House bank maintinence over winter

[JustCruisin]

I have a house bank of six 6v golf cart type batteries and a Charles 30a charger that goes into a float mode and keeps them at 13.2- 13.3 volts. I have maintained them with distilled water, very little has needed to be added this year. They are two years old, so my question is being that the boat is in the water over the winter is it best to just leave it on all the time in float mode or should the be periodiacally be partially discharged and then re-charged. I have not found this answer so hopefully those with experience might give some advice. Thanks in advance...

 

[Comodave]

I have a smart charger and leave mine plugged in all winter. But I am there almost every day doing something to the boat so it would be a pain disconnecting it every day.

 

[JustCruisin]

I was just wondering if it was better for the batteries to let them discharge a bit and then recharge them or just let the charger keep them topped up all the time. I visit my boat a lot so either way is no problem.

 

[STB]

My knee jerk reaction is that I'd want to let it continuously float charge. FLA batteries go bad less quickly quickly when maintained at a high SoC. They can be float charged for YEARS without discharge.

Of course things can get more complicated if extremely cold environments are mixed with silly chargers. That can lead to overcharging.

How cold will the batteries be in winter? And how smart is your charger?

 

[SteveK]

I am getting mixed feelings whether to float or not to float.
I have been away from one of my boats for near two months and the monitoring system was showing 13.9 - 14.1 float. It was never over 13.6-13.8 so something may not be right. I had an onsite turn off the inverter/charger until I can get there.
One thing I had noticed before is loss of fluid with the constant float, so that suggests overcharging.
It was always good to float charge when regular use was possible to keep batteries at the ready. Now I am leaning to programmed recharge and no float while it is in storage mode.

Searches bring up mixed opinions to float or not so there is no definitive answer.

 

[DDW]

Does the charger have a temp sensor on the battery bank? Float voltage varies with temperature. Victron chargers have a "storage" mode that goes to a lower float voltage most of the time, wakes up every 7 days and does a quick charge cycle. You could emulate that by simply putting the charger on a timer.

 

[sunchaser]

I have a house bank of six 6v golf cart type batteries and a Charles 30a charger that goes into a float mode and keeps them at 13.2- 13.3 volts. I have maintained them with distilled water, very little has needed to be added this year.

This sounds like a good situation. I'd not change it in fact mine are in a similar situation for months on end. If you're overly concerned install a volt meter that allows an app to connect to your cell phone.

 

[rslifkin]

If they're being floated at a low enough voltage that they don't consume much water, let them float all winter and just check the water level periodically. Keeping them topped off will be the best thing you can do for their lifespan.

 

[STB]

I am getting mixed feelings whether to float or not to float.
I have been away from one of my boats for near two months and the monitoring system was showing 13.9 - 14.1 float. It was never over 13.6-13.8 so something may not be right. I had an onsite turn off the inverter/charger until I can get there.
One thing I had noticed before is loss of fluid with the constant float, so that suggests overcharging.
It was always good to float charge when regular use was possible to keep batteries at the ready. Now I am leaning to programmed recharge and no float while it is in storage mode.

Searches bring up mixed opinions to float or not so there is no definitive answer.

Something sounds off in your situation. If the BMS is reporting 13.9v-14.1v, what is reporting the 13.6-13.8v? What is the difference in where and how the voltage is measured?

Either of those voltages seem higher than I'd want to float charge FLA batteries. I usually think ~2.25v/cell, so ~13.5-13.6v for "12v" batteries. I wouldn't be surprised to see more significant water loss at higher voltages.

 

[SteveK]

Something sounds off in your situation. If the BMS is reporting 13.9v-14.1v, what is reporting the 13.6-13.8v? What is the difference in where and how the voltage is measured?

Either of those voltages seem higher than I'd want to float charge FLA batteries. I usually think ~2.25v/cell, so ~13.5-13.6v for "12v" batteries. I wouldn't be surprised to see more significant water loss at higher voltages.

13.6 is the recommended and for years was where it was. in the past month it went to 14 average. So something is not right and it is turned off until I get there to check on it. the battery is sitting at 12.7 today.
The upswing to 14 was during our local cold snap, maybe that is what it should do.

 

[rslifkin]

13.6 is the recommended and for years was where it was. in the past month it went to 14 average. So something is not right and it is turned off until I get there to check on it. the battery is sitting at 12.7 today.
The upswing to 14 was during our local cold snap, maybe that is what it should do.

If your charger has temperature compensation, then higher voltage as the batteries get colder is normal (and necessary for proper charging of lead-acid batteries).

 

[Pete Meisinger]

I think it is important that you are on your boat often. I don't think that every day is a requirement, but the more often the better. Whenever I am on my boat I use some 12 volt lights, etc. A little activity is good for batteries.

pete

 

[SteveK]

If your charger has temperature compensation, then higher voltage as the batteries get colder is normal (and necessary for proper charging of lead-acid batteries).

yes it does, thanks for that.
If fluids are good I will turn it back on. Maybe turn off float, let it cycle.

 

[Barrie]

Your lucky you can plug in a charger. Our marina won't allow it.
Six years of experience has me comfortable charging the batteries right up - disconnecting them - and saying good bye till the spring. When I come on board the first time I check and they are holding 90% charge. I charge before launch and no issues. we can hit -35c here
(I hope I didn't just jinx myself)
Barrie
The six stages of life: Toyboat, Sailboat, Motorboat, Motor Home, Nursing Home, Funeral Home.

 

[rslifkin]

Your lucky you can plug in a charger. Our marina won't allow it.
Six years of experience has me comfortable charging the batteries right up - disconnecting them - and saying good bye till the spring. When I come on board the first time I check and they are holding 90% charge. I charge before launch and no issues. we can hit -35c here
(I hope I didn't just jinx myself)
Barrie
The six stages of life: Toyboat, Sailboat, Motorboat, Motor Home, Nursing Home, Funeral Home.

Ours is similar rules-wise. Boats can't be plugged in on land if you're not there. So I power down everything except the actual battery monitor shunt and the stereo memory, cutting draw down to just a few milliamps. And then I plug the boat in whenever I'm there to check on things, do some work, etc. That ends up being at least a few hours of charge time every week or so, which has been plenty to keep things topped off and happy.

 

[tiltrider1]

I don't think it matters. I think running an equalization charge at the end of winter is more important than whether they are in float mode or not.

 

[Steve DAntonio]

Battery winterization: https://stevedmarineconsulting.com/wp-content/uploads/2014/03/gearhead-nov-17.pdf

 

[JDCAVE]

A datum point: just swapped out my T-105’s after 9 years. Other than topping them up with distilled water, there has been no maintenance and no equalization charging. They were left on float charge continuously at the dock. Magnum charger with temperature sensor. Also use solar power when cruising to maintain SOC at a minimum of 90%.

After removal, I left them for 2 weeks and the individual charges were 6.45 volts. My son put them in his boat.

Jim