Alternator voltage

[elias]

Hi !
D2 55 engine , factory alternator , at 1800rpm I have house bank 13.7v and motor 14 , after 2hiurs of motoring …should I suspect something bad?

[Yngmar]

Sounds good, why do you think there's something wrong?

[elias]

I had my solar controller at float , meaning that the battery bank should be topped , meaning that I should have 14,4 or 14 not 13,7v . I saw a fire on boat near me 2 days ago and I got a little concerned too

[Yngmar]

With AGM batteries, ~13.7V is float voltage, so still sounds right. 14.4V means they haven't completed the absorption stage yet. Once that's done, the charger should drop down to 13.7V.

[elias]

Hmmm I had it different in my mind, that the voltage of 13.7 on the alternator is because it drops due to absorption . So once the battery is full the alternator regulates the voltage to lower than 14.4 ?

Still thanks for the help and advice

[Yngmar]

Depends on what you have on your boat. We've got a multi-stage regulator, which does go to float once the batteries have been charged fully.

[elias]

I believe factory setup , alternator with one yellow cable coming from the engine battery , and the positive from the alternator on a Victron splitter diode and then two cables to each battery

[tiger79]

I believe factory setup , alternator with one yellow cable coming from the engine battery , and the positive from the alternator on a Victron splitter diode and then two cables to each battery

That's just a basic system; the alternator will maintain a constant voltage, it can't do anything else.  Are you measuring the voltages with a multimeter at the battery terminals?  Or relying on the Bavaria panel (which isn't as accurate)?

[elias]

Bavaria panel and the battery voltage indication through Victron Bluetooth app