Charger or Batteries Gone?

[Papawads]

Timing is everything, my mother-in-law arrives in two days, breathing judgemental fire, for her first visit to (his) boat, and 12V power has gone weird. Happy with any suggestions.

Three weeks ago we boiled one of three 12V gel leisure batteries. Since removing it and running on two, it’s been AOK. Then 2 days ago noted charger running HOT at 51 degrees Celsius on shore power charging!!

Started to notice batteries running low, as instruments / plotter not working when not on shore power, but lights on ok, but they all worked with engine running!!!

Tonight, when I turned off shore power battery charger, we lost all 12V.

So I two days I’ve gone badly wrong. Isolated batteries and they say 13.4 volts!!

Please help, before this latest f-Up is added to my life quota by the dragon :-(

[Wolfe10]

Originally Posted by Papawads

Tonight, when I turned off shore power battery charger, we lost all 12V.

Isolated batteries and they say 13.4 volts!!

OK, batteries at 13.4 VDC but it is not getting to the distribution/switch (don't know what boat you have or how it is set up).


So, pull out your multimeter and start at the batteries. See where 13.4 VAC is lost.


Certainly verify all battery connections are clean and tight.

[GordMay]

What Wolfe said - that battery appears to be fully charged [@ 13.4V 'Rested' Open Circuit Voltage].

[Be Free]

I'm confused. The problem has to be between the battery and the main bus but...



If the engine/charger were connected to the main bus then everything would work when either was on and that would mean that the problem is between the bus and the battery since nothing works on battery.


But if that were the case then how is the battery ever getting charged? The same wire that allows the battery to energize the bus is the one that the charging current should be coming through.


If the charge sources are direct to the battery then it would get charged but the main bus would not ever be energized because the suspect wire is the one that connects the battery to the main bus.


Is it me or is something missing in the described circuits?

[OS2Dude]

As I understand it, the batteries charge when there are excess watts available. If your 12v loads are sucking up all the output of your charger(s), then no, the batteries will not be charged. If the charger(s) produce more watts then are being used, then the batteries will be able to absorb it and charge. At a low SOC the batteries become a load to the charger source(s).

[Be Free]

As I understand it:

• The battery is charged (13.4v)

• House loads work when engine is running or if battery charger is on

• House loads do not work when running on battery

His complaint is not that the battery is not charging, it is that none of his 12V devices work when the battery is the only source of power.


That sounds to me like the charger and alternator are both connected to the main bus, not to the battery. That would allow house loads to work with the engine or the shore charger.


But... that arrangement would then have the battery attached to the main bus as well, perhaps through a switch. If that connection failed it would match his description -except- that the battery would not charge if that connection was not working.


Is it possible that the connection between the battery and the main bus failed after the battery was charged?



An accurate wiring diagram would be very helpful, but in any case it would be interesting to find out if the battery voltage changes when the engine or shore power is engaged now.

[Boatyarddog]

Originally Posted by Papawads

Timing is everything, my mother-in-law arrives in two days, breathing judgemental fire, for her first visit to (his) boat, and 12V power has gone weird. Happy with any suggestions.

Three weeks ago we boiled one of three 12V gel leisure batteries. Since removing it and running on two, it’s been AOK. Then 2 days ago noted charger running HOT at 51 degrees Celsius on shore power charging!!

Started to notice batteries running low, as instruments / plotter not working when not on shore power, but lights on ok, but they all worked with engine running!!!

Tonight, when I turned off shore power battery charger, we lost all 12V.

So I two days I’ve gone badly wrong. Isolated batteries and they say 13.4 volts!!

Please help, before this latest f-Up is added to my life quota by the dragon :-(

Is there a house battery circuit isolator in the circuit or just your basic off/1/2 both battery switch?
How'd the AGM boil?
Boatyarddog

[hzcruiser]

That sounds like your charger is not working anymore, just getting hot, and you were running off the batts, killing one after the other?

Please measure the voltage at the batt terminals and a few other spots, like bus bars and report back. Quite likely you'll find the problem yourself while doing that.

[Papawads]

Guys, thank you for you many, kind and intelligent replies. #lovethisforum Now I’m going to have to confess…. I’d been working hard and late for a few days, preparing for the fire-breather, and early the previous day, had disconnected and then not properly reconnected the batteries!! Mea Culpa. Please feel free to pelt me in virtual tomatoes or whatever else come to mind. :-) again, thanks for the help anyways

[hzcruiser]

No worries, getting some suggestions from the forum can't hurt and might have helped you look at the right place(s).

[Gary Matthesen]

Big Bird says we all mistakes...
I put a new set of 4 6volt deep cycles in my boat one year. Waiting for spring until I tried to start the engine, not able to turn the engine fast enough to start. Well come on, I have new batteries, and they are fully charged! Do I need a new overpriced starter motor?
Make a long story short, there were 2 negative ground wires. One went through the panel, one directly to the engine block. Not enough Amps getting through for the starter. When I put the batteries in during a dark winter day under the tarp, I didn't see the second wire and sat the batteries on top of it.
This does though reenforce the need for good wires and clean terminals. It makes a big difference.

[hzcruiser]

Originally Posted by Gary Matthesen

Big Bird says we all mistakes...
I put a new set of 4 6volt deep cycles in my boat one year. Waiting for spring until I tried to start the engine, not able to turn the engine fast enough to start. Well come on, I have new batteries, and they are fully charged! Do I need a new overpriced starter motor?
Make a long story short, there were 2 negative ground wires. One went through the panel, one directly to the engine block. Not enough Amps getting through for the starter. When I put the batteries in during a dark winter day under the tarp, I didn't see the second wire and sat the batteries on top of it.
This does though reenforce the need for good wires and clean terminals. It makes a big difference.

Not sure I can follow your long story cut short, sorry...

What about the second wire under a tarp on a dark winter day? One ground to the engine, the other to the panel? Really?

Let alone you're using 6V deep cycle to start your engine?

[Lancerbye]

If you are measuring 13.4 volts after the batteries have been sitting off the charger for 24 hours, you have a bad battery. The resting voltage should be 12.6 volts. A high voltage can indicate a battery with a high internal resistance which measures enough voltage but will not produce any current. Get your battery load tested.

[Boatyarddog]

Originally Posted by Lancerbye

If you are measuring 13.4 volts after the batteries have been sitting off the charger for 24 hours, you have a bad battery. The resting voltage should be 12.6 volts. A high voltage can indicate a battery with a high internal resistance which measures enough voltage but will not produce any current. Get your battery load tested.

I agree, a load test will determine the battery state.
From there, it's distribution.
Boatyarddog

[Gary Matthesen]

To clarify, it was dark in the cabin (under the tarp) when I installed the batteries, so one of two black negative ground wire was not easily visible. And no, my 6 volt batteries are two in series for 12 volts, then in parallel to produce 460 Ah of power. Plenty to turn over the engine,