Engine Details : Mercury 40HP 4Cyl. Classic 2-Stroke 1991
Model : 40 PTTO Serial : 09682741
Boat out of the water for a couple of years old fishfinder replaced and New VHF and Plotter fitted
Now VHF and Fishfinder reporting Excessive Input Voltage - When I found out about the issue the multimeter readings at the battery were :
Engine Off : 13.5V
Egine On Idle : 16.5V
Engine On 3000+ RPM : 18.8V
When I removed the rectifier the +VE ring terminal was pretty melted into the plastic body and I also noticed the silicone filler was cracked all around the edge almost in a circle. I tested the Rectifier PN. 816770, no continuity shown between terminals A,C and Ground tried both +ve and -ve lead to ground same results - Manual states to replace rectifier - which I did with this one of ebay : 135632 NEW MERCURY MARINE OUTBOARD RECTIFIER 62351A1 62351A2 816770 816770T | eBay
Last Night - before fitting the new one. I ran the same tests on it - Confusing Results, in that it also tested the same - no continuity shown between terminals A,C and Ground again tried both +ve and -ve lead to ground same results. I swapped out the rectifier anyway and ran the engine - same readings as before:
Engine Off : 13.5V
Egine On Idle : 16.5V
Engine On 3000+ RPM : 18.8V
I'm scratching my head at this point, then I followed one of the basic tests to test the stator - Mine is the Red 9A Type. Apparently readings on the Ohmeter between the 2 yellow wires should be in the range of 0.4 > 1.0 ohms. When Tested, due to capacitance "I Think..." its showed results decreasing from 1.1 ohm down to 0.3 ohms but in most cases stabilised around the 0.4 ohm point. I know there are other tests for Amps etc which can be carried out but Wasn't really sure how to do these.
While I was out on the mooring I happened to have with me a new Leisure battery I bought as a backup - I am eventually planning the dual batter setup with a Perko Selector switch. I remembered a couple of months ago while the boat was in the driveway that the battery box had filled up with water and covered the terminals (engine still connected) - Maybe that did something to the battery ?? Anyway I thought I'd try the leisure battery and after fitting it it gave the following readings :
Engine Off : 12.5V
Egine On Idle : 14.5V
Engine On 3000+ RPM : 15.2V
I went for a short run and even at W.O.T no instruments reported high voltage - Solved ! .... I thought
Today I was going to head out on another run and before I even got out of the moorings at 1300 RPM I got the dreaded "Excessive Input Voltage" Alarm on th VHF. Moored up again and put the voltmeter on the Battery - Readings as follows :
Engine Off : 12.5V
Egine On Idle : 14.5V > 15V
Engine On 3000+ RPM : 16.8V
I'm Really stumped now and not sure how to go forward - Looking forward to any suggestions
Diagram Attached of boats current wiring
Model : 40 PTTO Serial : 09682741
Boat out of the water for a couple of years old fishfinder replaced and New VHF and Plotter fitted
Now VHF and Fishfinder reporting Excessive Input Voltage - When I found out about the issue the multimeter readings at the battery were :
Engine Off : 13.5V
Egine On Idle : 16.5V
Engine On 3000+ RPM : 18.8V
When I removed the rectifier the +VE ring terminal was pretty melted into the plastic body and I also noticed the silicone filler was cracked all around the edge almost in a circle. I tested the Rectifier PN. 816770, no continuity shown between terminals A,C and Ground tried both +ve and -ve lead to ground same results - Manual states to replace rectifier - which I did with this one of ebay : 135632 NEW MERCURY MARINE OUTBOARD RECTIFIER 62351A1 62351A2 816770 816770T | eBay
Last Night - before fitting the new one. I ran the same tests on it - Confusing Results, in that it also tested the same - no continuity shown between terminals A,C and Ground again tried both +ve and -ve lead to ground same results. I swapped out the rectifier anyway and ran the engine - same readings as before:
Engine Off : 13.5V
Egine On Idle : 16.5V
Engine On 3000+ RPM : 18.8V
I'm scratching my head at this point, then I followed one of the basic tests to test the stator - Mine is the Red 9A Type. Apparently readings on the Ohmeter between the 2 yellow wires should be in the range of 0.4 > 1.0 ohms. When Tested, due to capacitance "I Think..." its showed results decreasing from 1.1 ohm down to 0.3 ohms but in most cases stabilised around the 0.4 ohm point. I know there are other tests for Amps etc which can be carried out but Wasn't really sure how to do these.
While I was out on the mooring I happened to have with me a new Leisure battery I bought as a backup - I am eventually planning the dual batter setup with a Perko Selector switch. I remembered a couple of months ago while the boat was in the driveway that the battery box had filled up with water and covered the terminals (engine still connected) - Maybe that did something to the battery ?? Anyway I thought I'd try the leisure battery and after fitting it it gave the following readings :
Engine Off : 12.5V
Egine On Idle : 14.5V
Engine On 3000+ RPM : 15.2V
I went for a short run and even at W.O.T no instruments reported high voltage - Solved ! .... I thought
Today I was going to head out on another run and before I even got out of the moorings at 1300 RPM I got the dreaded "Excessive Input Voltage" Alarm on th VHF. Moored up again and put the voltmeter on the Battery - Readings as follows :
Engine Off : 12.5V
Egine On Idle : 14.5V > 15V
Engine On 3000+ RPM : 16.8V
I'm Really stumped now and not sure how to go forward - Looking forward to any suggestions
Diagram Attached of boats current wiring