. Removing the batteries for the winter gets me an easy access to top off the cells with distilled water and charge them. I'll charge them again in the spring before the maintenance done then.

I would pull them and put them on a float/maintainer. A good point mentioned earlier, both VP and Merc may come with a active corrosion device tied 24/7 to the battery. Unless you disconnect it the device will drain the one battery in a month regardless if the switch is OFF.

Mike in SC wrote: Thu Nov 10, 2022 9:32 pm I must be missing something. My Mercathode system will kill my battery in a few weeks. Nothing wrong, that's just how it works. It's wired to be one of the two loads that stay powered with the battery switch in off. Removing the batteries for the winter gets me an easy access to top off the cells with distilled water and charge them. I'll charge them again in the spring before the maintenance done then.

Good point regarding the Mercathode. In addition to it there is also the current drain of the ACR if equipped. Although Cobalt wired mine on the switched side Blue Seas insists it be tied on the battery side.

stifflkd wrote: Fri Nov 11, 2022 10:50 am I would pull them and put them on a float/maintainer. A good point mentioned earlier, both VP and Merc may come with a active corrosion device tied 24/7 to the battery. Unless you disconnect it the device will drain the one battery in a month regardless if the switch is OFF.

I discovered that my MerCathode was connected to the battery #1 post on the battery switch earlier this year, so turning the battery switch off does not disconnect the MerCathode. Yet my undersized #1 battery (only 550 CCA deep cycle) can still start the boat after several months?

I should verify that the MerCathode system is still working. We probably do not need the MerCathode as we only boat in fresh water and rarely have the boat in the water overnight.

stifflkd wrote: Fri Nov 11, 2022 10:58 am Good point regarding the Mercathode. In addition to it there is also the current drain of the ACR if equipped. Although Cobalt wired mine on the switched side Blue Seas insists it be tied on the battery side.

Mine was wired by Cobalt on the battery side. I moved it to the load side so it the ACR would not connect while the battery switch was off and my dual battery charger was on.

The ACR only draws 15mA which would could be significant over 90 days(over 30AH) if no charger was used.