Azimut battery alarm

check the voltage of all individual batteries. One bad cell can cause seemingly unrelated issues.

This, at 3 years old REPLACE all of the batteries. They're past their lifespan. You might be able to use an infrared thermometer and check the temperature of each battery, a lot of times when 1 is bad it will be noticeably warmer than the others. ALSO, check the battery charger with a multi meter on AC voltage and make sure the battery charger is not leaking AC voltage to the batteries. Either/or will cause the issues you're having.

I run a euro boat with 4 group 31's for the engines and every 2.5 years 1 battery goes bad in the bank. I immediately know because the port man 1100 hp common rail has all kinds of strange engine alarms......it'll show like 4 alarms 10-30 seconds after startup...…...and it's time to replace all of the batteries.

What kind of charger do you have on your Azimut? I fondly refer to my rectifier as my battery slow cooker, and yes it has fried a few on me. It’s the factory original charger/inverter combo and I’m about ready to replac it with mastervolt mass combi ultra 24/3500 100 -230 volt unit which from the research I’ve done so far offeres the greatest capacity, intelligence and options

If someone knows of an alternative I’m all ears..

https://www.mastervolt.com/products/mass-combi-ultra-24-v/mass-combi-ultra-24-3500-100-230-v/

For just a charger look at the; Skylla-i Battery Charger 24/100 (3) . Make sure your looking at the one with the (3) at the end of the model number.
Replaces Mastervolt units on later Hatteras great.
Download the spec sheet from https://www.victronenergy.com/chargers/skylla-i .
Mastervolt and Victron come from the same hood. We sell both brands. Fell in luv with this model about 2 years ago and been puching them sinse.

Look up inverter chargers here also. More special options with Victron.

For the OP; I know the Muts schematics are poorly followed or detailed if available at all.
Need to find where the alarm signal comes from and check that point with a DVM.
Ensure there is a real failure. If it really is low, work towards VB plus AND negative till the bad / loose connect is found.

This is a charger low alarm or a battery low alarm?
Model of current charger?
Model of current batteries?
With a DVM, what does B+ & - read at the engines, charger and batteries when this alarm sounds.

It's amazing that electric shops just spin up alternators and watch voltage and current come out. All are happy during this 1 minute test.
Thru my life, I have found alternators that make a good charge spun up but at idle leak current off and will drain a battery.
Bad diodes are usually the problem.
Go back to post #8 and ensure the alternators are warm, charger off, at low and fast idles when using your DVM.

Cat 3126s Usually have the Delco SI20 or 21 alternators. Yep, they can have leaking or bad diode packs and still put out some current when spun up..

Please re-read #9 above.

A bad diode here does happen. If your worried about the charger, disconnect it. You may have breakers or fuses to open on each charger out put.

Sounds like you need a red neck in Sweden. I'll be available in 4 weeks.
Sadly, traveling the wrong way, one of my crew returning home, thru Amsterdam Wednesday night from Port Varna.

I have doubdts that the problem is in a bad diode, however this could be a very unexpected trick.

FWIW I have encountered the same issue with Azimut 42 Evolution (2006) I have just acquired.

The audio alarm (5 rapid beeps/3 rapid beeps, recurring) sounded as the Stbd engine shut down while at low revs, after 40 mins of cruising. Had problems restarting, although as this was my first trip out on the boat, this may have been due to not understanding the electronic throttle command position selection protocol/not having both throttles perfectly in neutral!

Once back at marina, restarted both engines without shore power on first attempt.

Engine oil and temp readings on both engines fine before and after restart.
Checked water/oil filters/oil levels/coolant etc. All good. Engines fully serviced within last 6 months.

Guys at Sea Start here in Solent, UK were very helpful on phone.

In summary, seems that running certain electrical services on DC while underway was the cause, albeit that it shouldn't be!

I also noticed that on the main fuse switch panel (lower left side of lower helm poistion) certain electrical services had been colour coded by the previous owner (eg stereo, heads, wash down, domestic water pump), which I now deduce means SWITCH OFF when not on shore power/generator.

Have done this each time I have taken her out (6 times) and so far the issue has not recurred.

Nothing,, NOTHING should be on an engine lead, breaker or battery..
Very sadly, correctly done requires more batteries, Cables, room and money, so our wishes are not realized every time.
Put a volt meter on that engine breaker. Do you find at least 28Vdc (Battery charger off)? If not, move backwards to the battery until you do.

Thanks Pascal and Capt Ralph for your comments. I will check the points you raised.