Service Batteries - run out of charge

[mpolonia]

I have a Cranchi-41 (with 2 VOLVO PENTA KAD44) and in the last few days the "service batteries" run out of charge after a few hours of sailing...
My mechanical has been checking, battery to battery and says they are good, He also checked the alternator in progress and says it loads, but what is certain is that after 2 hours of sailing they are very weak (the Radar stops working, I am unable to use the toilet pump, the flaps do not go up/down, etc. ...).
Can someone give me a tip/light on what to do more?

 

[dingbat]

My mechanical has been checking, battery to battery and says they are good,

How is he checking them?
A voltage test doesn't cut it. Batteries need to be load tested.

 

[mpolonia]

How is he checking them?
A voltage test doesn't cut it. Batteries need to be load tested.

He has disconnected all batteries after charged at Marina 220v point electricity, and did some test after that (I don't understand this electricity area).
And he had some test sailing (alternator's engine I think)

 

[dingbat]

He has disconnected all batteries after charged at Marina 220v point electricity, and did some test after that (I don't understand this electricity area).
And he had some test sailing (alternator's engine I think)

Classic "weak" battery symptoms.
How old and what size are your batteries?

Unless you have a large parasitic drain, I'm betting the battery has a dead or dying cell and you need new battery

 

[mike_i]

As dingbat said, the batteries need to be load tested. You don't charge a battery and measure the voltage then say they're good. Also waiting to hear the age and size of the batteries. Are they wet cell? If so have you checked the water level?

 

[mpolonia]

As dingbat said, the batteries need to be load tested. You don't charge a battery and measure the voltage then say they're good. Also waiting to hear the age and size of the batteries. Are they wet cell? If so have you checked the water level?

Hi!
I'll do that. I bought this boat 3 mounths ago, so I don't know the baterries's age. I'll find some expert in this field.
Thanks again

 

[mike_i]

Look all over the batteries to see if there are any letters or numbers/date burnt into the plastic case, as with tires there may be a date code. Sometimes there's a sticker with the date on it. Depending on where you are many auto parts stores load test batteries too.

Hi!
I'll do that. I bought this boat 3 mounths ago, so I don't know the baterries's age. I'll find some expert in this field.
Thanks again

 

[Scott Danforth]

take the batteries to any automotive service center and have them load tested