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Yamaha F150 Alternator issue

Old 05-28-2016, 08:56 AM
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Default Yamaha F150 Alternator issue

Was out cruising to the sandbar and looked down at simrad to see voltage at 12.8 while running. Pulled throttle back and shut motor down. Would not start back up. Switched to other battery fired it up and watched gauge. It is bouncing from 14.1 to 12.8 like the alternator is coming and going. Is this possible? One battery now has 10.8v and other has 12.8. I have a yandina combiner and used boat last weekend didn't pay much attention to voltage. Both brand new Duracell 31 AGM batteries.

When alternator is bad, does it work intermittently?

Thanks from the sandbar!
Old 05-28-2016, 09:01 AM
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Fwiw all connections at batteries and switch are tight. Combined light comes on the yandina and then goes off intermittently so I'd assume that's when it's getting a charge from motor.
Old 05-28-2016, 09:10 AM
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I would check voltage before the Yandina to see if it's doing the same thing, If it is, then wire the engine direct to a battery and recheck, if it isn't then you have an issue with the yandina, the batteries or just need to clean connections.
Old 05-28-2016, 09:58 AM
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Originally Posted by midcap View Post
I would check voltage before the Yandina to see if it's doing the same thing, If it is, then wire the engine direct to a battery and recheck, if it isn't then you have an issue with the yandina, the batteries or just need to clean connections.
Where does the MFD get the voltage readout from? I know one battery is dead as hell and have no idea how it got that way. I don't have a volt meter with me.
Old 05-28-2016, 03:35 PM
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I would think going by your description that the voltage regulator is losing control. As the voltage levels are bouncing between normal charge voltage and normal battery voltage, I would first look at the carbon brushes they run on the slip rings of the armature. As they wear down the spring pressure is at its weakest strength and if they have overheated in the past, lost their compression as well making them bounce or lose contact. I would also make sure the out put wire was tight.
As for voltage readings it depends on whether or not you have the engine interfaced and source selection set up.

Last edited by isitstuffed; 05-28-2016 at 03:47 PM.
Old 05-28-2016, 05:00 PM
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Originally Posted by isitstuffed View Post
I would think going by your description that the voltage regulator is losing control. As the voltage levels are bouncing between normal charge voltage and normal battery voltage, I would first look at the carbon brushes they run on the slip rings of the armature. As they wear down the spring pressure is at its weakest strength and if they have overheated in the past, lost their compression as well making them bounce or lose contact. I would also make sure the out put wire was tight.
As for voltage readings it depends on whether or not you have the engine interfaced and source selection set up.
It's really strange. It shows 14.4v for a little bit and then drops back down to 13.3 and fades to 12.8.

It has to have been acting up for a while because I used the boat last weekend without ever changing the switch and when I discovered it the one battery had 10.8 Volts.

The only thing that concerns me that I might have screwed up is at the dock this morning my slave evo2 wasn't coming on so I turned the batt switch to off while the engine was running. I didn't think about it at the time as I was concerned about the MFD. Would this cause an issue?

I have the engine cable running to the network. That's the only voltage reading I assume the MFD can get.
Old 05-28-2016, 05:42 PM
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A Yamaha F150 does not use a belt driven alternator with a field coil. It uses a permanent magnet generator. No brushes. No slip ring.
Old 05-28-2016, 06:56 PM
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Originally Posted by alloyboy View Post
A Yamaha F150 does not use a belt driven alternator with a field coil. It uses a permanent magnet generator. No brushes. No slip ring.
I was wondering that but went with OPs Post Title
Being Sunday I have no service manuals home.
Old 05-28-2016, 07:40 PM
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Originally Posted by alloyboy View Post
A Yamaha F150 does not use a belt driven alternator with a field coil. It uses a permanent magnet generator. No brushes. No slip ring.
Can it work intermittently or would it totally fail? When simrad showing voltage is it showing the battery that is selected on the switch or the avg of the two batteries being combined by the yandina or what?
Old 05-28-2016, 09:53 PM
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Originally Posted by gsujeff55 View Post
The only thing that concerns me that I might have screwed up is at the dock this morning my slave evo2 wasn't coming on so I turned the batt switch to off while the engine was running. I didn't think about it at the time as I was concerned about the MFD. Would this cause an issue?
t.

this is a good way to blow up an alternator.
Old 05-28-2016, 09:55 PM
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Originally Posted by gsujeff55 View Post
Can it work intermittently or would it totally fail? When simrad showing voltage is it showing the battery that is selected on the switch or the avg of the two batteries being combined by the yandina or what?

if the yandina is on, both batteries will be the exact same voltage. so you'd be reading both.

if it's off, you'd reading which every battery is powereing the unit. but the voltage will be unit voltage, not battery voltage. which will be slightly lower due to drop in all the cables and wiring.

edit: if you have the engine gateway then you'd be reading power at the motor, not voltage at plotter, but it's all similar.

you should definitely get the boat plugged in and charging ASAP. leaving that battery at 10.8v will destroy it. if not already
Old 05-29-2016, 03:10 AM
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Originally Posted by gsujeff55 View Post

The only thing that concerns me that I might have screwed up is at the dock this morning my slave evo2 wasn't coming on so I turned the batt switch to off while the engine was running. I didn't think about it at the time as I was concerned about the MFD. Would this cause an issue?
.
If you turned of the battery switch off, the engine would have stopped as if the ignition was turned off. Doubt any damage if an alternator was running because it would be at a low RPM and the field current cut instantly. But there is doubt that you have an alternator.

