Low voltage warning

[Matt N]

I have a 2016 Sundancer 350, every time when I turn the ignition switches on before starting the engines I'm getting a low voltage warning on the starboard engine. This happens even when plugged in to shore power (for long enough time for batteries to be fully charged) and battery charger on.

Load tested the batteries and seem to be healthy. The voltage reads at 13V-14V on VesselView at times and it still throws the warning.

I'm new to these modern systems that are heavily reliant on electronics. I've heard they are very sensitive to low voltage, but a bit stumped b/c batteries seem ok.

 

[Shaps]

...Load tested the batteries and seem to be healthy....

Seem?
How old are the batteries?

 

[Matt N]

Seem?
How old are the batteries?

I had batteries load tested and told they were fine. I’m not sure how old, just bought boat and no date on them unfortunately.

 

[Wanderer 290]

It is possible for batteries to test and display 12.5+ volts but with diminished amps capacity.
What type of batteries are installed, deep cycle, hybrid deep cycle or starting batteries?
In any event installing new batteries would probably be a good idea especially if they are original.

 

[Brite Idea]

I have a 2010 310 Sundancer and was experiencing a similar voltage problem on the starboard engine. If I left the boat without shore power the batteries would drain until I had dead batteries. If I left the boat plugged in and charging it was fine. Batteries were tested and they were fine, cables were suspected but in the end it turned out to be the trim limit switch was bad. Now I asked why if I turn the battery switches off does it still happen and have yet to get an answer that makes sense? The point is there's lots to go wrong with the sophisticated electronics we have on these boats but getting them repaired is now a nightmare!

 

[Matt N]

I have a 2010 310 Sundancer and was experiencing a similar voltage problem on the starboard engine. If I left the boat without shore power the batteries would drain until I had dead batteries. If I left the boat plugged in and charging it was fine. Batteries were tested and they were fine, cables were suspected but in the end it turned out to be the trim limit switch was bad. Now I asked why if I turn the battery switches off does it still happen and have yet to get an answer that makes sense? The point is there's lots to go wrong with the sophisticated electronics we have on these boats but getting them repaired is now a nightmare!

So this is interesting, I'm also having another fault related to the starboard trim sensor not working. Trim works fine on starboard engine, but the sensor doesn't show trim being adjusted (port side works fine). I didn't include this info b/c I figured it wasn't related, but maybe it is.

 

[Matt N]

It is possible for batteries to test and display 12.5+ volts but with diminished amps capacity.
What type of batteries are installed, deep cycle, hybrid deep cycle or starting batteries?
In any event installing new batteries would probably be a good idea especially if they are original.

They are dual purpose. Link below
https://www.interstatebatteries.com/products/31m-agm

Will definitely replace if nothing else works, just trying all options before $350/each!

 

[Wanderer 290]

They are dual purpose. Link below
https://www.interstatebatteries.com/products/31m-agm
Since only the SB is alarming try switching batteries?
Will definitely replace if nothing else works, just trying all options before $350/each!

I have tried dual purpose batteries from 2 different mfgs. And they both failed at 36 mos exactly.
I use starting batteries for starting and have gotten 8-10 years on them. Presently I have 9 years on the current set.
I use a true deep cycle for the house and have 15 years on the current battery.

 

[Brite Idea]

I agree dual purpose have a shorter life. The last boat I switched to Interstate 1000 starting batteries in a Group 27 and they were great! I don't know how long they last because I sold the boat a couple of years later and they were still going strong!

 

[JimT]

Had a similar problem with 2 year old AGMs. Periodic low voltage when underway. Two mechanics couldn’t diagnose. Turned out to be bad batteries.

 

[tony1b2000]

I had the same problem on my 350 Sundancer. From what I remember, The electronics talking to the computer works on 5 volts. The mechanic found it a 1 volt. He started disconnecting things one by one. Once he disconnected the TRIM SENDER, the voltage jumped back to 5 volts!
Of course he was using the G3 software on a laptop to see the voltage. TI am sure there are others ways to check without the software.

The trim sender can easily be disconnected in the transom as is just a push on connector. I was on my way on a trip and waited till I was hauled out at the end of season for the repair. Only issue is that I got a warning on the trim sender every time I used the boat. Canceled and I was fine for 3 months.

Trim senders are notorious for corrosion! BTW, you always can simply see your drive is in the down position just by looking at it from the platform. The the sender is to me a optional item. Not worth $400 haul out just for that.