Disconnect Batteries When on the Hard

Feb 6, 1998
11,667
Canadian Sailcraft 36T Casco Bay, ME
This is a cautionary FWIW category post.

Customer #1:

I get a call from customer #1 on Saturday morning. His boat is out and on the hard for winter. During a recent rain storm his bilge filled with water enough to kick on the bilge switch. Unfortunately his el-chapo Rule Bilge Switch stuck in the ON position. He did not get back to the boat for nearly a week and when he did he found his BRAND NEW TPPL AGM batteries, on Saturday, at 00.3V!!!! His garboard drain should have been removed the second he went on the hard and the batteries 100% disconnected from the vessel after being charged to 100% SOC. This was 100% preventable! Any vessel that stores mast up, with a keel stepped spar, should have a garboard drain installed if possible. If you store mast up and can't install a garboard drain think twice about mast up on the hard.

Customer #2:

Last Tuesday I got a call from Customer #2 who thought he "blew a fuse". When I get to the boat I find his 680Ah AGM bank at 00.12V. Once again his bilge pump stuck on and would not shut off. This was caused by his "check valve" sticking and refusing to open. He does not have a garboard drain and does store with mast up. No garboard drain is just a poor practice for mast up storage. Again his batteries should have been 100% disconnected when he left the vessel.

His bilge pump also does not have any OFF position which I have recommended multiple times. He insists on just pulling the fuse for winter but he "had not got to that yet". We have no idea how long his batteries sat at 0.12V but he had not been to the boat in approx 23 days. His batteries were not recoverable.

Once again bilge pump mistakes have costs thousands of $$$$$ in damages. Customer #2's AGM's were not recoverable and even after charging could barely muster 3.5Ah's for a 220Ah battery. They were brand new in May. I had suggested removing the check valve and installing a proper bilge pump system no less than 3 times and each time it was put off because "It seems to work.". The new bilge system would have cost less than 20% the cost of his battery bank..

Key Points:

*When on the hard batteries should ALWAYS be 100% disconnected from the vessel. Turning OFF the battery switch is NOT sufficient. Parasitic loads almost always exist and this will murder your batteries over the winter even without bilge pump mistakes.. Most boat yards require that batteries be 100% disconnected while on the hard.

*When on the hard and stored mast up, especially with keel stepped spars, you should have a garboard drain installed. This should be removed as soon as you are done pressure washing the bottom.

*Please, please please stop using check-valves on centrifugal Rule type bilge pumps. This is an incorrect & poor installation practice with almost all centrifugal style pumps. This horrid installation practice murders tens of thousands in batteries each year just in my small market (over 4k just last week alone). I can't imagine how many banks are destroyed nationally by the incorrect use of check-valves. If you need a check-valve use a diaphragm pump for nuisance water.

*Please, please please stop using cheap crappy Rule type float switches. Please use a time proven reliable bilge switch such as the Ultra Safety Systems Senior or Junior switches.

*Please always have a way of turning off your bilge pump other than via pulling a fuse.

*Expensive batteries can be murdered just as easily as inexpensive ones. These two incidents alone will cost $1900.00 in Northstar thin plate pure lead (TPPL) AGM's (unless they recover suitably) and about $2100.00 in Lifeline AGM's. These events could have been 100% prevented had quality equipment been chosen, proper installation practices had been followed (no check valve) and best practices for on the hard winter storage had been adhered to.
 
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Likes: Bob S
Sep 25, 2008
7,077
Alden 50 Sarasota, Florida
Another option for anyone who, like many, keep their boat "in" all year as well as those who prefer a safe way to maintain power while in storage is this:

https://dqzrr9k4bjpzk.cloudfront.net/images/4116263/359054711.jpg

Among the variants, West Mountain radio makes a battery cut-off which can safely disable a bilge pump should voltage go below 11v.


