Constant drain of 1 of 2 batteries

[crazy charlie]

1988 Regal 280 twin 5.0LX with alpha drives.Replaced battery that I assumed was bad. It was not. The replacement is constantly getting drained to zero. Every switch and light is turned off.Fridge is on shore power. I'm puzzled??? Where to look?? Nothing is on. Charlie

 

[alldodge]

Alternator, Bilge pump, Mercathode
Is it a start Bat only or combined with house Bat?

 

[mike_i]

Do you have a digital voltmeter that reads current?

 

[Chris1956]

Usually, alternators bilge pumps and Mer Cathodes bypass the battery switches.
Alternators have diodes which can short to ground. The test is to check resistance from battery pos cable to ground, with the battery switch off. You should have infinite resistance on the Rx1 scale. If you do not have infinite resistance on that scale, you will need to trace it to the pump, cathode or alternator.

 

[crazy charlie]

I have a multimeter but this sounds like something I should have ck.out by a pro. I ha e zero experience in this area

 

[crazy charlie]

BTW I have a 2 battery system with no. Battery switch

 

[cwella]

1988 Regal 280 twin 5.0LX with alpha drives.Replaced battery that I assumed was bad. It was not. The replacement is constantly getting drained to zero. Every switch and light is turned off.Fridge is on shore power. I'm puzzled??? Where to look?? Nothing is on. Charlie

A new battery going flat with everything off points to a parasitic drain. Check with a multimeter between the negative terminal and cable to see if there is current draw.

Common culprits on boats are the bilge pump float switch, stereo memory, alarms, engine electronics, and a faulty alternator diode feeding power back. Finding the draw is the quickest way to locate the problem.

 

[crazy charlie]

UPDATE, ha e not had ti.e to ck anything but today it seems to have stopped the draining. Gotta ask wife if she has been leaving anything on..??? Charlie

 

[Lou C]

No battery switch? When you leave the boat do you shut everything off? The bilge pumps should be connected directly to the battery, so they work with everything off.
My boat wasn't wired with the bilge pump auto switch direct to battery (I have long since changed that) so I used to have to leave one battery on. What was draining power? An auto on function on a fish finder! Now with it wired properly battery switch is turned to OFF whenever I leave the boat.

 

[crazy charlie]

This 280 Regal never had a battery switch and I never had an issue so leave well enough alone. Our Grady White has a battery switch that is turned off when not in use.. I'm still assuming the drain was from a cabin light switched on but bulb was not tight so it didn't light. Does not sound like the culprit but battery held charge overnight and that was the only thing that my wife claimed to have touched soooo ,still assuming

 

[airshot]

This drain takes place over how long a period of time? A small cabin light should not drain it overnight. If it is getting drained overnight it needs to be a pretty good draw. Had a similar issue last year, but it took a good week or two to drain the battery.

 

[crazy charlie]

This drain takes place over how long a period of time? A small cabin light should not drain it overnight. If it is getting drained overnight it needs to be a pretty good draw. Had a similar issue last year, but it took a good week or two to drain the battery.

Thanks ,overnight has been draining down. Battery was newts spring

 

[Chris1956]

Charlie, My battery cable had a nick in the insulation. The nick sat in the salt water, and leaked battery voltage into the water, since the negative was grounded to the water. The battery cable rotted thru in 24 hours and had to be replaced. The point is that small things can discharge your battery

 

[airshot]

Thanks ,overnight has been draining down. Battery was newts spring

If drawing down overnight you have a healthy draw or the battery may have an internal short. Disconnect the battery and see how long it takes to drop down. You might even hookup a small 12v test light to keep the battery from going to sleep. If it drops quickly while disconnected you have a battery issue. If only when connected you have a bad connection or two in your boat. Unfortunately, I have saw many new batteries go bad in a short time, anyone can get a bad one on ocassion. Good Luck

 

[crazy charlie]

Still searching....still draining down

 

[alldodge]

Does your fridge have 2 breakers (1 for shore, 1 for Bat) or is there just 1 and it switches automatically when taken off shore power?

 

[nola mike]

Ok, so no switch. You have the 2 batteries wired in parallel, with no separate house/boat batteries, but only 1 is draining? That doesn't make sense. Or do you have 2 completely separate systems for house/boat and only 1 is draining? Assuming scenario #2. Disconnect the neg (how many wires?) from the battery. Take your DVM on current/amps setting and connect 1 probe to batt neg and the other to the wire(s), one at a time if multiple. You should see no current. if there is, that's your bad circuit. If it's your main/only connection, pull fuses one at a time. If/when the current drops to zero, then the drain is on the circuit supplied by the fuse. Then will need to narrow it down more from there. Reading over this makes it sound much harder than it is.

 

[airshot]

Still searching....still draining down

Does it drain down when disconnected ?

 

[dingbat]

Sounds crazy, but switch your bilge pump selector from auto to off or pull the 5A in-line fuse(s) that feed the bilge pump(s) at the back of the boat.

Unbeknown to me, the aft bilge pump shorted in the windings back feeding power to the helm through the switch.
Would have never found it had I not gone out after dark and found the light on the bilge switch dimly lite even with the batteries off