Hunter 27 (89-94) Battery Charging

[MarkW11]

Hello,
I'm a new owner of a Hunter 27-2 (1990) and trying to understand when batteries are being charged. Previous owner told me that when shore power is plugged in both batteries are charging regardless of the batt switch position. I find no evidence of this.

I put a voltmeter on each battery with shore power plugged in and always found about 12.6v. If batteries were being charged I would expect at least 13.5v, correct? I also don't see any kind of battery charger or charge controller in the boat. The shore power connects directly to the electrical panel.

With engine running I found 13.6v on only one battery regardless of the batt switch position. The other battery showed 12.6v.

Does any of this sound correct? Could the battery switch be faulty?

Mark

 

[Sailor_Jeff]

Perhaps check the battery voltage after sitting over night, then plug in shore power and see if it comes up. I suppose there could be a low voltage trickle charger on your system. Perhaps not a real battery charger.

The switch sounds suspicious.

If it were my boat I would take everything out of the shelves, carefully draw a schematic diagram of the electrical system while I visually search for a charger and other things.

 

[Benny17441]

Ok most inboard battery charger connections are made to a dedicated 120V circuit with a breaker switch at the electrical panel. For the charger to operate the main 120V breaker must be ON as well as the breaker switch for dedicated circuit. If it is not clear to which breaker switch it may be connected go ahead and flip them all ON. Most good chargers have 2 or 3 sets of output leads going to different battery banks. They go directly to the battery banks by-passing the switch and that is why they would charge both batteries irrespective of the switch position. On the other hand the output of the engine's alternator is usually controlled by the battery switch whether you want to charge #1, #2 or both. It is also the switch that controls which battery(s) is supplying the power to meet the load of the different fixtures and components. I have described how things are usually connected but previous owners may have changed things around. To locate an inboard charger just follow the thin wire leads which should be connected to the batteries. From what you describe the Battery Switch may not have been properly wired but we will not know if it was done intentionally or accidentally unless we see how your batteries are connected. Battery switches can fail but it is rare and when at fault it is usually due to bad or loose connections. Do make sure all connections are clean and tight. You seem to think that one of the batteries is getting no charge at all from shorepower or the alternator but if it shows a voltage of 12.6V that battery is almost fully charged and must be getting charge from somewhere. I would recommend you get a book, "Sailboat Electrics Simplified" by Don Casey as it will explain how things work and should be connected.

 

[MarkW11]

Just wanted to follow up on this post. There is no battery charger on the boat that I have found. The only wires on the batteries are the thick cables which go to the switch and to ground. Regardless of which panel switches are on, the battery voltage always measures about 12.6 so I conclude that there is no charger while on shore power.

The battery switch was faulty and only making a connection to one of the batteries. I have changed this out and the system is working normally, although I still get a 'low' battery after a few days.

My next step is to disconnect a few items which may be causing a draw and are always live to see if the battery still goes low after a few days. I have 3 items like this. A fixed vhf, an am/fm stereo, and the bilge pump.

The vhf and the stereo are switched by the 'spare' switch on the dc panel which is always live. This switch is coloured red (all the others are black). I can turn this on and get power even if the DC MAIN is off.

Would anyone know why the 'spare' is a different colour and always live?