Dead Battery, Slow Tach, No Charge

[TopNotch]

Well after years of having no problems with my engine (1986 Evinrude V6-150), i am back.<br /><br />This week, a late night fishing trip resulted in a dead battery, 3 miles out. Things seemed pretty normal on the way out. When we finished the nights fishing, we go to crank it up—Dead. Call for a tow boat, try the jumper pack, but it didnt have the power. Had to do the battery switch (I know its bad for the V-Reg, but we had to get in).<br /><br />Charged the battery back up, dropped it in... And I get 12.4 V on all three Voltmeters, started the engine—No change, still 12.4V. My tach is slow between 0-2000 rpms, when I rev the engine it stops around 3000 rpms, but I know the engine is well around 4000.<br /><br />I dont have any other info than that, and I am not good with electric. My guess, of course would be the V Reg, Rectifier, Stator, Power Pack... but if you could help me out maybe you could tell me where I could start to fix the problem...<br /><br />Thank you in advance!

 

[chuckz]

Re: Dead Battery, Slow Tach, No Charge

12.4 volts indicates a discharged or bad battery. Each cell in a battery is 2.2 volts. There are six cells in a 12 volt battery. A charged 12 volt battery should measure 6 X 2.2 or 13.2 volts. Before you can do anything you need to charge the battery.<br /><br />After you charge the battery measure the battery voltage, if it sn't 13.2 volts, the battery is bad. You can confirm this with a cheap automotive type battery hydrometer.<br /><br />If the battery measures 13.2 volts, re-install it in the boat. Start the boat, the voltage should rise to about 14.2 to 14.6 volts. This indicates that the charging system is working. If it doesn't and the tachometer reads properly, the alternator stator is OK. It's either the regulator or rectifier.

 

[BoatBuoy]

Re: Dead Battery, Slow Tach, No Charge

Chuck, are marine batteries different than car batteries? I've never seen a car battery with voltage that high when not being charged. They're usually 12V +/- .1

 

[chuckz]

Re: Dead Battery, Slow Tach, No Charge

No, this is true of all lead acid batteries and all the new technologies have been designed to emulate lead acid so that the charging systems are compatible. <br /><br />If your meter always read 12+/- 1 volt when you measure a car battery, it's time to get a new meter

 

[TopNotch]

Re: Dead Battery, Slow Tach, No Charge

Its a Die Hard Gold, (the big one-1000ca), running about 3 seasons.

 

[chuckz]

Re: Dead Battery, Slow Tach, No Charge

I will give you engineering information. I'm not a chemist so I won't try to explain the reactions that take place in a battery. A freshly charged battery when it is mmeasued under no load conditions will measure 13.2 volts. If that battery is allowed to sit the voltage will slowly decrease and stabalize at 12.6 volts. In order to charge this same battery you need to provide enough energy to start the process. The voltage level is 2.7 volts per cell times 6 cells or 14.2 volt. That number should look familiar, it is what you're voltmeter reads when your charging system is operating properly.

 

[TopNotch]

Re: Dead Battery, Slow Tach, No Charge

My battery was charged 20 hours, 2A slow charge. My three voltmeters (Dash Gauge, FF, GPS) said 12.4. With the accessories off it would probally be close to 12.6...... <br /><br />Well Im definitely getting no charge from the engine... It didnt raise the voltage at all when I reved it up.

 

[chuckz]

Re: Dead Battery, Slow Tach, No Charge

20 hours at 2 amps is only 20ahr (amp hours), not enough to charge a battery that is rated at several hundred ahr. You can't get more energy out than you put in.<br /><br />Did your tach work better? If it did, the stator is ok, it's either regulator or rectifier problems. <br /><br />On some alternator set ups you can test the alternator and rectifiers by full fielding the alternator. What you do is connect the positive battery output to the field input of the alternator. This bypasses the regulator and makes the alternator go to full output. Without a wiring diagram I can't tell you if you cant do this on your alternator. It only works on alternator with external regulators.

 

[TopNotch]

Re: Dead Battery, Slow Tach, No Charge

Well the night that it happened, the tach was pegged around 6000 rpm. When I came back to the boat with the charged battery, the tach Zero'ed out, and was working, but incorrectly.

 

[TopNotch]

Re: Dead Battery, Slow Tach, No Charge

^BUMP^ - Just want to see if anyone else has a take on my situation... Thanks!

 

[tomed01]

Re: Dead Battery, Slow Tach, No Charge

Salute All<br />Isnt the battery on boat only used primarily for starting like in a car and then the altenator takes over to power system and trickle charge battery? in old days if we wanted to see if altenater was working we started engine then unhooked positive cable to battery and if engine keeps running then altenater is good if engine dies altenater bad.can you do this on boat?

 

[TopNotch]

Re: Dead Battery, Slow Tach, No Charge

I dont think outboards are made to have an open circuit, and will blow the sensitive circuitry in voltage regulator and rectifier.<br /><br />I, reluctantly, switched batteries so that I could get home. And I am guessing I have blown that circuitry. However, when I unhooked the battery, it continued to run.

 

[Daniel Beckman]

Re: Dead Battery, Slow Tach, No Charge

Well to me it sound like a fault rectifier.<br />Had the same prob. and then it was the rectifier.

 

[TopNotch]

Re: Dead Battery, Slow Tach, No Charge

Well I ran the boat this weekend.... The voltage was typically 12.6v, however at a couple points during the day I had voltage between 13.6 and 14.4, and the tach worked while it had the juice... Mostly it said 12.6 though, and the tach was inaccurate...<br /><br /><br />Now I am thinking loose wire, but perhaps i just jostled the fried circuit from a big wake. Grr.

 

[Daniel Beckman]

Re: Dead Battery, Slow Tach, No Charge

Search for testing the rectifier on this forum just to make sure its not the fault.<br /><br />Try here.<br /><br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=28;t=025528#000001

 

[ET1]

Re: Dead Battery, Slow Tach, No Charge

When my 120HP Johnson was doing the same thing it was the power pak. I changed it and everything worked just fine including the tach, the voltmeter (charging).