Batteries over winter

[vyv_cox]

Those batteries were in where Aegean over a summer ???

Leros.

 

[lw395]

I leave my boat for at least six months of the year. Having tried all sorts of regimes I was advised by a marina specialist who I trust totally to disconnect them from everything, including themselves in a bank. I have found this to be totally successful. When I left the boat with all connected to a 40 W solar panel through a controller I was prevented from returning by health problems and didn't come back for 18 months. They were all boiled dry.

This is a possible problem with most controllers.
They default to a substantial period of over 14V every time the sun comes out.
Leaving anything unsupervised for 18 months is a big ask.
18 months of zero use is probably not a scenario the controller designers had in mind.

The opposite problem is that no battery manufacturer will assure you it's OK to leave the battery for months on end without a float charge.
If they could guarantee that, they'd corner certain markets.

My observation is that the need for a float charge varies from unit to unit as well as across battery types and brands.
Also the gain from a float charge tends to increase as the battery gets older.

I think whatever chargers you have, some sort of voltage and if possible electrolyte level check periodically is a good thing.

 

[pandroid]

In the UK, close to home, I plug the boat in once a month and charge them overnight. In the Baltic, inside a shed, I disconnect the batteries in September and do nothing to them until the following May. We get 7+ years out of our Lead-acid so seems to work.

 

[vyv_cox]

This is a possible problem with most controllers.
They default to a substantial period of over 14V every time the sun comes out.
Leaving anything unsupervised for 18 months is a big ask.
18 months of zero use is probably not a scenario the controller designers had in mind.

The opposite problem is that no battery manufacturer will assure you it's OK to leave the battery for months on end without a float charge.
If they could guarantee that, they'd corner certain markets.

My observation is that the need for a float charge varies from unit to unit as well as across battery types and brands.
Also the gain from a float charge tends to increase as the battery gets older.

I think whatever chargers you have, some sort of voltage and if possible electrolyte level check periodically is a good thing.

I think you are correct. On our little motorsailer in UK that has unfortunately not had a lot of use for similar reasons, we have a 10W panel on the domestic bank of 220Ah and a 5 W on the starter battery, fairly large as the engine is a 2.2 litre BMC diesel. Last time we visited after a long break all seemed to be well and the engine started within about 5 seconds, a record for this engine..

 

[PaulRainbow]

This is a possible problem with most controllers.
They default to a substantial period of over 14V every time the sun comes out.

A decent controller shouldn't do that. Victron controllers certainly don't.

The controller is also configurable and user defined presets can be saved. So it would be a simple task to set the controller to a max amperage output, just enough for a maintenance trickle charge, if leaving the boat for a lengthy period.

 

[lw395]

A decent controller shouldn't do that. Victron controllers certainly don't.

The controller is also configurable and user defined presets can be saved. So it would be a simple task to set the controller to a max amperage output, just enough for a maintenance trickle charge, if leaving the boat for a lengthy period.

There are lots of charge controllers out there.
There are many methods of determining the end of the daily absorption phase.

Another possible issue is too high a float voltage. 13.8 is widely touted as standard, but it's a function of temperature and a lot of battery manufacturers specify less.

 

[macd]

In the Baltic, inside a shed, I disconnect the batteries in September and do nothing to them until the following May. We get 7+ years out of our Lead-acid so seems to work.

I presume yours batteries are lead/calcium. I certainly wouldn't do that annually with lead/antimony.

 

[James_Calvert]

Re disconnecting batteries make sure you do just that. I've got an item connected directly to the battery, ie not through the master switch. It draws enough current to flatten the battery in a few months if forgotten about.

 

[Denek]

Thanks a lot for all this advice guys. Seems there are lots of options here so I will not worry too much. Boat handover on Friday and then the responsibility is all mine�� I will going with a notepad to make a list of things to do before during and after the winter. See you on the water. Thanks again.
Ps I will be back with more questions I am sure.