Battery sorta charging

[surrender]

'96 88 special. Replaced rectifier in January and all was well, good tach and battery charged up to 16 volts(unregulated system). Last couple of times out battery never goes above 13.2 while running and tach is acting funny. It will read 6000 or so when I know I'am only doing 4800 or so. the other day when cruising along about 5000 it suddenly pegged past 7000 and stayed that way until I throttled down. Seems ok at idle. Anyway battery is charging but not like it used to. Could I have fried battery with the overcharge? Could stator be going bad? Or can rectifier sorta work but be going bad?

 

[ezeke]

Re: Battery sorta charging

It's fairly common for one or more of the diodes in a rectifier to be damaged without ruining all of them.

You can test the unregulated rectifier using an ohmmeter; disconnect the battery and the rectifier wires before testing: http://forums.iboats.com/showthread.php?t=190638

Rectifier diodes are destroyed by anything that causes voltage to flow in the wrong direction, including a bad ignition switch, loose or failing battery cables, disconnecting the battery while running, reversing battery cables, etc.

More here: http://cdielectronics.com/downloads...ues, Regulator-Rectifiers and Tachometers.pdf

 

[surrender]

Re: Battery sorta charging

Thanks, going to test today. So if one of the test fails rectifier is bad BUT it isnt completely bad so battery will kinda charge(still needs to be replaced of course) as mine does?

 

[surrender]

Re: Battery sorta charging

Ok so tested rectifier and all was good except the reading to the red wire was HIGHER not lower as the test says it should be. Any thoughts? All test were correct as far as reading in one direction and not the other just the red wire read higher than the others. Bad rectifier?

 

[ezeke]

Re: Battery sorta charging

When testing the red wire to the case, you should get a high reading in one direction and no reading in the other direction.

When testing red wire to each of the other wires, you should also get a high reading in one direction only.

 

[surrender]

Re: Battery sorta charging

Got high reading in one direction only both times. Didnt test procedure say red wire would test lower then other two wires?

"Note that the reading obtained from the red rectifier wire will be lower then what is obtained from the other wires. "

 

[Vic.S]

Re: Battery sorta charging

I would leave out those parts of the rectifier test that involve measuring between the case and the red wire. I cannot see that they serve any useful purpose if you measure both ways between the red and each of the yellows and likewise between the case and each of the yellows.

Provided on each pair you get a reading one way and no reading (infinite resistance) the other way the rectifier is good. All the readings should be similar and any one vastly different to the others would indicate a problem.

If at any stage you get no reading in either direction it means the diode there is burnt out. If you get a low reading both ways then the diode is shorted.

I would not like to predict what actual readings you get between the red (positive) and the case ( negative) but provided its a reading one way and no reading the other all should be well but as I say ignore that part of the test.

I just tried a test on a good rectifier ... I did not get the readings I was expecting between the negative and positive connections!

 

[F_R]

Re: Battery sorta charging

The problem is more likely to be a poor connection somewhere, anyway.

 

[surrender]

Re: Battery sorta charging

Cleaned up connections. QWuestion: Could battery be fried to the point of not able to charge higher? I guess I may not have caught the higher charge(up to 16 volts, may have gone higher) when everything was working right. I had battery on trickle charger overnight and it charged to 13.2 and charger light indicated it was not fully charged. After 20 hours on trickle you would think it would have charged more then from 12.3 to 13.2? I think battery has lost a cell.

 

[ezeke]

Re: Battery sorta charging

Depends on the battery. It takes almost 48 hours for me to recharge my big deep cycle batteries on a trickle charger.

If you have bad cables, battery connections or a weak battery, the system charge is never going to work well. The way to check a battery is to take it to a dealer and have it load tested.

Use voltage drop tests on your battery wiring circuit.