how to winterize the elec. system ?

jssailem · Nov 11, 2017

Pat
Here is a link from Optima Batteries that addresses the issue. Worse condition is batteries that are discharged and left in the winter till spring.
https://www.optimabatteries.com/en-.../how-does-your-marina-maintain-your-batteries
Many folks remove their batteries from the boat and store them in a shed/garage where the batteries can stay above the minus 0 conditions sometimes experienced on the plains of KS. Frozen batteries are not good.

jssailem · Nov 11, 2017

It is also a good time to check all of your connections to clean and or grease the connections. Replace any that show heat damage or corrosion in the wire.

Davidasailor26 · Nov 11, 2017

Rule of thumb is that leaving them connected and not charging is probably the worst combination. There will be small parasitic loads that slowly drain the batteries, and having them sit for months at less than full charge is quite harmful. Leaving the boat plugged in to charge them all winter is frowned upon in many yards, from the standpoint of potential fires and also potential safety issues depending on grounding and any AC leakage. Best is to fully charge them then leave them completely disconnected, or remove them from the boat. US Battery says that “A fully charged battery has a freezing point around -80 °F while a discharged battery has a freezing point around 20 °F”. My preference is to leave them disconnected but in-place. In the low temperatures of winter they should have minimal self discharge. I stop by once every 2 or 3 months over the winter to charge them for a few hours just in case, but they never take much.

Dalliance · Nov 14, 2017

I leave my batteries in place on the boat over the winter. Fully charged and completely disconnected. My experience has been that they discharge very little over the winter that way. The cold doesn't seem to hurt them as long as they start the winter fully charged.

Maine Sail · Nov 15, 2017

This is simple..

Charge to 100% SOC (a few days on the charger)
100% disconnect the batteries from the vessel, each other and the charger
Never a bad idea to remove expensive electronics too
Done

IStream · Nov 15, 2017

It should probably be stated that this is for boats on the hard. I leave my boat in the water over the winter and leave the bilge pump connected.

Dalliance · Nov 15, 2017

IStream said:
It should probably be stated that this is for boats on the hard. I leave my boat in the water over the winter and leave the bilge pump connected.

Yes. Good point to clarify. Only for boats on the hard.

Maine Sail · Nov 16, 2017

IStream said:
It should probably be stated that this is for boats on the hard. I leave my boat in the water over the winter and leave the bilge pump connected.

Unfortunately there is no good way to deal with this, in an area that freezes. Here in Maine I have seen countless bilge pumps with blown fuses or oversized fuses and the resulting melted / fried pump due to the bilge water freezing, even with PG in it. I got a call from this very panicked live-aboard one winter. I measured the sea water temp at 28F, it had been -10F or colder for about 4 days, and the -50PG he'd filled the bilge with had become diluted and froze .... Even with an on-board temp in the boat of 65F to 70F his bilge was frozen solid. Because he replaced the fuse when it blew, with the wrong size fuse, when the bilge contents finally melted the bilge pump was dead......

njlarry · Nov 16, 2017

Dalliance said:
I leave my batteries in place on the boat over the winter. Fully charged and completely disconnected. My experience has been that they discharge very little over the winter that way. The cold doesn't seem to hurt them as long as they start the winter fully charged.

Same here. Spring voltage is only .1 or .2 volts lower than before disconnecting in fall. I have flooded multi purpose group 24 that I abuse all season due to electric refrigeration and anchoring out a lot. Forgive me Maine Sail. Batteries are now over 4 years old.

IStream · Nov 16, 2017

I guess I should clarify further: for areas that don't freeze with regularity.

Maine Sail · Nov 16, 2017

IStream said:
I guess I should clarify further: for areas that don't freeze with regularity.

Your points make for excellent conversation...

Some points to consider:

If you keep the boat in the water for winter storage a good practice is to still 100% charge the house bank then physically disconnect it from the vessel and the batteries from each other, if they're in parallel.Series connections can stay connected so long as parallel and batteries from vessel are isolated.

You would then keep the much less expensive start/reserve battery on-line, and on the charger, for the bilge pump or cabin lights when you visit to check on it during the storage period. Doing this protects your much more expensive house bank from any sort of charger malfunction (not at all uncommon), internal cell failure, dock power outage, which are becoming increasingly more common with the new NEC/NFPA standards for ground fault compliance, etc. etc..

Any of the above failures, plus stuck bilge switch, can and do easily take out an entire house bank even with the charger left connected. For example I've had half a dozen or so stuck bilge switches force chargers back to absorption and destroy thousands of dollars in expensive house banks while no one was there to monitor this..

If your start/reserve battery is an expensive AGM or GEL you can pick up what I refer to as a sacrificial battery (like an anode you just accept as a cost of boating) for $19.87 (Wal*Mart) such as a U1 or similar lawn and garden battery to use as your 12V buffer during the off season. If all goes well the little U1 may last 5 years doing this however, if a failure or problem occurs, you're only out the $19.87 for your sacrificial battery and your expensive house and start batteries are protected.

So long as your charger is larger than the bilge pumps load the charger is the device powering the bilge pump and the battery is nothing more than a buffer..

Doing what I do for a living I see far too many good banks ruined by long term unattended charging resulting in many thousands of dollars in ruined batteries each year..

On the flip side I've yet to see a hibernating, decommissioned / isolated bank that was ruined come spring due to a charger malfunction, power outage, stuck bilge switch etc. etc....

A lot of folks never consider all the failure modes that can occur with unattended charging and it is one reason many boat yards disallow the unattended charging with boats stored on the hard....