Battery problem

jhundert · #1 (**permalink**) 07-02-2008

I have a new sailboat with AC and shore 30A shore power input. We use a 30A Y-splitter to two female 30A. We have not had any problems with this configuration at our slip. Over the weekend we went to another club and plugged in. On day 1 we used the AC, but not on day 2 and 3. On day 3 both house batteries were totally dead, although we were plugged in as described and had the battery charger on. Does anyone have any idea of what could have gone wrong?

negrini · #2 (**permalink**) 07-02-2008

Hard to guess with little information. Does your AC runs from a dedicated shore input ? Where you aboard on day 2 and 3 ? What was runing to drain your batts ? A dead charger ? Did you check the new club pins (G-N-P) ?

Faster · #3 (**permalink**) 07-02-2008

Definitely sounds like you had a load on for some time.. Negrini's suggestions make sense. If there was a polarity problem your charger may have protection and had not been charging after all.

I trust you had isolated your starting battery so that you were able to carry on!?!?

jjns · #4 (**permalink**) 07-02-2008

Any chance that the terminal you were plugged into might have tripped a breaker on day 1 or 2 so that you were running actually running on the house instead? I would be making sure that there really is a problem before tearing things apart.

camaraderie · #5 (**permalink**) 07-02-2008

So...you have 2 30amp male sockets on the boat....and you split a SINGLE 30 amp power feed to provide input into those 2 sockets. Right?
You had power from the dock on day 1 since you ran the air. But you don't know if you had power from the dock on day 2 & 3 because you did not run any AC loads. Your DC loads pulled down the batteies on the boat because the charger did not work.
The obvious and first place to start is at the dock pedestal. Chances are you popped a breaker and simply had no power to the boat.
Now that you are back home...the thing to do to check the rest is to plug in and turn the AC on. If you have cooling...you have power to ONE socket. Now switch the plugs and try again. If you have cooling...the splitter and both sockets are working just fine. Now the only thing you need to do is check the charging circuit and charger. If it has operating lights and they are on...chances are everything is fine. But you can check output with a simple voltmeter at the battery terminals and you should see something in excess of 13.3V even if the batteries are fully charged. If not...then use your voltmeter to check the incoming A/C power to the charger and you should see around 115V at the charger input terminal. If not...the problem is perhaps a breaker or a poor or corroded connnection in the lines leading to the charger. If you do get 115V at the charger and less than 13.3V at the batteries then you have a charger problem.
Sorry for the length of this but it is a step by step process to narrow it down. Hopefully it is just a tripped dockside breaker!
Note ALSO that splitting a 30amp line into two does NOT give you more than 30 amps to work with. The start up or cycling on/off loads of a marine air conditioner can require 2x more amps than the running amps of the AC. SO...do NOT use other high amp draws like an inverter and microwave etc. while the AC is turned on or you will sometimes trip a breaker on the boat or on dockside.

Melrna · #6 (**permalink**) 07-02-2008

Since you said you have a new boat, there are a few things to check first that are easy..
#1 check to see if the #1 120AC power receptacle has power to the panel. There should be another circuit breaker for each 120 AC receptacles somewhere on the boat. Mine is hidden in the lazzerate where the 120AC receptacles come into the boat. Don't ask how I know this.
#2. Check that the main DC selector (Off,1,2 both) switch is in both. Some stupid boat manufactures wire their battery charges to charge the batteries through this switch.. Don't ask why I know this either.
3. Check battery charger - lights on panel, fuse etc.
4. Check batteries - water, connection, 400 amp fuse etc
5. I would never spit a single 30amp power source into two to run the AC. If the AC is drawing all the power the battery charger may not work due to low amps left over. Marina dockside power may say 30amps but I would take that with a grain of salt. It could be more but is usually less. They are notorious for voltages and amps being all over the spectrum.

After that have your favorite beverage and read what the real experts here have to say.

garymbsail · #7 (**permalink**) 07-02-2008

Is there any chance your inverter kicked in after a shorepower failure? If the circuits are not separated by an automatic switch, it's possible the batteries were charging themselves through the battery charger receiving AC power from the inverter.

jhundert · #8 (**permalink**) 07-03-2008

I thank everyone for the helpful comments. The battery problem is still not solved. Throughout the period I was connected, I did get AC. The inverter was definitely off. When I saw that there was a battery problem, I checked the charger and it had lights on it. I am going to get a technician to look at it.

Thanks again