Cruisers Forum

Join CruisersForum Today

Thread Tools Rate Thread Display Modes
Old 06-08-2009, 17:30   #1
Registered User

Join Date: Jan 2008
Location: St Catharines, Ontario
Boat: CS33 - Arlex
Posts: 49
AC-DC Converter

My battery charger is hooked up to my ac-dc converter.
If I want to run my lights from shore power, my charger needs to be on or my lights won't work.
I've tried to unplug the charger(newmar) and turn on the lights and they won't work.
I made the mistake of leaving my converter on for a weekend and fried my batteries.
Is this the correct way to have your charger hooked up?
I bought my boat from the original owner,but unfortunately he had a severe stroke and is unable to help.

squarehead is offline   Reply With Quote
Old 06-08-2009, 17:48   #2
Moderator Emeritus
David M's Avatar

Cruisers Forum Supporter

Join Date: Sep 2007
Location: San Francisco Bay
Boat: research vessel
Posts: 9,844
I'm not really sure what you are doing so I will make a guess at it.

You really need for a battery charger to have an actual battery in the circuit. You could buy a smaller car battery in the mean time until you replace the larger batteries that burned up. This is provided you do not need to run any large loads off the small battery when the charger is not on.

An alternative would be for you to purchase a 12VDC power supply with sufficient current to power whatever it is you need powered.

How did your "converter" (inverter or charger?) destroy your batteries? You need to find the problem before installing replacement batteries.

I would just go ahead and find the problem, fix it and then replace the original batteries that burned up. This way you are not reliant on shore power 100% of the time.

There are lots of good books on boat electrical systems that would be of help.


Life begins where land ends.
David M is offline   Reply With Quote
Old 07-08-2009, 12:49   #3
Registered User

Join Date: Jan 2008
Location: St Catharines, Ontario
Boat: CS33 - Arlex
Posts: 49
My battery charger didn't shut off when the batteries were fully charged.
My fridge also runs off the batteries.So if I want cold drinks without using ice I need to figure out a way to run my system from the converter.

I have purchased 2 new batteries and shut off the battery charger which lets me run my lights and fridge when needed, and protects my batteries from being overcharged.

My question is why can this not be done using my ac-dc converter switch?

Is it common to have a battery charger on this line?
squarehead is offline   Reply With Quote
Old 07-08-2009, 13:58   #4

Cruisers Forum Supporter

Join Date: Apr 2006
Posts: 12,077
"My battery charger didn't shut off when the batteries were fully charged."
It sounds like you are using an automotive charger for your batteries--and that's not suitable for a boat.
A proper three stage marine charger doesn't ever actually "shut off", instead it charges at different rates depending on the state of the battery. When the battery is fully charged, it goes to a "float" rate which pretty much can go on for months without doing any harm.
You'll also hear claims for 4-stage and 5-stage chargers, but in reality that's just a numbers game.

So part of the question is how big is the boat, how much batterry capacity do you carry, and what kind of charger are you using?

The dock AC power should be feeding a battery charger, which feeds your batteries, which in turn feed a DC-to-AC inverter to provide AC onboard (when away from the dock) as well as the 12-volt systems like the boat's lights. The inverter may or may not be permanently wired up, there are options depending on price and purpose there too.

But if you've got a cheap auto-style battery jump-start charger...that's just the wrong equipment for a boat.
hellosailor is offline   Reply With Quote
Old 08-08-2009, 10:29   #5
Registered User

Join Date: Jul 2009
Location: Gibraltar waiting for the Schengen clock, headed to the Med this fall
Boat: Amazon 49 cutter, custom steel boat built in Surrey, Canada
Posts: 283
Images: 1
Well, there is a lot to your question. I agree a good book on DC systems will help you.

First, the battery charger (I believe this is what you were referring to as an "AC to DC converter") should be permanently wired to charge the batteries. This means that when the charger is plugged into AC power, it is supplying current to all of the DC loads on your boat. This includes the lights, refrigerator, radio, etc.

(To head off some other postings on this, a purist may say the current comes from the batteries, and the charger recharges the batteries. Until we can trace the paths of individual electrons, this is not worth arguing about.)

The type of battery charger you have will depend on how you use your boat. I had a boat once with a Newmar charger, and it did not fry my batteries when left on. If yours did fry your batteries, you have a problem that needs repair.

Second, I understand you want cold drinks in the fridge, but a refrigerator will quickly drain you two new batteries unless you have something to keep them charged. While at the dock, this will be your battery charger.

So, trying to directly answer your question about the "AC to DC Converter switch" - you should not have to operate any switches on your battery charger to run your refrigerator or your lights. The battery charger you have should be able to handle variations in load (for example, as the fridge cycles on and off) without you turning it on or off. You should be able to leave the charger on without fear of damaging your batteries. If you can't do this, you probably have a problem with the charger.
steve77 is offline   Reply With Quote
Old 26-08-2009, 18:34   #6
Registered User

Join Date: Jan 2008
Location: St Catharines, Ontario
Boat: CS33 - Arlex
Posts: 49
Thanks for your help.
I have a Newmar ABC 12-15 2 bank charger that is more than likely not working properly.
I ordered a Newmar PT-25 as a replacement that will be arriving tomorrow.
This hopefully will solve my problem and allow me the option of adding an extra battery if need be.
I'm not sure of the age of the original charger and didn't want to take a chance on having it fixed.

squarehead is offline   Reply With Quote

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Olin 25MM Flare Launcher Converter Notice svHyLyte Health, Safety & Related Gear 0 01-07-2009 07:45
Is a DC TO DC 12V Regulator / Converter Required? BlueSovereign Marine Electronics 4 24-05-2009 15:03
Spraying AwlCraft Using Brushing Converter? geoffschultz Construction, Maintenance & Refit 1 27-04-2009 04:50
TV Converter Box Dilemma svcattales Marine Electronics 16 19-10-2008 13:52

Our Communities

Our communities encompass many different hobbies and interests, but each one is built on friendly, intelligent membership.

» More about our Communities

Automotive Communities

Our Automotive communities encompass many different makes and models. From U.S. domestics to European Saloons.

» More about our Automotive Communities

Marine Communities

Our Marine websites focus on Cruising and Sailing Vessels, including forums and the largest cruising Wiki project on the web today.

» More about our Marine Communities

Copyright 2002-2015 Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 13:15.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2016, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2016, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.