Dips in DC mains voltage with weird knocking noises

[Ruthine]

That's actually good news.

You do want a good digital multimeter. It can help you know if the batteries need replacing.

Keep us posted, happy to help as much as possible.

dj

Thank you DJ honestly the advice we have had on this forum has really helped. Have a fab evening!

 

[kappykaplan]

We ran the engine today as it was a very dull day in La Linea (pouring now) and the batteries weren’t charging at all from the solar panels.

But did the batteries get charged while you ran the engine?

 

[Ruthine]

This could be the problem. Aged batteries have less capacity and will draw down quickly. The sound you are hearing could be a solenoid controlling some device like a heater or air conditioner. Or maybe the contactors in an inverter.

Hi d, thank you for this advice. The batteries are old and likely we are going to try replacing some of the corroded battery connectors to see if that sorts it. Really hoping we don’t have to replace the batteries

 

[Ruthine]

But did the batteries get charged while you ran the engine?

Hiya, yes they did charge which was a relief!!! One less thing to worry about We only ran the engine for about an hour or so… just long enough to sort our another problem we were having that needed the battery power… Then called it a day and went out to our fav restaurant for a meal and a drink! But tomorrow is another day… Big repair day methinks

 

[dLj]

Hi d, thank you for this advice. The batteries are old and likely we are going to try replacing some of the corroded battery connectors to see if that sorts it. Really hoping we don’t have to replace the batteries

Do you know how old the batteries are?

At a minimum they should go through a complete equalization cycle - you likely don't have the capability on-board but if you can provide photos of your inverter charger, then there may be a possibility.

dj

 

[marcham]

Can anyone advise?

Whilst moored in the marina, we experienced dips in DC mains voltage with the low voltage management system also bleeping intermittently.
The voltage indicator would dip slightly and briefly when the low voltage manager bleeped, then return to its previous position.
We also had a weird noise like something hitting the side and underneath of the boat. It would reverberate through the boat.

At the time we were using fridge, freezer, and three cabin lights.
We turned off the fridge, freezer and two cabin lights but no change.

All issues were resolved when we briefly turned off the main DC switch and then turned it back on again. After that, the weird noises stopped and the DC manager no longer bleeped intermittently.

(For background info) We were not running the engine, were connected to the marina mains and also have solar power.

Hello and welcome to the forum.

A) Is the issue with the AC Main (ie: shore power) or the onboard DC (ie: battery power) ?

B) What was the volts when the voltage manager beeped? (AC or DC ?) ?

C) Were you plugged into shore power? If so, what was the shore power voltage (AC) ? Is there any corrosion on the shore power cord terminals?

D) If you disconnect shore power, how long will the battery last before the lights and refrigeration go out?

E) Do you have a battery charger or an inverter-charger to charge the (DC) batteries from the (AC) mains ? When charging, your battery voltage should be 13.6V or higher. When not charging, the voltage will be between 11.5V and 12.8V. If the batteries go below 11.5V, you will start to have problems, ideally they should never go below 12.0V.

F) Is this a new to you boat ? If yes, are there any recommendations in the pre-purchase survey regarding the electrical system?

If you are new to boating I would suggest reading this book ASAP, it gives you a good overview of essential boat systems:

Amazon.com

Boatowners Mechanical and Electrical Manual
by Nigel Calder


¡Que te vaya bien!