Do we have a Battery or a Fridge issue?

Jun 24, 2019
21
Beneteau Oceanis 40 Rock Hall
Hi all,
On our Beneteau 40 2008, we still have the original Fridge and top loader Freezer. Last year, no issues.
The boat was on the hard between November 2020 and the end of April 2021.
When the boat was back in the water, initially, Fridge as well as Freezer was working. Then all of the sudden the Fridge stopped working but the Freezer was doing fine. I tried to find out what was wrong and realized that our main battery on the control panel was showing only 11.9 V. That was different last season. While our enginge battery always showed an erratic number like 7 volt or lower (direct measurement shows about 12.6V - charger off) the main battery always showed more realistic numbers around 12.5 V or more.
At some point we got the Fridge working again for some time but then it failed again. Unfortunately now also the Freezer failed. Two weeks ago, both, Freezer and Fridge worked at least for some time. This weekend both worked initially than first the Fridge stoped working than the Freezer.
The house battery voltage on the main panel is jumping up and down, goes as low as 10V and if I stop everything it goes up to 12.5V.
If I wait for a while until the house battery voltage has increased back to about 12.5 V and then hit the Fridge switch on the panel both the Fridge and Freezer starting.
Based on that I would assume that I have issues with the house battery and that there is not always enough to start the compressor, but If I measure voltage on the house battery directly while charger is off, I get 12.9V.
Confusing.
Any thoughts how to get closer to the problem?

Thanks
Christoph
 
Jun 24, 2019
21
Beneteau Oceanis 40 Rock Hall
@kappykaplan
The age of the batteries is somewhat unclear. I bought the boat early last year and we never identified the age of the batteries. So I have no idea. I might remember that they were fairly new but I looked at so many boats that I may confuse this info with other boats. So they could be old. In addition we had planed to come to the boat yard during the winter an charge the batteries a couple of times. Due to many reason that didn't happen and the batteries went about 4 month without being charged. I was concerned that they wouldn't survive that, but the frist time we were back at the boat yard I measured the load before connectiong the charger and it was around 12.3 - 12.4 on all batteries.
 
May 1, 2011
2,317
Pearson 37 Lusby MD
My gut feeling is that the batteries are old from the symptoms described. Perhaps a load test on the batteries is the next step.
 
Oct 22, 2014
16,123
CAL 35 Cruiser moored EVERETT WA
Some clever engineers built a low battery cutoff into the fridge/freezer circuit. It serves as a fail safe, to protect the boat owner from the boat owner who wants cold drinks and forgets to maintain his batteries.

From the information it sounds like you have a battery issue. It is worthy of inspection. Age, poor charging patterns, bad circuits, corrosion, all conspire to terminate batteries... Since they are the normal consumable, that is where I would start my investigation.

You can have the batteries tested.

Crown Batteries offers this advise...
CHECK FOR DAMAGE
You can often detect problems with your battery simply by looking for:

  • Broken or loose terminals: If any terminals or connections are loose, damaged, or corroded then they can result in dangerous short circuits.
  • Leaking or a damaged battery case: In flooded batteries, a leak can indicate a damaged battery case. While the damage wouldn’t prevent the battery from working, it is dangerous to operate a battery with a damaged case. (Leakage will not occur with an AGM battery, even with a damaged case.)
  • Dirt and grime: During your inspection, check the top of the battery and terminals for dirt and grime. This corrosive buildup could cause the battery to self-discharge when not in use. Make it a point to remove any corrosion from your battery terminals or connecting cables to ensure the battery is working and charging efficiently.
SIMPLE AND SAFE INSPECTION PROCESS
Fluid Inspection

  • Using a hydrometer, to measure the specific gravity of the acid within the battery fluid.
  • Following battery charging service, the hydrometer reading of all cells should be at least 1.225 -- and show less than 50 points difference between the high and low reading.
  • A fully charged and healthy battery will show clear fluid with no discoloration and a hydrometer reading of 1.265.
  • you can also use a Refractometer to examine the specific gravity of th eacid.
  • Refractometer | Test sulfuric acid specific gravity in lead acid-batteries
Voltage Inspection

  • Battery voltage after charge is an effective indication of battery health.
  • Batteries with less than 100% voltage should be recharged before use. Let battery rest before checking to dissipate surface charge. A 12-volt battery will read 12.6 volts or higher after charge; a 6-volt battery will read 6.4 volts or higher after charge.
  • Make sure the battery terminals are free of corrosion before testing.
Load Test Inspection

  • Batteries must be at 100% voltage before a load test can be applied.
  • When load testing remove all battery cables from their terminals.
  • Using a load tester, apply a 15-second load equivalent to 50% of the battery's CCA rating.
  • Refer to the load testers minimum passing voltage to determine the battery condition. If the test voltage is below the minimum, replace the battery.
 
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Likes: Dave Groshong
Sep 25, 2008
6,315
Alden 50 Sarasota, Florida
follow Jssailmem's advice - start with the simple (read - cheap) stuff. Trace wiring with a voltmeter to see what actual voltage is and where it drops. usuially at a bad connection particularly if you've never opened, cleaned and reconnected them. The symptom that the voltage readings you cited are inconsistent points to an intermittent connection somewhere.
 
