All four batteries at 0.0V

ZZ13

ZZ13

Well-Known Member
Nov 25, 2009
5,329
Lady's Island, SC
Boat Info
2001 400 Sedan Bridge
Engines
Cummins 450 Diamond
2001 400 Sedan Bridge with Cummins 6CTA (not my boat but a friends). Boat was hauled two weeks ago for bottom paint and some gelcoat repair. I went and checked on it yesterday for the owner and all four main engine batteries were completely discharged. 0.0V. Brand new AGMs. The two main battery switches were on but all 12V breakers on the electrical panel were turned off. This is second time this has happened on this boat. A couple years ago the dock lost power for a while and all four batteries (brand new AGMs then, also - that's why these are now because those never came back) completely discharged as well (fridge was on for one of them so that's a reason for the starboard side). I guess something on both banks could have run continuously but that seems odd. I can see one float switch getting stuck but not two at the same time on separate battery banks. We'll go back and see if the work staff may have leaned on some of the bridge switches, but other than that there is stereo memory and some bridge electronics that could have had a very low continuous current draw.

Fishing for ideas here as to whether there is something abnormal going on with the wiring inside the boat.
 
Take a look at the engine alternators; if the diodes are failing, they will bleed current to ground.
0.0 is unrecoverable; I've never seen batteries that low and all of them.
Things that always have power on regardless of battery switches:
Bilge Pumps
Stereo memory
CO monitors
Engine room blowers
Systems Monitor
Engine unswitched (if your boat is electronically controlled)
Battery charger/converter

To completely kill all of the battery banks, however, maybe there are some electrical modifications that someone did causing.
 
This might be tuff. if all the breakers are off. you might have to see if there any leads coming off the battery or starter that might be powering other devices. I agree with TTmott the alternator could be blending off. you could put a VOM or a test light in series with it to confirm.
 
Thanks everyone. We are going to try to get good batteries in today, then I’ll run a current test at the alternator hot connection.

Also disconnected all four batteries and checked them individually. Each one is at around 5.0v. I had assumed 0v because the voltmeter on the electrical panel was pegged to the left.

Also found running light switch had been left on. Yard worker noticed lights on a few days ago and turned it off. They are incandescent bulbs on his boat , so that may explain the port battery drain. Still researching starboard battery drain.
 
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If they are AGM's and have 5V, put them on a 2A trickle charge for about 3 hrs, then a normal charge might bring them back. They will not accept a full charge without the 2A initial charge. I bet @ttmott could explain!
 
Got all four up to about 12.7v when the yard splashed it. Engines started right up. After the 10 mile ride to his home slip they were at 13.0v which is the 100% capacity for AGMs. Will see how well they hold capacity.
 
I hope they hold for you. I have seven batteries flooded on my boat and dread the day I need to replace them.
 
ttmott said:
Take a look at the engine alternators; if the diodes are failing, they will bleed current to ground.
0.0 is unrecoverable; I've never seen batteries that low and all of them.
Things that always have power on regardless of battery switches:
Bilge Pumps
Stereo memory
CO monitors
Engine room blowers
Systems Monitor
Engine unswitched (if your boat is electronically controlled)
Battery charger/converter

To completely kill all of the battery banks, however, maybe there are some electrical modifications that someone did causing.
Click to expand...
I current tested the port alternator and air grid heater today. Air grid heater was clean. No current draw. But alternator was pulling about 250 micro amps. He had a new spare alternator onboard so I grounded it and checked current draw from the removed hot alternator cable to it. No current draw. So it appears the alternator may be failed. Although 250 micro amps isn’t much, it’s not zero like the other one.
 
ZZ13 said:
I current tested the port alternator and air grid heater today. Air grid heater was clean. No current draw. But alternator was pulling about 250 micro amps. He had a new spare alternator onboard so I grounded it and checked current draw from the removed hot alternator cable to it. No current draw. So it appears the alternator may be failed. Although 250 micro amps isn’t much, it’s not zero like the other one.
Click to expand...
And leakage can change as things get hot....
 
ZZ13 said:
I current tested the port alternator and air grid heater today. Air grid heater was clean. No current draw. But alternator was pulling about 250 micro amps. He had a new spare alternator onboard so I grounded it and checked current draw from the removed hot alternator cable to it. No current draw. So it appears the alternator may be failed. Although 250 micro amps isn’t much, it’s not zero like the other one.
Click to expand...

micro or milli amps? not sure many meters read microamps - and if they do, that 250uA would take a long time to kill a battery (sorry - too lazy to do the math).

Guess I’m just trying to say - if its micro, then I dont think your Alt is the issue.

Plus - you said both batt banks were dead right? Still think you have a gremlin or two running around - or some other yet to be explained issue that killed everything.
 
markrsimon said:
micro or milli amps? not sure many meters read microamps - and if they do, that 250uA would take a long time to kill a battery (sorry - too lazy to do the math).

Guess I’m just trying to say - if its micro, then I dont think your Alt is the issue.

Plus - you said both batt banks were dead right? Still think you have a gremlin or two running around - or some other yet to be explained issue that killed everything.
Click to expand...
No I’m wondering. I’ll retest.
 
A little update. The owner decided to install a Victron battery monitor. After that we turned all 12v breakers off but left battery switch on. Steady draw of .8 amps. That’ll drain his batteries to zero capacity in about five days. With battery switch then turned off the draw is 0.0 amps. So time to check everything on the battery switch load.
 
Which battery switch is the draw on. Just wondering as when I turn my battery switches on I can hear a “ click” from behind the power panel when I switch on one of them. Can’t remember which one it is now, never paid much attention, just assumed it is normal. I only hear it when the boat is in the building and it’s quiet. But then that’s the only time I ever turn the switches on and off because it’s not plugged in. Good luck.
Keep us posted.
 
ZZ13 said:
A little update. The owner decided to install a Victron battery monitor. After that we turned all 12v breakers off but left battery switch on. Steady draw of .8 amps. That’ll drain his batteries to zero capacity in about five days. With battery switch then turned off the draw is 0.0 amps. So time to check everything on the battery switch load.
Click to expand...
Bill, there is load even with the battery switches off. Bilge pumps but that should be zero, CO monitors-should be less than 1/4 amp, electronic memories - should be in the milliamp range.... With the battery switches on and all of the systems circuit breakers off there should be still the safety and memory loads. So unless the batteries are physically disconnected there will always be a load. Oh yea, on older wiring there develops leakage due to corrosion and contamination which will also drain a battery over time. So, you may be chasing ghosts..... The answer is to keep the charger / maintainer on at all times.
 
ttmott said:
Bill, there is load even with the battery switches off. Bilge pumps but that should be zero, CO monitors-should be less than 1/4 amp, electronic memories - should be in the milliamp range.... With the battery switches on and all of the systems circuit breakers off there should be still the safety and memory loads. So unless the batteries are physically disconnected there will always be a load. Oh yea, on older wiring there develops leakage due to corrosion and contamination which will also drain a battery over time. So, you may be chasing ghosts..... The answer is to keep the charger / maintainer on at all times.
Click to expand...
Yup, with you on that. And keep battery switches off when on the hard. FYI we disconnected CO monitors for the test.
 
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