Entire electrical system dead

[Stii]

2015 242. My boat has sat for approximately 4 months. I leave it on a battery tender. First engine started right up, I let it idle for 4 minutes, go to start 2nd engine while first engine still idling and first engine dies immediately and entire electrical system is dead. I didn't have time to mess with anything so I let it charge over night and battery tender is showing above 85% charge now. Still no power at all. No accessories, no blower. nothing, completely dead as if there is no batteries. I can hear the digital relay in battery compartment next to the 3 battery switches turning off and on and can see the red light in the corner. I turn all the battery switches on and absolutely no power. My main question is if there is a main fuse that could be blown? I checked a few fuses on the first engine circle fuse holder on the rear of the engine bay and they were fine but didn't check in the ecu. I wouldn't think a specific engine fuse would be bad though since the entire system is down, not just 1 engine. Is there some main control panel or fuse that I am over looking? Also the safety lanyard is connected, but that cant be it as the boat would turn over but not start with that off. Any guidance would be appreciated.

 

[Canuckjetboater]

2015 242. My boat has sat for approximately 4 months. I leave it on a battery tender. First engine started right up, I let it idle for 4 minutes, go to start 2nd engine while first engine still idling and first engine dies immediately and entire electrical system is dead. I didn't have time to mess with anything so I let it charge over night and battery tender is showing above 85% charge now. Still no power at all. No accessories, no blower. nothing, completely dead as if there is no batteries. I can hear the digital relay in battery compartment next to the 3 battery switches turning off and on and can see the red light in the corner. I turn all the battery switches on and absolutely no power. My main question is if there is a main fuse that could be blown? I checked a few fuses on the first engine circle fuse holder on the rear of the engine bay and they were fine but didn't check in the ecu. I wouldn't think a specific engine fuse would be bad though since the entire system is down, not just 1 engine. Is there some main control panel or fuse that I am over looking? Also the safety lanyard is connected, but that cant be it as the boat would turn over but not start with that off. Any guidance would be appreciated.

@Stii .....have you checked battery grounds and connections to the battery switchers? P.S. If that doesn't solve it look at the connections on the back of your ignition switch.

 

[F.M.]

Sounds like bad ground.

 

[Stii]

So I changed out the 2 20 fuses by the batteries just in case, one of them looked kind of bad, but no luck. However, now the light for the blower works but then fades away. I just happen to see it slightly lit up as the cover was still over the cockpit. I threw a seperate battery charger on them just to check, one battery is at 95% and the other is at 70%. I am very confused by this. For the ground issue, the first engine initially started no problem, was only an issue once I tried starting the 2nd engine.

 

[Babin Farms]

Check all of the battery connections even though it had started before.

 

[zipper]

The battery tender may have "gassed" your batteries. What type of "battery tender" are you using? Check the voltage of the battery(s) at rest. A couple of hours or more after being taken off the charger.

 

[Canuckjetboater]

The battery tender may have "gassed" your batteries. Check the voltage of the battery at rest. A couple of hours or more after being put on the charger.

View attachment 134801

@zipper has IMO offered an excellent possibility. If your battery charger has sulfated your batteries there is a process to shock them back but you have to know what you are doing to perform this. If unsure google it if still unsure have a marina do this - you must be CAREFUL doing this as you are dealing with explosive materials.

 

[jdkaeser]

Did the 2nd engine crank at all or did it do nothing as the the 1st died? If the 2nd engine did nothing, no relay click or starter turning, then your issue may be with the ignition switches. I don't have a dual motor boat but I would guess the power to the 2 ignition switches may be wired together in some fashion. If all your grounds are good, I would check the switches next, then everything from the switches to motor 2. Look under the helm for a fuse or something amiss as well. Sounds like something in motor 2's system fried or blew something that is shared by the entire system.

 

[AZMark]

You said you “turn all the battery switches on”, that’s just two right? You shouldn’t be doing anything with the emergency parallel switch.
If it’s not a ground issue then that 70% battery could have a short or be so dead it’s dragging down everything. Unhook the cables and check the voltage on each.

Edit: if that red light is on then your charger (or the first engine running) is causing the DVSR relay to link the two batteries even if you left the parallel switch off.
If one battery is really bad this could have caused the whole system voltage to have dropped too low from the extra load when you tried to crank the second engine.

 

[Stii]

I definitely think this has something to do with it. Going to take batteries in tomorrow to see what they say.

"If one battery is really bad this could have caused the whole system voltage to have dropped too low from the extra load when you tried to crank the second engine"

 

[AZMark]

I definitely think this has something to do with it. Going to take batteries in tomorrow to see what they say.

"If one battery is really bad this could have caused the whole system voltage to have dropped too low from the extra load when you tried to crank the second engine"

You might be able to start both engines at the same time if you unhook the charger and wait 20-30 seconds for the DVSR to disconnect.

 

[Stii]

Culprit was a bad power cable exasperated by batteries that are going bad. With the batteries fully charged to 100% I started to remove them to get tested and heard a spark. I then checked all the power cables and the red power cable to the house battery switch didn't have a good connection on the battery terminal. Cleaned the terminals and retightened and just barely had enough to get started. Once started, everything checked out and is running great now. Will still need new batteries though. Thanks for the guidance everybody, really kept me from just throwing my hands up and taking it in and also kept me from going down a rabbit hole.

 

[Canuckjetboater]

Culprit was a bad power cable exasperated by batteries that are going bad. With the batteries fully charged to 100% I started to remove them to get tested and heard a spark. I then checked all the power cables and the red power cable to the house battery switch didn't have a good connection on the battery terminal. Cleaned the terminals and retightened and just barely had enough to get started. Once started, everything checked out and is running great now. Will still need new batteries though. Thanks for the guidance everybody, really kept me from just throwing my hands up and taking it in and also kept me from going down a rabbit hole.

@Stii ......if replacing batteries and want awesome quality (yes more expensive) google AGM TPPL and see what you think. Charge up to 500% faster, hold charge much longer, last longer.......

 

[mistercool88]

I was going to say either a bad cable or a Fuse/Breaker. Not sure if Yamaha is the same as my previous I/O but I had a breaker connector pins corrode and was throwing me for a loop until I found it.