May 24, 2004
6,794
CC 30 South Florida
You may need to test all components separately to define the culprit. Electrical appliances as well as the circuits wiring develop higher resistances with age increasing the loads on the batteries. It is also improbable that your refrigerator and freezer will both fail so close to each other. I would start by testing the batteries; while a battery may show a healthy voltage of 12.6V at rest the actual capacity of Ah (ampere hours) may be significantly diminished. A "load test" should be conducted to measure the remaining capacity on your batteries. Each battery should be tested individually. It is very common for exhausted batteries to show signs of reduced capacity before they quickly die. Once you determine the batteries are healthy in voltage and capacity then check the circuits wiring insuring that 12V are reaching the appliances at their input point. If not check wiring resistance and all connections especially to ground. It is normal to record a voltage drop when the appliances are turned On but with batteries already determined to be healthy the voltage should not dip more than 1V. If after confirming that adequate input voltage is delivered to the appliances if they fail to start or the voltage dips by 2 or 3 Volts then the appliances are failing or have failed. So far without the benefit of an inspection I will say that the probabilities are that you have one or more failed batteries in your battery bank.
 
Jun 24, 2019
21
Beneteau Oceanis 40 Rock Hall
Hi all,

First, thank you all for your input here, that is really helpful for me.

Now, the Fridge and the Freezer worked all night. But the Fridge gave up after I started Navigation and Waterpump in the morning.
And yes, we are on shore power, the thing happens while we are on shore power, I think I forgot to mention that, sorry.
First I will check the house battery again but wait for a while after disconnecting it from the charger. If that comes out with low voltage it would probably be safe to say that the battery is toast. If that doesn’t come out with a low voltage I will get a battery tester so I can do a battery load test. If all of that is not going to give a reliable answer I will take a look at the wiring.

Thanks again,
Christoph
 
Last edited:
Oct 22, 2014
16,123
CAL 35 Cruiser moored EVERETT WA
I will get a battery tester so I can do a battery load test.
Through my years of boat ownership I have discovered a few resources to get or improve my understanding of the systems we have on our boats. MaineSail’s articles here on SBO and his website “MarineHowTo” are resources I use to understand or clarify the mysteries of boat electrical systems.

Here is one of his articles dealing with battery testers and the test used to understand battery health.

 
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May 24, 2004
6,794
CC 30 South Florida
Your fridge and freezers run on a system in which a battery charger replaces the power in the batteries used by the appliances. The system will not work if the battery is fouled. A bad battery with little or no reserves for handling the load demands will foul the system. Your appliances do not like operating on low voltages, I would turn them off until you find the fault and correct it.
 
May 17, 2004
3,477
Beneteau Oceanis 37 LE Havre de Grace
I’m with Mike - sounds to me more like voltage loss from a bad connection than bad batteries. The voltage loss will spike when amp draw increases. Measure voltage at the batteries with a constant load like the water pump, and see how it compares to voltage further down the circuit.
 
Jun 26, 2021
4
Beneteau 43 Dalhousie
That is an interesting post. At first I thought that I wrote it!!
It's almost identical to what has happened to our 2009 43 this year. Everything was perfect last year and this spring since launch we have had the exact issues. First fridge problems, then freezer and now both are off and on working BUT the difference from you is WE DID find one dead house battery this spring so we replaced it with a used one we had.... and our situation has not improved much and the other house battery may be an original (not sure on its age). Also, what has started happening is the fuse to the refrigeration unit has kicked out a few times. We did add a bit more coolant to the system (was a little low) and that did not improve things either. We are going to try with 2 new batteries to see if this fixes it.
 
Oct 22, 2014
16,123
CAL 35 Cruiser moored EVERETT WA
It is interesting when a fellow sailor has an issue that sounds similar. They have success fixing their problem so you decide, 'worked for them. I'll give it a go and buy the same part'. Things work better, but have you solved the problem or just over powered the symptoms.

There was a time when module coding was the rage. You have a glitch so you do a patch to see if that resolves the issue. It does so you move on. Only it did not really "Solve" the issue, just changed the path and added more code perhaps compounding future issues.

I encourage you do a careful inspection of the system. Find what is broken then fix that element. There may be more than one element at play. That is the nature of systems that break down. The weakest link starts to fail then another part goes and now things do not work. Only through methodical process of inspection and affirmation can you find and clean up the system putting back into long time reliable service.

Or just replace the whole system and go back to sailing. Bit more expensive but also a solution.

Test your batteries before you just replace them.That might give you the extra bucks to put into new sails in lieu of adding another patch.
 
Jun 24, 2019
21
Beneteau Oceanis 40 Rock Hall
Sounds similar. We never had any fuse problems.
Over night the Freezer continued to work while the Fridge stoped working at some point, still cold but no ice.
I start with measuring the batteries again, this time with and without load and see what the outcome is. Following the link from jssailem it appears that battery load testers are not as useful as expected. The ones from China seem to be flat out garbage, random number generators. Oh well, who would have thought that. :rolleyes: But what to do now, as a mere mortal without thousands of dollars to buy battery testing equipment. There may be places where batteries can be tested appropriately. However, that will unlikely be for free and may add significantly to the price of a new battery in the case that the tested battery is bad.
In the end it might be less expensive and labor intensive to just throw out the old batteries.
 
Jun 24, 2019
21
Beneteau Oceanis 40 Rock Hall
@jssailem
Ups, didn’t see your post before I send mine.
I agrree (if you can) test all components. But not everybody might be able to do that and testing a battery with the equipment I have on hand might not give me reliable information at all.
 
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Oct 22, 2014
16,123
CAL 35 Cruiser moored EVERETT WA
In the end it might be less expensive and labor intensive to just throw out the old batteries.
While battery tests at auto shops are good for cranking power and not super for status of health on a a marine boat system. They can give you a data point to help in your process. If the battery is dead the test equipment can indicate this. Most shops will test for free as it is a marketing model to selling you your replacement battery. You can ask the shop about this service.

You can run your own State of Health tests. The procedures are outlined here. How do I test AGM batteries for damage from overcharge?

Or if you can still read the date code of your batteries and your satisfied with the service they have given then head to the local battery store and charge up your system.