Specs:
  • Automatic safety switch turns off if voltage exceeds 15 volts or drops below 11.0 volts, turns back on when voltage in safe operating range
  • Momentary voltage dips below 11.0 volts are ignored to prevent false tripping while transmitting
  • Programming of custom trip limits available, contact sales for details
  • Rated for 40 amps maximum while transmitting, 30 amps continuous duty
  • Soft turn-on / turn-off solid state switch protects radio and reduces in-rush current...no relay contact bounce!
  • Indicator LEDs and audible alarm notify user when safety switch turns power off. Buzzer may be disabled by user
  • External sense input can be wired to a switch or low voltage (3-5 volt) DC input. May be used for:
    • Keyswitch to prevent rig use during antenna repairs or when unattended.
    • Cut power based on a sensor input such as a water alarm.
    • Power up based on a sensor such as light detector or low current switch.
  • Uses Anderson Powerpole® connectors
  • Dimensions: 1.25" H x 4.5" W x 2.75" D
 
Sep 23, 2009
1,475
O'Day 34-At Last Rock Hall, Md
Good advice. Thank you. Amazing the number of boats without drain plugs.
After disconnecting the batteries should any solar charger also be disconnected?
 
Feb 6, 1998
11,667
Canadian Sailcraft 36T Casco Bay, ME
Good advice. Thank you. Amazing the number of boats without drain plugs.
After disconnecting the batteries should any solar charger also be disconnected?
Most boat yards will not allow for it. In theory, if you have a good quality controller, you should be fine, but theory & real world often collide.

I have seen and witnessed a number of situations where small solar panels became occluded with snow/ice and the parasitic loads, on top of the controller load, sucked battery voltage below the safe cut-in/turn-on voltage for the controller. Even when the snow melted the solar could not recharge the batteries because the voltage was too low. Despite having solar the batteries were still murdered. I've also seen a very small controller-less solar panel murder a bank of golf cart batteries over a winter.

Safest bet is to charge to 100% SOC, equalize if they are capable of being equalized, and 100% disconnect them from the vessel. If you visit the boat over the winter charge them while you are visiting. Remember cold weather drastically slows self-discharge.
 
Mar 20, 2012
3,983
Cal 34-III, MacGregor 25 Salem, Oregon
Remember cold weather drastically slows self-discharge.
and also remember that freezing weather can damage a discharged battery beyond repair... but those that are reasonably charged will suffer thru the freezing temps without damage...
 

Gunni

.
Mar 16, 2010
5,937
Beneteau 411 Oceanis Annapolis
I believe the Beneteau negative disconnect, along with the battery positive disconnect effects this battery disconnect feature. MS, can you confirm? You can't install a garboard drain in most Beneteaus
 
Oct 1, 2007
1,856
Boston Whaler Super Sport Pt. Judith
What's the difference between mast in and mast out insofar as this issue goes?
 
Feb 6, 1998
11,667
Canadian Sailcraft 36T Casco Bay, ME
I believe the Beneteau negative disconnect, along with the battery positive disconnect effects this battery disconnect feature. MS, can you confirm? You can't install a garboard drain in most Beneteaus

The answer is, it depends. Generally speaking the negative/ground switch should isolate the banks but once anyone other than Beneteau gets in there all bets are off. On almost every Beneteau or Jenneau I have worked on the negative/ground switch had been by-passed by at least one or more parasitic bleeders and its isolation feature had been rendered useless..

On another note that disconnect switch does not meet US safety standards and is best re-purposed as an emergency parallel switch..
 
Feb 6, 1998
11,667
Canadian Sailcraft 36T Casco Bay, ME
and also remember that freezing weather can damage a discharged battery beyond repair... but those that are reasonably charged will suffer thru the freezing temps without damage...
A fully charged then disconnected battery will not freeze unless you hit temps approaching -72F... I was born in Fairbanks where temps reach -60F and battery freezing, even up there, is very rare. The only batteries I have ever seen freeze have been left connected to the vessel and were slowly discharged, by parasitic loads, until they froze....
 

Gunni

.
Mar 16, 2010
5,937
Beneteau 411 Oceanis Annapolis
On another note that disconnect switch does not meet US safety standards
What safety standard am I not meeting? I do have an auto bilge pump circuit that stays hot, but I simply pull the WAGO connect to turn it off.
 