The scenario for alternator damage by opening the battery switch is more of a concern for Diesel owners as killing the batteries in most cases won't stop the engine causing the voltage regulator to go into negative feedback due to sensing its own output which then oscillates and can generate over a hundred volts blowing the diodes and destroying the regulator.
Old 05-29-2016, 05:22 AM
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Originally Posted by isitstuffed View Post
If you turned of the battery switch off, the engine would have stopped as if the ignition was turned off. Doubt any damage if an alternator was running because it would be at a low RPM and the field current cut instantly. But there is doubt that you have an alternator.

The scenario for alternator damage by opening the battery switch is more of a concern for Diesel owners as killing the batteries in most cases won't stop the engine causing the voltage regulator to go into negative feedback due to sensing its own output which then oscillates and can generate over a hundred volts blowing the diodes and destroying the regulator.
I definitely turned it off and the engine definitely kept running. It was only for 5 seconds or so before I turned it back on.
Old 05-29-2016, 05:30 AM
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Originally Posted by smac999 View Post
if the yandina is on, both batteries will be the exact same voltage. so you'd be reading both.

if it's off, you'd reading which every battery is powereing the unit. but the voltage will be unit voltage, not battery voltage. which will be slightly lower due to drop in all the cables and wiring.

edit: if you have the engine gateway then you'd be reading power at the motor, not voltage at plotter, but it's all similar.

you should definitely get the boat plugged in and charging ASAP. leaving that battery at 10.8v will destroy it. if not already
I checked it this morning, 11.8 in 1 and 12.8 in other. I think I now know what happened, but cannot be sure. When I got to boat yesterday the battery switch was still on(I went to boat on Monday and messed with MFD and must have forgot to turn switch off). I didn't think much of it as everything was off but I turned it to the other battery in case and started it up. Everything was fine. I think in the shuffle of working on the 2nd MFD that wasn't powering on I turned switch off and then over to batt1(the one left on for a week). When I came to this realization I remember my switch for my sub amp had been on all week with the battery and likely killed it. It was dead enough the alternator was struggling to charge it.

Long story short I have them both on the Promariner now and hope I didn't damage anything and the alternator is working fine. The batt I used the rest of the day yesterday still has 12.8 volts in it this morning.

Will report back. Thanks for all the help guys. Hopefully my frantic lapse in judgment didn't screw up anything and hope the battery comes back from me draining it.
Old 05-29-2016, 06:21 AM
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Originally Posted by gsujeff55 View Post
I definitely turned it off and the engine definitely kept running. It was only for 5 seconds or so before I turned it back on.
If that's the case then the battery you turned off was not the one providing power to the engine.
Without power the ECU, Ignition coil, fuel pump etc would all stop.
I suggest you check how the combiner is wired because it may be on the engine side of the battery switch bypassing it to the other battery.
Old 05-29-2016, 07:45 AM
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Originally Posted by isitstuffed View Post
If that's the case then the battery you turned off was not the one providing power to the engine.
Without power the ECU, Ignition coil, fuel pump etc would all stop.
I suggest you check how the combiner is wired because it may be on the engine side of the battery switch bypassing it to the other battery.
The motor is making its own electrical power when it is running. It is possible for the motor to run with the battery disconnected. I suspect however that if the throttle had been advanced with the battery disconnected that the motor would have stopped.

At least that has been my experience with a number of Yamaha four strokes.
Old 05-29-2016, 07:52 AM
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Originally Posted by smac999 View Post
this is a good way to blow up an alternator.
OP's motor does not have an alternator as that term normally relates to a mechanically driven (belt, chain, gear) device that creates electrical power based on an electro-magnet, referred to as a field coil, inducing voltage in a coil.

OP's motor uses a permanent magnet generator to create electricity. Fixed magnets induce voltage in coils as the magnets pass by the coils.

Turning off the battery will have no effect of the electrical generation system of OP's motor. It might, but more than likely won't, affect the regulator/regulator on the motor.
Old 05-29-2016, 07:53 AM
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Originally Posted by isitstuffed View Post
If that's the case then the battery you turned off was not the one providing power to the engine.
Without power the ECU, Ignition coil, fuel pump etc would all stop.
I suggest you check how the combiner is wired because it may be on the engine side of the battery switch bypassing it to the other battery.
The combiner is wired to the battery switch as per instructions. The battery I shut off was the one powering the motor because off is off, correct? I know this because I cannot turn the key and have the motor start with the switch in the off position. It was only idling for 5 seconds with the switch off, perhaps that isn't a long enough time to have the motor shut down.
Old 05-29-2016, 09:48 AM
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Originally Posted by gsujeff55 View Post
Where does the MFD get the voltage readout from? I know one battery is dead as hell and have no idea how it got that way. I don't have a volt meter with me.
You will need one of those to start checking everything.

a yamaha MFD?
Old 05-29-2016, 11:59 AM
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First post mentions a Simrad. Presume this to be the MFD that is providing an indication of battery/generator voltage.

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