1981 Evinrude 90 not charging the battery

[ezmobee]

I have a suspicion that my motor is not charging the battery. I haven't had any issues with a dead or weak battery but I have a brand new overkill-sized marine starting battery that I do throw on the charger at home from time to time. So it's possible it's just never been drained enough to be a problem. My motor starts easily also so it's not like I've done a lot of cranking.

Anyway, the reason I suspect I have this problem is that I just recently installed some gauges (had none before) and attempted to connect the tach to the gray lead in the control box and also installed a voltmeter. Well my tach doesn't work at all and the voltmeter never moves off of 12V. So I'm thinking my charging system is not working. I probably would have just assumed a wiring issue with the tach pulse feed if it were not for the constant 12V reading on the voltmeter.

How do I verify that I do indeed have a problem, and if I do, I believe it would either be the stator or rectifier that's bad. This motor starts and runs PERFECTLY. Would that indicate a probability that my stator is good? or does the stator have nothing to do with anything other than charging?

Thanks everyone.

 

[bruce--69]

Re: 1981 Evinrude 90 not charging the battery

First thing is to put a voltmeter on your battery before you start it. After starting it and running high idle you should have voltage higher than when you started. Your tach is related to your charging system, so that explains why they both do not work.
Your stator is two fold, voltage for your charging system, voltage for your ignition system. Put a voltmeter across the 2 yellow leads coming from your stator, when running you should have AC voltage. That hardly ever goes bad, its probably your rectifier, its round with one red and 2 yellow leads. I changes AC to DC. Ohm between the red and each yellow wire on the rectifier. Then swap the meter leads and ohm them again. One way you should have an ohm reading, one way you should not. I'm betting you have an open rectifier. Change that out and your probably ready to go.
If you have Trim and Tilt, you'll have a regulator too. If everything else checks out OK, replace your regulator.
Bruce

 

[emdsapmgr]

Re: 1981 Evinrude 90 not charging the battery

No good Johnson or Evinrude question is a pest-type question. Since the engine makes it's own ignition power and runs on it, instead of the battery, it's not unusual for owners to not know there is a charging problem. Your stator is divided into two sections, the part for the ignition, the other part for battery charging. Once the engine is started, the only battery draw is when the trim is activated or one of the accesssories, like the radio, bilge pump, lights, etc. That's why the gauges wind up being of benefit to any owner. Bruce 69 has some good thoughts. I'll fill in a little background. Your engine came in two versions, the non-power trim and the power trim models. The non power trim units uses 6 amp charging coils in the stator, with a rectifier only. When the engine has run for a while, the rectifier will permit the volts to the battery to creep up to 16+ volts on the volt gauge. The power trim units have 10 amp coils in the stator, and also has a regulator in the system. When you run this model engine for 15 minutes, it will charge at a rate of around 13.5 volts-max. The latter engine is somewhat easier on batteries (the water level) during a long summer. Your logic that something is not charging is a good deduction. I concur that the rectifiers and/or rectifiers with regulators are usually the culprit-as opposed to the stator. You typically will replace a rectifier 3 times before you would a stator.

 

[ezmobee]

Re: 1981 Evinrude 90 not charging the battery

Thanks guys. Sounds like bruce nailed it. My motor is indeed the power trim version. I'll check the rectified as directed above. Looks like a rectifier is fairly inexpensive while the other possibilities are quite expensive. Here's hoping it's the rectifier.

 

[bruce--69]

Re: 1981 Evinrude 90 not charging the battery

Glad I could help. I ran a marine service shop for 16 yrs until a career change came my way. Its sort of fun to troubleshoot and help people out again. The biggest thing I do miss from the shop is getting a simple thank you from customers for helping them out with some information. I didnt realize that was something I got from that job, but I do miss it.
Good luck, Bruce

 

[ezmobee]

Re: 1981 Evinrude 90 not charging the battery

Well the WELCOME and please stick around! Glad to have you. Do you know Mercury's also? We have a real need for some more Mercury outboard tech tech advice.

 

[bruce--69]

Re: 1981 Evinrude 90 not charging the battery

Yeah, I worked on them all. Chrysler/Force/ Mercury/Mariner/Johnson/Evinrude. I left the shop in 2006, so I've been out of it for 5+ yrs, but I still work on them on the side for people who know me from the shop. Its fun now because its not my job, more like a hobby. When it becomes 'work' its suddenly not as fun. Funny how that works.

Bruce

 

[ezmobee]

Re: 1981 Evinrude 90 not charging the battery

Rectifier fixed it. Ended up being able to get one locally for same or less $$ than ordering it online Tach works perfectly and my voltage is up around 13-14V now while running. WOT RPM with 2 adults and 3 kids in the boat was 5300. I think I'll stick with the same pitch when I order a new prop.