To charge or not to charge - that's the question

[Juliet 15]

I was winterizing my boat the other day and began thinking about why I leave the chargers on all the time when in the slip. IOW, why do I have the chargers constantly on?



My car battery doesn't need to be plugged in and trickle charged or float charged whenever it's parked, even if I don't use it for a month or more. My car batteries generally last around 5 years or so, even after sitting outside in through winters and summers.



I've never had a car battery spit acid out the vents; never had one blow the little plugs out of the cells, or bulge out on the sides. I've never had my car battery gas off so much acid the plates start to show.


But I've had all those things happen with my boat batteries, despite expensive "smart" chargers.


How come we don't treat boat batteries like car batteries, and leave the chargers switched off except for occasional, maybe once a month, charging? Not making a statement, just not sure I know the answer...


Now, back to winterizing.

 

[MurrayM]

We only have ours plugged in for the winter, to run heaters, etc. During the rest of year our using the boat would keep the batteries charged. This year, Life intervened and we hardly used the boat, but a newly installed solar panel kept things charged.

We live 15 minutes from the marina, so I check on the boat often.

The number one reason I can think of, especially if you can't get to the boat on a regular basis, is that your bilge pump may need to run heroically/continually until you come back or some dock neighbour notices it's running constantly and gives you a call.

 

[C lectric]

That's what I do.
I check on the boat every few days and can do so though.
I am aware and take regular voltage readings and plug the battery charger in when needed.
I do not leave it on all the time.

 

[rslifkin]

Most of us have minor and/or occasional battery draws, so without the charger floating the batteries all the time, the batteries would be slowly drained with attendant sulfation issues.

 

[kchace]

Most of us have minor and/or occasional battery draws, so without the charger floating the batteries all the time, the batteries would be slowly drained with attendant sulfation issues.

Exactly. Also, cars are usually used much more regularly than some boats so the battery is more often topped off.

Ken

 

[High Wire]

Once per month for 12-24 hours would be fine. Make sure there is no drainage. Things like a stereo memory will drag a battery down to 0 percent SOC over time. My batteries get a full charge then completely disconnected for 6 months at a time. After 6 months of Florida summer storage my banks will be around 50 percent.

 

[FF]

An LA batt depending on age will loose 1/2% to 3% per month.

The small battery tenders for each batt do a better job than a big buck charger.

The big charger has no way to understand when a cell goes bad , so the Entire set will usually be overcharged to oblivion.

 

[Chrisjs]

Our marina did not permit boats to be plugged in during the Winter. Any left afloat got no power. Those on the hard were not allowed to stay plugged in. Fortunately, we were usually close enough to a shore outlet that I was able to top the batteries off every 4-6 weeks. When you have a couple of grand "invested" in batteries, it is worth the drive to make sure.

 

[Bacchus]

I do the same for oyr cars but I don't have a fridge or holding tank bubbler running 24/7 in my cars.

 

[Porgy]

With no charger on, if you developed a leak, even a small one, the bilge pumps would kill the batteries and the boat could sink.

 

[jgwinks]

Our marina did not permit boats to be plugged in during the Winter. Any left afloat got no power. Those on the hard were not allowed to stay plugged in. Fortunately, we were usually close enough to a shore outlet that I was able to top the batteries off every 4-6 weeks. When you have a couple of grand "invested" in batteries, it is worth the drive to make sure.

That's pretty common, especially in storage areas. Often only a few plugs for all to share, let alone the cost to the yard for all the amp hours used. That's where a small solar panel cones in handy. The "proper" way to store a battery is to fully charge then completely disconnect. The self discharge slows down in cold weather so they don't discharge much in a cold climate. That being said I usually have projects to work on over winter so I don't want to disconnect the batteries, running lights and stereo, and occasionally power tools through the inverter while I'm working. I just top up the water and leave the solar hooked up. The batts stay healthy and everything's ready to go when I need it. Some authorities recommend removing the batteries to a warm storage area, but that speeds up the self discharge, risks stirring up the sediment in the bottoms of cases, let alone what it does to your back. (You want to pull those 8D's every year?) I'm in Michigan, so we're on the hard all winter and no bilge pump to worry about.

 

[bayview]

One reason is to keep the bilge pumps running if there is a problem

 

[koliver]

Battery life improves with constant charging, so long as it isn't overdone.
Even cars, especially newer, more sophisticated cars, will benefit from constant charging.
Low amperage "battery minders" are adequate for most FLA batteries in boats or cars, unless there are likely to be larger draws, then a more sophisticated charger will be required.
If you have an old style, dumb charger, probably better NOT left on for months at a time.
Modern Inverter/chargers can be left on.
On my boat, the charger is left on. It also serves to keep the ER warm.
On my cars, left for months at a time, the small battery minder on all the time has lengthened battery life from the typical 5 yrs to ...? My newest car, bought new in 2005, is still on its original battery, though left for winters on a minder, for the last several years.
My boat, the last battery replacement, on the constant charging regime, was for 11 yrs old FLA GC 6v house set.
YMMV

 

[tiltrider1]

In the case of our OP, I suspect there is more to the story and something is not right. A 58’ boat has a lot systems that have small parasitic drains that could kill a battery bank over time if not left on a charger. What is not mentioned is which batteries are suffering issues. Is it the start batteries, the house batteries, or auxiliary batteries. Start batteries often get combined with house batteries for charging which means they are constantly over charged. In the case of house batteries unbalanced wiring can cause overcharging issues on individual batteries with in a bank. Mixing dissimilar batteries in a bank can cause overcharging issues.

This is why I recommend Smart ACR’s over ACR’s. A Smart ACR will allow a start or auxiliary battery to receive a charge from the house bank if a charge is present. It will regulates the amp flow to prevent overcharging and it will disconnect if necessary to prevent overcharging.