Mercury 4 Stroke 115hp Charging Issue?

[Skyharbor12209]

I fired up my 2017 Mercury 115hp 4 stroke EFI engine this weekend. The engine fired right up and I let it run for about 30 minutes at 2500 rpm. The voltmeter never got above maybe 12 volts. I took my digital and analog voltmeter and measured about 12.5 volts taken at the battery terminals. My thought is that I should have seen at least 13 volts if not more charging. Is this 12.56 normal for a 4 year old battery? Someone who works on boats said that the battery is old and should be replaced. But my thinking is that even with an old battery, shouldn't the stator/rectifier still put out 13-15volts? Any other places to check? Would an older battery actually show this 12.56 charging status?

 

[QBhoy]

Do you have the smart craft gauges ? You can see the exact output voltage direct from engine there. If your battery is rubbish it will soon sap up the volts from your dash or a test across the terminals. Or you have something else on with a heavy draw. They don’t put out too much voltage at idle. Especially after first start up. But they are able to up the output of the engine detects a low or weak state. Mine will sit at about 12.8v after starting at idle then slowly climb if left or quicker once under way on load.
I wouldn’t leave your engine at idle doing 2500 rpm too long. It has a limiter around those rpm to protect it from doing damage. Can’t have been good for it.

 

[Skyharbor12209]

Not sure what you mean by "smart craft gauges?" The dash has the gauges that came with the Bayliner VR5. I can try to take a reading from the back of the gauges if I can shimmy under that.

Mercury tells me that my 12.6 volts is still within normal range. I got a new battery and will check it again.

What is the limiter for at 2500 rpm? I have always idled boat engines for years with no apparent damage. What would be damaged? Tnx.

 

[QBhoy]

Not sure what you mean by "smart craft gauges?" The dash has the gauges that came with the Bayliner VR5. I can try to take a reading from the back of the gauges if I can shimmy under that.

Mercury tells me that my 12.6 volts is still within normal range. I got a new battery and will check it again.

What is the limiter for at 2500 rpm? I have always idled boat engines for years with no apparent damage. What would be damaged? Tnx.

It’s the most you can rev a modern merc outboard in nuetral these days. Or not far off it. Limiter is there to protect from damage. Smart craft gauges are gauges that tell you additional date from engine. Like fuel use. Temps and pressures that you wouldn’t get on normal gauges. Has a wee digital screen at bottom of it. Your engine is compatible with them and they are fitted as an option on low end boats and perhaps standard on higher.