Need help figuring out what in my outboard is causing my batteries to die

[Budwiiser]

Hi everyone,

I've done quite a bit of troubleshooting and narrowing down, so I'm hoping someone can help me get over this next hurdle. Everything I tested points to something in my outboard motor that is constantly drawing off my battery, so it keeps causing dead cells in my batteries. I've isolated it to the outboard (or should I say that I haven't counted out the tilt/trim or the throttle box yet. When I check the pos and neg wires coming from the outboard that's where I'm finding it). I'm not familiar with the electrical components of outboard engines, so I was hoping I could get some help here!

I have a 1991 115hp evinrude engine. What would be the first things that I should check on the engine that might cause this. or perhaps any components that are usual suspects? Thanks!

 

[MH Hawker]

rectifier

 

[Budwiiser]

Thanks MH Hawker, anything in particular I should do to test it?

 

[Budwiiser]

oh, one more question.... the rectifier and power pack are different, correct?

 

[NicoPags]

welcome to iBoats. and yep they are different. Pull out meter and test rectifier leads. do you have a tach installed and does it currently function properly?

 

[Budwiiser]

welcome to iBoats. and yep they are different. Pull out meter and test rectifier leads. do you have a tach installed and does it currently function properly?

Thanks NicoPags! I didn't get around to testing the leads today, but I do have a tach and it appears to be functioning properly. I did do another test thought. I tested the voltage of the battery with nothing hooked up to it. Then tested with only the outboard hooked up, then tested with the outboard hooked up and idling, then tested with the outboard hooked up and revved. The needle on the volt meter never budged in all three scenarios... hmmm?

 

[NicoPags]

if you didn't get a voltage spike whilst the outboard is running above idle than your charging circuit is faulty. If I'm correct, the working tach can eliminate a rotten stator as it reads an unrectified +12v aka AC. However, your rectifier plays an integral role in converting the energy/current produced by your outboard charging circuit. Think of it as a filter, which takes Alternating current and converts It into Direct Current AC/DC. When the rectifier goes, your outboard is not converting this current and your charging ceases. It could be that general use alone is discharging your battery, and that a bad rectifier is not doing its job in providing DC to recharge the battery.

question, your batteries go dead after a day on the water or a couple days of use? or say, overnight you wake up with a discharged battery?

 

[NicoPags]

also a quick road map for an electrical circuit.
A stator creates an electrical current when running. This current is alternating. By sending this alternating current through a rectifier, the rectifier filters the alternating current into a Direct Current which is sent to the power pack for storage. The power packs role is to receive, store, and release the direct current into the ignition coil. The ignition coil then magnifies this current to thousands of volts and delivers it to a certain cylinder via the sparkplugs which ignites the fuel and runs your motor. All this happens simultaneously by a trigger receiving a signal from magnets inside of the flywheel. This is a basic roadmap which should be true on most ob's. But it should help you in mapping your system.


A rectifier can be instantly destroyed by something as simple as hooking a battery up backwards.

btw your rectifier is p/n 582399 which is very very affordable on iBoats

 

[Budwiiser]

if you didn't get a voltage spike whilst the outboard is running above idle than your charging circuit is faulty. If I'm correct, the working tach can eliminate a rotten stator as it reads an unrectified +12v aka AC. However, your rectifier plays an integral role in converting the energy/current produced by your outboard charging circuit. Think of it as a filter, which takes Alternating current and converts It into Direct Current AC/DC. When the rectifier goes, your outboard is not converting this current and your charging ceases. It could be that general use alone is discharging your battery, and that a bad rectifier is not doing its job in providing DC to recharge the battery.

question, your batteries go dead after a day on the water or a couple days of use? or say, overnight you wake up with a discharged battery?

Thanks, this is quite helpful! Unfortunately, I don't have a straight forward answer to your question. I took the boat out only 1 day. However, I did not check the state of the battery after that day, before sitting it up for a few weeks. I burned roughtly 18 gallons in that one day. In my boat, that's about 4 to 5 hours of run time. Most of the time was at really slow speeds as we were checking crab nets and traps. Probably about 1.5 hours of that time was running around 4500 rpm, the rest crabbing. So, I don't know where most, any, or all of the drain came from. Based on the tests I've run, I have to guess a little of both? it certainly appears that there's no charge going to the battery, and it also appears that I'm drawing current when the boat isn't running. might even be 2 different issues? Even if it's two issues, I've already purchased an onboard charger that will be hooked up all the time when not running. that combined with a master power on/off switch should take care of any drain while the boat is sitting in my back yard, and I'm hoping a new rectifier will give it some juice while running. it would be nice if all I had to do is replace the rectifier and all the problems went away. I can deal with a battery needing charging, but the bad cells is what's bothering me.

 

[MH Hawker]

this may help you can down load it,and it sounds like it is the rectifier, due to no charging voltage and draining a battery

 

[sam am I]

Does sound to be charge system issue........Not sure but, this might help, I looked up you motor and i'm still not sure if your charge system has separated rec, reg or the "all in one" rec/reg package.

But regardless and to perhaps quickly determine if the any of charge system components (rec, reg or rec/reg) are drawing current with the motor off, Is to just disconnect the charge wire and measure for leakage.......Trace down/locate the charge feed wire that comes from the charge system and disconnected it from where it connects to the battery. This is typically on the battery side terminal at the starter's solenoid. Once disconnected.......


1) Using a test lamp with the alligator clip lead to the batt+, probe the disconnected charge wire that leads back into the charge system (rec/reg), the lamp should NOT light.

or

2) Using a multi-meter in current meter mode, place the red/positive lead of the meter on the batt+ and the blk/negative lead of the meter to the disconnected charge wire the leads back into the charge system (rec/reg), the meter should read zero or a very very small amount of current, like .1ma for example.

Also it's a good idea to disconnect the stator's winding's from the charge system to isolate it........You can preform the above test with and without being disconnected. If being connected is causing/effecting a leakage test failure, ya might want to test the stator in that the winding's aren't shorting to ground causing issues as well as there may be more than one failure going on.

If these tests show failed, then ya definitely have to start pulling charge system parts and testing.

If you boat has a separate rec from the reg, like MH has shown, use his attached inof to go through the rec test procedure.........If the rec. test good, it's the reg that leaking and you can just replace that knowing its the only other thing that could be leaking in the charge system.

If your boat has the "all in one" rec/reg, it's a bit of a different test you'll need but, beings it's an "all in one" unit, and it failed the leak test above, you can just replace the unit knowing it's shot.

Hope something here helped.........GL