Dead Batteries - Low Voltage Alarm?

[RVM]

Hi Everyone,

We have a 2017 350 Sundancer with 8.2l merc. mag. axius and Vessel View 4.

We woke this morning on our mooring with nearly entirely dead batteries for "the house". The engines started when keyed on and shortly after the lights, blower, etc. began working as well.

We got a "low voltage" error on the port engine, followed by a "port trim sensor" error, which still hasn't cleared even after 2.5 hours back across from Catalina and after being reconnected to the battery charger at the dock.

It seems reasonable that the port would experience low voltage, since 3 of the 4 batteries are on the port and it seems then would try to equilibrate with each other, but I am not sure if this is the case or if there is another issue.

Coming across, the starboard voltage was 13.9v and the port ranged from 12.7 - 13.9v, so it doesn't seem like an alternator issue. I am hoping when fully charged from the charger when I go back and turn the keys on, the voltage will be back to normal, but it doesn't seem like this should create all of this for hours after.

Any thoughts or advice are much appreciated.

 

[Lazy Daze]

Did you use something overnight that would have drawn them down that much?

Computer systems (Axius, DTS, etc) are very voltage sensitive and things go wonky when they're not getting the voltage they wont. Standard practice here is to charge the batteries fully and then load test them. However, a quick test (although not always completely reliable) would be to, again fully charge, then disconnect all of the negative leads and put a voltmeter on each battery. Come back the next day (or at least later in the day) and do it again. Post your results.

 

[RVM]

Did you use something overnight that would have drawn them down that much?

Computer systems (Axius, DTS, etc) are very voltage sensitive and things go wonky when they're not getting the voltage they wont. Standard practice here is to charge the batteries fully and then load test them. However, a quick test (although not always completely reliable) would be to, again fully charge, then disconnect all of the negative leads and put a voltmeter on each battery. Come back the next day (or at least later in the day) and do it again. Post your results.

We spent 2 nights on the mooring and ran the refrigerator, lights, water pump, etc. Our generator was acting up so we didnt get to charge the batteries for any length of time. It makes sense that we drained them using this, but are new to the mooring thing and weren't really sure how long we could go.

Much appreciated for the response and I will post an update later in the week when I get back to the boat. Thank you again

 

[Lazy Daze]

I once went (as a test) 3 days and 4 nights on ONE group 27 deep cycle battery. Now, smaller boat so smaller fridge - but I still had plenty of power to start the engine on the last day. I did run the engine - but only for a total of about an hour the whole time.

The most likely scenario (and easiest to fix) is that the batteries are simply getting old and not holding their charge as long. Testing them will tell us more. Autozone (and others) test batteries for free, by the way. Or, if there's a shop nearby that you're on good terms with, they may let you borrow their load tester.

 

[RVM]

I once went (as a test) 3 days and 4 nights on ONE group 27 deep cycle battery. Now, smaller boat so smaller fridge - but I still had plenty of power to start the engine on the last day. I did run the engine - but only for a total of about an hour the whole time.

The most likely scenario (and easiest to fix) is that the batteries are simply getting old and not holding their charge as long. Testing them will tell us more. Autozone (and others) test batteries for free, by the way. Or, if there's a shop nearby that you're on good terms with, they may let you borrow their load tester.

Much appreciated. They are about 5 years old, so that would make sense. I will see how things go with them and certainly let you know. Thank you again

 

[RVM]

As luck would have it, we had our boat pulled out for a bad trim sensor. They replaced both sensors around 3 months ago. The mechanic came out yesterday, tested the system, and found that one of the sensors is defective and this is what created the low voltage problem. We need to pull the boat again and have the sensor replaced under warranty, but apparently the haul out isn't covered so we are trying to contact mercury and see if anything can be done. As for the batteries, we tested all 4 while there and they are all holding a charge.

There is no battery cut-off switch anywhere on the boat, which according to the manual "is optional on some models" Does anyone happen to know if the house batteries are isolated from the 2 main batteries (if no battery switch), so at least we know the boat should start when on a mooring if the house batteries die?

Much appreciated everyone, this forum is great

 

[Pirate Lady]

That makes no sense. I never ever seen a boat without a Perko switch. Its like the main breaker in a house. How can it be optional?

 

[RVM]

That makes no sense. I never ever seen a boat without a Perko switch. Its like the main breaker in a house. How can it be optional?

Believe me, I agree with you. I looked all over the place more than once and the mechanic can't find it either

 

[Pirate Lady]

the house batteries are isolated from the 2 main batteries (if no battery switch)
Here what i don’t get in that, how can you isolate batteries if no switch?

 

[RVM]

the house batteries are isolated from the 2 main batteries (if no battery switch)
Here what i don’t get in that, how can you isolate batteries if no switch?

I don't get it either, but when I asked the mechanic he said the house shouldn't draw on the engine batteries, only the 2 house batteries. Hoping someone can confirm, because I would hate to get stuck on a mooring far from home.

 

[Bt Doctur]

some simple tests
Look everywhere for a battery switch even if you have to follow the Red wire from the battery.
Remove all the Positive cables, reattach only 1 and see what works and what doesnt. Remove that one and attach the next, retest.
Do this for all the batteries

 

[Pirate Lady]

I don't get it either, but when I asked the mechanic he said the house shouldn't draw on the engine batteries, only the 2 house batteries. Hoping someone can confirm, because I would hate to get stuck on a mooring far from home.

So what he saying is that every house dc system(cabin lights, fresh water pump, stereo, cockpit lights) are direct wired to one set of batts. But operating systems(bilge pumps, starter, blower) are direct wired to another set of batts? Unless you see a whole lot of wires coming off each battery, that ain’t happening. Before you start searching for a hidden Perko switch, start searching for a new mechanic. Cause not a GD thing about this makes sense.

 

[ocgrant]

There is not going to be manual switches on that boat it is electronic I am sure. you have battery switches on your main panel somewhere that control a solenoid. But sounds like you already solved your issue plus if you are sure they are 5 years old and you are going to start using this boat buy some new ones.