Help trouble shoot electrical problem

DKRanger22

DKRanger22

Member
Apr 28, 2009
135
Eastlake, OH
Boat Info
300 Weekender, 1985
Engines
Twin 350 Crusaders, 270 HP
When plugged in to shore-power, my breaker shows that I am getting power (the meter reads 110). Outlets and Fridge work without problem. However, when I was down below putting things away, I noticed my cabin lights getting dimmer and dimmer. Went to the helm and tried my nav and cockpit lights - same thing. I went over to the breaker to make sure the converter was switched "ON", which it was. So basically, the boat is getting shore power, but it's not converting it to low voltage to run the 12 V system.

I didn't have a chance to really get into things, as it was getting dark and a pretty nasty storm was about to roll through. I'll be going down in the morning, but want some insight as to things I should be looking for. Is there a fuse for the 12 V DC converter? If so, where is it located?

Any insight is appreciated, as I'm not an electrical guru.
 
DKRanger22 said:
When plugged in to shore-power, my breaker shows that I am getting power (the meter reads 110). Outlets and Fridge work without problem. However, when I was down below putting things away, I noticed my cabin lights getting dimmer and dimmer. Went to the helm and tried my nav and cockpit lights - same thing. I went over to the breaker to make sure the converter was switched "ON", which it was. So basically, the boat is getting shore power, but it's not converting it to low voltage to run the 12 V system.

I didn't have a chance to really get into things, as it was getting dark and a pretty nasty storm was about to roll through. I'll be going down in the morning, but want some insight as to things I should be looking for. Is there a fuse for the 12 V DC converter? If so, where is it located?

Any insight is appreciated, as I'm not an electrical guru.
Click to expand...


Your boat has 2 different electrical systems; one 120 VAC and one 12 VDC. Your running lights and your cabin lights will be 12 VDC which run off your battery all the time nothing to do with shore power. If the lights are getting dim then your charger is not charging your batteries and they are discharged.

Ken
 
Could it also be a bad battery that is not taking a charge? A bad battery does strange things.
 
The batteries are brand new this season.

Ken - I know the 2 systems are separate. But when on shore-power, the converter should utilize the 110 V shorepower and charge the batteries (which run the 12 V DC system). So ruling out batteries as they are new, I'm guessing that the converter is where I should focus my efforts?

Does this sound reasonable?
 
Sounds like you need to check the fuse(s) on your charger.
Mine has a couple as you can see in the pix. I set it up so that output from the charger goes to the waterproof box on the right. Do you have indicator lights on your charger to show the state of the charge on your batteries? At this point you don't know if you have lost the 120V input to the charger or the 12V output.
BattCharger-1.jpg
 
DKRanger22 said:
The batteries are brand new this season.

Ken - I know the 2 systems are separate. But when on shore-power, the converter should utilize the 110 V shorepower and charge the batteries (which run the 12 V DC system). So ruling out batteries as they are new, I'm guessing that the converter is where I should focus my efforts?

Does this sound reasonable?
Click to expand...

The system does not run off the charger when there is 120 (shore or generator) connected to it, it runs off the batteries or the alternator when running. The charger senses the condition of the batteries and chargers the batteries if they need charging. I would look at the fuse as mentioned but also the neg for the charger, I had that happen when I changed my batteries a few years back. The boat would charge them when running but there was no charge off the on board charger because I missed putting the neg back on.

Ken
 
You really need to check with a multi-meter. Check all connections, fuses and conductors. Start at one point and work your way back metering every connection. Sounds like your batteries are not charging...
 
I would also revisit the "new battery" install job to be sure a battery charger wire was not left off.
 
First check the batterys.
I replaced a two week old batt this year, it was bad off the shelf.
A load tester is good or hydrometer can check each cell.
A voltmeter alone wont tell you much.
:)
 
You didn't say what your DC voltmeter was reading. Keep in mind that if your charger is not working and you leave the fridge on, you are going to discharge the batteries totally.
BTW: There is a breaker on your main electrical panel for the 120V supply to the charger/converter. Did you check it to make sure that it had not tripped?
 
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I had the same symptoms this weekend: 120V system running but the 12V systems running down (lights, etc.) It was a blown 30 amp fuse inside my battery charger - a 5 minute fix. Good luck.
 
Really appreciate all of the responses, fella's.

Found my problem to be a bad connection (lots of corrison) on the negative lead going to my starboard engine battery. I am very thankful for this to have been such an easy fix. I should have caught this when installing the new batteries, but overlooked it.

Thanks again for the collective brain storming! I was ready to start chasing things down with a multi-meter, but figured I'd start from square one.

Hope everyone had a safe Memorial Day on the water!
 
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