Dead battery

[TNMarty]

I have a standard 2021 Z-18 pro with Humminbird fishfinders. Original battery with 9/20 stamped on it. Charges fine with the Gen3. With motor running registers 14 volts at console.
Turn main circuit breaker off at end of day.
Battery dead in AM. Can get a "Beep" but no motor turnover. Sometimes not even a "Beep."
Charged battery and brought to NAPA auto. Did load test and said battery good. Charged to 12+ volts.
Nothing in boat is on when stowed. All electronics are off and main power switch is off.
Jumped battery from trolling battery in AM. Ran motor for 10 minutes and could turn motor over with main battery after that. So taking a charge from the motor's alternator.
All electronics and ignition are connected directly to the battery.
I'm thinking of disconnecting everything from the battery except for the motor and see if dead in the morning?
Any ideas?
Thanks.

 

[olefisherman456]

you might try pulling the positive lead off the battery so that it completely isolated. then if its dead you will know that there is an internal short and the battery is no good .if not dead then it possible that there is a bad diode in the charging system.leaving the battery connected only to the motor will find this . good luck .

 

[TNMarty]

Thanks! Will give it a try.

 

[Pat Dilling]

Had a similar experience with my 2021 Z19. The Interstate Group 31 AGM battery that they put in these boats is just not up to the task. After having mine replaced under warranty, and then having it do the same thing 4 months later, I bit the bullet and bought an Odyssey Group 31. I have not had a problem since.

 

[TNMarty]

Just looked up that battery. You aren't kidding. That's some bullet!

 

[Larry Williams]

It is very likely that your alternator is bad. I've had this happen to me twice and it's a know issue. (one of the few and the only problems i've ever had) The Alternator will discharge the battery with the key and power off. YOu mentioned turning off a battery circute. If you are fully disconnecting the engine battery then that is not the issue. I installed the Perko battery disconnect and keep it off unless I'm on the water. I bought a a new 2017 Z18 and the alternator went bad inside the fisrt year. Then again near the end of my 5 year warranty expiration- a second alternator replacement, with the exact same problem.

 

[TNMarty]

So to be clear. I'm turning off the battery circuit and still have drained battery. So once I disconnect the battery completely from everything and maintain a charge, it's the alternator. If battery drains, it's the battery. But how is the alternator draining a battery if the motor isn't running? It is functioning by charging the battery when running?

 

[Larry Williams]

the alternator has an electronic circuit that will discharge the battery if faulty. Alternator will still produce a charge to the battery when the engine is running but consumes battery power any time enging is not running even with power off. If you are using a engine battery disconnect, like the PERKO isolator, that isolates the battery from your engine then that would not be the issue.

 

[Larry Williams]

If the alternator is faulty, it will likey produce some heat that you can detect when the engine is completely cold.

 

[TNMarty]

Thanks! So since I'm using the disconnect that came with the boat, it's unlikely. Of course, this could be faulty too! I still have to do the battery disconnect test. I'll have to report back.

 

[Larry Williams]

Yeah, not likely that the disconnect is faulty but it's wise to check the simple stuff first. Good luck with that issue. Just keep in mind that Mercury seems to have an issue with alternators. Mechanics here have said that is the only issue they encounter regulary with the late model four stroke engines.

 

[Outcast]

TNmarty, do you have your Hummingbirds connected by Ethernet cables? The etehernet switch remains live and will drain a battery if you don’t have a shut off switch. If you have a Minnkota trolling motor with a GPS puck, that remains live and on as well.

 

[TNMarty]

I've got the 2 Humminbird Helix 7s. The Minnkota Ultrex up front and puck in the rear! So there is no way to disconnect that stuff? Makes no sense. Every Nitro would have to be plugged in or have a dead battery. They are ethernet connected.
I used volt meter and touched the + side of battery and the 4 wires that are connected to it separately. One of the wires read 12v with the boat off and circuit switch off. Can't tell what the fused wire goes to. Since I have two of them, I have to assume each one goes to the Humminbirds? The bow one was disconnected, so for all I know it would have read 12v too!
I disconnected the power wire from the ethernet switch and still got 12v at the positive wire.
So having all equipment off makes no difference. Something still pulls 12 volts and drains the battery. The main Power Switch at the dash is off too.
Has anyone installed a second circuit switch to turn off all electronics? This makes no sense.

 

[Pat Dilling]

As mentioned above I had a similar problem. I also have a similar set up, except that I have 2 Helix 8s and a Helix 10, also have the Ultrex with the puck. I had one Interstate AGM replaced under warranty, just 4 months old. Another 4 months and the replacement did the same thing, would not crank after 4 hours and had to jump it. The dealer service writer insisted it was my "current sucking Humminbirds.", but the specs say together they draw less that 5 amps. Since I got the Odyssey, I have never had the problem again and it has been almost a year. I do not think there is anything wrong with your boat or the connections. Those batteries are just not up to the task.

 

[jerry shack]

I've got the 2 Humminbird Helix 7s. The Minnkota Ultrex up front and puck in the rear! So there is no way to disconnect that stuff? Makes no sense. Every Nitro would have to be plugged in or have a dead battery. They are ethernet connected.
I used volt meter and touched the + side of battery and the 4 wires that are connected to it separately. One of the wires read 12v with the boat off and circuit switch off. Can't tell what the fused wire goes to. Since I have two of them, I have to assume each one goes to the Humminbirds? The bow one was disconnected, so for all I know it would have read 12v too!
I disconnected the power wire from the ethernet switch and still got 12v at the positive wire.
So having all equipment off makes no difference. Something still pulls 12 volts and drains the battery. The main Power Switch at the dash is off too.
Has anyone installed a second circuit switch to turn off all electronics? This makes no sense.

You can hook up a separate switch for the 2 wires that are hot all the time. Just a on/off switch will work many boats still employ this as a accessory switch.

 

[Outcast]

That is what I did. The gps puck and the Ethernet switch will drain your batteries

 

[maybrfd]

Do you own an amp meter? If so, after switching the breaker, check the positive and then the negative leads at the battery. This will tell you if you have a drain or not. If you do, good Ole fashion, find the connection, and chase the source.

 

[TNMarty]

Not sure if I totally understand the testing protocol. I had the black (-) hooked up. Disconnected everything connected to the Red (+). Then I put one lead of the volt meter to the (+) terminal and one lead on the Red wires from the accessories. Only one read 12v. All the others were zero. So doesn't that mean there is a connection that is drawing from the battery? According to Pat and Outcast, this makes sense since they are still drawing power from the battery. I'll plan a second switch. For $13 seems like a good and easy fix. Thanks for all your help and input.

 

[Z-Man 21XL]

More than likely the battery has an intermittent internal short on one of the cells. I've had the same problem a couple times over the years. Battery will test and will jump fine most times but will be dead in the mornings after being on the charger all night. Charging causes heat, heat makes the metal expand and lose continuity and shows no voltage! Take it off the charger and let it cool and I bet it shows a full charge and will fire the motor right up!!

 

[Larry Williams]

TNMarty, did you find a resolution to the battery issue?