Feb 6, 1998
11,667
Canadian Sailcraft 36T Casco Bay, ME
What's the difference between mast in and mast out insofar as this issue goes?
Rain water comes down the spar, even with the boat covered, and fills the bilge. With mast down the cover prevents water getting into the boat with mast up you can't prevent this unless you have a water-tight deck-stepped spar which some boats do...
 

MitchM

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Jan 20, 2005
1,011
Nauticat 321 pilothouse 32 Erie PA
i have had some luck in reviving dead 12v AGM s which have discharged to 6 v by using a 3 phase top quality 'automotive' charger set on 'equalize' charge, several times. once the voltage drops below a certain point on he house batteries, the on board 'top of the line' chargers (like my master volt) simply won't charge them. i now carry the auto 3 phase charger with me on the boat, since one never knows when a kid will leave the refrigerator on all week when we're not connected to shore power. the top of line auto chargers also have an 'engine start' feature.
 
Oct 1, 2007
1,856
Boston Whaler Super Sport Pt. Judith
Rain water comes down the spar, even with the boat covered, and fills the bilge. With mast down the cover prevents water getting into the boat with mast up you can't prevent this unless you have a water-tight deck-stepped spar which some boats do...
Yup. Such as mine.
 
May 17, 2004
5,032
Beneteau Oceanis 37 Havre de Grace
The answer is, it depends. Generally speaking the negative/ground switch should isolate the banks but once anyone other than Beneteau gets in there all bets are off. On almost every Beneteau or Jenneau I have worked on the negative/ground switch had been by-passed by at least one or more parasitic bleeders and its isolation feature had been rendered useless.
The problem isn't just aftermarket stuff. Ours came from the factory with the bilge pump and remote controlled LED cabin and cockpit lights bypassing the master switches. Combined they draw about 22mA. And if you make the mistake of not turning off the master switches then the DC panel itself, even with all breakers off, adds another 150mA.
 
Feb 6, 2013
437
Hunter 31 Deale, MD
So...a keel-stepped mast always leaks and there's no way to prevent it?

BTW, my boat stays in the water year round so the bilge pump has to be operational. When I winterize I pour antifreeze into the bilge so it pumps out and replaces any water in the drain line. This also allows me to monitor the bilge over the winter to see if any water has come in. So far, bone dry.
 
Dec 1, 1999
2,391
Hunter 28.5 Chesapeake Bay
What always surprises me are the number of boat owners who forget about their boats once they are hauled for the winter. Visiting your boat frequently in winter to check on things is cheap insurance -- plus it's fun to muck around in your boat, or in a boatyard, in mid-winter.
 
Nov 8, 2010
11,386
Beneteau First 36.7 & 260 Minneapolis MN & Bayfield WI
I believe the Beneteau negative disconnect, along with the battery positive disconnect effects this battery disconnect feature. MS, can you confirm? You can't install a garboard drain in most Beneteaus
Most beneteau also have deck stepped masts. ;^)

@Gunni , Look at the back side of your T-switches to see where always-on loads are mounted.
 

DougM

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Jul 24, 2005
2,242
Beneteau 323 Manistee, MI
. Visiting your boat frequently in winter to check on things is cheap insurance -- plus it's fun to muck around in your boat, or in a boatyard, in mid-winter.
Fun to do if your boat isn't buried under three feet of snow, not including drifts, in a fenced and locked yard a thousand miles away that hasn't been plowed out all winter...
 
Feb 6, 1998
11,667
Canadian Sailcraft 36T Casco Bay, ME
Fun to do if your boat isn't buried under three feet of snow, not including drifts, in a fenced and locked yard a thousand miles away that hasn't been plowed out all winter...
I sometimes need to bring snowshoes to work on some boats...:wink:
 
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Likes: SailormanDan
Jul 7, 2004
8,402
Hunter 30T Cheney, KS
This is my second off season with the boat. I left her plugged in last winter to keep the batteries charged while in the yard. This year I plan to investigate my holding tank located under the 3 batteries. MS's post makes me feel better about removing and taking them home in order to get to the tank stowage.
There must be a sequence for reconnecting batteries so that they don't accidently short when reinstalling them. I am taking pics and labeling because there are more wires than just the cables attached. Need to assess the correctness of that too.