Strange rectifier for Johnson 110 hp -86

[teflonharry]

Hi!<br /><br />When I measure the voltage over the battery it is 12.7 V from start. The voltage increases slow and after about 5 minutes at 4000 rpm it is 14.7 V.<br /><br />Does anyone know what the problem can be?<br />The rectifier passed the "rectifier test".<br /><br />Can it still be the rectifier?

 

[Dhadley]

Re: Strange rectifier for Johnson 110 hp -86

Which rectifier do you have? The small round one with 3 wires (rectifier only) or the water cooled one on top of the block (rectifier / regulator)?

 

[seahorse5]

Re: Strange rectifier for Johnson 110 hp -86

14.7 is not excessive voltage for an outboard. Are you measuring the voltage on the battery terminals using a digital meter, or is this from your voltmeter on the dash?

 

[teflonharry]

Re: Strange rectifier for Johnson 110 hp -86

HI!<br />It is the water cooled rectifier on the top.<br />I'm measuring the voltage on the battery terminals using a digital meter. The battery is fully charged just before I start the engine.<br /><br />Why doesn't the voltage increase to 14,7 V at once.<br /><br />Should it be like this? When I do the same on my car it increases to ~14,7 at once.<br /><br />/Harry

 

[seahorse5]

Re: Strange rectifier for Johnson 110 hp -86

Your car alternator probably charges as high as 60 amps or so. After you start the engine, it only takes a few moments to re-charge the battery to 14 to 15 volts.<br /><br />Your outboard only charges a few amps at low speeds and a max of 6 or 9 amps at high speeds. To recharge your battery takes longer. Your boat battery also "sits" for long periods of time in a damp environment to it does self discharge over time. That combined with the juice needed to start the engine, the low output alternator will have to run for a while to get the state of charge back to around 14.7 volts.