Will running with a bad rectifier kill the battery?

[Ms54Coupe]

I have no accessories running off my battery so all it has to do is crank the starter...but I am not sure if there is a draw on the battery while the engine is running or not? I have a new battery and the other day my boat stalled on it's own and then the cranking was much slower after...I already ordered a rectifier (as I put a new stator in last week) but I don't know if running the motor on the party boat would draw down the battery low enough that it would not support the motor's ignition system while running? This is an 86 Merc 45 hp.

 

[Chris1956]

Re: Will running with a bad rectifier kill the battery?

That motor should not rely on the battery to power it's ignition.

 

[Georgesalmon]

Re: Will running with a bad rectifier kill the battery?

Without the rectifier working you may have some large AC voltages getting to your motor's electronics and could take them out. If the rectifier is out and not shorted you might be OK for some running time with a charged up batt.

 

[Ms54Coupe]

Re: Will running with a bad rectifier kill the battery?

Well I'm almost positive that my rectifier is toast but I'm wondering if it is responsible for my motor stalling and would not restart after a 15 minute ride. Noticed after the stall that the battery was weak however 20
Minutes earlier it was not weak.

 

[Ms54Coupe]

Re: Will running with a bad rectifier kill the battery?

On another note if the starter gear remains engaged with the flywheel while engine runs...1) how do I fix this and 2) would this cause damage to the engine / drain the battery somehow?

 

[Chinewalker]

Re: Will running with a bad rectifier kill the battery?

I've had bad rectifiers melt into a shorting condition, which can in turn put a constant load on the battery. The rectifier is not wired to be "shut off" with the key, so it is always attached to the battery. Even if it is a low draw short, it will eventually make the battery go dead... Best to replace it regardless.

 

[Ms54Coupe]

Re: Will running with a bad rectifier kill the battery?

I have to check the fuse but somehow I was able to cook the stator and rectifier and yet the fuse was not blown...what does this fuse even protect aha

 

[Chris1956]

Re: Will running with a bad rectifier kill the battery?

It is doubtful the stator or rectifier are fused. Normally the fuse would be on the +12VDC supply to the ign key for energizing the starter solenoid and accessories. You need to clean and grease your bendix to allow the starter gear to kick out, when the motor fires.

 

[Ms54Coupe]

Re: Will running with a bad rectifier kill the battery?

No I mean I'm wondering why the boat died maybe it blew the ignition fuse otherwise it just doesn't make sense why the sudden stall and not even a fire or pop after that

 

[Yesterday]

Re: Will running with a bad rectifier kill the battery?

On another note if the starter gear remains engaged with the flywheel while engine runs...1) how do I fix this and 2) would this cause damage to the engine / drain the battery somehow?

Your bendix is likely corroded and needs cleaned & lubed. Possibly a spring replacement. Your starter motor turns into a DC generator in this case, but as long as the solenoid isn't engaged the produced current doesn't go anywhere. I'm sure that will wreak havoc on the starter motor's bushings/bearings though.

 

[Ms54Coupe]

Re: Will running with a bad rectifier kill the battery?

Cleaned and lubed the bendix tonight when I got home.

 

[Yesterday]

Re: Will running with a bad rectifier kill the battery?

After thinking about this some....
When a rectifier blows, chances are very high that it "open circuits" as opposed to shorting. It's not impossible for it to short and possibly damage the stator or to throughput AC voltage, but it's not very likely. Putting an analogue multimeter across the supposed DC output of the rectifier (disconnecting anything else from the output) and rolling the engine over will show you a visual sign of what it's doing. If the meter seems to be vibrating (around the zero)or bouncing rapidly indicates an AC throughput, but it it shows nothing, the rectifier has opened. More than likely the rectifier simply stopped working.

When you say party boat, I'm thinking stereo? The stator is only to output 7 amps or so on that motor, while a stereo (depending on it's amplifier) can draw upwards of 20 Amps. If the battery is aged any, a few hours periodically starting the engine, and supplying a stereo while not being charged, will discharge it. An open rectifier will likely halt all charge to the battery.

 

[carholme]

Re: Will running with a bad rectifier kill the battery?

Just test the rectifier and replace it.

http://imageshack.us/a/img203/78/9kp1.jpg

Gerry

 

[Ms54Coupe]

Re: Will running with a bad rectifier kill the battery?

When you say party boat, I'm thinking stereo? The stator is only to output 7 amps or so on that motor, while a stereo (depending on it's amplifier) can draw upwards of 20 Amps. If the battery is aged any, a few hours periodically starting the engine, and supplying a stereo while not being charged, will discharge it. An open rectifier will likely halt all charge to the battery.

Thank you for the response!

Here is the deal though...I have no accessories drawing from the battery...it is a party boat but no radio yet as the motor needed attention first :facepalm:

The motor was running great after lots of work and as I rounded a bend across the lake from my house (after running great for 15 mins) the motor stalled on me out of the blue...brand new battery etc.

I went to crank it over and it sounded like a weak crank and would not fire

I don't see any damage to the 2 day old stator but am almost positive that the rectifier was bad during this 15 minute cruise...so I'm trying to figure out why it stalled and would not start again and seeing if I can link that stall to the rectifier somehow...I have a new rectifier coming on Thurs.

In the meantime I got new battery terminals and I greased the Bendix to prepare...hoping I did not damage the new stator or the power pack on my 15 minute ride!

 

[Yesterday]

Re: Will running with a bad rectifier kill the battery?

I'd tend to agree with chris1956 though couldn't confirm it %100 without looking at the wiring diagram for that specific motor. It's doubtful the dead rectifier would have fried the switch box, stator or battery. No way the bendix issue did either. Have you since charged the battery some and tried it w/o the rectifier connected?

 

[Ms54Coupe]

Re: Will running with a bad rectifier kill the battery?

I just charged the battery up last night and put new terminals on the boat pos and neg leads they were wing nutted in before which I have read is potential trouble. I took the suspect rectifier out last night so when I hook the fresh battery up I should be able to test the engine and ignition and see what I'm dealing with...will update soon

 

[quicktach]

Re: Will running with a bad rectifier kill the battery?

Switch box issues ? Check stator and trigger coils. Check all wiring and particularly check grounds and look for frayed or worn wiring under the power head. Any loose connectors or wires loose at connectors? Download the CDI manual and use it.