Crank Battery Drained

[Triton Dave]

Back from fishing this morning. 800 RPM's at idle. The voltmeter started to increase between 1000-1100 RPM's.

Saturday night I did swap my #1 battery on trolling motor for my #3 crank battery. Both the same models and size- Sears Platinum Marine, 31. The voltmeter was registering 12.5-13 when I started the motor. Have not seen it this high with original battery #3. Ran fine and started all morning- will keep you posted.

[Joe Reeves]

Hmmm, That does sound like you have a faulty battery doesn't it?

[Rdenker]

Could be either the voltage regulator or the rectifier. Depending on the failure mode, the regulator could cause a load on the battery. A bad diode in the rectifier would cause an A/C component to ride on the battery line which would also cause the battery voltage to drop.

[Triton Dave]

OK, fished Weds night. Motor started OK with no hesitation at the end of the evening. Stopped & released fish, with big motor idling, and continued on. Then, noticed tach jumping around from 1200, to 3000, back to 2000. I put gear in neutral, punched throttle to 3500 (estimate), then let idle. The tach came back to normal idle (800) and began to idle home. I am going to take this in to Evinrude dealer to have checked out next week.

[Joe Reeves]

(Testing Tachometer With Water Cooled Regulator/Rectifier)
(J. Reeves)

A quick check is to simply plug in a another new tachometer as a piece of test equipment. If the new tach works properly and the old tach didn't, obviously the old tach is faulty.... but usually boaters don't carry around a spare tach (see below).

A faulty rectifier wouldn't damage the tachometer, the tachometer simply wouldn't work. This is due to the fact that the tachometer operates off of the charging system and the rectifier converts AC voltage to DC voltage, enabling the charging system. A faulty rectifier disables the charging system, and the tachometer simply doesn't register.

However.... those water cooled regulator/rectifiers that are used on the 35 ampere charging systems (and some others) bring into play a different type problem, and as you've probably found out, they are really a pain to troubleshoot via the proper procedure. There's an easier way.

The tachometer sending/receiving setup operates off of the gray wire at the tachometer. That same gray wire exists at the engine wiring harness which is connected to the engine electrical terminal strip. You'll see that there is a gray wire leading from the regulator/rectifier to that terminal strip, and that there is another gray wire attached to it. That other gray wire is the wire leading to the tachometer which is the one you're looking for.

NOTE: For the later models that DO NOT incorporate a wiring terminal strip, splicing into the "Yellow Wire" mentioned will be necessary.

Normally the Gray wire leading from the tachometer is attached at the terminal strip to another Gray wire which leads from the water cooled voltage regulator/rectifier...... remove the gray wire that leads to the tachometer. Now, find the two (2) yellow wires leading from the stator to that terminal strip. Hopefully one of them is either yellow/gray or is connected to a yellow/gray wire at the terminal strip. If so, connect the gray wire you removed previously to that yellow/gray terminal. Start the engine and check the tachometers operation, and if the tachometer operates as it should, then the regulator/rectifier is faulty and will require replacing. If the tachometer is still faulty, replace the tachometer.

If neither of the yellow wires from the stator is yellow/gray, and neither is attached to a yellow/gray wire, then attach that gray tachometer wire to either yellow stator wire, then the other yellow wire, checking the tachometer operation on both connections.

I've found this method to be a quick and efficient way of finding out which component is faulty.... the tachometer or the regulator/rectifier. It sounds drawn out but really only takes a very short time to run through. If the water cooled regulator/rectifier proves to be faulty, don't put off replacing it as they have been known to catch on fire with disastrous consequences.

[Triton Dave]

Joe- you are correct- I do not have a new spare tach. I will definitely look and see if I can follow the wiring diagram to find the gray wire and the electrical terminal strip on the motor. Since this is a 2000 year model, hopefully this will be there instead of having to splice into any wires. I'll print these directions and follow step by step. Or, just have the rectifier & tach replaced as opposed to having this go up in flames. Thanks again and will keep you posted on the results.

[Triton Dave]

What am I looking at ($) to have a rectifier replaced and installed by marine dealer? New Tachometer?

[Joe Reeves]

I suspect that your tachometer is okay. However, I have no knowledge of what the repair cost of replacement is anymore (retired 1991).... better to check with the dealership first.

[Triton Dave]

OK. Will be taking in next Thursday. Will report back.

[Triton Dave]

Update from Dealer

Took boat to my local Evinrude dealer and they confirmed that it is a bad battery. Alternator, charger, and 2 other batteries checked out fine. I have this now in writing and on my way back to Sears for them to honor their 2 year warranty. We will see how that goes?!

[sunrisehimlam]

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[Triton Dave]

Never buy sears batteries!

Returning to Sears with my marine dealers receipt in hand, Sears Mgr told me that they would put it on their battery tester to check the suspect bad battery. I returned after 3 hours and they said that the battery tested fine. Not surprised, as the store manager said that if I read the Sears warranty (who does that?!) it says that Sears will not replace if their tester shows battery checks out. How convenient- I will never buy another Sears battery, or other products again!

[Joe Reeves]

Sears battery tester, along with Pep Boys, Discount Auto (Advantage Auto), K-Mart auto center, etc etc is a State Of The Art piece of shit designed to show a battery in any failed state of failure to be just so dandy fine.

This is why when I take a battery back for replacement that I take along a Hydrometer to check the individual cells. One way or another, I will get into any battery in order to check it out with a hydrometer to show those State Of The Art idiots that the battery does indeed have a bad cell.

And I don't leave.... if you leave to come back later, who is to say they did anything in the way of checking. One jerk threatened to call the police... I whipped out my cell phone and called the police right in front of him. When I know I'm right, I raise Hell so half the store can hear me!

[baddog1016]

AGM batteries can't be checked with a hydrometer. Do you only have the one battery to crank the engine with? If it cranked right over on a second battery you an rule out the starter motor/solenoid. Are all the connections clean and tight? If the engine runs it's not the alternator because the Fichts need 40 volts to fire the injectors and 250 volts for the ignition. The battery can't do those step ups for very long. I actually think the engine won't stay running at all without the alternator but I'm not sure about that.

[baddog1016]

Funny thing about those testers, I have seen Sears, AAA and an unnamed new car dealer's and they were all made by the same company, Medtronic's. I had a lot of experience with the dealerships that would test a battery as good that AAA's condemned. The dealer could not warranty a battery unless there tester said that the battery was NG. They had to submit a hexadecimal code to the manufacture for warranty to work. Clearly the programming in the testers was different.