Need help - lost 12v

[George_SD]

Hi all,
So just got out first boat, started with cleaning in the slip. Boat is plugged into the shore power and has "Battery charger: ON". Turned on the stereo to listen to some music. While I was washing it, I've turned off shore power switch, disconnected shore power cable and then reconnected the cable before I left it for the night. However, I forgot to flip the "Shore AC" on. I did use built in battery tester on the panel and it showed 12.4v or so.

Today came back - flipped it back. All seems ok, so spent the day doing more cleaning. On the way out - i try to turn on the 12v panel to check some of the cabin lights and get nothing. No lights on switches, nothing on built-in battery tester.

Charger is on and was showing "Ready" (not "Charging" like it usually does).

I looked at the main breaker by shore power cable - it's fine, not tripped. . Connections on the battery are fine - solid and secure. Shore power works fine, but nothing on the 12v

I plan on bringing a multimeter tomorrow to start troubleshooting. Probably will put it on the battery directly first to see if maybe both of them are completely depleted.
Next will probably take the 12v panel off yo see if some breakers/fuses may be went out.

Any other ideas?

Boat is a stock 2005 Beneteau 323

[JimsCAL]

Hard to tell without further info, but my wild guess is the batteries are dead. Maybe weak already, left without the charger on with loads on the DC side, and run down. New batteries may be in your immediate future.

[George_SD]

I'm afraid that may be the case. However what is really strange is that i get 0 needle movement on the panel. Not even a twitch. I'm going back there tomorrow with the multimeter.


Additionally - shouldn't I have 12v still working from shore power or is it always form batteries only?

[hlev00]

Do you have a battery switch? Maybe you turned it off and didn’t realize it.

[George_SD]

Got two separate battery switches, both have not been touched and I've verified that they are in the ON position.
There are two batteries, I assume a "house" and "starting".

Reading the manual for Xantrex TrueCharge20+ that is installed. Maybe will find some helpful information there. Otherwise I'm in for a somewhat expensive trip to the store.

[Spot]

Hopefully it looks better in the light of a new day. Could be a combination of switches defeating charger and normal battery function.


I am working on a boat in the driveway and am using a 50w solar panel to keep the battery topped. On sunny days there is more than enough generated to run a 12v fan like one used to see in a semi truck or school bus for the driver. The controller also turns a 'night light' on for an hour or so after dark.

[Stewie12]

If the charger is on you should have 12 volts, regardless of the state of the batteries.

[Jdeuel]

Does your charger need to ‘see’ a minimum voltage to start charging? I use Battery Tenders on motorcycles and cars, and sometimes I need to use my Li-Ion jumpstart box to ‘fool’ the battery tender.

[SV__Grace]

Sounds like a breaker or fuse on the boat side. Whenever I have had these kind of problems my electrician simply reminds me "Check the power supply" and darn it, when I look closely and trace the power supply from shore to panel to wherever, I can almost always find the problem.

Most obvious would be a breaker or fuse on the DC panel but if you have an inverter, inverter/charger, isolation transformer, etc, look for a thermal breaker that might have tripped. Among other reasons, those things get tripped when shore power gets hooked up in the wrong order, if a shore power plug is loose (turn the plug a few times before insertion so it keeps a snug connection), if something overheated, etc.

Your charger can be on, but if it has a tripped thermal breaker it is protecting your boat by cutting off power until you find the problem.

[Cpt Mark]

you say the charger is on and showing "ready" but not charging. That is your problem. Look in the manual for troubleshooting and/or call the manufacturer. Hmm, on 2nd thought, if your boat is wired and fused correctly you should have a fuse or fuses withing 7" of the positive battery terminal. Check and see if those are blown.

[Sailmonkey]

Originally Posted by Stewie12

If the charger is on you should have 12 volts, regardless of the state of the batteries.

Actually no.

Modern chargers won’t start charging a battery with a voltage lower than roughly 10 volts.

So if your batteries were severely depleted you’ll need to boost them with something like a jump pack or a ferro-resonant charger to get the good charger going.

[RobertoD]

Had exactly same problem in the spring. Boat hauls with mast in, so keep bilge pump on as rain and snow get down mast. Couldn't get in to p lug in power to charger for 3 months due to other problems and when I got to boat, exactly same results. Boat charger wouldn't chg batteries (2 house, 1 engine). tried heavy duty charger, did charge batteries but they wouldn't hold chg for long. So . . .3 new batteries. My volt meter on electrical panel responded as yours did. Tough lesson.

[George_SD]

Stewie12 - that's how i thought it worked, but didn't know for sure.

Jdeuel - i do not know. I didn't find any information on that so far.

SV__Grace - i hope that's the case. I plan on trying that today.

As far as i understand (this boat is new to me), this is what the chain looks like so far for 12v side of things

Shore plug->Transom plug->main breaker->Charger*->Batteries*-> switch panel* ->Main/House ON/OFF switches -> Fixtures and devices

Ones with the stars are likely to have fuses that could be at play here.

[rmhutch59]

Common problem means a common source.

1. Dead battery, my favorite.
2. Switch in wrong position.
3. bad ground connection.

[George_SD]

Originally Posted by RobertoD

Had exactly same problem in the spring. Boat hauls with mast in, so keep bilge pump on as rain and snow get down mast. Couldn't get in to p lug in power to charger for 3 months due to other problems and when I got to boat, exactly same results. Boat charger wouldn't chg batteries (2 house, 1 engine). tried heavy duty charger, did charge batteries but they wouldn't hold chg for long. So . . .3 new batteries. My volt meter on electrical panel responded as yours did. Tough lesson.

Well, but the battery was not charged for just one night and I don't think there were any loads ON as all DC panel switches were in the OFF position. Just odd.