SeaKnots

My batteries are not getting charged from the engine.  After starting the engine and running for a while, my engine start battery registered 12.4 V (and trended lower) and the house bank about 12.8 at the VDO panel meter.  My alternator seemed to be putting out okay (I measured 13.1 V at cruising rpm) at the connection to the "battery isolator" which is a small electrical box located behind the house battery box that is under the sitting area in the aft cabin.  This battery isolator also has connections to the house bank and the engine battery.  The voltages of the engine battery terminal at the isolator showed a drop of about 0.6V relative to the alternator terminal at the isolator, which indicated the engine battery was not connected to the alternator.

 

Once I shut down the engine and switch on the shore power charger, the batteries all charge up nicely to 13.3 V, so I don't think the problem is with the batteries themselves.

 

My question is, has anyone experienced this problem?  Is 13V output of the alternator normal, or should it be higher?  Sould I see the same voltage at the engine battery as the alternator output (13.1 V), if not does that indicate a problem with the battery isolator?

 

Any advice from the esteemed group is welcomed.

 

Thanks,

 

Pieter Wybro

B40 hull #144

Views: 398

Replies to This Discussion

The isolators are known to fail. Sounds like that is the issue here. Is the alternator stock ? here is a file on the isolator .
Attachments:

You have to be carefull charging dead or severely depleated batteries by running the engine/alternator. With the new alternators, with the regulator built in, they are not real big and will blow out quickly. I've found that you can install an older, external regulator that's built much stronger and will take the current better. I installed a new Delco marinized alternator with the small internal regulator and tried to charge low batteries. Didn't work. The repair tech explained what happened. That's why you need to charge up your batteries first or have something like a shore powered charger or even a solar charger hooked up to keep them topped off. 

The standard 80amp alternator will only put out about 35 to 45 amps at 1200-1400 RPMs, about what you might expect while trying to recharge at anchor. Since these boats can easily consume 120+ ahrs a day it only takes about 3 or 4 days and you'll need to plug in to shore power to fully recharge the house batteries. That's based on a reluctance to not run the engine for 3+ hrs a day to recharge back to 80%. It's also based on the 450 ahrs we have on our boat. Smaller battery banks will only make the need to plug in happen sooner. I believe the battery charger also passes the current through the isolator so if you charge up while plugged in then it may be you're just using more than you can replace while at anchor.

RSS

Latest Activity

Patrick Findaro posted a discussion

Leading ASP.NET Development Company

ASP.NET is a popular web development framework that is widely used by developers and businesses to build robust and scalable web applications. ASP.NET supports a wide range of programming languages, including C# and Visual Basic, which makes it a versatile choice for developers who are familiar with these languages. ASP.NET is designed to be scalable, which means it can handle large amounts of traffic and data. This can be a good choice for businesses that anticipate rapid growth in their user…See More
3 hours ago
Patrick Findaro is now a member of SeaKnots
6 hours ago
Robert & Sandy replied to sam's discussion eyebrow salon window re-bed in the group Beneteau 40 & 43
"Hello all, I realise coming into this year old conversation could be somewhat strange though sharing advice is always beneficial.. Our B43 had her port large saloon window repaired under warranty after it developed a gap and obvious leak. The boat…"
Mar 12
dryfirewood is now a member of SeaKnots
Mar 4
zeehag left a comment for ___/)ances With Sails
"bubba died  but he seems tohave sent a nother special boy to me..a scared  confuzed precious  with name pusskins which i changed  to sir puurrcival pusskins.  much more refined name for such a precious furry one.  he is…"
Mar 3
___/)ances With Sails commented on LOLA's group SAILBOATS and SLIPS FOR SALE
"My boats for sale. Search Craigslist/New Orleans/S211_A"
Feb 22
___/)ances With Sails left a comment for Lola
"Happy belated holidays!  I'll email you. "
Feb 22
___/)ances With Sails left a comment for zeehag
"Karen!! Dang!!!!  How did Bubba use up 9 lives already? Sorry to read that, kid."
Feb 22
ADVERTISE ON SEAKNOTS CONTACT US AT: 
candrac@sailforwater.com

© 2024   Created by CAN DRAC.   Powered by

Badges  |  Report an Issue  |  Terms of Service